[PATCH V7 2/3] coresight: etm: Make cycle count threshold user configurable

[Anshuman Khandual]

When cycle counting is enabled, we use a default threshold value i.e 0x100
for the instruction trace cycle counting.

This patch makes the cycle threshold user configurable via perf event
attributes( 'cc_threshold' => event->attr.config3[11:0] ), falling back
to the current default if unspecified.

Cc: Suzuki K Poulose <suzuki.poulose at arm.com>
Cc: Mike Leach <mike.leach at linaro.org>
Cc: James Clark <james.clark at arm.com>
Cc: Leo Yan <leo.yan at linaro.org>
Cc: coresight at lists.linaro.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-doc at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Reviewed-by: Mike Leach <mike.leach at linaro.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
---
 drivers/hwtracing/coresight/coresight-etm-perf.c   | 2 ++
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 5ca6278baff4..09f75dffae60 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -68,6 +68,7 @@ PMU_FORMAT_ATTR(preset,		"config:0-3");
 PMU_FORMAT_ATTR(sinkid,		"config2:0-31");
 /* config ID - set if a system configuration is selected */
 PMU_FORMAT_ATTR(configid,	"config2:32-63");
+PMU_FORMAT_ATTR(cc_threshold,	"config3:0-11");
 
 
 /*
@@ -101,6 +102,7 @@ static struct attribute *etm_config_formats_attr[] = {
 	&format_attr_preset.attr,
 	&format_attr_configid.attr,
 	&format_attr_branch_broadcast.attr,
+	&format_attr_cc_threshold.attr,
 	NULL,
 };
 
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 9619d9d0bbb1..5b6a878a2ac5 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -644,7 +644,7 @@ static int etm4_parse_event_config(struct coresight_device *csdev,
 	struct etmv4_config *config = &drvdata->config;
 	struct perf_event_attr *attr = &event->attr;
 	unsigned long cfg_hash;
-	int preset;
+	int preset, cc_threshold;
 
 	/* Clear configuration from previous run */
 	memset(config, 0, sizeof(struct etmv4_config));
@@ -667,7 +667,12 @@ static int etm4_parse_event_config(struct coresight_device *csdev,
 	if (attr->config & BIT(ETM_OPT_CYCACC)) {
 		config->cfg |= TRCCONFIGR_CCI;
 		/* TRM: Must program this for cycacc to work */
-		config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT;
+		cc_threshold = attr->config3 & ETM_CYC_THRESHOLD_MASK;
+		if (!cc_threshold)
+			cc_threshold = ETM_CYC_THRESHOLD_DEFAULT;
+		if (cc_threshold < drvdata->ccitmin)
+			cc_threshold = drvdata->ccitmin;
+		config->ccctlr = cc_threshold;
 	}
 	if (attr->config & BIT(ETM_OPT_TS)) {
 		/*
-- 
2.25.1