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- /*
- * DT idle states parsing code.
- *
- * Copyright (C) 2014 ARM Ltd.
- * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #define pr_fmt(fmt) "DT idle-states: " fmt
- #include <linux/cpuidle.h>
- #include <linux/cpumask.h>
- #include <linux/errno.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/of.h>
- #include <linux/of_device.h>
- #include "dt_idle_states.h"
- static int init_state_node(struct cpuidle_state *idle_state,
- const struct of_device_id *matches,
- struct device_node *state_node)
- {
- int err;
- const struct of_device_id *match_id;
- const char *desc;
- match_id = of_match_node(matches, state_node);
- if (!match_id)
- return -ENODEV;
- /*
- * CPUidle drivers are expected to initialize the const void *data
- * pointer of the passed in struct of_device_id array to the idle
- * state enter function.
- */
- idle_state->enter = match_id->data;
- err = of_property_read_u32(state_node, "wakeup-latency-us",
- &idle_state->exit_latency);
- if (err) {
- u32 entry_latency, exit_latency;
- err = of_property_read_u32(state_node, "entry-latency-us",
- &entry_latency);
- if (err) {
- pr_debug(" * %s missing entry-latency-us property\n",
- state_node->full_name);
- return -EINVAL;
- }
- err = of_property_read_u32(state_node, "exit-latency-us",
- &exit_latency);
- if (err) {
- pr_debug(" * %s missing exit-latency-us property\n",
- state_node->full_name);
- return -EINVAL;
- }
- /*
- * If wakeup-latency-us is missing, default to entry+exit
- * latencies as defined in idle states bindings
- */
- idle_state->exit_latency = entry_latency + exit_latency;
- }
- err = of_property_read_u32(state_node, "min-residency-us",
- &idle_state->target_residency);
- if (err) {
- pr_debug(" * %s missing min-residency-us property\n",
- state_node->full_name);
- return -EINVAL;
- }
- err = of_property_read_string(state_node, "idle-state-name", &desc);
- if (err)
- desc = state_node->name;
- idle_state->flags = 0;
- if (of_property_read_bool(state_node, "local-timer-stop"))
- idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
- /*
- * TODO:
- * replace with kstrdup and pointer assignment when name
- * and desc become string pointers
- */
- strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
- strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1);
- return 0;
- }
- /*
- * Check that the idle state is uniform across all CPUs in the CPUidle driver
- * cpumask
- */
- static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
- const cpumask_t *cpumask)
- {
- int cpu;
- struct device_node *cpu_node, *curr_state_node;
- bool valid = true;
- /*
- * Compare idle state phandles for index idx on all CPUs in the
- * CPUidle driver cpumask. Start from next logical cpu following
- * cpumask_first(cpumask) since that's the CPU state_node was
- * retrieved from. If a mismatch is found bail out straight
- * away since we certainly hit a firmware misconfiguration.
- */
- for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
- cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
- cpu_node = of_cpu_device_node_get(cpu);
- curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
- idx);
- if (state_node != curr_state_node)
- valid = false;
- of_node_put(curr_state_node);
- of_node_put(cpu_node);
- if (!valid)
- break;
- }
- return valid;
- }
- /**
- * dt_init_idle_driver() - Parse the DT idle states and initialize the
- * idle driver states array
- * @drv: Pointer to CPU idle driver to be initialized
- * @matches: Array of of_device_id match structures to search in for
- * compatible idle state nodes. The data pointer for each valid
- * struct of_device_id entry in the matches array must point to
- * a function with the following signature, that corresponds to
- * the CPUidle state enter function signature:
- *
- * int (*)(struct cpuidle_device *dev,
- * struct cpuidle_driver *drv,
- * int index);
- *
- * @start_idx: First idle state index to be initialized
- *
- * If DT idle states are detected and are valid the state count and states
- * array entries in the cpuidle driver are initialized accordingly starting
- * from index start_idx.
- *
- * Return: number of valid DT idle states parsed, <0 on failure
- */
- int dt_init_idle_driver(struct cpuidle_driver *drv,
- const struct of_device_id *matches,
- unsigned int start_idx)
- {
- struct cpuidle_state *idle_state;
- struct device_node *state_node, *cpu_node;
- int i, err = 0;
- const cpumask_t *cpumask;
- unsigned int state_idx = start_idx;
- if (state_idx >= CPUIDLE_STATE_MAX)
- return -EINVAL;
- /*
- * We get the idle states for the first logical cpu in the
- * driver mask (or cpu_possible_mask if the driver cpumask is not set)
- * and we check through idle_state_valid() if they are uniform
- * across CPUs, otherwise we hit a firmware misconfiguration.
- */
- cpumask = drv->cpumask ? : cpu_possible_mask;
- cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
- for (i = 0; ; i++) {
- state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
- if (!state_node)
- break;
- if (!of_device_is_available(state_node)) {
- of_node_put(state_node);
- continue;
- }
- if (!idle_state_valid(state_node, i, cpumask)) {
- pr_warn("%s idle state not valid, bailing out\n",
- state_node->full_name);
- err = -EINVAL;
- break;
- }
- if (state_idx == CPUIDLE_STATE_MAX) {
- pr_warn("State index reached static CPU idle driver states array size\n");
- break;
- }
- idle_state = &drv->states[state_idx++];
- err = init_state_node(idle_state, matches, state_node);
- if (err) {
- pr_err("Parsing idle state node %s failed with err %d\n",
- state_node->full_name, err);
- err = -EINVAL;
- break;
- }
- of_node_put(state_node);
- }
- of_node_put(state_node);
- of_node_put(cpu_node);
- if (err)
- return err;
- /*
- * Update the driver state count only if some valid DT idle states
- * were detected
- */
- if (i)
- drv->state_count = state_idx;
- /*
- * Return the number of present and valid DT idle states, which can
- * also be 0 on platforms with missing DT idle states or legacy DT
- * configuration predating the DT idle states bindings.
- */
- return i;
- }
- EXPORT_SYMBOL_GPL(dt_init_idle_driver);
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