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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;
/*
* Since this is not a "coupled" state, it's safe to assume interrupts
* won't be enabled when it exits allowing the tick to be frozen
* safely. So enter() can be also enter_freeze() callback.
*/
idle_state->enter_freeze = 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))
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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