[PATCH v5 08/11] arm-cci: Provide hook for writing to PMU counters

Mark Rutland
2016-01-11T10:54:54Z

On Mon, Jan 04, 2016 at 11:54:47AM +0000, Suzuki K. Poulose wrote:
> Add a hook for writing to CCI PMU counters. This callback
> can be used for CCI models which requires some extra work
> to program the PMU counter values. To accommodate group writes
> and single counter writes, the call back accepts a bitmask
> of the counter indices which need to be programmed with the
> given value.
>
> Cc: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
> ---
> drivers/bus/arm-cci.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
> index 2f1fcf0..47c9581 100644
> --- a/drivers/bus/arm-cci.c
> +++ b/drivers/bus/arm-cci.c
> @@ -134,6 +134,7 @@ struct cci_pmu_model {
> struct event_range event_ranges[CCI_IF_MAX];
> int (*validate_hw_event)(struct cci_pmu *, unsigned long);
> int (*get_event_idx)(struct cci_pmu *, struct cci_pmu_hw_events *, unsigned long);
> + void (*write_counters)(struct cci_pmu *, unsigned long *, u32 val);
> };
>
> static struct cci_pmu_model cci_pmu_models[];
> @@ -846,7 +847,15 @@ static void pmu_write_counter(struct perf_event *event, u32 value)
> dev_err(&cci_pmu->plat_device->dev, "Invalid CCI PMU counter %d\n", idx);
> return;
> }
> - __pmu_write_counter(cci_pmu, value, idx);
> +
> + if (cci_pmu->model->write_counters) {
> + unsigned long mask[BITS_TO_LONGS(cci_pmu->num_cntrs)];
> +
> + memset(mask, 0, BITS_TO_LONGS(cci_pmu->num_cntrs) * sizeof(unsigned long));
> + set_bit(idx, mask);
> + cci_pmu->model->write_counters(cci_pmu, mask, value);
> + } else
> + __pmu_write_counter(cci_pmu, value, idx);
> }

It would be much simpler to always log writes here, and only do the real
wirtes in batches when we re-enable the PMU (with appropriate
disable/enable calls in the IRQ handler).

We'd still need special hooks for CCIs which require a special dance to
program them, but all the logic to handle the writes would be in one
place.

This should work, regardless.

Thanks,
Mark.

>
> /* Write a value to a given set of counters */
> @@ -861,7 +870,10 @@ static void __pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask, u
> static void __maybe_unused
> pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask, u32 value)
> {
> - __pmu_write_counters(cci_pmu, mask, value);
> + if (cci_pmu->model->write_counters)
> + cci_pmu->model->write_counters(cci_pmu, mask, value);
> + else
> + __pmu_write_counters(cci_pmu, mask, value);
> }
>
> static u64 pmu_event_update(struct perf_event *event)
> --
> 1.7.9.5
>