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 1 17 #define RISCV_PMU_LEGACY_NUM_CTR 2 18 19 static bool pmu_init_done; 20 21 static int pmu_legacy_ctr_get_idx(struct perf_event *event) 22 { 23 struct perf_event_attr *attr = &event->attr; 24 25 if (event->attr.type != PERF_TYPE_HARDWARE) 26 return -EOPNOTSUPP; 27 if (attr->config == PERF_COUNT_HW_CPU_CYCLES) 28 return RISCV_PMU_LEGACY_CYCLE; 29 else if (attr->config == PERF_COUNT_HW_INSTRUCTIONS) 30 return RISCV_PMU_LEGACY_INSTRET; 31 else 32 return -EOPNOTSUPP; 33 } 34 35 /* For legacy config & counter index are same */ 36 static int pmu_legacy_event_map(struct perf_event *event, u64 *config) 37 { 38 return pmu_legacy_ctr_get_idx(event); 39 } 40 41 static u64 pmu_legacy_read_ctr(struct perf_event *event) 42 { 43 struct hw_perf_event *hwc = &event->hw; 44 int idx = hwc->idx; 45 u64 val; 46 47 if (idx == RISCV_PMU_LEGACY_CYCLE) { 48 val = riscv_pmu_ctr_read_csr(CSR_CYCLE); 49 if (IS_ENABLED(CONFIG_32BIT)) 50 val = (u64)riscv_pmu_ctr_read_csr(CSR_CYCLEH) << 32 | val; 51 } else if (idx == RISCV_PMU_LEGACY_INSTRET) { 52 val = riscv_pmu_ctr_read_csr(CSR_INSTRET); 53 if (IS_ENABLED(CONFIG_32BIT)) 54 val = ((u64)riscv_pmu_ctr_read_csr(CSR_INSTRETH)) << 32 | val; 55 } else 56 return 0; 57 58 return val; 59 } 60 61 static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival) 62 { 63 struct hw_perf_event *hwc = &event->hw; 64 u64 initial_val = pmu_legacy_read_ctr(event); 65 66 /** 67 * The legacy method doesn't really have a start/stop method. 68 * It also can not update the counter with a initial value. 69 * But we still need to set the prev_count so that read() can compute 70 * the delta. Just use the current counter value to set the prev_count. 71 */ 72 local64_set(&hwc->prev_count, initial_val); 73 } 74 75 /* 76 * This is just a simple implementation to allow legacy implementations 77 * compatible with new RISC-V PMU driver framework. 78 * This driver only allows reading two counters i.e CYCLE & INSTRET. 79 * However, it can not start or stop the counter. Thus, it is not very useful 80 * will be removed in future. 81 */ 82 static void pmu_legacy_init(struct riscv_pmu *pmu) 83 { 84 pr_info("Legacy PMU implementation is available\n"); 85 86 pmu->num_counters = RISCV_PMU_LEGACY_NUM_CTR; 87 pmu->ctr_start = pmu_legacy_ctr_start; 88 pmu->ctr_stop = NULL; 89 pmu->event_map = pmu_legacy_event_map; 90 pmu->ctr_get_idx = pmu_legacy_ctr_get_idx; 91 pmu->ctr_get_width = NULL; 92 pmu->ctr_clear_idx = NULL; 93 pmu->ctr_read = pmu_legacy_read_ctr; 94 95 perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW); 96 } 97 98 static int pmu_legacy_device_probe(struct platform_device *pdev) 99 { 100 struct riscv_pmu *pmu = NULL; 101 102 pmu = riscv_pmu_alloc(); 103 if (!pmu) 104 return -ENOMEM; 105 pmu_legacy_init(pmu); 106 107 return 0; 108 } 109 110 static struct platform_driver pmu_legacy_driver = { 111 .probe = pmu_legacy_device_probe, 112 .driver = { 113 .name = RISCV_PMU_LEGACY_PDEV_NAME, 114 }, 115 }; 116 117 static int __init riscv_pmu_legacy_devinit(void) 118 { 119 int ret; 120 struct platform_device *pdev; 121 122 if (likely(pmu_init_done)) 123 return 0; 124 125 ret = platform_driver_register(&pmu_legacy_driver); 126 if (ret) 127 return ret; 128 129 pdev = platform_device_register_simple(RISCV_PMU_LEGACY_PDEV_NAME, -1, NULL, 0); 130 if (IS_ERR(pdev)) { 131 platform_driver_unregister(&pmu_legacy_driver); 132 return PTR_ERR(pdev); 133 } 134 135 return ret; 136 } 137 late_initcall(riscv_pmu_legacy_devinit); 138 139 void riscv_pmu_legacy_skip_init(void) 140 { 141 pmu_init_done = true; 142 } 143