1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
new file mode 100644
index 000000000000..34c862f213c7
--- /dev/null
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -0,0 +1,256 @@
+/*
+ * ACPI probing code for ARM performance counters.
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/cpumask.h>
+#include <linux/init.h>
+#include <linux/percpu.h>
+#include <linux/perf/arm_pmu.h>
+
+#include <asm/cputype.h>
+
+static DEFINE_PER_CPU(struct arm_pmu *, probed_pmus);
+static DEFINE_PER_CPU(int, pmu_irqs);
+
+static int arm_pmu_acpi_register_irq(int cpu)
+{
+	struct acpi_madt_generic_interrupt *gicc;
+	int gsi, trigger;
+
+	gicc = acpi_cpu_get_madt_gicc(cpu);
+	if (WARN_ON(!gicc))
+		return -EINVAL;
+
+	gsi = gicc->performance_interrupt;
+	if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
+		trigger = ACPI_EDGE_SENSITIVE;
+	else
+		trigger = ACPI_LEVEL_SENSITIVE;
+
+	/*
+	 * Helpfully, the MADT GICC doesn't have a polarity flag for the
+	 * "performance interrupt". Luckily, on compliant GICs the polarity is
+	 * a fixed value in HW (for both SPIs and PPIs) that we cannot change
+	 * from SW.
+	 *
+	 * Here we pass in ACPI_ACTIVE_HIGH to keep the core code happy. This
+	 * may not match the real polarity, but that should not matter.
+	 *
+	 * Other interrupt controllers are not supported with ACPI.
+	 */
+	return acpi_register_gsi(NULL, gsi, trigger, ACPI_ACTIVE_HIGH);
+}
+
+static void arm_pmu_acpi_unregister_irq(int cpu)
+{
+	struct acpi_madt_generic_interrupt *gicc;
+	int gsi;
+
+	gicc = acpi_cpu_get_madt_gicc(cpu);
+	if (!gicc)
+		return;
+
+	gsi = gicc->performance_interrupt;
+	acpi_unregister_gsi(gsi);
+}
+
+static int arm_pmu_acpi_parse_irqs(void)
+{
+	int irq, cpu, irq_cpu, err;
+
+	for_each_possible_cpu(cpu) {
+		irq = arm_pmu_acpi_register_irq(cpu);
+		if (irq < 0) {
+			err = irq;
+			pr_warn("Unable to parse ACPI PMU IRQ for CPU%d: %d\n",
+				cpu, err);
+			goto out_err;
+		} else if (irq == 0) {
+			pr_warn("No ACPI PMU IRQ for CPU%d\n", cpu);
+		}
+
+		per_cpu(pmu_irqs, cpu) = irq;
+	}
+
+	return 0;
+
+out_err:
+	for_each_possible_cpu(cpu) {
+		irq = per_cpu(pmu_irqs, cpu);
+		if (!irq)
+			continue;
+
+		arm_pmu_acpi_unregister_irq(cpu);
+
+		/*
+		 * Blat all copies of the IRQ so that we only unregister the
+		 * corresponding GSI once (e.g. when we have PPIs).
+		 */
+		for_each_possible_cpu(irq_cpu) {
+			if (per_cpu(pmu_irqs, irq_cpu) == irq)
+				per_cpu(pmu_irqs, irq_cpu) = 0;
+		}
+	}
+
+	return err;
+}
+
+static struct arm_pmu *arm_pmu_acpi_find_alloc_pmu(void)
+{
+	unsigned long cpuid = read_cpuid_id();
+	struct arm_pmu *pmu;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		pmu = per_cpu(probed_pmus, cpu);
+		if (!pmu || pmu->acpi_cpuid != cpuid)
+			continue;
+
+		return pmu;
+	}
+
+	pmu = armpmu_alloc();
+	if (!pmu) {
+		pr_warn("Unable to allocate PMU for CPU%d\n",
+			smp_processor_id());
+		return NULL;
+	}
+
+	pmu->acpi_cpuid = cpuid;
+
+	return pmu;
+}
+
+/*
+ * This must run before the common arm_pmu hotplug logic, so that we can
+ * associate a CPU and its interrupt before the common code tries to manage the
+ * affinity and so on.
+ *
+ * Note that hotplug events are serialized, so we cannot race with another CPU
+ * coming up. The perf core won't open events while a hotplug event is in
+ * progress.
+ */
+static int arm_pmu_acpi_cpu_starting(unsigned int cpu)
+{
+	struct arm_pmu *pmu;
+	struct pmu_hw_events __percpu *hw_events;
+	int irq;
+
+	/* If we've already probed this CPU, we have nothing to do */
+	if (per_cpu(probed_pmus, cpu))
+		return 0;
+
+	irq = per_cpu(pmu_irqs, cpu);
+
+	pmu = arm_pmu_acpi_find_alloc_pmu();
+	if (!pmu)
+		return -ENOMEM;
+
+	cpumask_set_cpu(cpu, &pmu->supported_cpus);
+
+	per_cpu(probed_pmus, cpu) = pmu;
+
+	/*
+	 * Log and request the IRQ so the core arm_pmu code can manage it.  In
+	 * some situations (e.g. mismatched PPIs), we may fail to request the
+	 * IRQ. However, it may be too late for us to do anything about it.
+	 * The common ARM PMU code will log a warning in this case.
+	 */
+	hw_events = pmu->hw_events;
+	per_cpu(hw_events->irq, cpu) = irq;
+	armpmu_request_irq(pmu, cpu);
+
+	/*
+	 * Ideally, we'd probe the PMU here when we find the first matching
+	 * CPU. We can't do that for several reasons; see the comment in
+	 * arm_pmu_acpi_init().
+	 *
+	 * So for the time being, we're done.
+	 */
+	return 0;
+}
+
+int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
+{
+	int pmu_idx = 0;
+	int cpu, ret;
+
+	if (acpi_disabled)
+		return 0;
+
+	/*
+	 * Initialise and register the set of PMUs which we know about right
+	 * now. Ideally we'd do this in arm_pmu_acpi_cpu_starting() so that we
+	 * could handle late hotplug, but this may lead to deadlock since we
+	 * might try to register a hotplug notifier instance from within a
+	 * hotplug notifier.
+	 *
+	 * There's also the problem of having access to the right init_fn,
+	 * without tying this too deeply into the "real" PMU driver.
+	 *
+	 * For the moment, as with the platform/DT case, we need at least one
+	 * of a PMU's CPUs to be online at probe time.
+	 */
+	for_each_possible_cpu(cpu) {
+		struct arm_pmu *pmu = per_cpu(probed_pmus, cpu);
+		char *base_name;
+
+		if (!pmu || pmu->name)
+			continue;
+
+		ret = init_fn(pmu);
+		if (ret == -ENODEV) {
+			/* PMU not handled by this driver, or not present */
+			continue;
+		} else if (ret) {
+			pr_warn("Unable to initialise PMU for CPU%d\n", cpu);
+			return ret;
+		}
+
+		base_name = pmu->name;
+		pmu->name = kasprintf(GFP_KERNEL, "%s_%d", base_name, pmu_idx++);
+		if (!pmu->name) {
+			pr_warn("Unable to allocate PMU name for CPU%d\n", cpu);
+			return -ENOMEM;
+		}
+
+		ret = armpmu_register(pmu);
+		if (ret) {
+			pr_warn("Failed to register PMU for CPU%d\n", cpu);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int arm_pmu_acpi_init(void)
+{
+	int ret;
+
+	if (acpi_disabled)
+		return 0;
+
+	/*
+	 * We can't request IRQs yet, since we don't know the cookie value
+	 * until we know which CPUs share the same logical PMU. We'll handle
+	 * that in arm_pmu_acpi_cpu_starting().
+	 */
+	ret = arm_pmu_acpi_parse_irqs();
+	if (ret)
+		return ret;
+
+	ret = cpuhp_setup_state(CPUHP_AP_PERF_ARM_ACPI_STARTING,
+				"perf/arm/pmu_acpi:starting",
+				arm_pmu_acpi_cpu_starting, NULL);
+
+	return ret;
+}
+subsys_initcall(arm_pmu_acpi_init)