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/*
* ARM/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 arm: " 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 <linux/slab.h>
#include <linux/topology.h>
#include <asm/cpuidle.h>
#include "dt_idle_states.h"
/*
* arm_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 arm_enter_idle_state(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int idx)
{
/*
* Pass idle state index to arm_cpuidle_suspend which in turn
* will call the CPU ops suspend protocol with idle index as a
* parameter.
*/
return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
}
static struct cpuidle_driver arm_idle_driver __initdata = {
.name = "arm_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 = arm_enter_idle_state,
.exit_latency = 1,
.target_residency = 1,
.power_usage = UINT_MAX,
.name = "WFI",
.desc = "ARM WFI",
}
};
static const struct of_device_id arm_idle_state_match[] __initconst = {
{ .compatible = "arm,idle-state",
.data = arm_enter_idle_state },
{ },
};
/*
* arm_idle_init_cpu
*
* Registers the arm 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 arm_idle_init_cpu(int cpu)
{
int ret;
struct cpuidle_driver *drv;
drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
if (!drv)
return -ENOMEM;
drv->cpumask = (struct cpumask *)cpumask_of(cpu);
/*
* 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, arm_idle_state_match, 1);
if (ret <= 0) {
ret = ret ? : -ENODEV;
goto out_kfree_drv;
}
/*
* Call arch CPU operations in order to initialize
* idle states suspend back-end specific data
*/
ret = arm_cpuidle_init(cpu);
/*
* Allow the initialization to continue for other CPUs, if the reported
* failure is a HW misconfiguration/breakage (-ENXIO).
*/
if (ret) {
pr_err("CPU %d failed to init idle CPU ops\n", cpu);
ret = ret == -ENXIO ? 0 : ret;
goto out_kfree_drv;
}
ret = cpuidle_register(drv, NULL);
if (ret)
goto out_kfree_drv;
return 0;
out_kfree_drv:
kfree(drv);
return ret;
}
/*
* arm_idle_init - Initializes arm cpuidle driver
*
* Initializes arm cpuidle driver for all CPUs, if any CPU fails
* to register cpuidle driver then rollback to cancel all CPUs
* registeration.
*/
static int __init arm_idle_init(void)
{
int cpu, ret;
struct cpuidle_driver *drv;
struct cpuidle_device *dev;
for_each_possible_cpu(cpu) {
ret = arm_idle_init_cpu(cpu);
if (ret)
goto out_fail;
}
return 0;
out_fail:
while (--cpu >= 0) {
dev = per_cpu(cpuidle_devices, cpu);
drv = cpuidle_get_cpu_driver(dev);
cpuidle_unregister(drv);
kfree(drv);
}
return ret;
}
device_initcall(arm_idle_init);
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