diff options
Diffstat (limited to 'drivers/perf/riscv_pmu_legacy.c')
| -rw-r--r-- | drivers/perf/riscv_pmu_legacy.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/perf/riscv_pmu_legacy.c b/drivers/perf/riscv_pmu_legacy.c new file mode 100644 index 0000000000..79fdd66792 --- /dev/null +++ b/drivers/perf/riscv_pmu_legacy.c @@ -0,0 +1,168 @@ +// 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/mod_devicetable.h> +#include <linux/perf/riscv_pmu.h> +#include <linux/platform_device.h> + +#define RISCV_PMU_LEGACY_CYCLE 0 +#define RISCV_PMU_LEGACY_INSTRET 2 + +static bool pmu_init_done; + +static int pmu_legacy_ctr_get_idx(struct perf_event *event) +{ + struct perf_event_attr *attr = &event->attr; + + if (event->attr.type != PERF_TYPE_HARDWARE) + return -EOPNOTSUPP; + if (attr->config == PERF_COUNT_HW_CPU_CYCLES) + return RISCV_PMU_LEGACY_CYCLE; + else if (attr->config == PERF_COUNT_HW_INSTRUCTIONS) + return RISCV_PMU_LEGACY_INSTRET; + else + return -EOPNOTSUPP; +} + +/* For legacy config & counter index are same */ +static int pmu_legacy_event_map(struct perf_event *event, u64 *config) +{ + return pmu_legacy_ctr_get_idx(event); +} + +static u64 pmu_legacy_read_ctr(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + int idx = hwc->idx; + u64 val; + + if (idx == RISCV_PMU_LEGACY_CYCLE) { + val = riscv_pmu_ctr_read_csr(CSR_CYCLE); + if (IS_ENABLED(CONFIG_32BIT)) + val = (u64)riscv_pmu_ctr_read_csr(CSR_CYCLEH) << 32 | val; + } else if (idx == RISCV_PMU_LEGACY_INSTRET) { + val = riscv_pmu_ctr_read_csr(CSR_INSTRET); + if (IS_ENABLED(CONFIG_32BIT)) + val = ((u64)riscv_pmu_ctr_read_csr(CSR_INSTRETH)) << 32 | val; + } else + return 0; + + return val; +} + +static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival) +{ + struct hw_perf_event *hwc = &event->hw; + u64 initial_val = pmu_legacy_read_ctr(event); + + /** + * The legacy method doesn't really have a start/stop method. + * It also can not update the counter with a initial value. + * But we still need to set the prev_count so that read() can compute + * the delta. Just use the current counter value to set the prev_count. + */ + local64_set(&hwc->prev_count, initial_val); +} + +static uint8_t pmu_legacy_csr_index(struct perf_event *event) +{ + return event->hw.idx; +} + +static void pmu_legacy_event_mapped(struct perf_event *event, struct mm_struct *mm) +{ + if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && + event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) + return; + + event->hw.flags |= PERF_EVENT_FLAG_USER_READ_CNT; +} + +static void pmu_legacy_event_unmapped(struct perf_event *event, struct mm_struct *mm) +{ + if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && + event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) + return; + + event->hw.flags &= ~PERF_EVENT_FLAG_USER_READ_CNT; +} + +/* + * This is just a simple implementation to allow legacy implementations + * compatible with new RISC-V PMU driver framework. + * This driver only allows reading two counters i.e CYCLE & INSTRET. + * However, it can not start or stop the counter. Thus, it is not very useful + * will be removed in future. + */ +static void pmu_legacy_init(struct riscv_pmu *pmu) +{ + pr_info("Legacy PMU implementation is available\n"); + + pmu->cmask = BIT(RISCV_PMU_LEGACY_CYCLE) | + BIT(RISCV_PMU_LEGACY_INSTRET); + pmu->ctr_start = pmu_legacy_ctr_start; + pmu->ctr_stop = NULL; + pmu->event_map = pmu_legacy_event_map; + pmu->ctr_get_idx = pmu_legacy_ctr_get_idx; + pmu->ctr_get_width = NULL; + pmu->ctr_clear_idx = NULL; + pmu->ctr_read = pmu_legacy_read_ctr; + pmu->event_mapped = pmu_legacy_event_mapped; + pmu->event_unmapped = pmu_legacy_event_unmapped; + pmu->csr_index = pmu_legacy_csr_index; + + perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW); +} + +static int pmu_legacy_device_probe(struct platform_device *pdev) +{ + struct riscv_pmu *pmu = NULL; + + pmu = riscv_pmu_alloc(); + if (!pmu) + return -ENOMEM; + pmu_legacy_init(pmu); + + return 0; +} + +static struct platform_driver pmu_legacy_driver = { + .probe = pmu_legacy_device_probe, + .driver = { + .name = RISCV_PMU_LEGACY_PDEV_NAME, + }, +}; + +static int __init riscv_pmu_legacy_devinit(void) +{ + int ret; + struct platform_device *pdev; + + if (likely(pmu_init_done)) + return 0; + + ret = platform_driver_register(&pmu_legacy_driver); + if (ret) + return ret; + + pdev = platform_device_register_simple(RISCV_PMU_LEGACY_PDEV_NAME, -1, NULL, 0); + if (IS_ERR(pdev)) { + platform_driver_unregister(&pmu_legacy_driver); + return PTR_ERR(pdev); + } + + return ret; +} +late_initcall(riscv_pmu_legacy_devinit); + +void riscv_pmu_legacy_skip_init(void) +{ + pmu_init_done = true; +} |