[PATCH v11 6/7] arm64: pmu: Detect and enable multiple PMUs in an ACPI system

Jeremy Linton
2016-12-02T18:56:00Z

Its possible that an ACPI system has multiple CPU types in it
with differing PMU counters. Iterate the CPU's and make a determination
about how many of each type exist in the system. Then take and create
a PMU platform device for each type, and assign it the interrupts parsed
from the MADT. Creating a platform device is necessary because the PMUs
are not described as devices in the DSDT table.

This code is loosely based on earlier work by Mark Salter.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
---
drivers/perf/arm_pmu.c | 8 +-
drivers/perf/arm_pmu_acpi.c | 231 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 238 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index f676573..fa40294 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -1068,7 +1068,13 @@ int arm_pmu_device_probe(struct platform_device *pdev,
if (!ret)
ret = init_fn(pmu);
} else if (probe_table) {
- ret = probe_plat_pmu(pmu, probe_table, read_cpuid_id());
+ if (acpi_disabled) {
+ /* use the current cpu. */
+ ret = probe_plat_pmu(pmu, probe_table,
+ read_cpuid_id());
+ } else {
+ ret = probe_plat_pmu(pmu, probe_table, pdev->id);
+ }
}

if (ret) {
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index 2008001..e4e107c 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -2,13 +2,17 @@
* ARM ACPI PMU support
*
* Copyright (C) 2015 Red Hat Inc.
+ * Copyright (C) 2016 ARM Ltd.
* Author: Mark Salter <msalter@redhat.com>
+ * Jeremy Linton <jeremy.linton@arm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/

+#define pr_fmt(fmt) "ACPI-PMU: " fmt
+
#include <asm/cpu.h>
#include <linux/acpi.h>
#include <linux/irq.h>
@@ -20,9 +24,16 @@
struct pmu_irq {
int gsi;
int trigger;
+ int irq;
bool used;
};

+struct pmu_types {
+ struct list_head list;
+ int cpu_type;
+ int cpu_count;
+};
+
static struct pmu_irq pmu_irqs[NR_CPUS];

/*
@@ -38,3 +49,223 @@ void __init arm_pmu_parse_acpi(int cpu, struct acpi_madt_generic_interrupt *gic)
else
pmu_irqs[cpu].trigger = ACPI_LEVEL_SENSITIVE;
}
+
+static void __init arm_pmu_acpi_handle_alloc_failure(struct list_head *pmus)
+{
+ int i;
+ struct pmu_types *pmu, *safe_temp;
+
+ list_for_each_entry_safe(pmu, safe_temp, pmus, list) {
+ list_del(&pmu->list);
+ kfree(pmu);
+ }
+
+ for_each_possible_cpu(i)
+ if (pmu_irqs[i].irq > 0)
+ acpi_unregister_gsi(pmu_irqs[i].gsi);
+}
+
+/*
+ * Count number and type of CPU cores in the system. Returns the number
+ * of "unused" MADT entries we could not associate with a PMU. This can
+ * be the result of CPU's not being online, or errors in the MADT.
+ * Under normal circumstances this will be 0.
+ */
+static int __init arm_pmu_acpi_determine_cpu_types(struct list_head *pmus)
+{
+ int i;
+ int unused_madt_entries = 0;
+
+ for_each_possible_cpu(i) {
+ u32 reg_midr = read_specific_cpuid(i);
+ struct pmu_types *pmu;
+
+ /*
+ * Ignore GSI registration failure for now, as
+ * some of the MADT entries may not be used.
+ */
+ pmu_irqs[i].irq = acpi_register_gsi(NULL, pmu_irqs[i].gsi,
+ pmu_irqs[i].trigger,
+ ACPI_ACTIVE_HIGH);
+ /* likely not online */
+ if (reg_midr == 0) {
+ unused_madt_entries++;
+ continue;
+ }
+
+ list_for_each_entry(pmu, pmus, list) {
+ if (pmu->cpu_type == reg_midr) {
+ pmu->cpu_count++;
+ break;
+ }
+ }
+
+ /* we didn't find the CPU type, add an entry to identify it */
+ if (&pmu->list == pmus) {
+ pmu = kzalloc(sizeof(struct pmu_types), GFP_KERNEL);
+ if (!pmu) {
+ pr_err("Unable to allocate pmu_types\n");
+ arm_pmu_acpi_handle_alloc_failure(pmus);
+ break;
+ }
+ pmu->cpu_type = reg_midr;
+ pmu->cpu_count++;
+ list_add_tail(&pmu->list, pmus);
+ }
+ }
+
+ return unused_madt_entries;
+}
+
+static int __init arm_pmu_acpi_register_device(int count, struct resource *res,
+ int cpu_id)
+{
+ struct platform_device *pdev;
+ int err = -ENOMEM;
+
+ pdev = platform_device_alloc(ARMV8_PMU_PDEV_NAME, cpu_id);
+ if (pdev) {
+ err = platform_device_add_resources(pdev, res, count);
+ if (!err)
+ err = platform_device_add(pdev);
+ if (err) {
+ pr_warn("Unable to register PMU device\n");
+ platform_device_put(pdev);
+ }
+ } else {
+ pr_warn("Unable to allocate platform device\n");
+ }
+
+ return err;
+}
+
+static void __init arm_pmu_acpi_unregister_pmu_gsi(int cpu_id)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+
+ if (read_specific_cpuid(i) == cpu_id) {
+ pmu_irqs[i].used = false;
+ if (pmu_irqs[i].irq > 0)
+ acpi_unregister_gsi(pmu_irqs[i].gsi);
+ pmu_irqs[i].gsi = -ENODEV;
+ }
+ }
+}
+
+/*
+ * Registers the group of PMU interfaces which correspond to the 'cpu_id'.
+ * This group utilizes 'count' resources in the 'res'.
+ */
+static int __init arm_pmu_acpi_register_pmu(int count, struct resource *res,
+ int cpu_id)
+{
+ int err;
+
+ err = arm_pmu_acpi_register_device(count, res, cpu_id);
+
+ /* unmark and unregister GSIs for this PMU */
+ if (err)
+ arm_pmu_acpi_unregister_pmu_gsi(cpu_id);
+
+ return err;
+}
+
+int arm_pmu_acpi_retrieve_irq(struct resource *res, int cpu)
+{
+ int irq = -ENODEV;
+
+ if (pmu_irqs[cpu].used) {
+ pr_info("CPU %d's interrupt is already used\n", cpu);
+ } else {
+ pmu_irqs[cpu].used = true;
+ res->start = pmu_irqs[cpu].irq;
+ res->end = pmu_irqs[cpu].irq;
+ res->flags = IORESOURCE_IRQ;
+ if (pmu_irqs[cpu].trigger == ACPI_EDGE_SENSITIVE)
+ res->flags |= IORESOURCE_IRQ_HIGHEDGE;
+ else
+ res->flags |= IORESOURCE_IRQ_HIGHLEVEL;
+ }
+ return irq;
+}
+
+/*
+ * For the given cpu/pmu type, walk all known GSIs, register them, and add
+ * them to the resource structure. Return the number of GSI's contained
+ * in the res structure, and the id of the last CPU/PMU we added.
+ */
+static int __init arm_pmu_acpi_gsi_res(struct pmu_types *pmus,
+ struct resource *res)
+{
+ int i, count;
+
+ /* lets group all the PMU's from similar CPU's together */
+ count = 0;
+ for_each_possible_cpu(i) {
+ u32 reg_midr = read_specific_cpuid(i);
+
+ if (pmus->cpu_type == reg_midr) {
+ if ((pmu_irqs[i].gsi == 0) && (reg_midr != 0))
+ continue;
+
+ /* likely not online */
+ if (!reg_midr)
+ continue;
+
+ arm_pmu_acpi_retrieve_irq(&res[count], i);
+ count++;
+ }
+ }
+ return count;
+}
+
+static int __init pmu_acpi_register(struct pmu_types *pmu)
+{
+ int count;
+ int err = -ENOMEM;
+ struct resource *res;
+
+ res = kcalloc(pmu->cpu_count, sizeof(struct resource), GFP_KERNEL);
+
+ /* for a given PMU type, collect all the GSIs. */
+ if (res) {
+ count = arm_pmu_acpi_gsi_res(pmu, res);
+ /* register this set of interrupts with a new PMU device */
+ err = arm_pmu_acpi_register_pmu(pmu->cpu_count, res,
+ pmu->cpu_type);
+ if (!err)
+ pr_info("Register %d devices for %X\n", count,
+ pmu->cpu_type);
+ kfree(res);
+ } else {
+ pr_warn("PMU unable to allocate interrupt resource\n");
+ arm_pmu_acpi_unregister_pmu_gsi(pmu->cpu_type);
+ }
+ return err;
+}
+
+static int __init pmu_acpi_init(void)
+{
+ struct pmu_types *pmu, *safe_temp;
+ bool unused_madt_entries;
+ LIST_HEAD(pmus);
+
+ if (acpi_disabled)
+ return 0;
+
+ unused_madt_entries = arm_pmu_acpi_determine_cpu_types(&pmus);
+
+ list_for_each_entry_safe(pmu, safe_temp, &pmus, list) {
+ pmu->cpu_count += unused_madt_entries;
+ pmu_acpi_register(pmu);
+
+ list_del(&pmu->list);
+ kfree(pmu);
+ }
+
+ return 0;
+}
+
+arch_initcall(pmu_acpi_init);
--
2.5.5