perf/ARM: Use common PMU interrupt disabled code

Make the ARM perf code use the new common PMU interrupt disabled code.

This allows perf to work on ARM machines without a working PMU
interrupt (for example, raspberry pi).

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
[peterz: applied changes suggested by Will]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1405161712190.11099@vincent-weaver-1.umelst.maine.edu
[ Small readability tweaks to the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/arm/kernel/perf_event.c

@@ -410,7 +410,7 @@ __hw_perf_event_init(struct perf_event *event)
 	 */
 	hwc->config_base	    |= (unsigned long)mapping;
 
-	if (!hwc->sample_period) {
+	if (!is_sampling_event(event)) {
 		/*
 		 * For non-sampling runs, limit the sample_period to half
 		 * of the counter width. That way, the new counter value

arch/arm/kernel/perf_event_cpu.c

@@ -126,8 +126,8 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
 
 	irqs = min(pmu_device->num_resources, num_possible_cpus());
 	if (irqs < 1) {
-		pr_err("no irqs for PMUs defined\n");
-		return -ENODEV;
+		printk_once("perf/ARM: No irqs for PMU defined, sampling events not supported\n");
+		return 0;
 	}
 
 	irq = platform_get_irq(pmu_device, 0);
@@ -191,6 +191,10 @@ static void cpu_pmu_init(struct arm_pmu *cpu_pmu)
 	/* Ensure the PMU has sane values out of reset. */
 	if (cpu_pmu->reset)
 		on_each_cpu(cpu_pmu->reset, cpu_pmu, 1);
+
+	/* If no interrupts available, set the corresponding capability flag */
+	if (!platform_get_irq(cpu_pmu->plat_device, 0))
+		cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
 }
 
 /*