perf: add hotplug support so that perf continues after hotplug

Current code doesn't restart perf after hotplug and power collapse
which makes monitoring in low power modes difficult. This patch adds
support for the hotplug notifier events and creates a common path for
the power collapse and hotplug events.

Change-Id: I52e6978b1c104fd78bc42e4600ceb111b47b3e11
Signed-off-by: Patrick Fay <pfay@codeaurora.org>

1 files changed, 93 insertions, 35 deletions

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 53e3af9052a9..71154ec99d3c 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -550,6 +550,7 @@ static void armpmu_init(struct arm_pmu *armpmu)
 		.stop		= armpmu_stop,
 		.read		= armpmu_read,
 		.filter_match	= armpmu_filter_match,
+		.events_across_hotplug = 1,
 	};
 }
 
@@ -686,31 +687,12 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
 	return 0;
 }
 
-/*
- * PMU hardware loses all context when a CPU goes offline.
- * When a CPU is hotplugged back in, since some hardware registers are
- * UNKNOWN at reset, the PMU must be explicitly reset to avoid reading
- * junk values out of them.
- */
-static int cpu_pmu_notify(struct notifier_block *b, unsigned long action,
-			  void *hcpu)
-{
-	int cpu = (unsigned long)hcpu;
-	struct arm_pmu *pmu = container_of(b, struct arm_pmu, hotplug_nb);
-
-	if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING)
-		return NOTIFY_DONE;
-
-	if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
-		return NOTIFY_DONE;
-
-	if (pmu->reset)
-		pmu->reset(pmu);
-	else
-		return NOTIFY_DONE;
-
-	return NOTIFY_OK;
-}
+struct cpu_pm_pmu_args {
+	struct arm_pmu	*armpmu;
+	unsigned long	cmd;
+	int		cpu;
+	int		ret;
+};
 
 #ifdef CONFIG_CPU_PM
 static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd)
@@ -758,15 +740,19 @@ static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd)
 	}
 }
 
-static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd,
-			     void *v)
+static void cpu_pm_pmu_common(void *info)
 {
-	struct arm_pmu *armpmu = container_of(b, struct arm_pmu, cpu_pm_nb);
+	struct cpu_pm_pmu_args *data	= info;
+	struct arm_pmu *armpmu		= data->armpmu;
+	unsigned long cmd		= data->cmd;
+	int cpu				= data->cpu;
 	struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
 	int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
 
-	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
-		return NOTIFY_DONE;
+	if (!cpumask_test_cpu(cpu, &armpmu->supported_cpus)) {
+		data->ret = NOTIFY_DONE;
+		return;
+	}
 
 	/*
 	 * Always reset the PMU registers on power-up even if
@@ -775,8 +761,12 @@ static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd,
 	if (cmd == CPU_PM_EXIT && armpmu->reset)
 		armpmu->reset(armpmu);
 
-	if (!enabled)
-		return NOTIFY_OK;
+	if (!enabled) {
+		data->ret = NOTIFY_OK;
+		return;
+	}
+
+	data->ret = NOTIFY_OK;
 
 	switch (cmd) {
 	case CPU_PM_ENTER:
@@ -784,15 +774,29 @@ static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd,
 		cpu_pm_pmu_setup(armpmu, cmd);
 		break;
 	case CPU_PM_EXIT:
-		cpu_pm_pmu_setup(armpmu, cmd);
 	case CPU_PM_ENTER_FAILED:
+		cpu_pm_pmu_setup(armpmu, cmd);
 		armpmu->start(armpmu);
 		break;
 	default:
-		return NOTIFY_DONE;
+		data->ret = NOTIFY_DONE;
+		break;
 	}
 
-	return NOTIFY_OK;
+	return;
+}
+
+static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd,
+			     void *v)
+{
+	struct cpu_pm_pmu_args data = {
+		.armpmu	= container_of(b, struct arm_pmu, cpu_pm_nb),
+		.cmd	= cmd,
+		.cpu	= smp_processor_id(),
+	};
+
+	cpu_pm_pmu_common(&data);
+	return data.ret;
 }
 
 static int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu)
@@ -808,8 +812,62 @@ static void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu)
 #else
 static inline int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu) { return 0; }
 static inline void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu) { }
+static inline void cpu_pm_pmu_common(void *info) { }
 #endif
 
+/*
+ * PMU hardware loses all context when a CPU goes offline.
+ * When a CPU is hotplugged back in, since some hardware registers are
+ * UNKNOWN at reset, the PMU must be explicitly reset to avoid reading
+ * junk values out of them.
+ */
+static int cpu_pmu_notify(struct notifier_block *b, unsigned long action,
+			  void *hcpu)
+{
+	unsigned long masked_action = (action & ~CPU_TASKS_FROZEN);
+	struct cpu_pm_pmu_args data = {
+		.armpmu	= container_of(b, struct arm_pmu, hotplug_nb),
+		.cpu	= (unsigned long)hcpu,
+	};
+
+	if (!cpumask_test_cpu(data.cpu, &data.armpmu->supported_cpus))
+		return NOTIFY_DONE;
+
+	switch (masked_action) {
+	case CPU_STARTING:
+		data.cmd = CPU_PM_EXIT;
+		break;
+	case CPU_DYING:
+		data.cmd = CPU_PM_ENTER;
+		break;
+	case CPU_DOWN_FAILED:
+		data.cmd = CPU_PM_ENTER_FAILED;
+		break;
+	case CPU_ONLINE:
+		if (data.armpmu->plat_device) {
+			struct platform_device *pmu_device =
+				data.armpmu->plat_device;
+			int irq = platform_get_irq(pmu_device, 0);
+
+			if (irq >= 0 && irq_is_percpu(irq)) {
+				smp_call_function_single(data.cpu,
+					cpu_pmu_enable_percpu_irq, &irq, 1);
+			}
+		}
+		return NOTIFY_DONE;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	if (smp_processor_id() == data.cpu)
+		cpu_pm_pmu_common(&data);
+	else
+		smp_call_function_single(data.cpu,
+			cpu_pm_pmu_common, &data, 1);
+
+	return data.ret;
+}
+
 static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
 {
 	int err;