[PATCH V6 22/26] coresight: introducing a global trace ID function

Mathieu Poirier
2015-12-03T21:06:08Z

TraceID values have to be unique for all tracers and
consistent between drivers and user space. As such
introducing a central function to be used whenever a
traceID value is required.

The patch also account for data traceIDs, which are usually
I(N) + 1.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/coresight-etm3x.c | 7 ++-----
include/linux/coresight-pmu.h | 12 ++++++++++++
2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index 6170df1b9e59..02186b722d88 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -27,6 +27,7 @@
#include <linux/cpu.h>
#include <linux/of.h>
#include <linux/coresight.h>
+#include <linux/coresight-pmu.h>
#include <linux/amba/bus.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
@@ -793,11 +794,7 @@ static void etm_init_arch_data(void *info)

static void etm_init_trace_id(struct etm_drvdata *drvdata)
{
- /*
- * A trace ID of value 0 is invalid, so let's start at some
- * random value that fits in 7 bits and go from there.
- */
- drvdata->traceid = 0x10 + drvdata->cpu;
+ drvdata->traceid = coresight_get_trace_id(drvdata->cpu);
}

static int etm_probe(struct amba_device *adev, const struct amba_id *id)
diff --git a/include/linux/coresight-pmu.h b/include/linux/coresight-pmu.h
index 6c5386b23b10..7d410260661b 100644
--- a/include/linux/coresight-pmu.h
+++ b/include/linux/coresight-pmu.h
@@ -19,9 +19,21 @@
#define _LINUX_CORESIGHT_PMU_H

#define CORESIGHT_ETM_PMU_NAME "cs_etm"
+#define CORESIGHT_ETM_PMU_SEED 0x10

/* ETMv3.5/PTM's ETMCR config bit */
#define ETM_OPT_CYCACC 12
#define ETM_OPT_TS 28

+static inline int coresight_get_trace_id(int cpu)
+{
+ /*
+ * A trace ID of value 0 is invalid, so let's start at some
+ * random value that fits in 7 bits and go from there. Since
+ * the common convention is to have data trace IDs be I(N) + 1,
+ * set instruction trace IDs as a function of the CPU number.
+ */
+ return (CORESIGHT_ETM_PMU_SEED + (cpu * 2));
+}
+
#endif
--
2.1.4