1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * DT idle states parsing code. 4 * 5 * Copyright (C) 2014 ARM Ltd. 6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> 7 */ 8 9 #define pr_fmt(fmt) "DT idle-states: " fmt 10 11 #include <linux/cpuidle.h> 12 #include <linux/cpumask.h> 13 #include <linux/errno.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/of.h> 17 18 #include "dt_idle_states.h" 19 20 static int init_state_node(struct cpuidle_state *idle_state, 21 const struct of_device_id *match_id, 22 struct device_node *state_node) 23 { 24 int err; 25 const char *desc; 26 27 /* 28 * CPUidle drivers are expected to initialize the const void *data 29 * pointer of the passed in struct of_device_id array to the idle 30 * state enter function. 31 */ 32 idle_state->enter = match_id->data; 33 /* 34 * Since this is not a "coupled" state, it's safe to assume interrupts 35 * won't be enabled when it exits allowing the tick to be frozen 36 * safely. So enter() can be also enter_s2idle() callback. 37 */ 38 idle_state->enter_s2idle = match_id->data; 39 40 err = of_property_read_u32(state_node, "wakeup-latency-us", 41 &idle_state->exit_latency); 42 if (err) { 43 u32 entry_latency, exit_latency; 44 45 err = of_property_read_u32(state_node, "entry-latency-us", 46 &entry_latency); 47 if (err) { 48 pr_debug(" * %pOF missing entry-latency-us property\n", 49 state_node); 50 return -EINVAL; 51 } 52 53 err = of_property_read_u32(state_node, "exit-latency-us", 54 &exit_latency); 55 if (err) { 56 pr_debug(" * %pOF missing exit-latency-us property\n", 57 state_node); 58 return -EINVAL; 59 } 60 /* 61 * If wakeup-latency-us is missing, default to entry+exit 62 * latencies as defined in idle states bindings 63 */ 64 idle_state->exit_latency = entry_latency + exit_latency; 65 } 66 67 err = of_property_read_u32(state_node, "min-residency-us", 68 &idle_state->target_residency); 69 if (err) { 70 pr_debug(" * %pOF missing min-residency-us property\n", 71 state_node); 72 return -EINVAL; 73 } 74 75 err = of_property_read_string(state_node, "idle-state-name", &desc); 76 if (err) 77 desc = state_node->name; 78 79 idle_state->flags = CPUIDLE_FLAG_RCU_IDLE; 80 if (of_property_read_bool(state_node, "local-timer-stop")) 81 idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; 82 /* 83 * TODO: 84 * replace with kstrdup and pointer assignment when name 85 * and desc become string pointers 86 */ 87 strscpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN); 88 strscpy(idle_state->desc, desc, CPUIDLE_DESC_LEN); 89 return 0; 90 } 91 92 /* 93 * Check that the idle state is uniform across all CPUs in the CPUidle driver 94 * cpumask 95 */ 96 static bool idle_state_valid(struct device_node *state_node, unsigned int idx, 97 const cpumask_t *cpumask) 98 { 99 int cpu; 100 struct device_node *cpu_node, *curr_state_node; 101 102 /* 103 * Compare idle state phandles for index idx on all CPUs in the 104 * CPUidle driver cpumask. Start from next logical cpu following 105 * cpumask_first(cpumask) since that's the CPU state_node was 106 * retrieved from. If a mismatch is found bail out straight 107 * away since we certainly hit a firmware misconfiguration. 108 */ 109 cpu = cpumask_first(cpumask) + 1; 110 for_each_cpu_from(cpu, cpumask) { 111 cpu_node = of_cpu_device_node_get(cpu); 112 curr_state_node = of_get_cpu_state_node(cpu_node, idx); 113 of_node_put(curr_state_node); 114 of_node_put(cpu_node); 115 if (state_node != curr_state_node) 116 return false; 117 } 118 119 return true; 120 } 121 122 /** 123 * dt_init_idle_driver() - Parse the DT idle states and initialize the 124 * idle driver states array 125 * @drv: Pointer to CPU idle driver to be initialized 126 * @matches: Array of of_device_id match structures to search in for 127 * compatible idle state nodes. The data pointer for each valid 128 * struct of_device_id entry in the matches array must point to 129 * a function with the following signature, that corresponds to 130 * the CPUidle state enter function signature: 131 * 132 * int (*)(struct cpuidle_device *dev, 133 * struct cpuidle_driver *drv, 134 * int index); 135 * 136 * @start_idx: First idle state index to be initialized 137 * 138 * If DT idle states are detected and are valid the state count and states 139 * array entries in the cpuidle driver are initialized accordingly starting 140 * from index start_idx. 141 * 142 * Return: number of valid DT idle states parsed, <0 on failure 143 */ 144 int dt_init_idle_driver(struct cpuidle_driver *drv, 145 const struct of_device_id *matches, 146 unsigned int start_idx) 147 { 148 struct cpuidle_state *idle_state; 149 struct device_node *state_node, *cpu_node; 150 const struct of_device_id *match_id; 151 int i, err = 0; 152 const cpumask_t *cpumask; 153 unsigned int state_idx = start_idx; 154 155 if (state_idx >= CPUIDLE_STATE_MAX) 156 return -EINVAL; 157 /* 158 * We get the idle states for the first logical cpu in the 159 * driver mask (or cpu_possible_mask if the driver cpumask is not set) 160 * and we check through idle_state_valid() if they are uniform 161 * across CPUs, otherwise we hit a firmware misconfiguration. 162 */ 163 cpumask = drv->cpumask ? : cpu_possible_mask; 164 cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); 165 166 for (i = 0; ; i++) { 167 state_node = of_get_cpu_state_node(cpu_node, i); 168 if (!state_node) 169 break; 170 171 match_id = of_match_node(matches, state_node); 172 if (!match_id) { 173 err = -ENODEV; 174 break; 175 } 176 177 if (!of_device_is_available(state_node)) { 178 of_node_put(state_node); 179 continue; 180 } 181 182 if (!idle_state_valid(state_node, i, cpumask)) { 183 pr_warn("%pOF idle state not valid, bailing out\n", 184 state_node); 185 err = -EINVAL; 186 break; 187 } 188 189 if (state_idx == CPUIDLE_STATE_MAX) { 190 pr_warn("State index reached static CPU idle driver states array size\n"); 191 break; 192 } 193 194 idle_state = &drv->states[state_idx++]; 195 err = init_state_node(idle_state, match_id, state_node); 196 if (err) { 197 pr_err("Parsing idle state node %pOF failed with err %d\n", 198 state_node, err); 199 err = -EINVAL; 200 break; 201 } 202 of_node_put(state_node); 203 } 204 205 of_node_put(state_node); 206 of_node_put(cpu_node); 207 if (err) 208 return err; 209 210 /* Set the number of total supported idle states. */ 211 drv->state_count = state_idx; 212 213 /* 214 * Return the number of present and valid DT idle states, which can 215 * also be 0 on platforms with missing DT idle states or legacy DT 216 * configuration predating the DT idle states bindings. 217 */ 218 return state_idx - start_idx; 219 } 220 EXPORT_SYMBOL_GPL(dt_init_idle_driver); 221