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-rw-r--r--drivers/perf/riscv_pmu.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
new file mode 100644
index 000000000..56897d4d4
--- /dev/null
+++ b/drivers/perf/riscv_pmu.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This implementation is based on old RISC-V perf and ARM perf event code
+ * which are in turn based on sparc64 and x86 code.
+ */
+
+#include <linux/cpumask.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+
+#include <asm/sbi.h>
+
+static unsigned long csr_read_num(int csr_num)
+{
+#define switchcase_csr_read(__csr_num, __val) {\
+ case __csr_num: \
+ __val = csr_read(__csr_num); \
+ break; }
+#define switchcase_csr_read_2(__csr_num, __val) {\
+ switchcase_csr_read(__csr_num + 0, __val) \
+ switchcase_csr_read(__csr_num + 1, __val)}
+#define switchcase_csr_read_4(__csr_num, __val) {\
+ switchcase_csr_read_2(__csr_num + 0, __val) \
+ switchcase_csr_read_2(__csr_num + 2, __val)}
+#define switchcase_csr_read_8(__csr_num, __val) {\
+ switchcase_csr_read_4(__csr_num + 0, __val) \
+ switchcase_csr_read_4(__csr_num + 4, __val)}
+#define switchcase_csr_read_16(__csr_num, __val) {\
+ switchcase_csr_read_8(__csr_num + 0, __val) \
+ switchcase_csr_read_8(__csr_num + 8, __val)}
+#define switchcase_csr_read_32(__csr_num, __val) {\
+ switchcase_csr_read_16(__csr_num + 0, __val) \
+ switchcase_csr_read_16(__csr_num + 16, __val)}
+
+ unsigned long ret = 0;
+
+ switch (csr_num) {
+ switchcase_csr_read_32(CSR_CYCLE, ret)
+ switchcase_csr_read_32(CSR_CYCLEH, ret)
+ default :
+ break;
+ }
+
+ return ret;
+#undef switchcase_csr_read_32
+#undef switchcase_csr_read_16
+#undef switchcase_csr_read_8
+#undef switchcase_csr_read_4
+#undef switchcase_csr_read_2
+#undef switchcase_csr_read
+}
+
+/*
+ * Read the CSR of a corresponding counter.
+ */
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr)
+{
+ if (csr < CSR_CYCLE || csr > CSR_HPMCOUNTER31H ||
+ (csr > CSR_HPMCOUNTER31 && csr < CSR_CYCLEH)) {
+ pr_err("Invalid performance counter csr %lx\n", csr);
+ return -EINVAL;
+ }
+
+ return csr_read_num(csr);
+}
+
+u64 riscv_pmu_ctr_get_width_mask(struct perf_event *event)
+{
+ int cwidth;
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (!rvpmu->ctr_get_width)
+ /**
+ * If the pmu driver doesn't support counter width, set it to default
+ * maximum allowed by the specification.
+ */
+ cwidth = 63;
+ else {
+ if (hwc->idx == -1)
+ /* Handle init case where idx is not initialized yet */
+ cwidth = rvpmu->ctr_get_width(0);
+ else
+ cwidth = rvpmu->ctr_get_width(hwc->idx);
+ }
+
+ return GENMASK_ULL(cwidth, 0);
+}
+
+u64 riscv_pmu_event_update(struct perf_event *event)
+{
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ struct hw_perf_event *hwc = &event->hw;
+ u64 prev_raw_count, new_raw_count;
+ unsigned long cmask;
+ u64 oldval, delta;
+
+ if (!rvpmu->ctr_read)
+ return 0;
+
+ cmask = riscv_pmu_ctr_get_width_mask(event);
+
+ do {
+ prev_raw_count = local64_read(&hwc->prev_count);
+ new_raw_count = rvpmu->ctr_read(event);
+ oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+ new_raw_count);
+ } while (oldval != prev_raw_count);
+
+ delta = (new_raw_count - prev_raw_count) & cmask;
+ local64_add(delta, &event->count);
+ local64_sub(delta, &hwc->period_left);
+
+ return delta;
+}
+
+void riscv_pmu_stop(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+
+ WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+
+ if (!(hwc->state & PERF_HES_STOPPED)) {
+ if (rvpmu->ctr_stop) {
+ rvpmu->ctr_stop(event, 0);
+ hwc->state |= PERF_HES_STOPPED;
+ }
+ riscv_pmu_event_update(event);
+ hwc->state |= PERF_HES_UPTODATE;
+ }
+}
+
+int riscv_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 overflow = 0;
+ uint64_t max_period = riscv_pmu_ctr_get_width_mask(event);
+
+ if (unlikely(left <= -period)) {
+ left = period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ overflow = 1;
+ }
+
+ if (unlikely(left <= 0)) {
+ left += period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ overflow = 1;
+ }
+
+ /*
+ * Limit the maximum period to prevent the counter value
+ * from overtaking the one we are about to program. In
+ * effect we are reducing max_period to account for
+ * interrupt latency (and we are being very conservative).
+ */
+ if (left > (max_period >> 1))
+ left = (max_period >> 1);
+
+ local64_set(&hwc->prev_count, (u64)-left);
+
+ return overflow;
+}
+
+void riscv_pmu_start(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ uint64_t max_period = riscv_pmu_ctr_get_width_mask(event);
+ u64 init_val;
+
+ if (flags & PERF_EF_RELOAD)
+ WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+
+ hwc->state = 0;
+ riscv_pmu_event_set_period(event);
+ init_val = local64_read(&hwc->prev_count) & max_period;
+ rvpmu->ctr_start(event, init_val);
+ perf_event_update_userpage(event);
+}
+
+static int riscv_pmu_add(struct perf_event *event, int flags)
+{
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx;
+
+ idx = rvpmu->ctr_get_idx(event);
+ if (idx < 0)
+ return idx;
+
+ hwc->idx = idx;
+ cpuc->events[idx] = event;
+ cpuc->n_events++;
+ hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+ if (flags & PERF_EF_START)
+ riscv_pmu_start(event, PERF_EF_RELOAD);
+
+ /* Propagate our changes to the userspace mapping. */
+ perf_event_update_userpage(event);
+
+ return 0;
+}
+
+static void riscv_pmu_del(struct perf_event *event, int flags)
+{
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+
+ riscv_pmu_stop(event, PERF_EF_UPDATE);
+ cpuc->events[hwc->idx] = NULL;
+ /* The firmware need to reset the counter mapping */
+ if (rvpmu->ctr_stop)
+ rvpmu->ctr_stop(event, RISCV_PMU_STOP_FLAG_RESET);
+ cpuc->n_events--;
+ if (rvpmu->ctr_clear_idx)
+ rvpmu->ctr_clear_idx(event);
+ perf_event_update_userpage(event);
+ hwc->idx = -1;
+}
+
+static void riscv_pmu_read(struct perf_event *event)
+{
+ riscv_pmu_event_update(event);
+}
+
+static int riscv_pmu_event_init(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+ int mapped_event;
+ u64 event_config = 0;
+ uint64_t cmask;
+
+ hwc->flags = 0;
+ mapped_event = rvpmu->event_map(event, &event_config);
+ if (mapped_event < 0) {
+ pr_debug("event %x:%llx not supported\n", event->attr.type,
+ event->attr.config);
+ return mapped_event;
+ }
+
+ /*
+ * idx is set to -1 because the index of a general event should not be
+ * decided until binding to some counter in pmu->add().
+ * config will contain the information about counter CSR
+ * the idx will contain the counter index
+ */
+ hwc->config = event_config;
+ hwc->idx = -1;
+ hwc->event_base = mapped_event;
+
+ if (!is_sampling_event(event)) {
+ /*
+ * For non-sampling runs, limit the sample_period to half
+ * of the counter width. That way, the new counter value
+ * is far less likely to overtake the previous one unless
+ * you have some serious IRQ latency issues.
+ */
+ cmask = riscv_pmu_ctr_get_width_mask(event);
+ hwc->sample_period = cmask >> 1;
+ hwc->last_period = hwc->sample_period;
+ local64_set(&hwc->period_left, hwc->sample_period);
+ }
+
+ return 0;
+}
+
+struct riscv_pmu *riscv_pmu_alloc(void)
+{
+ struct riscv_pmu *pmu;
+ int cpuid, i;
+ struct cpu_hw_events *cpuc;
+
+ pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
+ if (!pmu)
+ goto out;
+
+ pmu->hw_events = alloc_percpu_gfp(struct cpu_hw_events, GFP_KERNEL);
+ if (!pmu->hw_events) {
+ pr_info("failed to allocate per-cpu PMU data.\n");
+ goto out_free_pmu;
+ }
+
+ for_each_possible_cpu(cpuid) {
+ cpuc = per_cpu_ptr(pmu->hw_events, cpuid);
+ cpuc->n_events = 0;
+ for (i = 0; i < RISCV_MAX_COUNTERS; i++)
+ cpuc->events[i] = NULL;
+ }
+ pmu->pmu = (struct pmu) {
+ .event_init = riscv_pmu_event_init,
+ .add = riscv_pmu_add,
+ .del = riscv_pmu_del,
+ .start = riscv_pmu_start,
+ .stop = riscv_pmu_stop,
+ .read = riscv_pmu_read,
+ };
+
+ return pmu;
+
+out_free_pmu:
+ kfree(pmu);
+out:
+ return NULL;
+}