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/*
* Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
*
* Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
* and Jonas Aaberg <jonas.aberg@stericsson.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.
*/
#include <linux/module.h>
#include <linux/cpuidle.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/smp.h>
#include <linux/mfd/dbx500-prcmu.h>
#include <asm/cpuidle.h>
#include <asm/proc-fns.h>
static atomic_t master = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(master_lock);
static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
static inline int ux500_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
int this_cpu = smp_processor_id();
bool recouple = false;
if (atomic_inc_return(&master) == num_online_cpus()) {
/* With this lock, we prevent the other cpu to exit and enter
* this function again and become the master */
if (!spin_trylock(&master_lock))
goto wfi;
/* decouple the gic from the A9 cores */
if (prcmu_gic_decouple()) {
spin_unlock(&master_lock);
goto out;
}
/* If an error occur, we will have to recouple the gic
* manually */
recouple = true;
/* At this state, as the gic is decoupled, if the other
* cpu is in WFI, we have the guarantee it won't be wake
* up, so we can safely go to retention */
if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
goto out;
/* The prcmu will be in charge of watching the interrupts
* and wake up the cpus */
if (prcmu_copy_gic_settings())
goto out;
/* Check in the meantime an interrupt did
* not occur on the gic ... */
if (prcmu_gic_pending_irq())
goto out;
/* ... and the prcmu */
if (prcmu_pending_irq())
goto out;
/* Go to the retention state, the prcmu will wait for the
* cpu to go WFI and this is what happens after exiting this
* 'master' critical section */
if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
goto out;
/* When we switch to retention, the prcmu is in charge
* of recoupling the gic automatically */
recouple = false;
spin_unlock(&master_lock);
}
wfi:
cpu_do_idle();
out:
atomic_dec(&master);
if (recouple) {
prcmu_gic_recouple();
spin_unlock(&master_lock);
}
return index;
}
static struct cpuidle_driver ux500_idle_driver = {
.name = "ux500_idle",
.owner = THIS_MODULE,
.en_core_tk_irqen = 1,
.states = {
ARM_CPUIDLE_WFI_STATE,
{
.enter = ux500_enter_idle,
.exit_latency = 70,
.target_residency = 260,
.flags = CPUIDLE_FLAG_TIME_VALID |
CPUIDLE_FLAG_TIMER_STOP,
.name = "ApIdle",
.desc = "ARM Retention",
},
},
.safe_state_index = 0,
.state_count = 2,
};
int __init ux500_idle_init(void)
{
int ret, cpu;
struct cpuidle_device *device;
/* Configure wake up reasons */
prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
PRCMU_WAKEUP(ABB));
ret = cpuidle_register_driver(&ux500_idle_driver);
if (ret) {
printk(KERN_ERR "failed to register ux500 idle driver\n");
return ret;
}
for_each_online_cpu(cpu) {
device = &per_cpu(ux500_cpuidle_device, cpu);
device->cpu = cpu;
ret = cpuidle_register_device(device);
if (ret) {
printk(KERN_ERR "Failed to register cpuidle "
"device for cpu%d\n", cpu);
goto out_unregister;
}
}
out:
return ret;
out_unregister:
for_each_online_cpu(cpu) {
device = &per_cpu(ux500_cpuidle_device, cpu);
cpuidle_unregister_device(device);
}
cpuidle_unregister_driver(&ux500_idle_driver);
goto out;
}
device_initcall(ux500_idle_init);
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