arm64: 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, 54 insertions, 4 deletions

diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h
index e6f087806aaf..b7710a59672c 100644
--- a/arch/arm64/include/asm/pmu.h
+++ b/arch/arm64/include/asm/pmu.h
@@ -44,6 +44,7 @@ struct pmu_hw_events {
 struct arm_pmu {
         struct pmu              pmu;
         cpumask_t               active_irqs;
+        int                     *irq_affinity;
         const char              *name;
         irqreturn_t             (*handle_irq)(int irq_num, void *dev);
         void                    (*enable)(struct hw_perf_event *evt, int idx);
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 68a74151fa6c..195991dadc37 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -25,8 +25,10 @@
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
+#include <linux/of.h>
 #include <linux/perf_event.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>
 
@@ -405,7 +407,12 @@ armpmu_release_hardware(struct arm_pmu *armpmu)
                 free_percpu_irq(irq, &cpu_hw_events);
         } else {
                 for (i = 0; i < irqs; ++i) {
-                        if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
+                        int cpu = i;
+
+                        if (armpmu->irq_affinity)
+                                cpu = armpmu->irq_affinity[i];
+
+                        if (!cpumask_test_and_clear_cpu(cpu, &armpmu->active_irqs))
                                 continue;
                         irq = platform_get_irq(pmu_device, i);
                         if (irq > 0)
@@ -459,19 +466,24 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
                 on_each_cpu(armpmu_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 (armpmu->irq_affinity)
+                                cpu = armpmu->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_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
-                                                irq, i);
+                                                irq, cpu);
                                 continue;
                         }
 
@@ -485,7 +497,7 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
                                 return err;
                         }
 
-                        cpumask_set_cpu(i, &armpmu->active_irqs);
+                        cpumask_set_cpu(cpu, &armpmu->active_irqs);
                 }
         }
 
@@ -1298,9 +1310,46 @@ static const struct of_device_id armpmu_of_device_ids[] = {
 
 static int armpmu_device_probe(struct platform_device *pdev)
 {
+        int i, *irqs;
+
         if (!cpu_pmu)
                 return -ENODEV;
 
+        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);
+
         cpu_pmu->plat_device = pdev;
         return 0;
 }