[PATCH 09/26] coresight: etm4x: Adds trace return stack option programming for ETMv4.

[Mathieu Poirier]

From: Mike Leach <mike.leach at linaro.org>

Adds handling to program the return stack option into ETMv4 hardware if
specified in the perf command line.

If option is not supported by the hardware then it will be ignored.
This allows capture to move between core/ETM combinations that have the
hardware support to those that do not.

Signed-off-by: Mike Leach <mike.leach at linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier at linaro.org>
---
 drivers/hwtracing/coresight/coresight-etm4x.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 532adc9dd32a..ac77b4c973d8 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -224,6 +224,10 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata,
 	if (attr->config & BIT(ETM_OPT_TS))
 		/* bit[11], Global timestamp tracing bit */
 		config->cfg |= BIT(11);
+	/* return stack - enable if selected and supported */
+	if ((attr->config & BIT(ETM_OPT_RETSTK)) && drvdata->retstack)
+		/* bit[12], Return stack enable bit */
+		config->cfg |= BIT(12);
 
 out:
 	return ret;
-- 
2.7.4