Release 4.12 drivers/perf/arm_pmu_acpi.c
/*
* 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;
/*
* 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);
}
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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);
}
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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;
}
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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;
}
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/*
* 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;
}
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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;
}
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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;
}
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subsys_initcall(arm_pmu_acpi_init)
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