Re: [PATCHv2 1/3] drivers/perf: arm_pmu: Add platform hardware setup hooks.

[Robin Murphy]

Hi Sebastian,

On 06/02/18 14:26, Sebastian Reichel wrote:
Allow platform specific code to be called when enabling or
disabling the hardware.

Since arm_pmu_platdata wants to go away[1], does i.MX53 actually need 
all this machinery, or would it suffice to set DBG_EN from platform code 
at boot time and simply leave it that way?

Robin.

[1] 
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-February/557838.html

Signed-off-by: Martin Fuzzey <mfuz...@parkeon.com>
Signed-off-by: Peter Senna Tschudin <peter.se...@collabora.com>
[rebased to v4.12]
Signed-off-by: Nandor Han <nandor....@ge.com>
[Simplify and cleanup for upstreaming]
Signed-off-by: Sebastian Reichel <sebastian.reic...@collabora.co.uk>
---
  drivers/perf/arm_pmu.c       | 12 ++++++++++++
  include/linux/perf/arm_pmu.h |  5 +++++
  2 files changed, 17 insertions(+)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 7bc5eee96b31..9c282914ee67 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -452,8 +452,10 @@ static int armpmu_event_init(struct perf_event *event)
  static void armpmu_enable(struct pmu *pmu)
  {
        struct arm_pmu *armpmu = to_arm_pmu(pmu);
+       struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
        struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
        int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
+       int err;
  
  	/* For task-bound events we may be called on other CPUs */
        if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
@@ -461,17 +463,27 @@ static void armpmu_enable(struct pmu *pmu)
  
  	if (enabled)
                armpmu->start(armpmu);
+
+       if (platdata && platdata->reserve_hardware) {
+               err = platdata->reserve_hardware(armpmu);
+               if (err)
+                       dev_warn(&armpmu->plat_device->dev, "Could not reserve PMU 
hardware!\n");
+       }
  }
  
  static void armpmu_disable(struct pmu *pmu)
  {
        struct arm_pmu *armpmu = to_arm_pmu(pmu);
+       struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
  
  	/* For task-bound events we may be called on other CPUs */
        if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
                return;
  
  	armpmu->stop(armpmu);
+
+       if (platdata && platdata->release_hardware)
+               platdata->release_hardware(armpmu);
  }
  
  /*
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index af0f44effd44..942ae9bfe971 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -17,6 +17,8 @@
  #include <linux/sysfs.h>
  #include <asm/cputype.h>
  
+struct arm_pmu;
+
  /*
   * struct arm_pmu_platdata - ARM PMU platform data
   *
@@ -31,6 +33,8 @@
  struct arm_pmu_platdata {
        irqreturn_t (*handle_irq)(int irq, void *dev,
                                  irq_handler_t pmu_handler);
+       int (*reserve_hardware)(struct arm_pmu *arm_pmu);
+       void (*release_hardware)(struct arm_pmu *arm_pmu);
        unsigned long irq_flags;
  };
  
@@ -112,6 +116,7 @@ struct arm_pmu {
        int             (*map_event)(struct perf_event *event);
        int             num_events;
        u64             max_period;
+       bool            reserved_hardware;
        bool            secure_access; /* 32-bit ARM only */
  #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
        DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);