1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * RISC-V performance counter support. 4 * 5 * Copyright (C) 2021 Western Digital Corporation or its affiliates. 6 * 7 * This implementation is based on old RISC-V perf and ARM perf event code 8 * which are in turn based on sparc64 and x86 code. 9 */ 10 11 #include <linux/mod_devicetable.h> 12 #include <linux/perf/riscv_pmu.h> 13 #include <linux/platform_device.h> 14 15 #define RISCV_PMU_LEGACY_CYCLE 0 16 #define RISCV_PMU_LEGACY_INSTRET 2 17 18 static bool pmu_init_done; 19 20 static int pmu_legacy_ctr_get_idx(struct perf_event *event) 21 { 22 struct perf_event_attr *attr = &event->attr; 23 24 if (event->attr.type != PERF_TYPE_HARDWARE) 25 return -EOPNOTSUPP; 26 if (attr->config == PERF_COUNT_HW_CPU_CYCLES) 27 return RISCV_PMU_LEGACY_CYCLE; 28 else if (attr->config == PERF_COUNT_HW_INSTRUCTIONS) 29 return RISCV_PMU_LEGACY_INSTRET; 30 else 31 return -EOPNOTSUPP; 32 } 33 34 /* For legacy config & counter index are same */ 35 static int pmu_legacy_event_map(struct perf_event *event, u64 *config) 36 { 37 return pmu_legacy_ctr_get_idx(event); 38 } 39 40 /* cycle & instret are always 64 bit, one bit less according to SBI spec */ 41 static int pmu_legacy_ctr_get_width(int idx) 42 { 43 return 63; 44 } 45 46 static u64 pmu_legacy_read_ctr(struct perf_event *event) 47 { 48 struct hw_perf_event *hwc = &event->hw; 49 int idx = hwc->idx; 50 u64 val; 51 52 if (idx == RISCV_PMU_LEGACY_CYCLE) { 53 val = riscv_pmu_ctr_read_csr(CSR_CYCLE); 54 if (IS_ENABLED(CONFIG_32BIT)) 55 val = (u64)riscv_pmu_ctr_read_csr(CSR_CYCLEH) << 32 | val; 56 } else if (idx == RISCV_PMU_LEGACY_INSTRET) { 57 val = riscv_pmu_ctr_read_csr(CSR_INSTRET); 58 if (IS_ENABLED(CONFIG_32BIT)) 59 val = ((u64)riscv_pmu_ctr_read_csr(CSR_INSTRETH)) << 32 | val; 60 } else 61 return 0; 62 63 return val; 64 } 65 66 static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival) 67 { 68 struct hw_perf_event *hwc = &event->hw; 69 u64 initial_val = pmu_legacy_read_ctr(event); 70 71 /** 72 * The legacy method doesn't really have a start/stop method. 73 * It also can not update the counter with a initial value. 74 * But we still need to set the prev_count so that read() can compute 75 * the delta. Just use the current counter value to set the prev_count. 76 */ 77 local64_set(&hwc->prev_count, initial_val); 78 } 79 80 static uint8_t pmu_legacy_csr_index(struct perf_event *event) 81 { 82 return event->hw.idx; 83 } 84 85 static void pmu_legacy_event_mapped(struct perf_event *event, struct mm_struct *mm) 86 { 87 if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && 88 event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) 89 return; 90 91 event->hw.flags |= PERF_EVENT_FLAG_USER_READ_CNT; 92 } 93 94 static void pmu_legacy_event_unmapped(struct perf_event *event, struct mm_struct *mm) 95 { 96 if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && 97 event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) 98 return; 99 100 event->hw.flags &= ~PERF_EVENT_FLAG_USER_READ_CNT; 101 } 102 103 /* 104 * This is just a simple implementation to allow legacy implementations 105 * compatible with new RISC-V PMU driver framework. 106 * This driver only allows reading two counters i.e CYCLE & INSTRET. 107 * However, it can not start or stop the counter. Thus, it is not very useful 108 * will be removed in future. 109 */ 110 static void pmu_legacy_init(struct riscv_pmu *pmu) 111 { 112 pr_info("Legacy PMU implementation is available\n"); 113 114 pmu->cmask = BIT(RISCV_PMU_LEGACY_CYCLE) | 115 BIT(RISCV_PMU_LEGACY_INSTRET); 116 pmu->ctr_start = pmu_legacy_ctr_start; 117 pmu->ctr_stop = NULL; 118 pmu->event_map = pmu_legacy_event_map; 119 pmu->ctr_get_idx = pmu_legacy_ctr_get_idx; 120 pmu->ctr_get_width = pmu_legacy_ctr_get_width; 121 pmu->ctr_clear_idx = NULL; 122 pmu->ctr_read = pmu_legacy_read_ctr; 123 pmu->event_mapped = pmu_legacy_event_mapped; 124 pmu->event_unmapped = pmu_legacy_event_unmapped; 125 pmu->csr_index = pmu_legacy_csr_index; 126 pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT; 127 pmu->pmu.capabilities |= PERF_PMU_CAP_NO_EXCLUDE; 128 129 perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW); 130 } 131 132 static int pmu_legacy_device_probe(struct platform_device *pdev) 133 { 134 struct riscv_pmu *pmu = NULL; 135 136 pmu = riscv_pmu_alloc(); 137 if (!pmu) 138 return -ENOMEM; 139 pmu_legacy_init(pmu); 140 141 return 0; 142 } 143 144 static struct platform_driver pmu_legacy_driver = { 145 .probe = pmu_legacy_device_probe, 146 .driver = { 147 .name = RISCV_PMU_LEGACY_PDEV_NAME, 148 }, 149 }; 150 151 static int __init riscv_pmu_legacy_devinit(void) 152 { 153 int ret; 154 struct platform_device *pdev; 155 156 if (likely(pmu_init_done)) 157 return 0; 158 159 ret = platform_driver_register(&pmu_legacy_driver); 160 if (ret) 161 return ret; 162 163 pdev = platform_device_register_simple(RISCV_PMU_LEGACY_PDEV_NAME, -1, NULL, 0); 164 if (IS_ERR(pdev)) { 165 platform_driver_unregister(&pmu_legacy_driver); 166 return PTR_ERR(pdev); 167 } 168 169 return ret; 170 } 171 late_initcall(riscv_pmu_legacy_devinit); 172 173 void riscv_pmu_legacy_skip_init(void) 174 { 175 pmu_init_done = true; 176 } 177