gpio: add support of new GPIO direction flag

This commit manages the new dir flags that can be used in gpio
specifiers to indicate the pull-up or pull-down resistor
configuration for output gpio (GPIO_PULL_UP, GPIO_PULL_DOWN)
or the Open Drain/Open Source configuration for input gpio
(GPIO_OPEN_DRAIN, GPIO_OPEN_SOURCE).

These flags are already supported in Linux kernel in gpio lib.

This patch only parse and save the direction flags in GPIO
descriptor (desc->flags), it prepares the introduction of new ops
to manage them.
The GPIO uclass supports new GPIO flags from device-tree
(GPIO_XXX define in include/dt-bindings/gpio/gpio.h)
and translate them in the dir flags (GPIOD_XXX):
- GPIO_PULL_UP     => GPIOD_PULL_UP
- GPIO_PULL_DOWN   => GPIOD_PULL_DOWN
- GPIO_OPEN_DRAIN  => GPIOD_OPEN_DRAIN
- GPIO_OPEN_SOURCE => GPIOD_OPEN_SOURCE

This patch also adds protection in the check_dir_flags function for
new invalid configuration of the dir flags.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

2 files changed, 35 insertions, 1 deletions

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 9550e45e6c..25263994d2 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -145,6 +145,24 @@ int gpio_xlate_offs_flags(struct udevice *dev, struct gpio_desc *desc,
 	if (args->args[1] & GPIO_ACTIVE_LOW)
 		desc->flags |= GPIOD_ACTIVE_LOW;
 
+	/*
+	 * need to test 2 bits for gpio output binding:
+	 * OPEN_DRAIN (0x6) = SINGLE_ENDED (0x2) | LINE_OPEN_DRAIN (0x4)
+	 * OPEN_SOURCE (0x2) = SINGLE_ENDED (0x2) | LINE_OPEN_SOURCE (0x0)
+	 */
+	if (args->args[1] & GPIO_SINGLE_ENDED) {
+		if (args->args[1] & GPIO_LINE_OPEN_DRAIN)
+			desc->flags |= GPIOD_OPEN_DRAIN;
+		else
+			desc->flags |= GPIOD_OPEN_SOURCE;
+	}
+
+	if (args->args[1] & GPIO_PULL_UP)
+		desc->flags |= GPIOD_PULL_UP;
+
+	if (args->args[1] & GPIO_PULL_DOWN)
+		desc->flags |= GPIOD_PULL_DOWN;
+
 	return 0;
 }
 
@@ -521,6 +539,18 @@ static int check_dir_flags(ulong flags)
 		return -EINVAL;
 	}
 
+	if ((flags & GPIOD_PULL_UP) && (flags & GPIOD_PULL_DOWN)) {
+		log_debug("%s: flags 0x%lx has GPIOD_PULL_UP and GPIOD_PULL_DOWN\n",
+			  __func__, flags);
+		return -EINVAL;
+	}
+
+	if ((flags & GPIOD_OPEN_DRAIN) && (flags & GPIOD_OPEN_SOURCE)) {
+		log_debug("%s: flags 0x%lx has GPIOD_OPEN_DRAIN and GPIOD_OPEN_SOURCE\n",
+			  __func__, flags);
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 1329d02f87..42c9ab29ca 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -119,8 +119,12 @@ struct gpio_desc {
 	unsigned long flags;
 #define GPIOD_IS_OUT		BIT(1)	/* GPIO is an output */
 #define GPIOD_IS_IN		BIT(2)	/* GPIO is an input */
-#define GPIOD_ACTIVE_LOW	BIT(3)	/* value has active low */
+#define GPIOD_ACTIVE_LOW	BIT(3)	/* GPIO is active when value is low */
 #define GPIOD_IS_OUT_ACTIVE	BIT(4)	/* set output active */
+#define GPIOD_OPEN_DRAIN	BIT(5)	/* GPIO is open drain type */
+#define GPIOD_OPEN_SOURCE	BIT(6)	/* GPIO is open source type */
+#define GPIOD_PULL_UP		BIT(7)	/* GPIO has pull-up enabled */
+#define GPIOD_PULL_DOWN		BIT(8)	/* GPIO has pull-down enabled */
 
 	uint offset;		/* GPIO offset within the device */
 	/*