Re: [PATCH v3] perf/arm_cspmu: Add Arm system PMU

[Ilkka Koskinen <ilkka@os.amperecomputing.com>]

On Mon, 5 Oct 2026, Robin Murphy wrote:
> Arm's latest Compute Subsystems and SoCs are using a common PMU block
> in various places which can mostly just be driven as a generic 64-bit
> CoreSight PMU, but does have an IMP-DEF register for additional
> filtering. The details of event and filter encodings depend on the
> particular PMU instance, so are left to the higher level Arm Telemetry
> Solution tooling.
>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Looks good to me,

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


> ---
>
> v3: Fix 32-bit COMPILE_TEST to match arm_cspmu.c
>
> drivers/perf/arm_cspmu/Kconfig      |  7 +++
> drivers/perf/arm_cspmu/Makefile     |  1 +
> drivers/perf/arm_cspmu/arm_cspmu.c  |  7 +++
> drivers/perf/arm_cspmu/arm_cspmu.h  |  1 +
> drivers/perf/arm_cspmu/arm_syspmu.c | 67 +++++++++++++++++++++++++++++
> 5 files changed, 83 insertions(+)
> create mode 100644 drivers/perf/arm_cspmu/arm_syspmu.c
>
> diff --git a/drivers/perf/arm_cspmu/Kconfig b/drivers/perf/arm_cspmu/Kconfig
> index 6f4e28fc84a2..25bd55f036a4 100644
> --- a/drivers/perf/arm_cspmu/Kconfig
> +++ b/drivers/perf/arm_cspmu/Kconfig
> @@ -27,3 +27,10 @@ config AMPERE_CORESIGHT_PMU_ARCH_SYSTEM_PMU
>
> 	  In the first phase, the driver enables support on MCU PMU used in
> 	  AmpereOne SoC family.
> +
> +config ARM_SYSTEM_PMU
> +	tristate "Arm System PMU"
> +	depends on ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU
> +	help
> +	  Support additional event filtering attributes for the CoreSight-based
> +	  PMU blocks found in various parts of Arm Compute Subsystems and SoCs.
> diff --git a/drivers/perf/arm_cspmu/Makefile b/drivers/perf/arm_cspmu/Makefile
> index 220a734efd54..90c3cd710157 100644
> --- a/drivers/perf/arm_cspmu/Makefile
> +++ b/drivers/perf/arm_cspmu/Makefile
> @@ -8,3 +8,4 @@ arm_cspmu_module-y := arm_cspmu.o
>
> obj-$(CONFIG_NVIDIA_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += nvidia_cspmu.o
> obj-$(CONFIG_AMPERE_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += ampere_cspmu.o
> +obj-$(CONFIG_ARM_SYSTEM_PMU) += arm_syspmu.o
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
> index 912f03ce3ef5..9f298ea1a974 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> @@ -358,6 +358,13 @@ static struct arm_cspmu_impl_match impl_match[] = {
> 		.module		= NULL,
> 		.impl_init_ops	= NULL,
> 	},
> +	{
> +		.module_name	= "arm_syspmu",
> +		.pmiidr_val	= ARM_CSPMU_IMPL_ID_ARM,
> +		.pmiidr_mask	= PMIIDR_IMPLEMENTER,
> +		.module		= NULL,
> +		.impl_init_ops	= NULL,
> +	},
> 	{
> 		.module_name	= "ampere_cspmu",
> 		.pmiidr_val	= ARM_CSPMU_IMPL_ID_AMPERE,
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.h b/drivers/perf/arm_cspmu/arm_cspmu.h
> index c4058d602477..03e34692a965 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.h
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.h
> @@ -149,6 +149,7 @@
>
> /* JEDEC-assigned JEP106 identification code */
> #define ARM_CSPMU_IMPL_ID_NVIDIA	0x36B
> +#define ARM_CSPMU_IMPL_ID_ARM		0x43B
> #define ARM_CSPMU_IMPL_ID_AMPERE	0xA16
>
> /* PMDEVARCH */
> diff --git a/drivers/perf/arm_cspmu/arm_syspmu.c b/drivers/perf/arm_cspmu/arm_syspmu.c
> new file mode 100644
> index 000000000000..2f5ceda5c4d1
> --- /dev/null
> +++ b/drivers/perf/arm_cspmu/arm_syspmu.c
> @@ -0,0 +1,67 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/module.h>
> +
> +#include "arm_cspmu.h"
> +
> +#define PMEVFILT3R	0x200
> +
> +static struct attribute *arm_syspmu_format_attrs[] = {
> +	ARM_CSPMU_FORMAT_EVENT_ATTR,
> +	ARM_CSPMU_FORMAT_FILTER_ATTR,
> +	ARM_CSPMU_FORMAT_FILTER2_ATTR,
> +	ARM_CSPMU_FORMAT_ATTR(filter3, "config3:0-63"),
> +	NULL,
> +};
> +
> +static struct attribute **arm_syspmu_get_format_attrs(const struct arm_cspmu *cspmu)
> +{
> +	return devm_kmemdup(cspmu->dev, arm_syspmu_format_attrs,
> +			    sizeof(arm_syspmu_format_attrs), GFP_KERNEL);
> +}
> +
> +static void arm_syspmu_set_ev_filter(struct arm_cspmu *cspmu,
> +				     const struct perf_event *event)
> +{
> +	u32 offset = 8 * event->hw.idx;
> +
> +	writeq(event->attr.config1, cspmu->base0 + PMEVFILTR + offset);
> +	writeq(event->attr.config2, cspmu->base0 + PMEVFILT2R + offset);
> +	writeq(event->attr.config3, cspmu->base0 + PMEVFILT3R + offset);
> +}
> +
> +static int arm_syspmu_init_ops(struct arm_cspmu *cspmu)
> +{
> +	switch (FIELD_GET(PMIIDR_PRODUCTID, cspmu->impl.pmiidr)) {
> +	case 0x9c3:
> +		cspmu->impl.ops.set_ev_filter = arm_syspmu_set_ev_filter;
> +		cspmu->impl.ops.get_format_attrs = arm_syspmu_get_format_attrs;
> +		break;
> +	default:
> +		break;
> +	}
> +	return 0;
> +}
> +
> +static const struct arm_cspmu_impl_match arm_syspmu_param = {
> +	.pmiidr_val	= ARM_CSPMU_IMPL_ID_ARM,
> +	.module		= THIS_MODULE,
> +	.impl_init_ops	= arm_syspmu_init_ops
> +};
> +
> +static int __init arm_syspmu_init(void)
> +{
> +	return arm_cspmu_impl_register(&arm_syspmu_param);
> +}
> +
> +static void __exit arm_syspmu_exit(void)
> +{
> +	arm_cspmu_impl_unregister(&arm_syspmu_param);
> +}
> +
> +module_init(arm_syspmu_init);
> +module_exit(arm_syspmu_exit);
> +
> +MODULE_DESCRIPTION("Arm System PMU Driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.54.0.dirty
>
>
>