--- /dev/null
+/*
+ * 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)
projects / karo-tx-linux.git / commitdiff