Subject: [PATCH 2/4] arm64: pmu: add fallback probe table

From: [email-masked] (nleeder at codeaurora.org)
Date: Wed, 16 Mar 2016 17:39:11 -0400

On 2016-03-13 19:23, Jeremy Linton wrote:
> From: Mark Salter <[email-masked]>
> 
> In preparation for ACPI support, add a pmu_probe_info table to
> the arm_pmu_device_probe() call. This table gets used when
> probing in the absence of a devicetree node for PMU.
> 
> Signed-off-by: Mark Salter <[email-masked]>
> ---
>  arch/arm64/kernel/perf_event.c | 10 +++++++++-
>  include/linux/perf/arm_pmu.h   |  3 +++
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/perf_event.c 
> b/arch/arm64/kernel/perf_event.c
> index 767c4f6..03e0957 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -901,9 +901,17 @@ static const struct of_device_id
> armv8_pmu_of_device_ids[] = {
>  	{},
>  };
> 
> +static const struct pmu_probe_info armv8_pmu_probe_table[] = {
> +	ARMV8_PMU_PART_PROBE(ARM_CPU_PART_CORTEX_A53, armv8_a53_pmu_init),
> +	ARMV8_PMU_PART_PROBE(ARM_CPU_PART_CORTEX_A57, armv8_a57_pmu_init),
> +	PMU_PROBE(0, 0, armv8_pmuv3_init), /* if all else fails... */
> +	{ /* sentinel value */ }
> +};
> +
>  static int armv8_pmu_device_probe(struct platform_device *pdev)
>  {
> -	return arm_pmu_device_probe(pdev, armv8_pmu_of_device_ids, NULL);
> +	return arm_pmu_device_probe(pdev, armv8_pmu_of_device_ids,
> +				    armv8_pmu_probe_table);
>  }
> 
>  static struct platform_driver armv8_pmu_driver = {
> diff --git a/include/linux/perf/arm_pmu.h 
> b/include/linux/perf/arm_pmu.h
> index 4196c90..495332f 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -145,6 +145,9 @@ struct pmu_probe_info {
>  #define XSCALE_PMU_PROBE(_version, _fn) \
>  	PMU_PROBE(ARM_CPU_IMP_INTEL << 24 | _version, ARM_PMU_XSCALE_MASK, 
> _fn)
> 
> +#define ARMV8_PMU_PART_PROBE(_part, _fn) \
> +	PMU_PROBE((_part) << MIDR_PARTNUM_SHIFT, MIDR_PARTNUM_MASK, _fn)
> +
>  int arm_pmu_device_probe(struct platform_device *pdev,
>  			 const struct of_device_id *of_table,
>  			 const struct pmu_probe_info *probe_table);

Hi Jeremy,
Thanks for pulling these patches together.

Just one comment: MIDR part numbers are not guaranteed unique across 
implementors, so I'd suggest that ARMV8_PMU_PART_PROBE include the 
MIDR_IMPLEMENTOR in the cpuid and mask.

Otherwise everything looks good - I successfully used this patchset as a 
base for getting my pmu driver running with ACPI.

-- Neil
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum, a Linux Foundation Collaborative Project