coresight: tmc: adding mode of operation for link/sinks

Moving tmc_drvdata::enable to a local_t mode.  That way the
sink interface is aware of it's orgin and the foundation for
mutual exclusion between the sysFS and Perf interface can be
laid out.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index d6999b4..0c10781 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -86,6 +86,7 @@ static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
 {
 	int ret = 0;
 	bool used = false;
+	long val;
 	unsigned long flags;
 	void __iomem *vaddr = NULL;
 	dma_addr_t paddr;
@@ -122,6 +123,15 @@ static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
 		goto out;
 	}
 
+	val = local_xchg(&drvdata->mode, mode);
+	/*
+	 * In sysFS mode we can have multiple writers per sink.  Since this
+	 * sink is already enabled no memory is needed and the HW need not be
+	 * touched.
+	 */
+	if (val == CS_MODE_SYSFS)
+		goto out;
+
 	/*
 	 * If drvdata::buf == NULL, use the memory allocated above.
 	 * Otherwise a buffer still exists from a previous session, so
@@ -137,7 +147,6 @@ static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
 	memset(drvdata->vaddr, 0, drvdata->size);
 
 	tmc_etr_enable_hw(drvdata);
-	drvdata->enable = true;
 out:
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
@@ -153,6 +162,7 @@ out:
 
 static void tmc_disable_etr_sink(struct coresight_device *csdev)
 {
+	long val;
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -162,8 +172,11 @@ static void tmc_disable_etr_sink(struct coresight_device *csdev)
 		return;
 	}
 
-	tmc_etr_disable_hw(drvdata);
-	drvdata->enable = false;
+	val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
+	/* Disable the TMC only if it needs to */
+	if (val != CS_MODE_DISABLED)
+		tmc_etr_disable_hw(drvdata);
+
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_info(drvdata->dev, "TMC-ETR disabled\n");
@@ -200,7 +213,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
 	}
 
 	/* Disable the TMC if need be */
-	if (drvdata->enable)
+	if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
 		tmc_etr_disable_hw(drvdata);
 
 	drvdata->reading = true;
@@ -223,7 +236,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
 	spin_lock_irqsave(&drvdata->spinlock, flags);
 
 	/* RE-enable the TMC if need be */
-	if (drvdata->enable) {
+	if (local_read(&drvdata->mode) == CS_MODE_SYSFS) {
 		/*
 		 * The trace run will continue with the same allocated trace
 		 * buffer. As such zero-out the buffer so that we don't end