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/*
* ARM64 generic CPU idle driver.
*
* 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) "CPUidle arm64: " fmt
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/cpu_pm.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <asm/cpuidle.h>
#include "dt_idle_states.h"
/*
* arm64_enter_idle_state - Programs CPU to enter the specified state
*
* dev: cpuidle device
* drv: cpuidle driver
* idx: state index
*
* Called from the CPUidle framework to program the device to the
* specified target state selected by the governor.
*/
static int arm64_enter_idle_state(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int idx)
{
int ret;
if (!idx) {
cpu_do_idle();
return idx;
}
ret = cpu_pm_enter();
if (!ret) {
/*
* Pass idle state index to cpu_suspend which in turn will
* call the CPU ops suspend protocol with idle index as a
* parameter.
*/
arm_cpuidle_suspend(idx);
cpu_pm_exit();
}
return ret ? -1 : idx;
}
static struct cpuidle_driver arm64_idle_driver = {
.name = "arm64_idle",
.owner = THIS_MODULE,
/*
* State at index 0 is standby wfi and considered standard
* on all ARM platforms. If in some platforms simple wfi
* can't be used as "state 0", DT bindings must be implemented
* to work around this issue and allow installing a special
* handler for idle state index 0.
*/
.states[0] = {
.enter = arm64_enter_idle_state,
.exit_latency = 1,
.target_residency = 1,
.power_usage = UINT_MAX,
.name = "WFI",
.desc = "ARM64 WFI",
}
};
static const struct of_device_id arm64_idle_state_match[] __initconst = {
{ .compatible = "arm,idle-state",
.data = arm64_enter_idle_state },
{ },
};
/*
* arm64_idle_init
*
* Registers the arm64 specific cpuidle driver with the cpuidle
* framework. It relies on core code to parse the idle states
* and initialize them using driver data structures accordingly.
*/
static int __init arm64_idle_init(void)
{
int cpu, ret;
struct cpuidle_driver *drv = &arm64_idle_driver;
/*
* Initialize idle states data, starting at index 1.
* This driver is DT only, if no DT idle states are detected (ret == 0)
* let the driver initialization fail accordingly since there is no
* reason to initialize the idle driver if only wfi is supported.
*/
ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
if (ret <= 0)
return ret ? : -ENODEV;
/*
* Call arch CPU operations in order to initialize
* idle states suspend back-end specific data
*/
for_each_possible_cpu(cpu) {
ret = arm_cpuidle_init(cpu);
if (ret) {
pr_err("CPU %d failed to init idle CPU ops\n", cpu);
return ret;
}
}
return cpuidle_register(drv, NULL);
}
device_initcall(arm64_idle_init);
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