LXR linux/drivers/cpuidle/dt_idle

   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
  21static 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 */
  97static 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_get_cpu_state_node(cpu_node, idx);
 115                if (state_node != curr_state_node)
 116                        valid = false;
 117
 118                of_node_put(curr_state_node);
 119                of_node_put(cpu_node);
 120                if (!valid)
 121                        break;
 122        }
 123
 124        return valid;
 125}
 126
 127/**
 128 * dt_init_idle_driver() - Parse the DT idle states and initialize the
 129 *                         idle driver states array
 130 * @drv:          Pointer to CPU idle driver to be initialized
 131 * @matches:      Array of of_device_id match structures to search in for
 132 *                compatible idle state nodes. The data pointer for each valid
 133 *                struct of_device_id entry in the matches array must point to
 134 *                a function with the following signature, that corresponds to
 135 *                the CPUidle state enter function signature:
 136 *
 137 *                int (*)(struct cpuidle_device *dev,
 138 *                        struct cpuidle_driver *drv,
 139 *                        int index);
 140 *
 141 * @start_idx:    First idle state index to be initialized
 142 *
 143 * If DT idle states are detected and are valid the state count and states
 144 * array entries in the cpuidle driver are initialized accordingly starting
 145 * from index start_idx.
 146 *
 147 * Return: number of valid DT idle states parsed, <0 on failure
 148 */
 149int dt_init_idle_driver(struct cpuidle_driver *drv,
 150                        const struct of_device_id *matches,
 151                        unsigned int start_idx)
 152{
 153        struct cpuidle_state *idle_state;
 154        struct device_node *state_node, *cpu_node;
 155        const struct of_device_id *match_id;
 156        int i, err = 0;
 157        const cpumask_t *cpumask;
 158        unsigned int state_idx = start_idx;
 159
 160        if (state_idx >= CPUIDLE_STATE_MAX)
 161                return -EINVAL;
 162        /*
 163         * We get the idle states for the first logical cpu in the
 164         * driver mask (or cpu_possible_mask if the driver cpumask is not set)
 165         * and we check through idle_state_valid() if they are uniform
 166         * across CPUs, otherwise we hit a firmware misconfiguration.
 167         */
 168        cpumask = drv->cpumask ? : cpu_possible_mask;
 169        cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
 170
 171        for (i = 0; ; i++) {
 172                state_node = of_get_cpu_state_node(cpu_node, i);
 173                if (!state_node)
 174                        break;
 175
 176                match_id = of_match_node(matches, state_node);
 177                if (!match_id) {
 178                        err = -ENODEV;
 179                        break;
 180                }
 181
 182                if (!of_device_is_available(state_node)) {
 183                        of_node_put(state_node);
 184                        continue;
 185                }
 186
 187                if (!idle_state_valid(state_node, i, cpumask)) {
 188                        pr_warn("%pOF idle state not valid, bailing out\n",
 189                                state_node);
 190                        err = -EINVAL;
 191                        break;
 192                }
 193
 194                if (state_idx == CPUIDLE_STATE_MAX) {
 195                        pr_warn("State index reached static CPU idle driver states array size\n");
 196                        break;
 197                }
 198
 199                idle_state = &drv->states[state_idx++];
 200                err = init_state_node(idle_state, match_id, state_node);
 201                if (err) {
 202                        pr_err("Parsing idle state node %pOF failed with err %d\n",
 203                               state_node, err);
 204                        err = -EINVAL;
 205                        break;
 206                }
 207                of_node_put(state_node);
 208        }
 209
 210        of_node_put(state_node);
 211        of_node_put(cpu_node);
 212        if (err)
 213                return err;
 214        /*
 215         * Update the driver state count only if some valid DT idle states
 216         * were detected
 217         */
 218        if (i)
 219                drv->state_count = state_idx;
 220
 221        /*
 222         * Return the number of present and valid DT idle states, which can
 223         * also be 0 on platforms with missing DT idle states or legacy DT
 224         * configuration predating the DT idle states bindings.
 225         */
 226        return i;
 227}
 228EXPORT_SYMBOL_GPL(dt_init_idle_driver);
 229