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 #include <linux/of_device.h> 18 19 #include "dt_idle_states.h" 20 21 static int init_state_node(struct cpuidle_state *idle_state, 22 const struct of_device_id *match_id, 23 struct device_node *state_node) 24 { 25 int err; 26 const char *desc; 27 28 /* 29 * CPUidle drivers are expected to initialize the const void *data 30 * pointer of the passed in struct of_device_id array to the idle 31 * state enter function. 32 */ 33 idle_state->enter = match_id->data; 34 /* 35 * Since this is not a "coupled" state, it's safe to assume interrupts 36 * won't be enabled when it exits allowing the tick to be frozen 37 * safely. So enter() can be also enter_s2idle() callback. 38 */ 39 idle_state->enter_s2idle = match_id->data; 40 41 err = of_property_read_u32(state_node, "wakeup-latency-us", 42 &idle_state->exit_latency); 43 if (err) { 44 u32 entry_latency, exit_latency; 45 46 err = of_property_read_u32(state_node, "entry-latency-us", 47 &entry_latency); 48 if (err) { 49 pr_debug(" * %pOF missing entry-latency-us property\n", 50 state_node); 51 return -EINVAL; 52 } 53 54 err = of_property_read_u32(state_node, "exit-latency-us", 55 &exit_latency); 56 if (err) { 57 pr_debug(" * %pOF missing exit-latency-us property\n", 58 state_node); 59 return -EINVAL; 60 } 61 /* 62 * If wakeup-latency-us is missing, default to entry+exit 63 * latencies as defined in idle states bindings 64 */ 65 idle_state->exit_latency = entry_latency + exit_latency; 66 } 67 68 err = of_property_read_u32(state_node, "min-residency-us", 69 &idle_state->target_residency); 70 if (err) { 71 pr_debug(" * %pOF missing min-residency-us property\n", 72 state_node); 73 return -EINVAL; 74 } 75 76 err = of_property_read_string(state_node, "idle-state-name", &desc); 77 if (err) 78 desc = state_node->name; 79 80 idle_state->flags = 0; 81 if (of_property_read_bool(state_node, "local-timer-stop")) 82 idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; 83 /* 84 * TODO: 85 * replace with kstrdup and pointer assignment when name 86 * and desc become string pointers 87 */ 88 strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); 89 strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1); 90 return 0; 91 } 92 93 /* 94 * Check that the idle state is uniform across all CPUs in the CPUidle driver 95 * cpumask 96 */ 97 static bool idle_state_valid(struct device_node *state_node, unsigned int idx, 98 const cpumask_t *cpumask) 99 { 100 int cpu; 101 struct device_node *cpu_node, *curr_state_node; 102 bool valid = true; 103 104 /* 105 * Compare idle state phandles for index idx on all CPUs in the 106 * CPUidle driver cpumask. Start from next logical cpu following 107 * cpumask_first(cpumask) since that's the CPU state_node was 108 * retrieved from. If a mismatch is found bail out straight 109 * away since we certainly hit a firmware misconfiguration. 110 */ 111 for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); 112 cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { 113 cpu_node = of_cpu_device_node_get(cpu); 114 curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states", 115 idx); 116 if (state_node != curr_state_node) 117 valid = false; 118 119 of_node_put(curr_state_node); 120 of_node_put(cpu_node); 121 if (!valid) 122 break; 123 } 124 125 return valid; 126 } 127 128 /** 129 * dt_init_idle_driver() - Parse the DT idle states and initialize the 130 * idle driver states array 131 * @drv: Pointer to CPU idle driver to be initialized 132 * @matches: Array of of_device_id match structures to search in for 133 * compatible idle state nodes. The data pointer for each valid 134 * struct of_device_id entry in the matches array must point to 135 * a function with the following signature, that corresponds to 136 * the CPUidle state enter function signature: 137 * 138 * int (*)(struct cpuidle_device *dev, 139 * struct cpuidle_driver *drv, 140 * int index); 141 * 142 * @start_idx: First idle state index to be initialized 143 * 144 * If DT idle states are detected and are valid the state count and states 145 * array entries in the cpuidle driver are initialized accordingly starting 146 * from index start_idx. 147 * 148 * Return: number of valid DT idle states parsed, <0 on failure 149 */ 150 int dt_init_idle_driver(struct cpuidle_driver *drv, 151 const struct of_device_id *matches, 152 unsigned int start_idx) 153 { 154 struct cpuidle_state *idle_state; 155 struct device_node *state_node, *cpu_node; 156 const struct of_device_id *match_id; 157 int i, err = 0; 158 const cpumask_t *cpumask; 159 unsigned int state_idx = start_idx; 160 161 if (state_idx >= CPUIDLE_STATE_MAX) 162 return -EINVAL; 163 /* 164 * We get the idle states for the first logical cpu in the 165 * driver mask (or cpu_possible_mask if the driver cpumask is not set) 166 * and we check through idle_state_valid() if they are uniform 167 * across CPUs, otherwise we hit a firmware misconfiguration. 168 */ 169 cpumask = drv->cpumask ? : cpu_possible_mask; 170 cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); 171 172 for (i = 0; ; i++) { 173 state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); 174 if (!state_node) 175 break; 176 177 match_id = of_match_node(matches, state_node); 178 if (!match_id) { 179 err = -ENODEV; 180 break; 181 } 182 183 if (!of_device_is_available(state_node)) { 184 of_node_put(state_node); 185 continue; 186 } 187 188 if (!idle_state_valid(state_node, i, cpumask)) { 189 pr_warn("%pOF idle state not valid, bailing out\n", 190 state_node); 191 err = -EINVAL; 192 break; 193 } 194 195 if (state_idx == CPUIDLE_STATE_MAX) { 196 pr_warn("State index reached static CPU idle driver states array size\n"); 197 break; 198 } 199 200 idle_state = &drv->states[state_idx++]; 201 err = init_state_node(idle_state, match_id, state_node); 202 if (err) { 203 pr_err("Parsing idle state node %pOF failed with err %d\n", 204 state_node, err); 205 err = -EINVAL; 206 break; 207 } 208 of_node_put(state_node); 209 } 210 211 of_node_put(state_node); 212 of_node_put(cpu_node); 213 if (err) 214 return err; 215 /* 216 * Update the driver state count only if some valid DT idle states 217 * were detected 218 */ 219 if (i) 220 drv->state_count = state_idx; 221 222 /* 223 * Return the number of present and valid DT idle states, which can 224 * also be 0 on platforms with missing DT idle states or legacy DT 225 * configuration predating the DT idle states bindings. 226 */ 227 return i; 228 } 229 EXPORT_SYMBOL_GPL(dt_init_idle_driver); 230