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/*
* based on arch/arm/mach-kirkwood/cpuidle.c
*
* CPU idle support for AT91 SoC
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* The cpu idle uses wait-for-interrupt and RAM self refresh in order
* to implement two idle states -
* #1 wait-for-interrupt
* #2 wait-for-interrupt and RAM self refresh
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/cpuidle.h>
#include <asm/proc-fns.h>
#include <linux/io.h>
#include <linux/export.h>
#include "pm.h"
#define AT91_MAX_STATES 2
static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device);
static struct cpuidle_driver at91_idle_driver = {
.name = "at91_idle",
.owner = THIS_MODULE,
};
/* Actual code that puts the SoC in different idle states */
static int at91_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
struct timeval before, after;
int idle_time;
u32 saved_lpr;
local_irq_disable();
do_gettimeofday(&before);
if (index == 0)
/* Wait for interrupt state */
cpu_do_idle();
else if (index == 1) {
asm("b 1f; .align 5; 1:");
asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
saved_lpr = sdram_selfrefresh_enable();
cpu_do_idle();
sdram_selfrefresh_disable(saved_lpr);
}
do_gettimeofday(&after);
local_irq_enable();
idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
(after.tv_usec - before.tv_usec);
dev->last_residency = idle_time;
return index;
}
/* Initialize CPU idle by registering the idle states */
static int at91_init_cpuidle(void)
{
struct cpuidle_device *device;
struct cpuidle_driver *driver = &at91_idle_driver;
device = &per_cpu(at91_cpuidle_device, smp_processor_id());
device->state_count = AT91_MAX_STATES;
driver->state_count = AT91_MAX_STATES;
/* Wait for interrupt state */
driver->states[0].enter = at91_enter_idle;
driver->states[0].exit_latency = 1;
driver->states[0].target_residency = 10000;
driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[0].name, "WFI");
strcpy(driver->states[0].desc, "Wait for interrupt");
/* Wait for interrupt and RAM self refresh state */
driver->states[1].enter = at91_enter_idle;
driver->states[1].exit_latency = 10;
driver->states[1].target_residency = 10000;
driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[1].name, "RAM_SR");
strcpy(driver->states[1].desc, "WFI and RAM Self Refresh");
cpuidle_register_driver(&at91_idle_driver);
if (cpuidle_register_device(device)) {
printk(KERN_ERR "at91_init_cpuidle: Failed registering\n");
return -EIO;
}
return 0;
}
device_initcall(at91_init_cpuidle);
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