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 20static 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 */ 96static 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 bool valid = true; 102 103 /* 104 * Compare idle state phandles for index idx on all CPUs in the 105 * CPUidle driver cpumask. Start from next logical cpu following 106 * cpumask_first(cpumask) since that's the CPU state_node was 107 * retrieved from. If a mismatch is found bail out straight 108 * away since we certainly hit a firmware misconfiguration. 109 */ 110 for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); 111 cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { 112 cpu_node = of_cpu_device_node_get(cpu); 113 curr_state_node = of_get_cpu_state_node(cpu_node, idx); 114 if (state_node != curr_state_node) 115 valid = false; 116 117 of_node_put(curr_state_node); 118 of_node_put(cpu_node); 119 if (!valid) 120 break; 121 } 122 123 return valid; 124} 125 126/** 127 * dt_init_idle_driver() - Parse the DT idle states and initialize the 128 * idle driver states array 129 * @drv: Pointer to CPU idle driver to be initialized 130 * @matches: Array of of_device_id match structures to search in for 131 * compatible idle state nodes. The data pointer for each valid 132 * struct of_device_id entry in the matches array must point to 133 * a function with the following signature, that corresponds to 134 * the CPUidle state enter function signature: 135 * 136 * int (*)(struct cpuidle_device *dev, 137 * struct cpuidle_driver *drv, 138 * int index); 139 * 140 * @start_idx: First idle state index to be initialized 141 * 142 * If DT idle states are detected and are valid the state count and states 143 * array entries in the cpuidle driver are initialized accordingly starting 144 * from index start_idx. 145 * 146 * Return: number of valid DT idle states parsed, <0 on failure 147 */ 148int dt_init_idle_driver(struct cpuidle_driver *drv, 149 const struct of_device_id *matches, 150 unsigned int start_idx) 151{ 152 struct cpuidle_state *idle_state; 153 struct device_node *state_node, *cpu_node; 154 const struct of_device_id *match_id; 155 int i, err = 0; 156 const cpumask_t *cpumask; 157 unsigned int state_idx = start_idx; 158 159 if (state_idx >= CPUIDLE_STATE_MAX) 160 return -EINVAL; 161 /* 162 * We get the idle states for the first logical cpu in the 163 * driver mask (or cpu_possible_mask if the driver cpumask is not set) 164 * and we check through idle_state_valid() if they are uniform 165 * across CPUs, otherwise we hit a firmware misconfiguration. 166 */ 167 cpumask = drv->cpumask ? : cpu_possible_mask; 168 cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); 169 170 for (i = 0; ; i++) { 171 state_node = of_get_cpu_state_node(cpu_node, i); 172 if (!state_node) 173 break; 174 175 match_id = of_match_node(matches, state_node); 176 if (!match_id) { 177 err = -ENODEV; 178 break; 179 } 180 181 if (!of_device_is_available(state_node)) { 182 of_node_put(state_node); 183 continue; 184 } 185 186 if (!idle_state_valid(state_node, i, cpumask)) { 187 pr_warn("%pOF idle state not valid, bailing out\n", 188 state_node); 189 err = -EINVAL; 190 break; 191 } 192 193 if (state_idx == CPUIDLE_STATE_MAX) { 194 pr_warn("State index reached static CPU idle driver states array size\n"); 195 break; 196 } 197 198 idle_state = &drv->states[state_idx++]; 199 err = init_state_node(idle_state, match_id, state_node); 200 if (err) { 201 pr_err("Parsing idle state node %pOF failed with err %d\n", 202 state_node, err); 203 err = -EINVAL; 204 break; 205 } 206 of_node_put(state_node); 207 } 208 209 of_node_put(state_node); 210 of_node_put(cpu_node); 211 if (err) 212 return err; 213 214 /* Set the number of total supported idle states. */ 215 drv->state_count = state_idx; 216 217 /* 218 * Return the number of present and valid DT idle states, which can 219 * also be 0 on platforms with missing DT idle states or legacy DT 220 * configuration predating the DT idle states bindings. 221 */ 222 return state_idx - start_idx; 223} 224EXPORT_SYMBOL_GPL(dt_init_idle_driver); 225