coresight: etm4x: Hook pause and resume callbacks

Add callbacks for pausing and resuming the tracer.

A "paused" flag in the driver data indicates whether the tracer is
paused.  If the flag is set, the driver will skip starting the hardware
trace.  The flag is always set to false for the sysfs mode, meaning the
tracer will never be paused in the case.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250401180708.385396-4-leo.yan@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 3e084280b23eeee531025c865eb63dd67bfa6489..6a5898355a83893973b5aa0b769debae79961673 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -577,7 +577,8 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
                etm4x_relaxed_write32(csa, trcpdcr | TRCPDCR_PU, TRCPDCR);
        }
 
-       rc = etm4_enable_trace_unit(drvdata);
+       if (!drvdata->paused)
+               rc = etm4_enable_trace_unit(drvdata);
 done:
        etm4_cs_lock(drvdata, csa);
 
@@ -820,6 +821,9 @@ static int etm4_enable_perf(struct coresight_device *csdev,
 
        drvdata->trcid = path->trace_id;
 
+       /* Populate pause state */
+       drvdata->paused = !!READ_ONCE(event->hw.aux_paused);
+
        /* And enable it */
        ret = etm4_enable_hw(drvdata);
 
@@ -846,6 +850,9 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
 
        drvdata->trcid = path->trace_id;
 
+       /* Tracer will never be paused in sysfs mode */
+       drvdata->paused = false;
+
        /*
         * Executing etm4_enable_hw on the cpu whose ETM is being enabled
         * ensures that register writes occur when cpu is powered.
@@ -1080,10 +1087,43 @@ static void etm4_disable(struct coresight_device *csdev,
                coresight_set_mode(csdev, CS_MODE_DISABLED);
 }
 
+static int etm4_resume_perf(struct coresight_device *csdev)
+{
+       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+       struct csdev_access *csa = &csdev->access;
+
+       if (coresight_get_mode(csdev) != CS_MODE_PERF)
+               return -EINVAL;
+
+       etm4_cs_unlock(drvdata, csa);
+       etm4_enable_trace_unit(drvdata);
+       etm4_cs_lock(drvdata, csa);
+
+       drvdata->paused = false;
+       return 0;
+}
+
+static void etm4_pause_perf(struct coresight_device *csdev)
+{
+       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+       struct csdev_access *csa = &csdev->access;
+
+       if (coresight_get_mode(csdev) != CS_MODE_PERF)
+               return;
+
+       etm4_cs_unlock(drvdata, csa);
+       etm4_disable_trace_unit(drvdata);
+       etm4_cs_lock(drvdata, csa);
+
+       drvdata->paused = true;
+}
+
 static const struct coresight_ops_source etm4_source_ops = {
        .cpu_id         = etm4_cpu_id,
        .enable         = etm4_enable,
        .disable        = etm4_disable,
+       .resume_perf    = etm4_resume_perf,
+       .pause_perf     = etm4_pause_perf,
 };
 
 static const struct coresight_ops etm4_cs_ops = {

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index bd7db36ba197bdb68ac915bfab71ff0860615639..ac649515054d905fa365203bd35f1d839b03292f 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -983,6 +983,7 @@ struct etmv4_save_state {
  * @state_needs_restore: True when there is context to restore after PM exit
  * @skip_power_up: Indicates if an implementation can skip powering up
  *                the trace unit.
+ * @paused:    Indicates if the trace unit is paused.
  * @arch_features: Bitmap of arch features of etmv4 devices.
  */
 struct etmv4_drvdata {
@@ -1036,6 +1037,7 @@ struct etmv4_drvdata {
        struct etmv4_save_state         *save_state;
        bool                            state_needs_restore;
        bool                            skip_power_up;
+       bool                            paused;
        DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
 };