225 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*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: " fmt10 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 *data29 * pointer of the passed in struct of_device_id array to the idle30 * 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 interrupts35 * won't be enabled when it exits allowing the tick to be frozen36 * 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+exit62 * latencies as defined in idle states bindings63 */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 name85 * and desc become string pointers86 */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 driver94 * cpumask95 */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 the105 * CPUidle driver cpumask. Start from next logical cpu following106 * cpumask_first(cpumask) since that's the CPU state_node was107 * retrieved from. If a mismatch is found bail out straight108 * 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 the128 * idle driver states array129 * @drv: Pointer to CPU idle driver to be initialized130 * @matches: Array of of_device_id match structures to search in for131 * compatible idle state nodes. The data pointer for each valid132 * struct of_device_id entry in the matches array must point to133 * a function with the following signature, that corresponds to134 * 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 initialized141 *142 * If DT idle states are detected and are valid the state count and states143 * array entries in the cpuidle driver are initialized accordingly starting144 * from index start_idx.145 *146 * Return: number of valid DT idle states parsed, <0 on failure147 */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 the163 * driver mask (or cpu_possible_mask if the driver cpumask is not set)164 * and we check through idle_state_valid() if they are uniform165 * 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 can219 * also be 0 on platforms with missing DT idle states or legacy DT220 * configuration predating the DT idle states bindings.221 */222 return state_idx - start_idx;223}224EXPORT_SYMBOL_GPL(dt_init_idle_driver);225