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/*
* arch/arm/mach-kirkwood/cpuidle.c
*
* CPU idle Marvell Kirkwood SoCs
*
* 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 DDR self refresh in order
* to implement two idle states -
* #1 wait-for-interrupt
* #2 wait-for-interrupt and DDR self refresh
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/cpuidle.h>
#include <linux/io.h>
#include <asm/proc-fns.h>
#include <mach/kirkwood.h>
#define KIRKWOOD_MAX_STATES 2
static struct cpuidle_driver kirkwood_idle_driver = {
.name = "kirkwood_idle",
.owner = THIS_MODULE,
};
static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
/* Actual code that puts the SoC in different idle states */
static int kirkwood_enter_idle(struct cpuidle_device *dev,
int index)
{
struct timeval before, after;
int idle_time;
local_irq_disable();
do_gettimeofday(&before);
if (index == 0)
/* Wait for interrupt state */
cpu_do_idle();
else if (index == 1) {
/*
* Following write will put DDR in self refresh.
* Note that we have 256 cycles before DDR puts it
* self in self-refresh, so the wait-for-interrupt
* call afterwards won't get the DDR from self refresh
* mode.
*/
writel(0x7, DDR_OPERATION_BASE);
cpu_do_idle();
}
do_gettimeofday(&after);
local_irq_enable();
idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
(after.tv_usec - before.tv_usec);
/* Update last residency */
dev->last_residency = idle_time;
return index;
}
/* Initialize CPU idle by registering the idle states */
static int kirkwood_init_cpuidle(void)
{
struct cpuidle_device *device;
cpuidle_register_driver(&kirkwood_idle_driver);
device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
device->state_count = KIRKWOOD_MAX_STATES;
/* Wait for interrupt state */
device->states[0].enter = kirkwood_enter_idle;
device->states[0].exit_latency = 1;
device->states[0].target_residency = 10000;
device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[0].name, "WFI");
strcpy(device->states[0].desc, "Wait for interrupt");
/* Wait for interrupt and DDR self refresh state */
device->states[1].enter = kirkwood_enter_idle;
device->states[1].exit_latency = 10;
device->states[1].target_residency = 10000;
device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[1].name, "DDR SR");
strcpy(device->states[1].desc, "WFI and DDR Self Refresh");
if (cpuidle_register_device(device)) {
printk(KERN_ERR "kirkwood_init_cpuidle: Failed registering\n");
return -EIO;
}
return 0;
}
device_initcall(kirkwood_init_cpuidle);
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