linux-imx

/*

 * Copyright (C) 2014 Imagination Technologies

 * Author: Paul Burton <paul.burton@mips.com>

 *

 * 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.

 */

​

#include <linux/cpu_pm.h>

#include <linux/cpuidle.h>

#include <linux/init.h>

​

#include <asm/idle.h>

#include <asm/pm-cps.h>

​

/* Enumeration of the various idle states this driver may enter */

enum cps_idle_state {

    STATE_WAIT = 0,     /* MIPS wait instruction, coherent */

    STATE_NC_WAIT,      /* MIPS wait instruction, non-coherent */

    STATE_CLOCK_GATED,  /* Core clock gated */

    STATE_POWER_GATED,  /* Core power gated */

    STATE_COUNT

};

​

static int cps_nc_enter(struct cpuidle_device *dev,

            struct cpuidle_driver *drv, int index)

{

    enum cps_pm_state pm_state;

    int err;

​

    /*

     * At least one core must remain powered up & clocked in order for the

     * system to have any hope of functioning.

     *

     * TODO: don't treat core 0 specially, just prevent the final core

     * TODO: remap interrupt affinity temporarily

     */

    if (cpus_are_siblings(0, dev->cpu) && (index > STATE_NC_WAIT))

        index = STATE_NC_WAIT;

​

    /* Select the appropriate cps_pm_state */

    switch (index) {

    case STATE_NC_WAIT:

        pm_state = CPS_PM_NC_WAIT;

        break;

    case STATE_CLOCK_GATED:

        pm_state = CPS_PM_CLOCK_GATED;

        break;

    case STATE_POWER_GATED:

        pm_state = CPS_PM_POWER_GATED;

        break;

    default:

        BUG();

        return -EINVAL;

    }

​

    /* Notify listeners the CPU is about to power down */

    if ((pm_state == CPS_PM_POWER_GATED) && cpu_pm_enter())

        return -EINTR;

​

    /* Enter that state */