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