[PATCH v2 1/5] perf/arm_cspmu: Add arm_cspmu_acpi_dev_get

[Ilkka Koskinen]

On Tue, 23 Sep 2025, Besar Wicaksono wrote:

> Add interface to get ACPI device associated with the
> PMU. This ACPI device may contain additional properties
> not covered by the standard properties.
>
> Signed-off-by: Besar Wicaksono <bwicaksono at nvidia.com>
> ---
> drivers/perf/arm_cspmu/arm_cspmu.c | 22 ++++++++++++++++++++++
> drivers/perf/arm_cspmu/arm_cspmu.h |  9 +++++++++
> 2 files changed, 31 insertions(+)
>
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
> index efa9b229e701..75b2d80f783e 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> @@ -1090,6 +1090,28 @@ static int arm_cspmu_acpi_get_cpus(struct arm_cspmu *cspmu)
>
> 	return 0;
> }
> +
> +struct acpi_device *arm_cspmu_acpi_dev_get(const struct arm_cspmu *cspmu)
> +{
> +	char hid[16];
> +	char uid[16];
> +	struct acpi_device *adev;
> +	const struct acpi_apmt_node *apmt_node;
> +
> +	apmt_node = arm_cspmu_apmt_node(cspmu->dev);
> +	if (!apmt_node || apmt_node->type != ACPI_APMT_NODE_TYPE_ACPI)
> +		return NULL;
> +
> +	memset(hid, 0, sizeof(hid));
> +	memset(uid, 0, sizeof(uid));
> +
> +	memcpy(hid, &apmt_node->inst_primary, sizeof(apmt_node->inst_primary));
> +	sprintf(uid, "%u", apmt_node->inst_secondary);
> +
> +	adev = acpi_dev_get_first_match_dev(hid, uid, -1);
> +	return adev;

I would rather drop adev completely and just do
"return acpi_dev_get_first_match_dev(hid,  uid, -1);"

Regardless,

   Reviewed-by: Ilkka Koskinen <ilkka at os.amperecomputing.com>


Cheers, Ilkka

> +}
> +EXPORT_SYMBOL_GPL(arm_cspmu_acpi_dev_get);
> #else
> static int arm_cspmu_acpi_get_cpus(struct arm_cspmu *cspmu)
> {
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.h b/drivers/perf/arm_cspmu/arm_cspmu.h
> index 19684b76bd96..9c5f11f98acd 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.h
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.h
> @@ -8,6 +8,7 @@
> #ifndef __ARM_CSPMU_H__
> #define __ARM_CSPMU_H__
>
> +#include <linux/acpi.h>
> #include <linux/bitfield.h>
> #include <linux/cpumask.h>
> #include <linux/device.h>
> @@ -222,4 +223,12 @@ int arm_cspmu_impl_register(const struct arm_cspmu_impl_match *impl_match);
> /* Unregister vendor backend. */
> void arm_cspmu_impl_unregister(const struct arm_cspmu_impl_match *impl_match);
>
> +#if defined(CONFIG_ACPI)
> +/**
> + * Get ACPI device associated with the PMU.
> + * The caller is responsible for calling acpi_dev_put() on the returned device.
> + */
> +struct acpi_device *arm_cspmu_acpi_dev_get(const struct arm_cspmu *cspmu);
> +#endif
> +
> #endif /* __ARM_CSPMU_H__ */
> -- 
> 2.50.1
>
>