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 24static 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 31 match_id = of_match_node(matches, state_node); 32 if (!match_id) 33 return -ENODEV; 34 /* 35 * CPUidle drivers are expected to initialize the const void *data 36 * pointer of the passed in struct of_device_id array to the idle 37 * state enter function. 38 */ 39 idle_state->enter = 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(" * %s missing entry-latency-us property\n", 50 state_node->full_name); 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(" * %s missing exit-latency-us property\n", 58 state_node->full_name); 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(" * %s missing min-residency-us property\n", 72 state_node->full_name); 73 return -EINVAL; 74 } 75 76 idle_state->flags = CPUIDLE_FLAG_TIME_VALID; 77 if (of_property_read_bool(state_node, "local-timer-stop")) 78 idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; 79 /* 80 * TODO: 81 * replace with kstrdup and pointer assignment when name 82 * and desc become string pointers 83 */ 84 strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); 85 strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1); 86 return 0; 87} 88 89/* 90 * Check that the idle state is uniform across all CPUs in the CPUidle driver 91 * cpumask 92 */ 93static bool idle_state_valid(struct device_node *state_node, unsigned int idx, 94 const cpumask_t *cpumask) 95{ 96 int cpu; 97 struct device_node *cpu_node, *curr_state_node; 98 bool valid = true; 99 100 /* 101 * Compare idle state phandles for index idx on all CPUs in the 102 * CPUidle driver cpumask. Start from next logical cpu following 103 * cpumask_first(cpumask) since that's the CPU state_node was 104 * retrieved from. If a mismatch is found bail out straight 105 * away since we certainly hit a firmware misconfiguration. 106 */ 107 for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); 108 cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { 109 cpu_node = of_cpu_device_node_get(cpu); 110 curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states", 111 idx); 112 if (state_node != curr_state_node) 113 valid = false; 114 115 of_node_put(curr_state_node); 116 of_node_put(cpu_node); 117 if (!valid) 118 break; 119 } 120 121 return valid; 122} 123 124/** 125 * dt_init_idle_driver() - Parse the DT idle states and initialize the 126 * idle driver states array 127 * @drv: Pointer to CPU idle driver to be initialized 128 * @matches: Array of of_device_id match structures to search in for 129 * compatible idle state nodes. The data pointer for each valid 130 * struct of_device_id entry in the matches array must point to 131 * a function with the following signature, that corresponds to 132 * the CPUidle state enter function signature: 133 * 134 * int (*)(struct cpuidle_device *dev, 135 * struct cpuidle_driver *drv, 136 * int index); 137 * 138 * @start_idx: First idle state index to be initialized 139 * 140 * If DT idle states are detected and are valid the state count and states 141 * array entries in the cpuidle driver are initialized accordingly starting 142 * from index start_idx. 143 * 144 * Return: number of valid DT idle states parsed, <0 on failure 145 */ 146int dt_init_idle_driver(struct cpuidle_driver *drv, 147 const struct of_device_id *matches, 148 unsigned int start_idx) 149{ 150 struct cpuidle_state *idle_state; 151 struct device_node *state_node, *cpu_node; 152 int i, err = 0; 153 const cpumask_t *cpumask; 154 unsigned int state_idx = start_idx; 155 156 if (state_idx >= CPUIDLE_STATE_MAX) 157 return -EINVAL; 158 /* 159 * We get the idle states for the first logical cpu in the 160 * driver mask (or cpu_possible_mask if the driver cpumask is not set) 161 * and we check through idle_state_valid() if they are uniform 162 * across CPUs, otherwise we hit a firmware misconfiguration. 163 */ 164 cpumask = drv->cpumask ? : cpu_possible_mask; 165 cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); 166 167 for (i = 0; ; i++) { 168 state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); 169 if (!state_node) 170 break; 171 172 if (!idle_state_valid(state_node, i, cpumask)) { 173 pr_warn("%s idle state not valid, bailing out\n", 174 state_node->full_name); 175 err = -EINVAL; 176 break; 177 } 178 179 if (state_idx == CPUIDLE_STATE_MAX) { 180 pr_warn("State index reached static CPU idle driver states array size\n"); 181 break; 182 } 183 184 idle_state = &drv->states[state_idx++]; 185 err = init_state_node(idle_state, matches, state_node); 186 if (err) { 187 pr_err("Parsing idle state node %s failed with err %d\n", 188 state_node->full_name, err); 189 err = -EINVAL; 190 break; 191 } 192 of_node_put(state_node); 193 } 194 195 of_node_put(state_node); 196 of_node_put(cpu_node); 197 if (err) 198 return err; 199 /* 200 * Update the driver state count only if some valid DT idle states 201 * were detected 202 */ 203 if (i) 204 drv->state_count = state_idx; 205 206 /* 207 * Return the number of present and valid DT idle states, which can 208 * also be 0 on platforms with missing DT idle states or legacy DT 209 * configuration predating the DT idle states bindings. 210 */ 211 return i; 212} 213EXPORT_SYMBOL_GPL(dt_init_idle_driver); 214