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