ARM: pmu: add support for interrupt-affinity property

Historically, the PMU devicetree bindings have expected SPIs to be
listed in order of *logical* CPU number. This is problematic for
bootloaders, especially when the boot CPU (logical ID 0) isn't listed
first in the devicetree.

This patch adds a new optional property, interrupt-affinity, to the
PMU node which allows the interrupt affinity to be described using
a list of phandled to CPU nodes, with each entry in the list
corresponding to the SPI at the same index in the interrupts property.

Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 63 insertions, 7 deletions

diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index b1596bd59129..675e4ab79f68 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -92,6 +92,7 @@ struct pmu_hw_events {
 struct arm_pmu {
         struct pmu      pmu;
         cpumask_t       active_irqs;
+        int             *irq_affinity;
         char            *name;
         irqreturn_t     (*handle_irq)(int irq_num, void *dev);
         void            (*enable)(struct perf_event *event);
diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index 7eb86e294c68..91c7ba182dcd 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -92,11 +92,16 @@ static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu)
                 free_percpu_irq(irq, &hw_events->percpu_pmu);
         } else {
                 for (i = 0; i < irqs; ++i) {
-                        if (!cpumask_test_and_clear_cpu(i, &cpu_pmu->active_irqs))
+                        int cpu = i;
+
+                        if (cpu_pmu->irq_affinity)
+                                cpu = cpu_pmu->irq_affinity[i];
+
+                        if (!cpumask_test_and_clear_cpu(cpu, &cpu_pmu->active_irqs))
                                 continue;
                         irq = platform_get_irq(pmu_device, i);
                         if (irq >= 0)
-                                free_irq(irq, per_cpu_ptr(&hw_events->percpu_pmu, i));
+                                free_irq(irq, per_cpu_ptr(&hw_events->percpu_pmu, cpu));
                 }
         }
 }
@@ -128,32 +133,37 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
                 on_each_cpu(cpu_pmu_enable_percpu_irq, &irq, 1);
         } else {
                 for (i = 0; i < irqs; ++i) {
+                        int cpu = i;
+
                         err = 0;
                         irq = platform_get_irq(pmu_device, i);
                         if (irq < 0)
                                 continue;
 
+                        if (cpu_pmu->irq_affinity)
+                                cpu = cpu_pmu->irq_affinity[i];
+
                         /*
                          * If we have a single PMU interrupt that we can't shift,
                          * assume that we're running on a uniprocessor machine and
                          * continue. Otherwise, continue without this interrupt.
                          */
-                        if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
+                        if (irq_set_affinity(irq, cpumask_of(cpu)) && irqs > 1) {
                                 pr_warn("unable to set irq affinity (irq=%d, cpu=%u)\n",
-                                        irq, i);
+                                        irq, cpu);
                                 continue;
                         }
 
                         err = request_irq(irq, handler,
                                           IRQF_NOBALANCING | IRQF_NO_THREAD, "arm-pmu",
-                                          per_cpu_ptr(&hw_events->percpu_pmu, i));
+                                          per_cpu_ptr(&hw_events->percpu_pmu, cpu));
                         if (err) {
                                 pr_err("unable to request IRQ%d for ARM PMU counters\n",
                                         irq);
                                 return err;
                         }
 
-                        cpumask_set_cpu(i, &cpu_pmu->active_irqs);
+                        cpumask_set_cpu(cpu, &cpu_pmu->active_irqs);
                 }
         }
 
@@ -291,6 +301,48 @@ static int probe_current_pmu(struct arm_pmu *pmu)
         return ret;
 }
 
+static int of_pmu_irq_cfg(struct platform_device *pdev)
+{
+        int i;
+        int *irqs = kcalloc(pdev->num_resources, sizeof(*irqs), GFP_KERNEL);
+
+        if (!irqs)
+                return -ENOMEM;
+
+        for (i = 0; i < pdev->num_resources; ++i) {
+                struct device_node *dn;
+                int cpu;
+
+                dn = of_parse_phandle(pdev->dev.of_node, "interrupt-affinity",
+                                      i);
+                if (!dn) {
+                        pr_warn("Failed to parse %s/interrupt-affinity[%d]\n",
+                                of_node_full_name(dn), i);
+                        break;
+                }
+
+                for_each_possible_cpu(cpu)
+                        if (arch_find_n_match_cpu_physical_id(dn, cpu, NULL))
+                                break;
+
+                of_node_put(dn);
+                if (cpu >= nr_cpu_ids) {
+                        pr_warn("Failed to find logical CPU for %s\n",
+                                dn->name);
+                        break;
+                }
+
+                irqs[i] = cpu;
+        }
+
+        if (i == pdev->num_resources)
+                cpu_pmu->irq_affinity = irqs;
+        else
+                kfree(irqs);
+
+        return 0;
+}
+
 static int cpu_pmu_device_probe(struct platform_device *pdev)
 {
         const struct of_device_id *of_id;
@@ -315,7 +367,10 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
 
         if (node && (of_id = of_match_node(cpu_pmu_of_device_ids, pdev->dev.of_node))) {
                 init_fn = of_id->data;
-                ret = init_fn(pmu);
+
+                ret = of_pmu_irq_cfg(pdev);
+                if (!ret)
+                        ret = init_fn(pmu);
         } else {
                 ret = probe_current_pmu(pmu);
         }