drivers/cpuidle/dt_idle_states.c

   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
  20 static 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  */
  96 static 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  */
 148 int 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 }
 224 EXPORT_SYMBOL_GPL(dt_init_idle_driver);