drivers/perf: arm_pmu: manage interrupts per-cpu

When requesting or freeing interrupts, we use platform_get_irq() to find
relevant irqs, backing this up with additional information in an
optional irq_affinity table.

This means that our irq request and free paths are tied to a
platform_device, and our request path must jump through a number of
hoops in order to determine the required affinity of each interrupt.

Given that the affinity must be static, we can compute the affinity once
up-front at probe time, simplifying the irq request and free paths. By
recording interrupts in a per-cpu data structure, we simplify a few
paths, and permit a subsequent rework of the request and free paths.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[will: rename local nr_irqs variable to avoid conflict with global]
Signed-off-by: Will Deacon <will.deacon@arm.com>

include/linux/perf/arm_pmu.h

@@ -75,6 +75,8 @@ struct pmu_hw_events {
 	 * already have to allocate this struct per cpu.
 	 */
 	struct arm_pmu		*percpu_pmu;
+
+	int irq;
 };
 
 enum armpmu_attr_groups {
@@ -88,7 +90,6 @@ struct arm_pmu {
 	struct pmu	pmu;
 	cpumask_t	active_irqs;
 	cpumask_t	supported_cpus;
-	int		*irq_affinity;
 	char		*name;
 	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
 	void		(*enable)(struct perf_event *event);