cpuidle.c

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/*
 * arch/arm/mach-tegra/cpuidle.c
 *
 * CPU idle driver for Tegra CPUs
 *
 * Copyright (c) 2010-2012, NVIDIA Corporation.
 * Copyright (c) 2011 Google, Inc.
 * Author: Colin Cross <[email protected]>
 *         Gary King <[email protected]>
 *
 * Rework for 3.3 by Peter De Schrijver <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/hrtimer.h>

#include <asm/proc-fns.h>

#include <mach/iomap.h>

static int tegra_idle_enter_lp3(struct cpuidle_device *dev,
                struct cpuidle_driver *drv, int index);

struct cpuidle_driver tegra_idle_driver = {
    .name = "tegra_idle",
    .owner = THIS_MODULE,
    .state_count = 1,
    .states = {
        [0] = {
            .enter          = tegra_idle_enter_lp3,
            .exit_latency       = 10,
            .target_residency   = 10,
            .power_usage        = 600,
            .flags          = CPUIDLE_FLAG_TIME_VALID,
            .name           = "LP3",
            .desc           = "CPU flow-controlled",
        },
    },
};

static DEFINE_PER_CPU(struct cpuidle_device, tegra_idle_device);

static int tegra_idle_enter_lp3(struct cpuidle_device *dev,
    struct cpuidle_driver *drv, int index)
{
    ktime_t enter, exit;
    s64 us;

    local_irq_disable();
    local_fiq_disable();

    enter = ktime_get();

    cpu_do_idle();

    exit = ktime_sub(ktime_get(), enter);
    us = ktime_to_us(exit);

    local_fiq_enable();
    local_irq_enable();

    dev->last_residency = us;

    return index;
}

static int __init tegra_cpuidle_init(void)
{
    int ret;
    unsigned int cpu;
    struct cpuidle_device *dev;
    struct cpuidle_driver *drv = &tegra_idle_driver;

    ret = cpuidle_register_driver(&tegra_idle_driver);
    if (ret) {
        pr_err("CPUidle driver registration failed\n");
        return ret;
    }

    for_each_possible_cpu(cpu) {
        dev = &per_cpu(tegra_idle_device, cpu);
        dev->cpu = cpu;

        dev->state_count = drv->state_count;
        ret = cpuidle_register_device(dev);
        if (ret) {
            pr_err("CPU%u: CPUidle device registration failed\n",
                cpu);
            return ret;
        }
    }
    return 0;
}
device_initcall(tegra_cpuidle_init);