This adds core support for saving and restoring CPU PMU registers
for suspend/resume support i.e. deeper C-states in cpuidle terms.
This patch adds support only to ARMv7 PMU registers save/restore.
It needs to be extended to xscale and ARMv6 if needed.
I made this patch because DS-5 is not working on Marvell's CA7 based SoCs.
And it has consulted Sudeep KarkadaNagesha's patch set for multiple PMUs.
Thanks Will and Sudeep's suggestion to only save / restore used events.
Cc: Sudeep KarkadaNagesha <sudeep.karkadanage...@arm.com>
Signed-off-by: Neil Zhang <zhan...@marvell.com>
---
arch/arm/include/asm/pmu.h | 4 +++
arch/arm/kernel/perf_event.c | 2 ++
arch/arm/kernel/perf_event_cpu.c | 28 +++++++++++++++
arch/arm/kernel/perf_event_v7.c | 74 ++++++++++++++++++++++++++++++++++++++
4 files changed, 108 insertions(+)
diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index ae1919b..3de3db7 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -83,6 +83,10 @@ struct arm_pmu {
int (*request_irq)(struct arm_pmu *, irq_handler_t handler);
void (*free_irq)(struct arm_pmu *);
int (*map_event)(struct perf_event *event);
+ int (*register_pm_notifier)(struct arm_pmu *);
+ void (*unregister_pm_notifier)(struct arm_pmu *);
+ void (*save_regs)(struct arm_pmu *);
+ void (*restore_regs)(struct arm_pmu *);
int num_events;
atomic_t active_events;
struct mutex reserve_mutex;
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index a6bc431..08822de 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -326,6 +326,7 @@ static void
armpmu_release_hardware(struct arm_pmu *armpmu)
{
armpmu->free_irq(armpmu);
+ armpmu->unregister_pm_notifier(armpmu);
pm_runtime_put_sync(&armpmu->plat_device->dev);
}
@@ -339,6 +340,7 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
return -ENODEV;
pm_runtime_get_sync(&pmu_device->dev);
+ armpmu->register_pm_notifier(armpmu);
err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
if (err) {
armpmu_release_hardware(armpmu);
diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index 51798d7..79e1c06 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -19,6 +19,7 @@
#define pr_fmt(fmt) "CPU PMU: " fmt
#include <linux/bitmap.h>
+#include <linux/cpu_pm.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/of.h>
@@ -173,6 +174,31 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu,
irq_handler_t handler)
return 0;
}
+static int cpu_pmu_pm_notify(struct notifier_block *b,
+ unsigned long action, void *v)
+{
+ if (action == CPU_PM_ENTER && cpu_pmu->save_regs)
+ cpu_pmu->save_regs(cpu_pmu);
+ else if (action == CPU_PM_EXIT && cpu_pmu->restore_regs)
+ cpu_pmu->restore_regs(cpu_pmu);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block cpu_pmu_pm_notifier = {
+ .notifier_call = cpu_pmu_pm_notify,
+};
+
+static int cpu_pmu_register_pm_notifier(struct arm_pmu *cpu_pmu)
+{
+ return cpu_pm_register_notifier(&cpu_pmu_pm_notifier);
+}
+
+static void cpu_pmu_unregister_pm_notifier(struct arm_pmu *cpu_pmu)
+{
+ cpu_pm_unregister_notifier(&cpu_pmu_pm_notifier);
+}
+
static void cpu_pmu_init(struct arm_pmu *cpu_pmu)
{
int cpu;
@@ -187,6 +213,8 @@ static void cpu_pmu_init(struct arm_pmu *cpu_pmu)
cpu_pmu->get_hw_events = cpu_pmu_get_cpu_events;
cpu_pmu->request_irq = cpu_pmu_request_irq;
cpu_pmu->free_irq = cpu_pmu_free_irq;
+ cpu_pmu->register_pm_notifier = cpu_pmu_register_pm_notifier;
+ cpu_pmu->unregister_pm_notifier = cpu_pmu_unregister_pm_notifier;
/* Ensure the PMU has sane values out of reset. */
if (cpu_pmu->reset)
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index f4ef398..9069310 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -1237,6 +1237,78 @@ static void armv7_pmnc_dump_regs(struct arm_pmu *cpu_pmu)
}
#endif
+struct armv7_pmuregs {
+ u32 pmc;
+ u32 pmcntenset;
+ u32 pmintenset;
+ u32 pmxevttype[8];
+ u32 pmxevtcnt[8];
+};
+
+static DEFINE_PER_CPU(struct armv7_pmuregs, pmu_regs);
+
+static void armv7pmu_reset(void *info);
+
+static void armv7pmu_save_regs(struct arm_pmu *cpu_pmu)
+{
+ struct pmu_hw_events *events = cpu_pmu->get_hw_events();
+ struct armv7_pmuregs *regs;
+ int bit;
+
+ /* Check whether there are events used */
+ bit = find_first_bit(events->used_mask, cpu_pmu->num_events);
+ if (bit >= cpu_pmu->num_events)
+ return;
+
+ regs = this_cpu_ptr(&pmu_regs);
+ for_each_set_bit(bit, events->used_mask, cpu_pmu->num_events) {
+ if (bit) {
+ armv7_pmnc_select_counter(bit);
+ asm volatile("mrc p15, 0, %0, c9, c13, 1"
+ : "=r"(regs->pmxevttype[bit]));
+ asm volatile("mrc p15, 0, %0, c9, c13, 2"
+ : "=r"(regs->pmxevtcnt[bit]));
+ } else
+ asm volatile("mrc p15, 0, %0, c9, c13, 0"
+ : "=r" (regs->pmxevtcnt[0]));
+ }
+
+ asm volatile("mrc p15, 0, %0, c9, c12, 1" : "=r" (regs->pmcntenset));
+ asm volatile("mrc p15, 0, %0, c9, c14, 1" : "=r" (regs->pmintenset));
+ asm volatile("mrc p15, 0, %0, c9, c12, 0" : "=r" (regs->pmc));
+}
+
+static void armv7pmu_restore_regs(struct arm_pmu *cpu_pmu)
+{
+ struct pmu_hw_events *events = cpu_pmu->get_hw_events();
+ struct armv7_pmuregs *regs;
+ int bit;
+
+ /* Check whether there are events used */
+ bit = find_first_bit(events->used_mask, cpu_pmu->num_events);
+ if (bit >= cpu_pmu->num_events)
+ return;
+
+ armv7pmu_reset(cpu_pmu);
+
+ regs = this_cpu_ptr(&pmu_regs);
+ for_each_set_bit(bit, events->used_mask, cpu_pmu->num_events) {
+ if (bit) {
+ armv7_pmnc_select_counter(bit);
+ asm volatile("mcr p15, 0, %0, c9, c13, 1"
+ : : "r"(regs->pmxevttype[bit]));
+ asm volatile("mcr p15, 0, %0, c9, c13, 2"
+ : : "r"(regs->pmxevtcnt[bit]));
+ } else
+ asm volatile("mcr p15, 0, %0, c9, c13, 0"
+ : : "r" (regs->pmxevtcnt[0]));
+ }
+
+ asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r" (regs->pmcntenset));
+ asm volatile("mcr p15, 0, %0, c9, c14, 1" : : "r" (regs->pmintenset));
+ asm volatile("mcr p15, 0, %0, c9, c12, 0" : : "r" (regs->pmc));
+}
+
static void armv7pmu_enable_event(struct perf_event *event)
{
unsigned long flags;
@@ -1528,6 +1600,8 @@ static void armv7pmu_init(struct arm_pmu *cpu_pmu)
cpu_pmu->start = armv7pmu_start;
cpu_pmu->stop = armv7pmu_stop;
cpu_pmu->reset = armv7pmu_reset;
+ cpu_pmu->save_regs = armv7pmu_save_regs;
+ cpu_pmu->restore_regs = armv7pmu_restore_regs;
cpu_pmu->max_period = (1LLU << 32) - 1;
};
--
1.7.9.5
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