[PATCH v3 15/31] coresight: etm4x: Hook CPU PM callbacks

[Mike Leach]

On Mon, 15 Sept 2025 at 11:34, Leo Yan <leo.yan at arm.com> wrote:
>
> Since the CoreSight core layer has registered CPU PM notifiers, this
> patch hooks CPU save and restore callbacks to be invoked from the core
> layer.
>
> The CPU PM notifier in the ETMv4 driver is no longer needed, remove it
> along with its registration and unregistration code.
>
> Signed-off-by: Leo Yan <leo.yan at arm.com>
> ---
>  drivers/hwtracing/coresight/coresight-etm4x-core.c | 73 ++++++----------------
>  1 file changed, 18 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 7e66d094269de4a1344f5d962bc320b2603b7627..ec7e8d09ce58d62dac826fba9edafc967504a1a5 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -1186,19 +1186,6 @@ static void etm4_pause_perf(struct coresight_device *csdev)
>         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 = {
> -       .trace_id       = coresight_etm_get_trace_id,
> -       .source_ops     = &etm4_source_ops,
> -};
> -
>  static bool cpu_supports_sysreg_trace(void)
>  {
>         u64 dfr0 = read_sysreg_s(SYS_ID_AA64DFR0_EL1);
> @@ -1903,8 +1890,9 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
>         return ret;
>  }
>
> -static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
> +static int etm4_cpu_save(struct coresight_device *csdev)
>  {
> +       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>         int ret = 0;
>
>         if (pm_save_enable != PARAM_PM_SAVE_SELF_HOSTED)
> @@ -1927,8 +1915,10 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>         etm4_enable_hw(drvdata, false);
>  }
>
> -static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
> +static void etm4_cpu_restore(struct coresight_device *csdev)
>  {
> +       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +
>         if (pm_save_enable != PARAM_PM_SAVE_SELF_HOSTED)
>                 return;
>
> @@ -1936,38 +1926,19 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>                 __etm4_cpu_restore(drvdata);
>  }
>
> -static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
> -                             void *v)
> -{
> -       struct etmv4_drvdata *drvdata;
> -       unsigned int cpu = smp_processor_id();
> -
> -       if (!etmdrvdata[cpu])
> -               return NOTIFY_OK;
> -
> -       drvdata = etmdrvdata[cpu];
> -
> -       if (WARN_ON_ONCE(drvdata->cpu != cpu))
> -               return NOTIFY_BAD;
> -
> -       switch (cmd) {
> -       case CPU_PM_ENTER:
> -               if (etm4_cpu_save(drvdata))
> -                       return NOTIFY_BAD;
> -               break;
> -       case CPU_PM_EXIT:
> -       case CPU_PM_ENTER_FAILED:
> -               etm4_cpu_restore(drvdata);
> -               break;
> -       default:
> -               return NOTIFY_DONE;
> -       }
> -
> -       return NOTIFY_OK;
> -}
> +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,
> +       .save           = etm4_cpu_save,
> +       .restore        = etm4_cpu_restore,
> +};
>
> -static struct notifier_block etm4_cpu_pm_nb = {
> -       .notifier_call = etm4_cpu_pm_notify,
> +static const struct coresight_ops etm4_cs_ops = {
> +       .trace_id       = coresight_etm_get_trace_id,
> +       .source_ops     = &etm4_source_ops,
>  };
>
>  /* Setup PM. Deals with error conditions and counts */
> @@ -1975,16 +1946,12 @@ static int __init etm4_pm_setup(void)
>  {
>         int ret;
>
> -       ret = cpu_pm_register_notifier(&etm4_cpu_pm_nb);
> -       if (ret)
> -               return ret;
> -
>         ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING,
>                                         "arm/coresight4:starting",
>                                         etm4_starting_cpu, etm4_dying_cpu);
>
>         if (ret)
> -               goto unregister_notifier;
> +               return ret;
>
>         ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
>                                         "arm/coresight4:online",
> @@ -1998,15 +1965,11 @@ static int __init etm4_pm_setup(void)
>
>         /* failed dyn state - remove others */
>         cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
> -
> -unregister_notifier:
> -       cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
>         return ret;
>  }
>
>  static void etm4_pm_clear(void)
>  {
> -       cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
>         cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
>         if (hp_online) {
>                 cpuhp_remove_state_nocalls(hp_online);
>
> --
> 2.34.1
>

c.f. my previous comments regarding save/restore nameing and location

otherwise looks fine.

Mike

-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK