/* * 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 #include #include #include #include #include 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; /* * Per the ACPI spec, the MADT cannot describe a PMU that doesn't * have an interrupt. QEMU advertises this by using a GSI of zero, * which is not known to be valid on any hardware despite being * valid per the spec. Take the pragmatic approach and reject a * GSI of zero for now. */ if (!gsi) return 0; 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)