drivers/perf: arm_pmu: define armpmu_init_fn

We expect an ARM PMU's init function to have a particular prototype,
which we open-code in a few places. This is less than ideal, considering
that we cast a void value to this type in one location, and a mismatch
could easily be missed.

Add a typedef so that we can ensure this is consistent.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/perf/arm_pmu.c

@@ -989,7 +989,7 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 			 const struct pmu_probe_info *probe_table)
 {
 	const struct of_device_id *of_id;
-	const int (*init_fn)(struct arm_pmu *);
+	armpmu_init_fn init_fn;
 	struct device_node *node = pdev->dev.of_node;
 	struct arm_pmu *pmu;
 	int ret = -ENODEV;

include/linux/perf/arm_pmu.h

@@ -132,10 +132,12 @@ int armpmu_map_event(struct perf_event *event,
 						[PERF_COUNT_HW_CACHE_RESULT_MAX],
 		     u32 raw_event_mask);
 
+typedef int (*armpmu_init_fn)(struct arm_pmu *);
+
 struct pmu_probe_info {
 	unsigned int cpuid;
 	unsigned int mask;
-	int (*init)(struct arm_pmu *);
+	armpmu_init_fn init;
 };
 
 #define PMU_PROBE(_cpuid, _mask, _fn)	\