cpuidle.c

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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 <linux/io.h>
#include <linux/export.h>
#include <asm/proc-fns.h>
#include <asm/cpuidle.h>
#include <mach/cpu.h>

#include "pm.h"

#define AT91_MAX_STATES 2

static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device);

/* 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)
{
    if (cpu_is_at91rm9200())
        at91rm9200_standby();
    else if (cpu_is_at91sam9g45())
        at91sam9g45_standby();
    else
        at91sam9_standby();

    return index;
}

static struct cpuidle_driver at91_idle_driver = {
    .name           = "at91_idle",
    .owner          = THIS_MODULE,
    .en_core_tk_irqen   = 1,
    .states[0]      = ARM_CPUIDLE_WFI_STATE,
    .states[1]      = {
        .enter          = at91_enter_idle,
        .exit_latency       = 10,
        .target_residency   = 100000,
        .flags          = CPUIDLE_FLAG_TIME_VALID,
        .name           = "RAM_SR",
        .desc           = "WFI and DDR Self Refresh",
    },
    .state_count = AT91_MAX_STATES,
};

/* Initialize CPU idle by registering the idle states */
static int at91_init_cpuidle(void)
{
    struct cpuidle_device *device;

    device = &per_cpu(at91_cpuidle_device, smp_processor_id());
    device->state_count = AT91_MAX_STATES;

    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);