intel_th: Add switch triggering support

Add support for asserting window switch trigger when tracing to MSU output
ports. This allows for software controlled switching between windows of
the MSU buffer, which can be used for double buffering while exporting the
trace data further from the MSU.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/hwtracing/intel_th/gth.c b/drivers/hwtracing/intel_th/gth.c
index a879445ef451..fa9d34af87ac 100644
--- a/drivers/hwtracing/intel_th/gth.c
+++ b/drivers/hwtracing/intel_th/gth.c
@@ -308,6 +308,11 @@ static int intel_th_gth_reset(struct gth_device *gth)
 	iowrite32(0, gth->base + REG_GTH_SCR);
 	iowrite32(0xfc, gth->base + REG_GTH_SCR2);
 
+	/* setup CTS for single trigger */
+	iowrite32(CTS_EVENT_ENABLE_IF_ANYTHING, gth->base + REG_CTS_C0S0_EN);
+	iowrite32(CTS_ACTION_CONTROL_SET_STATE(CTS_STATE_IDLE) |
+		  CTS_ACTION_CONTROL_TRIGGER, gth->base + REG_CTS_C0S0_ACT);
+
 	return 0;
 }
 
@@ -595,6 +600,37 @@ static void intel_th_gth_enable(struct intel_th_device *thdev,
 }
 
 /**
+ * intel_th_gth_switch() - execute a switch sequence
+ * @thdev:	GTH device
+ * @output:	output device's descriptor
+ *
+ * This will execute a switch sequence that will trigger a switch window
+ * when tracing to MSC in multi-block mode.
+ */
+static void intel_th_gth_switch(struct intel_th_device *thdev,
+				struct intel_th_output *output)
+{
+	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
+	unsigned long count;
+	u32 reg;
+
+	/* trigger */
+	iowrite32(0, gth->base + REG_CTS_CTL);
+	iowrite32(CTS_CTL_SEQUENCER_ENABLE, gth->base + REG_CTS_CTL);
+	/* wait on trigger status */
+	for (reg = 0, count = CTS_TRIG_WAITLOOP_DEPTH;
+	     count && !(reg & BIT(4)); count--) {
+		reg = ioread32(gth->base + REG_CTS_STAT);
+		cpu_relax();
+	}
+	if (!count)
+		dev_dbg(&thdev->dev, "timeout waiting for CTS Trigger\n");
+
+	intel_th_gth_stop(gth, output, false);
+	intel_th_gth_start(gth, output);
+}
+
+/**
  * intel_th_gth_assign() - assign output device to a GTH output port
  * @thdev:	GTH device
  * @othdev:	output device
@@ -777,6 +813,7 @@ static struct intel_th_driver intel_th_gth_driver = {
 	.unassign	= intel_th_gth_unassign,
 	.set_output	= intel_th_gth_set_output,
 	.enable		= intel_th_gth_enable,
+	.trig_switch	= intel_th_gth_switch,
 	.disable	= intel_th_gth_disable,
 	.driver	= {
 		.name	= "gth",