ARM: perf: [WIP] Map PMU IRQ affinities correctly

This patch determines the (mpidr,irq) pairings associated with each
PMU from the DT at probe time, and uses this information to work
out which IRQs to request for which logical CPU when enabling an
event on a PMU.

This patch also ensures that each PMU's init function is called on
a CPU of the correct type.
Previously, this was relying on luck.

Signed-off-by: Dave Martin <dave.martin@linaro.org>

2 files changed, 100 insertions, 31 deletions

diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index c5ce783cbf3..a7eaad37497 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -78,6 +78,7 @@ struct arm_cpu_pmu {
 	bool			active;
 
 	u32			mpidr;
+	int			irq;
 
 	struct perf_event	*hw_events[ARMPMU_MAX_HWEVENTS];
 	unsigned long		used_mask[BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)];
diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index e9d1995b002..22459d545c7 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -89,46 +89,65 @@ static struct pmu_hw_events *cpu_pmu_get_cpu_events(struct arm_pmu *pmu)
 	return &this_cpu_ptr(pmu->cpu_pmus)->cpu_hw_events;
 }
 
-static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu)
+static int find_logical_cpu(u32 mpidr)
 {
-	int i, irq, irqs;
-	struct platform_device *pmu_device = cpu_pmu->plat_device;
-	int cpu = -1;
+	int cpu = bL_switcher_get_logical_index(mpidr);
 
-	irqs = min(pmu_device->num_resources, num_possible_cpus());
+	if (cpu != -EUNATCH)
+		return cpu;
 
-	for (i = 0; i < irqs; ++i) {
-		cpu = cpumask_next(cpu, &cpu_pmu->valid_cpus);
-		if (!cpumask_test_and_clear_cpu(cpu, &cpu_pmu->active_irqs))
+	return get_logical_index(mpidr);
+}
+
+static void cpu_pmu_free_irq(struct arm_pmu *pmu)
+{
+	int i;
+	int cpu;
+	struct arm_cpu_pmu *cpu_pmu;
+
+	for (i = 0; i < NR_CPUS; ++i) {
+		if (!(cpu_pmu = per_cpu_ptr(pmu->cpu_pmus, i)))
+			continue;
+
+		cpu = find_logical_cpu(cpu_pmu->mpidr);
+		if (cpu < 0)
+			continue;
+
+		if (!cpumask_test_and_clear_cpu(cpu, &pmu->active_irqs))
 			continue;
-		irq = platform_get_irq(pmu_device, i);
-		if (irq >= 0)
-			free_irq(irq, cpu_pmu);
+		if (cpu_pmu->irq >= 0)
+			free_irq(cpu_pmu->irq, pmu);
 	}
 }
 
-static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
+static int cpu_pmu_request_irq(struct arm_pmu *pmu, irq_handler_t handler)
 {
 	int i, err, irq, irqs;
-	struct platform_device *pmu_device = cpu_pmu->plat_device;
-	int cpu = -1;
+	int cpu;
+	struct arm_cpu_pmu *cpu_pmu;
 
-	if (!pmu_device)
-		return -ENODEV;
+	irqs = 0;
+	for (i = 0; i < NR_CPUS; i++)
+		if (per_cpu_ptr(pmu->cpu_pmus, i))
+			++irqs;
 
-	irqs = min(pmu_device->num_resources, num_possible_cpus());
 	if (irqs < 1) {
 		pr_err("no irqs for PMUs defined\n");
 		return -ENODEV;
 	}
 
-	for (i = 0; i < irqs; ++i) {
-		err = 0;
-		cpu = cpumask_next(cpu, &cpu_pmu->valid_cpus);
-		irq = platform_get_irq(pmu_device, i);
+	for (i = 0; i < NR_CPUS; i++) {
+		if (!(cpu_pmu = per_cpu_ptr(pmu->cpu_pmus, i)))
+			continue;
+
+		irq = cpu_pmu->irq;
 		if (irq < 0)
 			continue;
 
+		cpu = find_logical_cpu(cpu_pmu->mpidr);
+		if (cpu < 0 || cpu != i)
+			continue;
+
 		/*
 		 * If we have a single PMU interrupt that we can't shift,
 		 * assume that we're running on a uniprocessor machine and
@@ -136,19 +155,22 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
 		 */
 		if (irq_set_affinity(irq, cpumask_of(cpu)) && irqs > 1) {
 			pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
-				    irq, i);
+				    irq, cpu);
 			continue;
 		}
 
+		pr_debug("%s: requesting IRQ %d for CPU%d\n",
+			 pmu->name, irq, cpu);
+
 		err = request_irq(irq, handler, IRQF_NOBALANCING, "arm-pmu",
-				  cpu_pmu);
+				  pmu);
 		if (err) {
 			pr_err("unable to request IRQ%d for ARM PMU counters\n",
 				irq);
 			return err;
 		}
 
-		cpumask_set_cpu(cpu, &cpu_pmu->active_irqs);
+		cpumask_set_cpu(cpu, &pmu->active_irqs);
 	}
 
 	return 0;
@@ -349,6 +371,41 @@ static int bL_get_partner(int __always_unused cpu, int __always_unused cluster)
 }
 #endif
 
+static int find_irq(struct platform_device *pdev,
+		    struct device_node *pmu_node,
+		    struct device_node *cluster_node,
+		    u32 mpidr)
+{
+	int irq = -1;
+	u32 cluster;
+	u32 core;
+	struct device_node *cores_node;
+	struct device_node *core_node = NULL;
+
+	if (of_property_read_u32(cluster_node, "reg", &cluster) ||
+	    cluster != MPIDR_AFFINITY_LEVEL(mpidr, 1))
+		goto error;
+
+	cores_node = of_get_child_by_name(cluster_node, "cores");
+	if (!cores_node)
+		goto error;
+
+	for_each_child_of_node(cores_node, core_node)
+		if (!of_property_read_u32(core_node, "reg", &core) &&
+		    core == MPIDR_AFFINITY_LEVEL(mpidr, 0))
+			break;
+
+	if (!core_node)
+		goto error;
+
+	irq = platform_get_irq(pdev, core);
+
+error:
+	of_node_put(core_node);
+	of_node_put(cores_node);
+	return irq;
+}
+
 static int cpu_pmu_device_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *of_id;
@@ -370,6 +427,7 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
 		struct device_node *ncluster;
 		int cluster = -1;
 		cpumask_t sibling_mask;
+		cpumask_t phys_sibling_mask;
 		unsigned int i;
 
 		ncluster = of_parse_phandle(node, "cluster", 0);
@@ -397,6 +455,8 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
 			 */
 			BUG();
 
+		cpumask_copy(&phys_sibling_mask, cpu_possible_mask);
+
 		/*
 		 * HACK: Deduce how the switcher will modify the topology
 		 * in order to fill in PMU<->CPU combinations which don't
@@ -406,22 +466,30 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
 		for (i = 0; i < NR_CPUS; i++) {
 			int cpu = i;
 
-			if (cpu_topology[i].socket_id != cluster) {
-				int partner = bL_get_partner(i, cluster);
+			per_cpu_ptr(cpu_pmus, i)->mpidr = -1;
+			per_cpu_ptr(cpu_pmus, i)->irq = -1;
 
-				if (partner != -1)
-					cpu = partner;
+			if (cpu_topology[i].socket_id != cluster) {
+				cpumask_clear_cpu(i, &phys_sibling_mask);
+				cpu = bL_get_partner(i, cluster);
 			}
 
-			per_cpu_ptr(cpu_pmus, i)->mpidr =
-				cpu_logical_map(cpu);
+			if (cpu == -1)
+				cpumask_clear_cpu(i, &sibling_mask);
+			else {
+				int irq = find_irq(pdev, node, ncluster,
+						   cpu_logical_map(cpu));
+				per_cpu_ptr(cpu_pmus, i)->mpidr =
+					cpu_logical_map(cpu);
+				per_cpu_ptr(cpu_pmus, i)->irq = irq;
+			}
 		}
 
 		/*
 		 * This relies on an MP view of the system to choose the right
 		 * CPU to run init_fn:
 		 */
-		smp_call_function_any(&sibling_mask, init_fn, pmu, 1);
+		smp_call_function_any(&phys_sibling_mask, init_fn, pmu, 1);
 
 		bL_switcher_put_enabled();