On Tue, 11 Mar 2025 at 17:05, Leo Yan <leo.yan@xxxxxxx> wrote:
>
> 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@xxxxxxx>
> ---
> .../coresight/coresight-etm4x-core.c | 42 ++++++++++++++++++-
> drivers/hwtracing/coresight/coresight-etm4x.h | 2 +
> 2 files changed, 43 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 53cb0569dbbf..5b69446db947 100644
> --- 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 bd7db36ba197..ac649515054d 100644
> --- 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);
> };
>
> --
> 2.34.1
>
Reviewed-by: Mike Leach <mike.leach@xxxxxxxxxx>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
