[PATCH 3/5] csky: Add pmu interrupt support

Mao Han
2019-05-22T09:27:02Z

This patch add interrupt request and handler for csky pmu.
perf can record on hardware event with this patch applied.

Signed-off-by: Mao Han <han_mao@c-sky.com>
CC: Guo Ren <guoren@kernel.org>
CC: linux-csky@vger.kernel.org
---
arch/csky/kernel/perf_event.c | 277 +++++++++++++++++++++++++++++++++++++++---
1 file changed, 259 insertions(+), 18 deletions(-)

diff --git a/arch/csky/kernel/perf_event.c b/arch/csky/kernel/perf_event.c
index f1b3cdf..2ea9083 100644
--- a/arch/csky/kernel/perf_event.c
+++ b/arch/csky/kernel/perf_event.c
@@ -10,18 +10,49 @@

#define CSKY_PMU_MAX_EVENTS 32

-#define HPCR "<0, 0x0>" /* PMU Control reg */
-#define HPCNTENR "<0, 0x4>" /* Count Enable reg */
+#define HPCR "<0, 0x0>" /* PMU Control reg */
+#define HPSPR "<0, 0x1>" /* Start PC reg */
+#define HPEPR "<0, 0x2>" /* End PC reg */
+#define HPSIR "<0, 0x3>" /* Soft Counter reg */
+#define HPCNTENR "<0, 0x4>" /* Count Enable reg */
+#define HPINTENR "<0, 0x5>" /* Interrupt Enable reg */
+#define HPOFSR "<0, 0x6>" /* Interrupt Status reg */
+
+/* The events for a given PMU register set. */
+struct pmu_hw_events {
+ /*
+ * The events that are active on the PMU for the given index.
+ */
+ struct perf_event *events[CSKY_PMU_MAX_EVENTS];
+
+ /*
+ * A 1 bit for an index indicates that the counter is being used for
+ * an event. A 0 means that the counter can be used.
+ */
+ unsigned long used_mask[BITS_TO_LONGS(CSKY_PMU_MAX_EVENTS)];
+
+ /*
+ * Hardware lock to serialize accesses to PMU registers. Needed for the
+ * read/modify/write sequences.
+ */
+ raw_spinlock_t pmu_lock;
+};

static uint64_t (*hw_raw_read_mapping[CSKY_PMU_MAX_EVENTS])(void);
static void (*hw_raw_write_mapping[CSKY_PMU_MAX_EVENTS])(uint64_t val);

struct csky_pmu_t {
- struct pmu pmu;
- uint32_t sign_extend;
- uint32_t hpcr;
+ struct pmu pmu;
+ irqreturn_t (*handle_irq)(int irq_num);
+ void (*reset)(void *info);
+ struct pmu_hw_events __percpu *hw_events;
+ struct platform_device *plat_device;
+ uint32_t sign_extend;
+ uint32_t hpcr;
+ u64 max_period;
} csky_pmu;

+#define to_csky_pmu(p) (container_of(p, struct csky_pmu, pmu))
typedef int (*csky_pmu_init)(struct csky_pmu_t *);

#define cprgr(reg) \
@@ -803,6 +834,51 @@ static const int csky_pmu_cache_map[C(MAX)][C(OP_MAX)][C(RESULT_MAX)] = {
},
};

+int csky_pmu_event_set_period(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ s64 left = local64_read(&hwc->period_left);
+ s64 period = hwc->sample_period;
+ int ret = 0;
+
+ if (unlikely(left <= -period)) {
+ left = period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ ret = 1;
+ }
+
+ if (unlikely(left <= 0)) {
+ left += period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ ret = 1;
+ }
+
+ if (left > (s64)csky_pmu.max_period)
+ left = csky_pmu.max_period;
+
+ /* Interrupt may lose when period is too small. */
+ if (left < 10)
+ left = 10;
+
+ /*
+ * The hw event starts counting from this event offset,
+ * mark it to be able to extract future "deltas":
+ */
+ local64_set(&hwc->prev_count, (u64)(-left));
+
+ if (hw_raw_write_mapping[hwc->idx] != NULL)
+ hw_raw_write_mapping[hwc->idx]((u64)(-left) &
+ csky_pmu.max_period);
+
+ cpwcr(HPOFSR, ~BIT(hwc->idx) & cprcr(HPOFSR));
+
+ perf_event_update_userpage(event);
+
+ return ret;
+}
+
static void csky_perf_event_update(struct perf_event *event,
struct hw_perf_event *hwc)
{
@@ -825,6 +901,11 @@ static void csky_perf_event_update(struct perf_event *event,
local64_sub(delta, &hwc->period_left);
}

+static void csky_pmu_reset(void *info)
+{
+ cpwcr(HPCR, BIT(31) | BIT(30) | BIT(1));
+}
+
static void csky_pmu_read(struct perf_event *event)
{
csky_perf_event_update(event, &event->hw);
@@ -901,7 +982,9 @@ static void csky_pmu_disable(struct pmu *pmu)

static void csky_pmu_start(struct perf_event *event, int flags)
{
+ unsigned long irq_flags;
struct hw_perf_event *hwc = &event->hw;
+ struct pmu_hw_events *events = this_cpu_ptr(csky_pmu.hw_events);
int idx = hwc->idx;

if (WARN_ON_ONCE(idx == -1))
@@ -912,16 +995,35 @@ static void csky_pmu_start(struct perf_event *event, int flags)

hwc->state = 0;

+ csky_pmu_event_set_period(event);
+
+ raw_spin_lock_irqsave(&events->pmu_lock, irq_flags);
+
+ cpwcr(HPINTENR, BIT(idx) | cprcr(HPINTENR));
cpwcr(HPCNTENR, BIT(idx) | cprcr(HPCNTENR));
+
+ raw_spin_unlock_irqrestore(&events->pmu_lock, irq_flags);
}

-static void csky_pmu_stop(struct perf_event *event, int flags)
+static void csky_pmu_stop_event(struct perf_event *event)
{
+ unsigned long irq_flags;
struct hw_perf_event *hwc = &event->hw;
+ struct pmu_hw_events *events = this_cpu_ptr(csky_pmu.hw_events);
int idx = hwc->idx;

+ raw_spin_lock_irqsave(&events->pmu_lock, irq_flags);
+
+ cpwcr(HPINTENR, ~BIT(idx) & cprcr(HPINTENR));
+ cpwcr(HPCNTENR, ~BIT(idx) & cprcr(HPCNTENR));
+
+ raw_spin_unlock_irqrestore(&events->pmu_lock, irq_flags);
+}
+
+static void csky_pmu_stop(struct perf_event *event, int flags)
+{
if (!(event->hw.state & PERF_HES_STOPPED)) {
- cpwcr(HPCNTENR, ~BIT(idx) & cprcr(HPCNTENR));
+ csky_pmu_stop_event(event);
event->hw.state |= PERF_HES_STOPPED;
}

@@ -934,7 +1036,11 @@ static void csky_pmu_stop(struct perf_event *event, int flags)

static void csky_pmu_del(struct perf_event *event, int flags)
{
+ struct pmu_hw_events *hw_events = this_cpu_ptr(csky_pmu.hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+
csky_pmu_stop(event, PERF_EF_UPDATE);
+ hw_events->events[hwc->idx] = NULL;

perf_event_update_userpage(event);
}
@@ -942,12 +1048,10 @@ static void csky_pmu_del(struct perf_event *event, int flags)
/* allocate hardware counter and optionally start counting */
static int csky_pmu_add(struct perf_event *event, int flags)
{
+ struct pmu_hw_events *hw_events = this_cpu_ptr(csky_pmu.hw_events);
struct hw_perf_event *hwc = &event->hw;

- local64_set(&hwc->prev_count, 0);
-
- if (hw_raw_write_mapping[hwc->idx] != NULL)
- hw_raw_write_mapping[hwc->idx](0);
+ hw_events->events[hwc->idx] = event;

hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
if (flags & PERF_EF_START)
@@ -958,8 +1062,119 @@ static int csky_pmu_add(struct perf_event *event, int flags)
return 0;
}

+static irqreturn_t csky_pmu_handle_irq(int irq_num)
+{
+ struct perf_sample_data data;
+ struct pmu_hw_events *cpuc = this_cpu_ptr(csky_pmu.hw_events);
+ struct pt_regs *regs;
+ int idx;
+
+ /*
+ * Did an overflow occur?
+ */
+ if (!cprcr(HPOFSR))
+ return IRQ_NONE;
+
+ /*
+ * Handle the counter(s) overflow(s)
+ */
+ regs = get_irq_regs();
+
+ csky_pmu_disable(&csky_pmu.pmu);
+ for (idx = 0; idx < CSKY_PMU_MAX_EVENTS; ++idx) {
+ struct perf_event *event = cpuc->events[idx];
+ struct hw_perf_event *hwc;
+
+ /* Ignore if we don't have an event. */
+ if (!event)
+ continue;
+ /*
+ * We have a single interrupt for all counters. Check that
+ * each counter has overflowed before we process it.
+ */
+ if (!(cprcr(HPOFSR) & 1 << idx))
+ continue;
+
+ hwc = &event->hw;
+ csky_perf_event_update(event, &event->hw);
+ perf_sample_data_init(&data, 0, hwc->last_period);
+ csky_pmu_event_set_period(event);
+
+ if (perf_event_overflow(event, &data, regs))
+ csky_pmu_stop_event(event);
+ }
+ csky_pmu_enable(&csky_pmu.pmu);
+ /*
+ * Handle the pending perf events.
+ *
+ * Note: this call *must* be run with interrupts disabled. For
+ * platforms that can have the PMU interrupts raised as an NMI, this
+ * will not work.
+ */
+ irq_work_run();
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t csky_pmu_dispatch_irq(int irq, void *dev)
+{
+ int ret;
+
+ ret = csky_pmu.handle_irq(irq);
+
+ return ret;
+}
+
+static int csky_pmu_request_irq(irq_handler_t handler)
+{
+ int err, irq, irqs;
+ struct platform_device *pmu_device = csky_pmu.plat_device;
+
+ if (!pmu_device)
+ return -ENODEV;
+
+ irqs = min(pmu_device->num_resources, num_possible_cpus());
+ if (irqs < 1) {
+ pr_err("no irqs for PMUs defined\n");
+ return -ENODEV;
+ }
+
+ irq = platform_get_irq(pmu_device, 0);
+ if (irq < 0)
+ return -ENODEV;
+ err = request_percpu_irq(irq, handler, "csky-pmu",
+ this_cpu_ptr(csky_pmu.hw_events));
+ if (err) {
+ pr_err("unable to request IRQ%d for CSKY PMU counters\n",
+ irq);
+ return err;
+ }
+ enable_percpu_irq(irq, 0);
+
+ return 0;
+}
+
+static void csky_pmu_free_irq(void)
+{
+ int irq;
+ struct platform_device *pmu_device = csky_pmu.plat_device;
+
+ irq = platform_get_irq(pmu_device, 0);
+ if (irq >= 0)
+ free_percpu_irq(irq, this_cpu_ptr(csky_pmu.hw_events));
+}
+
int __init init_hw_perf_events(void)
{
+ int cpu;
+
+ csky_pmu.hw_events = alloc_percpu_gfp(struct pmu_hw_events,
+ GFP_KERNEL);
+ if (!csky_pmu.hw_events) {
+ pr_info("failed to allocate per-cpu PMU data.\n");
+ return -ENOMEM;
+ }
+
csky_pmu.pmu = (struct pmu) {
.pmu_enable = csky_pmu_enable,
.pmu_disable = csky_pmu_disable,
@@ -971,6 +1186,16 @@ int __init init_hw_perf_events(void)
.read = csky_pmu_read,
};

+ csky_pmu.handle_irq = csky_pmu_handle_irq;
+ csky_pmu.reset = csky_pmu_reset;
+
+ for_each_possible_cpu(cpu) {
+ struct pmu_hw_events *events;
+
+ events = per_cpu_ptr(csky_pmu.hw_events, cpu);
+ raw_spin_lock_init(&events->pmu_lock);
+ }
+
memset((void *)hw_raw_read_mapping, 0,
sizeof(hw_raw_read_mapping[CSKY_PMU_MAX_EVENTS]));

@@ -1031,11 +1256,7 @@ int __init init_hw_perf_events(void)
hw_raw_write_mapping[0x1a] = csky_pmu_write_l2wac;
hw_raw_write_mapping[0x1b] = csky_pmu_write_l2wmc;

- csky_pmu.pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
-
- cpwcr(HPCR, BIT(31) | BIT(30) | BIT(1));
-
- return perf_pmu_register(&csky_pmu.pmu, "cpu", PERF_TYPE_RAW);
+ return 0;
}

int csky_pmu_device_probe(struct platform_device *pdev,
@@ -1053,15 +1274,35 @@ int csky_pmu_device_probe(struct platform_device *pdev,
ret = init_fn(&csky_pmu);
}

+ if (ret) {
+ pr_notice("[perf] failed to probe PMU!\n");
+ return ret;
+ }
+
if (!of_property_read_u32(node, "reg-io-width", &cnt_width)) {
+ csky_pmu.max_period = ((u64)1 << cnt_width) - 1;
csky_pmu.sign_extend = 64 - cnt_width;
} else {
+ csky_pmu.max_period = 0xFFFFFFFFFFFF;
csky_pmu.sign_extend = 16;
}

+ csky_pmu.plat_device = pdev;
+
+ /* Ensure the PMU has sane values out of reset. */
+ if (csky_pmu.reset)
+ on_each_cpu(csky_pmu.reset, &csky_pmu, 1);
+
+ ret = csky_pmu_request_irq(csky_pmu_dispatch_irq);
if (ret) {
- pr_notice("[perf] failed to probe PMU!\n");
- return ret;
+ csky_pmu.pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+ pr_notice("[perf] PMU request irq fail!\n");
+ }
+
+ ret = perf_pmu_register(&csky_pmu.pmu, "cpu", PERF_TYPE_RAW);
+ if (ret) {
+ csky_pmu_free_irq();
+ free_percpu(csky_pmu.hw_events);
}

return ret;
--
2.7.4