staging: comedi: drivers: use comedi_fc.h cmdtest helpers

Use the cfc_check_trigger_src() helper for Step 1 in all the
driver cmdtest functions.

Use the cfc_check_trigger_is_unique() helper for Step 2 in all
the driver cmdtest functions. Note that single source triggers
do not need to be checked, they are already unique if they pass
Step 1.

For aesthetic reasons, change the comments in the cmdtest
functions for steps 1 and 2 so that they are all the same.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

46 files changed, 766 insertions, 1997 deletions

diff --git a/drivers/staging/comedi/drivers/8255.c b/drivers/staging/comedi/drivers/8255.c
index e2506dd25305..a256622e2dd7 100644
--- a/drivers/staging/comedi/drivers/8255.c
+++ b/drivers/staging/comedi/drivers/8255.c
@@ -82,6 +82,8 @@ I/O port base address can be found in the output of 'lspci -v'.
 
 #include <linux/ioport.h>
 #include <linux/slab.h>
+
+#include "comedi_fc.h"
 #include "8255.h"
 
 #define _8255_SIZE	4
@@ -229,39 +231,20 @@ static int subdev_8255_cmdtest(struct comedi_device *dev,
 			       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
-
-	/* step 1 */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2 */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
index d61fce081c14..f406dfb2a677 100644
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
@@ -479,57 +479,26 @@ int i_APCI3120_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 	struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;		/*  divisor1,divisor2; */
 
-	/*  step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-		cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-
-	if (cmd->convert_src != TRIG_TIMER)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
-
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
index f6f50923fa14..38ab49917d7e 100644
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
@@ -2560,7 +2560,6 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 {
 
 	int err = 0;
-	int tmp;		/*  divisor1,divisor2; */
 	unsigned int ui_ConvertTime = 0;
 	unsigned int ui_ConvertTimeBase = 0;
 	unsigned int ui_DelayTime = 0;
@@ -2571,41 +2570,32 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 	int i_Cpt = 0;
 	double d_ConversionTimeForAllChannels = 0.0;
 	double d_SCANTimeNewUnit = 0.0;
-	/*  step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
-	/* if(i_InterruptFlag==0) */
-	if (s_BoardInfos[dev->minor].i_InterruptFlag == 0) {
-		err++;
-		/*           printk("\nThe interrupt should be enabled\n"); */
-	}
+
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
+
+	if (s_BoardInfos[dev->minor].i_InterruptFlag == 0)
+		err |= -EINVAL;
+
 	if (err) {
 		i_APCI3200_Reset(dev);
 		return 1;
 	}
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT) {
-		err++;
-	}
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(&cmd->start_src);
+	err |= cfc_check_trigger_is_unique(&cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(&cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
+
 	if (cmd->start_src == TRIG_EXT) {
 		i_TriggerEdge = cmd->start_arg & 0xFFFF;
 		i_Triggermode = cmd->start_arg >> 16;
@@ -2619,21 +2609,6 @@ int i_APCI3200_CommandTestAnalogInput(struct comedi_device *dev, struct comedi_s
 		}
 	}
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-		cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-
-	if (cmd->convert_src != TRIG_TIMER)
-		err++;
-
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
-
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
-
 	if (err) {
 		i_APCI3200_Reset(dev);
 		return 2;
diff --git a/drivers/staging/comedi/drivers/adl_pci9111.c b/drivers/staging/comedi/drivers/adl_pci9111.c
index 91efaa4caadb..a87192ac2846 100644
--- a/drivers/staging/comedi/drivers/adl_pci9111.c
+++ b/drivers/staging/comedi/drivers/adl_pci9111.c
@@ -332,7 +332,7 @@ static int pci9111_ai_do_cmd_test(struct comedi_device *dev,
 	int range, reference;
 	int i;
 
-	/* Step 1 : check if trigger are trivialy valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	error |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
 	error |= cfc_check_trigger_src(&cmd->scan_begin_src,
diff --git a/drivers/staging/comedi/drivers/adl_pci9118.c b/drivers/staging/comedi/drivers/adl_pci9118.c
index f7b254d004dc..06ff65c85c9f 100644
--- a/drivers/staging/comedi/drivers/adl_pci9118.c
+++ b/drivers/staging/comedi/drivers/adl_pci9118.c
@@ -1102,7 +1102,7 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	unsigned int divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	err |= cfc_check_trigger_src(&cmd->start_src,
 					TRIG_NOW | TRIG_EXT | TRIG_INT);
@@ -1124,70 +1124,31 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 	if (err)
 		return 1;
 
-	/*
-	 * step 2:
-	 * make sure trigger sources are
-	 * unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
-
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_INT &&
-	    cmd->scan_begin_src != TRIG_FOLLOW) {
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		err++;
-	}
-
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
-
-	if (cmd->scan_end_src != TRIG_COUNT) {
-		cmd->scan_end_src = TRIG_COUNT;
-		err++;
-	}
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE &&
-	    cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_INT && cmd->stop_src != TRIG_EXT) {
-		cmd->stop_src = TRIG_COUNT;
-		err++;
-	}
+	/* Step 2b : and mutually compatible */
 
-	if (cmd->start_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
+	if (cmd->start_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT)
+		err |= -EINVAL;
 
-	if (cmd->start_src == TRIG_INT && cmd->scan_begin_src == TRIG_INT) {
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
+	if (cmd->start_src == TRIG_INT && cmd->scan_begin_src == TRIG_INT)
+		err |= -EINVAL;
 
 	if ((cmd->scan_begin_src & (TRIG_TIMER | TRIG_EXT)) &&
-	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_NOW)))) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_NOW))))
+		err |= -EINVAL;
 
 	if ((cmd->scan_begin_src == TRIG_FOLLOW) &&
-	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_EXT)))) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	    (!(cmd->convert_src & (TRIG_TIMER | TRIG_EXT))))
+		err |= -EINVAL;
 
-	if (cmd->stop_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT) {
-		cmd->stop_src = TRIG_COUNT;
-		err++;
-	}
+	if (cmd->stop_src == TRIG_EXT && cmd->scan_begin_src == TRIG_EXT)
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/adv_pci1710.c b/drivers/staging/comedi/drivers/adv_pci1710.c
index 0fd0210625f6..def37bcc2a66 100644
--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -1046,7 +1046,7 @@ static int pci171x_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	unsigned int divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
 	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
 	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
diff --git a/drivers/staging/comedi/drivers/amplc_dio200.c b/drivers/staging/comedi/drivers/amplc_dio200.c
index b7cfc13a951f..08f305210a69 100644
--- a/drivers/staging/comedi/drivers/amplc_dio200.c
+++ b/drivers/staging/comedi/drivers/amplc_dio200.c
@@ -210,6 +210,7 @@ order they appear in the channel list.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 #include "8253.h"
 
@@ -771,52 +772,24 @@ dio200_subdev_intr_cmdtest(struct comedi_device *dev,
 			   struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= (TRIG_NOW | TRIG_INT);
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= (TRIG_COUNT | TRIG_NONE);
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-		   compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pc236.c b/drivers/staging/comedi/drivers/amplc_pc236.c
index a957cd846088..eacb5e4735d7 100644
--- a/drivers/staging/comedi/drivers/amplc_pc236.c
+++ b/drivers/staging/comedi/drivers/amplc_pc236.c
@@ -56,6 +56,7 @@ unused.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 #include "plx9052.h"
 
@@ -313,39 +314,20 @@ static int pc236_intr_cmdtest(struct comedi_device *dev,
 			      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1 */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: ignored */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pci224.c b/drivers/staging/comedi/drivers/amplc_pci224.c
index 365f911b9b0e..1f65ec4d261e 100644
--- a/drivers/staging/comedi/drivers/amplc_pci224.c
+++ b/drivers/staging/comedi/drivers/amplc_pci224.c
@@ -720,53 +720,31 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	unsigned int tmp;
 
-	/* Step 1: make sure trigger sources are trivially valid. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT | TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_EXT | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually
-	 * compatible. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	/* There's only one external trigger signal (which makes these
-	 * tests easier).  Only one thing can use it. */
+	/* Step 2b : and mutually compatible */
+
+	/*
+	 * There's only one external trigger signal (which makes these
+	 * tests easier).  Only one thing can use it.
+	 */
 	tmp = 0;
 	if (cmd->start_src & TRIG_EXT)
 		tmp++;
@@ -775,7 +753,7 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	if (cmd->stop_src & TRIG_EXT)
 		tmp++;
 	if (tmp > 1)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/amplc_pci230.c b/drivers/staging/comedi/drivers/amplc_pci230.c
index 4c9f1314ea1d..bd8fb876ce2e 100644
--- a/drivers/staging/comedi/drivers/amplc_pci230.c
+++ b/drivers/staging/comedi/drivers/amplc_pci230.c
@@ -193,6 +193,7 @@ for (or detection of) various hardware problems added by Ian Abbott.
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 #include "8255.h"
 
@@ -958,23 +959,11 @@ static int pci230_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	unsigned int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* Step 1: make sure trigger sources are trivially valid.
-	 * "invalid source" returned by comedilib to user mode process
-	 * if this fails. */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
 
-	tmp = cmd->scan_begin_src;
+	tmp = TRIG_TIMER | TRIG_INT;
 	if ((thisboard->min_hwver > 0) && (devpriv->hwver >= 2)) {
 		/*
 		 * For PCI230+ hardware version 2 onwards, allow external
@@ -990,46 +979,23 @@ static int pci230_ao_cmdtest(struct comedi_device *dev,
 		 * scan_begin_src==TRIG_EXT support to be a bonus rather than a
 		 * guarantee!
 		 */
-		cmd->scan_begin_src &= TRIG_TIMER | TRIG_INT | TRIG_EXT;
-	} else {
-		cmd->scan_begin_src &= TRIG_TIMER | TRIG_INT;
+		tmp |= TRIG_EXT;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually compatible
-	 * "source conflict" returned by comedilib to user mode process
-	 * if this fails. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1610,75 +1576,45 @@ static int pci230_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	unsigned int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4,5 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* Step 1: make sure trigger sources are trivially valid.
-	 * "invalid source" returned by comedilib to user mode process
-	 * if this fails. */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	tmp = cmd->scan_begin_src;
-	/* Unfortunately, we cannot trigger a scan off an external source
-	 * on the PCI260 board, since it uses the PPIC0 (DIO) input, which
-	 * isn't present on the PCI260.  For PCI260+ we can use the
-	 * EXTTRIG/EXTCONVCLK input on pin 17 instead. */
+	tmp = TRIG_FOLLOW | TRIG_TIMER | TRIG_INT;
 	if ((thisboard->have_dio) || (thisboard->min_hwver > 0)) {
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_INT
-		    | TRIG_EXT;
-	} else {
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_INT;
+		/*
+		 * Unfortunately, we cannot trigger a scan off an external
+		 * source on the PCI260 board, since it uses the PPIC0 (DIO)
+		 * input, which isn't present on the PCI260.  For PCI260+
+		 * we can use the EXTTRIG/EXTCONVCLK input on pin 17 instead.
+		 */
+		tmp |= TRIG_EXT;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_INT | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* Step 2: make sure trigger sources are unique and mutually compatible
-	 * "source conflict" returned by comedilib to user mode process
-	 * if this fails. */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/* If scan_begin_src is not TRIG_FOLLOW, then a monostable will be
-	 * set up to generate a fixed number of timed conversion pulses. */
+	/*
+	 * If scan_begin_src is not TRIG_FOLLOW, then a monostable will be
+	 * set up to generate a fixed number of timed conversion pulses.
+	 */
 	if ((cmd->scan_begin_src != TRIG_FOLLOW)
 	    && (cmd->convert_src != TRIG_TIMER))
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_das16_cs.c b/drivers/staging/comedi/drivers/cb_das16_cs.c
index a3d53babe137..6d81d8b40ccc 100644
--- a/drivers/staging/comedi/drivers/cb_das16_cs.c
+++ b/drivers/staging/comedi/drivers/cb_das16_cs.c
@@ -46,6 +46,7 @@ Status: experimental
 #include <pcmcia/cistpl.h>
 #include <pcmcia/ds.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define DAS16CS_SIZE			18
@@ -169,47 +170,26 @@ static int das16cs_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and
-	 * mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c
index 4dd87c28ca20..de21a261ff45 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -803,58 +803,35 @@ static int cb_pcidas_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int i, gain, start_chan;
 
-	/* step 1: trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_NOW | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  make sure trigger sources are compatible with each other */
 	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->scan_begin_src != TRIG_FOLLOW && cmd->convert_src != TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->start_src == TRIG_EXT &&
 	    (cmd->convert_src == TRIG_EXT || cmd->scan_begin_src == TRIG_EXT))
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
@@ -1079,43 +1056,24 @@ static int cb_pcidas_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index 7168883eed41..0472a9088abe 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -2108,74 +2108,50 @@ static int ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 		      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg, tmp_arg2;
 	int i;
 	int aref;
 	unsigned int triggers;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
 
-	tmp = cmd->scan_begin_src;
 	triggers = TRIG_TIMER;
 	if (board(dev)->layout == LAYOUT_4020)
 		triggers |= TRIG_OTHER;
 	else
 		triggers |= TRIG_FOLLOW;
-	cmd->scan_begin_src &= triggers;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, triggers);
 
-	tmp = cmd->convert_src;
 	triggers = TRIG_TIMER;
 	if (board(dev)->layout == LAYOUT_4020)
 		triggers |= TRIG_NOW;
 	else
 		triggers |= TRIG_EXT;
-	cmd->convert_src &= triggers;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, triggers);
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_OTHER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  compatibility check */
 	if (cmd->convert_src == TRIG_EXT && cmd->scan_begin_src == TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 	if (cmd->stop_src != TRIG_COUNT &&
 	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
@@ -3466,55 +3442,33 @@ static int ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 		      struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  compatibility check */
 	if (cmd->convert_src == TRIG_EXT && cmd->scan_begin_src == TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 	if (cmd->stop_src != TRIG_COUNT &&
 	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/cb_pcidda.c b/drivers/staging/comedi/drivers/cb_pcidda.c
index ad9f3a3075a0..aef946df27e2 100644
--- a/drivers/staging/comedi/drivers/cb_pcidda.c
+++ b/drivers/staging/comedi/drivers/cb_pcidda.c
@@ -48,6 +48,7 @@ Please report success/failure with other different cards to
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "8255.h"
 
 /* PCI vendor number of ComputerBoards */
@@ -247,56 +248,26 @@ static int cb_pcidda_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually
-	 * compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER
-	    && cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_TIMER && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/comedi_parport.c b/drivers/staging/comedi/drivers/comedi_parport.c
index c9e40a9fea05..22ef94242590 100644
--- a/drivers/staging/comedi/drivers/comedi_parport.c
+++ b/drivers/staging/comedi/drivers/comedi_parport.c
@@ -85,6 +85,8 @@ pin, which can be used to wake up tasks.
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
+
 #define PARPORT_SIZE 3
 
 #define PARPORT_A 0
@@ -176,39 +178,20 @@ static int parport_intr_cmdtest(struct comedi_device *dev,
 				struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
-
-	/* step 1 */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: ignored */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index b0f0ec58dfed..7817def1556c 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -231,44 +231,23 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW | TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->convert_src != TRIG_NOW && cmd->convert_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c
index 744376a49d08..fcb8a32adb2f 100644
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -402,62 +402,42 @@ static int das16_cmd_test(struct comedi_device *dev, struct comedi_subdevice *s,
 	int gain, start_chan, i;
 	int mask;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
 
-	tmp = cmd->scan_begin_src;
 	mask = TRIG_FOLLOW;
 	/*  if board supports burst mode */
 	if (board->size > 0x400)
 		mask |= TRIG_TIMER | TRIG_EXT;
-	cmd->scan_begin_src &= mask;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, mask);
 
 	tmp = cmd->convert_src;
 	mask = TRIG_TIMER | TRIG_EXT;
 	/*  if board supports burst mode */
 	if (board->size > 0x400)
 		mask |= TRIG_NOW;
-	cmd->convert_src &= mask;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, mask);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/**
-	 * step 2: make sure trigger sources are unique and
-	 * mutually compatible
-	 */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/*  make sure scan_begin_src and convert_src dont conflict */
 	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 	if (cmd->scan_begin_src != TRIG_FOLLOW && cmd->convert_src != TRIG_NOW)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das16m1.c b/drivers/staging/comedi/drivers/das16m1.c
index 7f0668f8ed83..3f87d7598e5b 100644
--- a/drivers/staging/comedi/drivers/das16m1.c
+++ b/drivers/staging/comedi/drivers/das16m1.c
@@ -170,42 +170,24 @@ static int das16m1_cmd_test(struct comedi_device *dev,
 	const struct das16m1_board *board = comedi_board(dev);
 	unsigned int err = 0, tmp, i;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 711d4e243b88..2555f3297d7b 100644
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -784,59 +784,35 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev,
 				 struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	unsigned int tmp_arg;
 	int i;
 	int unipolar;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_EXT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src,
+					TRIG_COUNT | TRIG_EXT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
-	/*  uniqueness check */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_EXT)
-		err++;
-	/* compatibility check */
 	if (cmd->scan_begin_src != TRIG_FOLLOW &&
 	    cmd->convert_src != TRIG_TIMER)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index 8e89101ad3a2..215deac0a396 100644
--- a/drivers/staging/comedi/drivers/das800.c
+++ b/drivers/staging/comedi/drivers/das800.c
@@ -609,44 +609,24 @@ static int das800_ai_do_cmdtest(struct comedi_device *dev,
 	int gain, startChan;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dmm32at.c b/drivers/staging/comedi/drivers/dmm32at.c
index 0703ca5d8cb7..4d5c33c4750f 100644
--- a/drivers/staging/comedi/drivers/dmm32at.c
+++ b/drivers/staging/comedi/drivers/dmm32at.c
@@ -41,6 +41,8 @@ Configuration Options:
 #include "../comedidev.h"
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
+
 /* Board register addresses */
 
 #define DMM32AT_MEMSIZE 0x10
@@ -258,47 +260,26 @@ static int dmm32at_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int start_chan, gain, i;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER /*| TRIG_EXT */ ;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER /*| TRIG_EXT */ ;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER /*| TRIG_EXT */);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER /*| TRIG_EXT */);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	 * compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt2814.c b/drivers/staging/comedi/drivers/dt2814.c
index ce5d83768d4e..064a8f215e4d 100644
--- a/drivers/staging/comedi/drivers/dt2814.c
+++ b/drivers/staging/comedi/drivers/dt2814.c
@@ -45,6 +45,8 @@ addition, the clock does not seem to be very accurate.
 #include <linux/ioport.h>
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
+
 #define DT2814_SIZE 2
 
 #define DT2814_CSR 0
@@ -129,42 +131,22 @@ static int dt2814_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are
-	 * unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->stop_src != TRIG_TIMER && cmd->stop_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index b7c43c84d949..78d340716d1e 100644
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -582,47 +582,24 @@ static int dt282x_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique
-	 * and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -862,44 +839,22 @@ static int dt282x_ao_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique
-	 * and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/dt3000.c b/drivers/staging/comedi/drivers/dt3000.c
index 3a940a2f000e..43d05ef97157 100644
--- a/drivers/staging/comedi/drivers/dt3000.c
+++ b/drivers/staging/comedi/drivers/dt3000.c
@@ -63,6 +63,8 @@ AO commands are not supported.
 #include "../comedidev.h"
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
+
 #define PCI_VENDOR_ID_DT	0x1116
 
 static const struct comedi_lrange range_dt3000_ai = { 4, {
@@ -408,37 +410,19 @@ static int dt3k_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c
index 5d3fa711a515..abff6603952a 100644
--- a/drivers/staging/comedi/drivers/gsc_hpdi.c
+++ b/drivers/staging/comedi/drivers/gsc_hpdi.c
@@ -723,45 +723,24 @@ static int di_cmd_test(struct comedi_device *dev, struct comedi_subdevice *s,
 		       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	 * compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*  uniqueness check */
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/me4000.c b/drivers/staging/comedi/drivers/me4000.c
index d7c5146b41e3..22db35d091f8 100644
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -52,6 +52,7 @@ broken.
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #if 0
@@ -895,18 +896,6 @@ static int me4000_ai_do_cmd(struct comedi_device *dev,
 	return 0;
 }
 
-/*
- * me4000_ai_do_cmd_test():
- *
- * The demo cmd.c in ./comedilib/demo specifies 6 return values:
- * - success
- * - invalid source
- * - source conflict
- * - invalid argument
- * - argument conflict
- * - invalid chanlist
- * So I tried to adopt this scheme.
- */
 static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 				 struct comedi_subdevice *s,
 				 struct comedi_cmd *cmd)
@@ -923,81 +912,29 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 	/* Round the timer arguments */
 	ai_round_cmd_args(dev, s, cmd, &init_ticks, &scan_ticks, &chan_ticks);
 
-	/*
-	 * Stage 1. Check if the trigger sources are generally valid.
-	 */
-	switch (cmd->start_src) {
-	case TRIG_NOW:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->start_src &= TRIG_NOW | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid start source\n");
-		cmd->start_src = TRIG_NOW;
-		err++;
-	}
-	switch (cmd->scan_begin_src) {
-	case TRIG_FOLLOW:
-	case TRIG_TIMER:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid scan begin source\n");
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		err++;
-	}
-	switch (cmd->convert_src) {
-	case TRIG_TIMER:
-	case TRIG_EXT:
-		break;
-	case TRIG_ANY:
-		cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid convert source\n");
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
-	switch (cmd->scan_end_src) {
-	case TRIG_NONE:
-	case TRIG_COUNT:
-		break;
-	case TRIG_ANY:
-		cmd->scan_end_src &= TRIG_NONE | TRIG_COUNT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid scan end source\n");
-		cmd->scan_end_src = TRIG_NONE;
-		err++;
-	}
-	switch (cmd->stop_src) {
-	case TRIG_NONE:
-	case TRIG_COUNT:
-		break;
-	case TRIG_ANY:
-		cmd->stop_src &= TRIG_NONE | TRIG_COUNT;
-		err++;
-		break;
-	default:
-		dev_err(dev->class_dev, "Invalid stop source\n");
-		cmd->stop_src = TRIG_NONE;
-		err++;
-	}
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src,
+					TRIG_NONE | TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE | TRIG_COUNT);
+
 	if (err)
 		return 1;
 
-	/*
-	 * Stage 2. Check for trigger source conflicts.
-	 */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_end_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
+
 	if (cmd->start_src == TRIG_NOW &&
 	    cmd->scan_begin_src == TRIG_TIMER &&
 	    cmd->convert_src == TRIG_TIMER) {
@@ -1017,11 +954,7 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 		   cmd->scan_begin_src == TRIG_EXT &&
 		   cmd->convert_src == TRIG_EXT) {
 	} else {
-		dev_err(dev->class_dev, "Invalid start trigger combination\n");
-		cmd->start_src = TRIG_NOW;
-		cmd->scan_begin_src = TRIG_FOLLOW;
-		cmd->convert_src = TRIG_TIMER;
-		err++;
+		err |= -EINVAL;
 	}
 
 	if (cmd->stop_src == TRIG_NONE && cmd->scan_end_src == TRIG_NONE) {
@@ -1032,11 +965,9 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 	} else if (cmd->stop_src == TRIG_COUNT &&
 		   cmd->scan_end_src == TRIG_COUNT) {
 	} else {
-		dev_err(dev->class_dev, "Invalid stop trigger combination\n");
-		cmd->stop_src = TRIG_NONE;
-		cmd->scan_end_src = TRIG_NONE;
-		err++;
+		err |= -EINVAL;
 	}
+
 	if (err)
 		return 2;
 
diff --git a/drivers/staging/comedi/drivers/ni_6527.c b/drivers/staging/comedi/drivers/ni_6527.c
index 8125d5069899..51295f32ee89 100644
--- a/drivers/staging/comedi/drivers/ni_6527.c
+++ b/drivers/staging/comedi/drivers/ni_6527.c
@@ -44,6 +44,7 @@ Updated: Sat, 25 Jan 2003 13:24:40 -0800
 #include <linux/interrupt.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #define DRIVER_NAME "ni_6527"
@@ -224,40 +225,20 @@ static int ni6527_intr_cmdtest(struct comedi_device *dev,
 			       struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and */
-	/*         are mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_65xx.c b/drivers/staging/comedi/drivers/ni_65xx.c
index aab2b065cd54..2a73ff57a2fb 100644
--- a/drivers/staging/comedi/drivers/ni_65xx.c
+++ b/drivers/staging/comedi/drivers/ni_65xx.c
@@ -55,6 +55,7 @@ except maybe the 6514.
 #include <linux/slab.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #define NI6514_DIO_SIZE 4096
@@ -486,40 +487,20 @@ static int ni_65xx_intr_cmdtest(struct comedi_device *dev,
 				struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_FOLLOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_at_a2150.c b/drivers/staging/comedi/drivers/ni_at_a2150.c
index 5895d4dce30f..83950807b672 100644
--- a/drivers/staging/comedi/drivers/ni_at_a2150.c
+++ b/drivers/staging/comedi/drivers/ni_at_a2150.c
@@ -321,45 +321,23 @@ static int a2150_ai_cmdtest(struct comedi_device *dev,
 	int startChan;
 	int i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually
-	 * compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_atmio16d.c b/drivers/staging/comedi/drivers/ni_atmio16d.c
index 4108cbfaf29b..e91a620f9db3 100644
--- a/drivers/staging/comedi/drivers/ni_atmio16d.c
+++ b/drivers/staging/comedi/drivers/ni_atmio16d.c
@@ -40,6 +40,7 @@ Devices: [National Instruments] AT-MIO-16 (atmio16), AT-MIO-16D (atmio16d)
 
 #include <linux/ioport.h>
 
+#include "comedi_fc.h"
 #include "8255.h"
 
 /* Configuration and Status Registers */
@@ -246,45 +247,26 @@ static int atmio16d_ai_cmdtest(struct comedi_device *dev,
 			       struct comedi_subdevice *s,
 			       struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
+	int err = 0;
 
-	/* make sure triggers are valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique & mutually compatible */
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index d534e63d886e..28b91a6c3789 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -979,55 +979,33 @@ static int labpc_ai_cmdtest(struct comedi_device *dev,
 {
 	int err = 0;
 	int tmp, tmp2;
-	int stop_mask;
+	unsigned int stop_mask;
 	enum scan_mode mode;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
 
-	tmp = cmd->stop_src;
 	stop_mask = TRIG_COUNT | TRIG_NONE;
 	if (thisboard->register_layout == labpc_1200_layout)
 		stop_mask |= TRIG_EXT;
-	cmd->stop_src &= stop_mask;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->stop_src, stop_mask);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_EXT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/* can't have external stop and start triggers at once */
 	if (cmd->start_src == TRIG_EXT && cmd->stop_src == TRIG_EXT)
diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c
index 4bbb9798af7e..3e5fdae93163 100644
--- a/drivers/staging/comedi/drivers/ni_mio_common.c
+++ b/drivers/staging/comedi/drivers/ni_mio_common.c
@@ -2164,61 +2164,38 @@ static int ni_ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 {
 	int err = 0;
 	int tmp;
-	int sources;
+	unsigned int sources;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	if ((cmd->flags & CMDF_WRITE)) {
+	if ((cmd->flags & CMDF_WRITE))
 		cmd->flags &= ~CMDF_WRITE;
-	}
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
 	sources = TRIG_TIMER | TRIG_EXT;
-	if ((boardtype.reg_type == ni_reg_611x)
-	    || (boardtype.reg_type == ni_reg_6143))
+	if (boardtype.reg_type == ni_reg_611x ||
+	    boardtype.reg_type == ni_reg_6143)
 		sources |= TRIG_NOW;
-	cmd->convert_src &= sources;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, sources);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT && cmd->start_src != TRIG_EXT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_OTHER)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -3356,44 +3333,28 @@ static int ni_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	if ((cmd->flags & CMDF_WRITE) == 0) {
+	if ((cmd->flags & CMDF_WRITE) == 0)
 		cmd->flags |= CMDF_WRITE;
-	}
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -3643,51 +3604,21 @@ static int ni_cdio_cmdtest(struct comedi_device *dev,
 {
 	int err = 0;
 	int tmp;
-	int sources;
 	unsigned i;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	sources = TRIG_INT;
-	cmd->start_src &= sources;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique... */
-
-	if (cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE)
-		err++;
-	/* ... and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_pcidio.c b/drivers/staging/comedi/drivers/ni_pcidio.c
index 6a70e266b1a3..bc9313ec985c 100644
--- a/drivers/staging/comedi/drivers/ni_pcidio.c
+++ b/drivers/staging/comedi/drivers/ni_pcidio.c
@@ -60,6 +60,7 @@ comedi_nonfree_firmware tarball available from http://www.comedi.org
 #include <linux/firmware.h>
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
 #include "mite.h"
 
 #undef DPRINTK
@@ -683,45 +684,25 @@ static int ni_pcidio_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/ni_tiocmd.c b/drivers/staging/comedi/drivers/ni_tiocmd.c
index a9611587460a..8ee93d359bed 100644
--- a/drivers/staging/comedi/drivers/ni_tiocmd.c
+++ b/drivers/staging/comedi/drivers/ni_tiocmd.c
@@ -48,6 +48,7 @@ TODO:
 	Support use of both banks X and Y
 */
 
+#include "comedi_fc.h"
 #include "ni_tio_internal.h"
 #include "mite.h"
 
@@ -237,61 +238,35 @@ EXPORT_SYMBOL_GPL(ni_tio_cmd);
 int ni_tio_cmdtest(struct ni_gpct *counter, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
-	int sources;
+	unsigned int sources;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
 	sources = TRIG_NOW | TRIG_INT | TRIG_OTHER;
 	if (ni_tio_counting_mode_registers_present(counter->counter_dev))
 		sources |= TRIG_EXT;
-	cmd->start_src &= sources;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_EXT | TRIG_OTHER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	sources = TRIG_NOW | TRIG_EXT | TRIG_OTHER;
-	cmd->convert_src &= sources;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, sources);
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_FOLLOW | TRIG_EXT | TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_NOW | TRIG_EXT | TRIG_OTHER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique... */
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+
+	/* Step 2b : and mutually compatible */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_INT &&
-	    cmd->start_src != TRIG_EXT && cmd->start_src != TRIG_OTHER)
-		err++;
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_OTHER)
-		err++;
-	if (cmd->convert_src != TRIG_OTHER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_NONE)
-		err++;
-	/* ... and mutually compatible */
 	if (cmd->convert_src != TRIG_NOW && cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl711.c b/drivers/staging/comedi/drivers/pcl711.c
index ef77b15f19f7..89305a14eb5c 100644
--- a/drivers/staging/comedi/drivers/pcl711.c
+++ b/drivers/staging/comedi/drivers/pcl711.c
@@ -64,6 +64,7 @@ supported.
 #include <linux/ioport.h>
 #include <linux/delay.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define PCL711_SIZE 16
@@ -266,42 +267,24 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
 	int tmp;
 	int err = 0;
 
-	/* step 1 */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl812.c b/drivers/staging/comedi/drivers/pcl812.c
index d196343adb08..3cf55ff93083 100644
--- a/drivers/staging/comedi/drivers/pcl812.c
+++ b/drivers/staging/comedi/drivers/pcl812.c
@@ -117,6 +117,7 @@
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 /* hardware types of the cards */
@@ -533,49 +534,31 @@ static int pcl812_ai_cmdtest(struct comedi_device *dev,
 {
 	const struct pcl812_board *board = comedi_board(dev);
 	int err = 0;
+	unsigned int flags;
 	int tmp, divisor1, divisor2;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
 
-	tmp = cmd->convert_src;
 	if (devpriv->use_ext_trg)
-		cmd->convert_src &= TRIG_EXT;
+		flags = TRIG_EXT;
 	else
-		cmd->convert_src &= TRIG_TIMER;
-
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
+		flags = TRIG_TIMER;
+	err |= cfc_check_trigger_src(&cmd->convert_src, flags);
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are
-	 * unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index f65fd66cc8a2..0822de058e4d 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -41,6 +41,7 @@ Configuration Options:
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 #define DEBUG(x) x
@@ -458,48 +459,23 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
 	      pcl816_cmdtest_out(-1, cmd);
 	     );
 
-	/* step 1: make sure trigger sources are trivially valid */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_EXT | TRIG_TIMER;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_EXT | TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
+	/* Step 2a : make sure trigger sources are unique */
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 */
-
-	if (cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_TIMER) {
-		cmd->convert_src = TRIG_TIMER;
-		err++;
-	}
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index 023a27df0d29..d4b0859d81f2 100644
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -107,6 +107,7 @@ A word or two about DMA. Driver support DMA operations at two ways:
 #include <linux/io.h>
 #include <asm/dma.h>
 
+#include "comedi_fc.h"
 #include "8253.h"
 
 /* #define PCL818_MODE13_AO 1 */
@@ -1261,43 +1262,23 @@ static int ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	int err = 0;
 	int tmp, divisor1 = 0, divisor2 = 0;
 
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
 
-	if (cmd->stop_src != TRIG_NONE && cmd->stop_src != TRIG_COUNT)
-		err++;
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/pcm_common.c b/drivers/staging/comedi/drivers/pcm_common.c
index 474af7bc6c8b..85ee05ece9c8 100644
--- a/drivers/staging/comedi/drivers/pcm_common.c
+++ b/drivers/staging/comedi/drivers/pcm_common.c
@@ -1,60 +1,30 @@
 #include "../comedidev.h"
+
+#include "comedi_fc.h"
 #include "pcm_common.h"
 
-/*
- * 'do_cmdtest' function for an 'INTERRUPT' subdevice.  This is for
- * the PCM drivers.
- */
 int comedi_pcm_cmdtest(struct comedi_device *dev,
 		       struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	unsigned int tmp;
-
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= (TRIG_NOW | TRIG_INT);
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
 
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= (TRIG_COUNT | TRIG_NONE);
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and
-	 * mutually compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* these tests are true if more than one _src bit is set */
-	if ((cmd->start_src & (cmd->start_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
-		err++;
-	if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
-		err++;
-	if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
-		err++;
-	if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/quatech_daqp_cs.c b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
index e95a4eb0a67d..3e276f7a3380 100644
--- a/drivers/staging/comedi/drivers/quatech_daqp_cs.c
+++ b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
@@ -56,6 +56,8 @@ Devices: [Quatech] DAQP-208 (daqp), DAQP-308
 
 #include <linux/completion.h>
 
+#include "comedi_fc.h"
+
 /* Maximum number of separate DAQP devices we'll allow */
 #define MAX_DEV         4
 
@@ -456,51 +458,26 @@ static int daqp_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_NOW && cmd->convert_src != TRIG_TIMER)
-		err++;
-	if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/rtd520.c b/drivers/staging/comedi/drivers/rtd520.c
index d0e4844e5248..41d24b08913b 100644
--- a/drivers/staging/comedi/drivers/rtd520.c
+++ b/drivers/staging/comedi/drivers/rtd520.c
@@ -106,6 +106,8 @@ Configuration options:
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
+
 #define DRV_NAME "rtd520"
 
 /*======================================================================
@@ -976,52 +978,25 @@ static int rtd_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique
-	   and mutually compatible */
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT) {
-		err++;
-	}
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index 24878c815fd7..551d68b7837c 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -1505,56 +1505,28 @@ static int s626_ai_cmdtest(struct comedi_device *dev,
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.  Using
-	 * the cmdtest ioctl, a user can create a valid cmd and then have it
-	 * executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests the
-	 * command passes. */
-
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT | TRIG_EXT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT | TRIG_FOLLOW;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT | TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_INT | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT | TRIG_FOLLOW);
+	err |= cfc_check_trigger_src(&cmd->convert_src,
+					TRIG_TIMER | TRIG_EXT | TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually
-	   compatible */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT
-	    && cmd->scan_begin_src != TRIG_FOLLOW)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER &&
-	    cmd->convert_src != TRIG_EXT && cmd->convert_src != TRIG_NOW)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/skel.c b/drivers/staging/comedi/drivers/skel.c
index eb70baca49d8..b70cdf300bbd 100644
--- a/drivers/staging/comedi/drivers/skel.c
+++ b/drivers/staging/comedi/drivers/skel.c
@@ -76,6 +76,8 @@ Configuration Options:
 
 #include <linux/pci.h>		/* for PCI devices */
 
+#include "comedi_fc.h"
+
 /* Imaginary registers for the imaginary board */
 
 #define SKEL_SIZE 0
@@ -349,60 +351,40 @@ static int skel_ai_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
 	return n;
 }
 
+/*
+ * cmdtest tests a particular command to see if it is valid.
+ * Using the cmdtest ioctl, a user can create a valid cmd
+ * and then have it executes by the cmd ioctl.
+ *
+ * cmdtest returns 1,2,3,4 or 0, depending on which tests
+ * the command passes.
+ */
 static int skel_ai_cmdtest(struct comedi_device *dev,
-			   struct comedi_subdevice *s, struct comedi_cmd *cmd)
+			   struct comedi_subdevice *s,
+			   struct comedi_cmd *cmd)
 {
 	int err = 0;
 	int tmp;
 
-	/* cmdtest tests a particular command to see if it is valid.
-	 * Using the cmdtest ioctl, a user can create a valid cmd
-	 * and then have it executes by the cmd ioctl.
-	 *
-	 * cmdtest returns 1,2,3,4 or 0, depending on which tests
-	 * the command passes. */
-
-	/* step 1: make sure trigger sources are trivially valid */
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/* step 2: make sure trigger sources are unique and mutually compatible
-     */
+	/* Step 2a : make sure trigger sources are unique */
 
-	/* note that mutual compatibility is not an issue here */
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbdux.c b/drivers/staging/comedi/drivers/usbdux.c
index bc5fc5cc4641..b536bba74351 100644
--- a/drivers/staging/comedi/drivers/usbdux.c
+++ b/drivers/staging/comedi/drivers/usbdux.c
@@ -98,6 +98,8 @@ sampling rate. If you sample two channels you get 4kHz and so on.
 
 #include "../comedidev.h"
 
+#include "comedi_fc.h"
+
 /* timeout for the USB-transfer in ms*/
 #define BULK_TIMEOUT 1000
 
@@ -929,9 +931,9 @@ static int usbduxsub_submit_OutURBs(struct usbduxsub *usbduxsub)
 static int usbdux_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
-	int err = 0, tmp, i;
-	unsigned int tmpTimer;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0, i;
+	unsigned int tmpTimer;
 
 	if (!(this_usbduxsub->probed))
 		return -ENODEV;
@@ -939,51 +941,23 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ai_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* start a new _scan_ with a timer */
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1488,8 +1462,9 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 static int usbdux_ao_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0;
+	unsigned int flags;
 
 	if (!this_usbduxsub)
 		return -EFAULT;
@@ -1500,69 +1475,46 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ao_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* just now we scan also in the high speed mode every frame */
-	/* this is due to ehci driver limitations */
 	if (0) {		/* (this_usbduxsub->high_speed) */
-		/* start immediately a new scan */
 		/* the sampling rate is set by the coversion rate */
-		cmd->scan_begin_src &= TRIG_FOLLOW;
+		flags = TRIG_FOLLOW;
 	} else {
 		/* start a new scan (output at once) with a timer */
-		cmd->scan_begin_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, flags);
 
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	/* we always output at 1kHz just now all channels at once */
 	if (0) {		/* (this_usbduxsub->high_speed) */
 		/*
-		 * in usb-2.0 only one conversion it transmitted but with 8kHz/n
+		 * in usb-2.0 only one conversion it transmitted
+		 * but with 8kHz/n
 		 */
-		cmd->convert_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	} else {
-		/* all conversion events happen simultaneously with a rate of
-		 * 1kHz/n */
-		cmd->convert_src &= TRIG_NOW;
+		/*
+		 * all conversion events happen simultaneously with
+		 * a rate of 1kHz/n
+		 */
+		flags = TRIG_NOW;
 	}
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, flags);
 
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbduxfast.c b/drivers/staging/comedi/drivers/usbduxfast.c
index 0f6c1392f6ce..1154a7e2895d 100644
--- a/drivers/staging/comedi/drivers/usbduxfast.c
+++ b/drivers/staging/comedi/drivers/usbduxfast.c
@@ -549,10 +549,10 @@ static int usbduxfast_ai_cmdtest(struct comedi_device *dev,
 				 struct comedi_subdevice *s,
 				 struct comedi_cmd *cmd)
 {
-	int err = 0, stop_mask = 0;
+	struct usbduxfastsub_s *udfs = dev->private;
+	int err = 0;
 	long int steps, tmp;
 	int minSamplPer;
-	struct usbduxfastsub_s *udfs = dev->private;
 
 	if (!udfs->probed)
 		return -ENODEV;
@@ -563,57 +563,31 @@ static int usbduxfast_ai_cmdtest(struct comedi_device *dev,
 	       "scan_begin_arg=%u\n",
 	       dev->minor, cmd->convert_arg, cmd->scan_begin_arg);
 #endif
-	/* step 1: make sure trigger sources are trivially valid */
-
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_EXT | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	tmp = cmd->scan_begin_src;
-	cmd->scan_begin_src &= TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_TIMER | TRIG_EXT;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	tmp = cmd->stop_src;
-	stop_mask = TRIG_COUNT | TRIG_NONE;
-	cmd->stop_src &= stop_mask;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src,
+					TRIG_NOW | TRIG_EXT | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src,
+					TRIG_TIMER | TRIG_FOLLOW | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_TIMER | TRIG_EXT);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 */
+	/* Step 2a : make sure trigger sources are unique */
 
-	if (cmd->start_src != TRIG_NOW &&
-	    cmd->start_src != TRIG_EXT && cmd->start_src != TRIG_INT)
-		err++;
-	if (cmd->scan_begin_src != TRIG_TIMER &&
-	    cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT)
-		err++;
-	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_EXT)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT &&
-	    cmd->stop_src != TRIG_EXT && cmd->stop_src != TRIG_NONE)
-		err++;
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
+	err |= cfc_check_trigger_is_unique(cmd->convert_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	/* can't have external stop and start triggers at once */
 	if (cmd->start_src == TRIG_EXT && cmd->stop_src == TRIG_EXT)
-		err++;
+		err |= -EINVAL;
 
 	if (err)
 		return 2;
diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index b4ab83f1215f..b1694121f845 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -897,9 +897,9 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s,
 			     struct comedi_cmd *cmd)
 {
-	int err = 0, tmp, i;
-	unsigned int tmpTimer;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0, i;
+	unsigned int tmpTimer;
 
 	if (!(this_usbduxsub->probed))
 		return -ENODEV;
@@ -907,51 +907,23 @@ static int usbdux_ai_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ai_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
-
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* start a new _scan_ with a timer */
-	cmd->scan_begin_src &= TRIG_TIMER;
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
-	cmd->convert_src &= TRIG_NOW;
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
 
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;
@@ -1558,8 +1530,9 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s,
 			     struct comedi_cmd *cmd)
 {
-	int err = 0, tmp;
 	struct usbduxsub *this_usbduxsub = dev->private;
+	int err = 0;
+	unsigned int flags;
 
 	if (!this_usbduxsub)
 		return -EFAULT;
@@ -1570,63 +1543,35 @@ static int usbdux_ao_cmdtest(struct comedi_device *dev,
 	dev_dbg(&this_usbduxsub->interface->dev,
 		"comedi%d: usbdux_ao_cmdtest\n", dev->minor);
 
-	/* make sure triggers are valid */
-	/* Only immediate triggers are allowed */
-	tmp = cmd->start_src;
-	cmd->start_src &= TRIG_NOW | TRIG_INT;
-	if (!cmd->start_src || tmp != cmd->start_src)
-		err++;
+	/* Step 1 : check if triggers are trivially valid */
+
+	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
 
-	/* trigger should happen timed */
-	tmp = cmd->scan_begin_src;
-	/* just now we scan also in the high speed mode every frame */
-	/* this is due to ehci driver limitations */
 	if (0) {		/* (this_usbduxsub->high_speed) */
-		/* start immediately a new scan */
-		/* the sampling rate is set by the coversion rate */
-		cmd->scan_begin_src &= TRIG_FOLLOW;
+		/*
+		 * start immediately a new scan
+		 * the sampling rate is set by the coversion rate
+		 */
+		flags = TRIG_FOLLOW;
 	} else {
 		/* start a new scan (output at once) with a timer */
-		cmd->scan_begin_src &= TRIG_TIMER;
+		flags = TRIG_TIMER;
 	}
-	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
-		err++;
-
-	/* scanning is continuous */
-	tmp = cmd->convert_src;
+	err |= cfc_check_trigger_src(&cmd->scan_begin_src, flags);
 
-	/* all conversion events happen simultaneously */
-	cmd->convert_src &= TRIG_NOW;
-
-	if (!cmd->convert_src || tmp != cmd->convert_src)
-		err++;
-
-	/* issue a trigger when scan is finished and start a new scan */
-	tmp = cmd->scan_end_src;
-	cmd->scan_end_src &= TRIG_COUNT;
-	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
-		err++;
-
-	/* trigger at the end of count events or not, stop condition or not */
-	tmp = cmd->stop_src;
-	cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
-	if (!cmd->stop_src || tmp != cmd->stop_src)
-		err++;
+	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
+	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
+	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err)
 		return 1;
 
-	/*
-	 * step 2: make sure trigger sources
-	 * are unique and mutually compatible
-	 * note that mutual compatibility is not an issue here
-	 */
-	if (cmd->scan_begin_src != TRIG_FOLLOW &&
-	    cmd->scan_begin_src != TRIG_EXT &&
-	    cmd->scan_begin_src != TRIG_TIMER)
-		err++;
-	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
-		err++;
+	/* Step 2a : make sure trigger sources are unique */
+
+	err |= cfc_check_trigger_is_unique(cmd->start_src);
+	err |= cfc_check_trigger_is_unique(cmd->stop_src);
+
+	/* Step 2b : and mutually compatible */
 
 	if (err)
 		return 2;