cpuidle.c

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/*
 * CPU idle for DaVinci SoCs
 *
 * Copyright (C) 2009 Texas Instruments Incorporated. http://www.ti.com/
 *
 * Derived from Marvell Kirkwood CPU idle code
 * (arch/arm/mach-kirkwood/cpuidle.c)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#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/cpuidle.h>
#include <mach/ddr2.h>

#define DAVINCI_CPUIDLE_MAX_STATES  2

struct davinci_ops {
    void (*enter) (u32 flags);
    void (*exit) (u32 flags);
    u32 flags;
};

/* Actual code that puts the SoC in different idle states */
static int davinci_enter_idle(struct cpuidle_device *dev,
                struct cpuidle_driver *drv,
                        int index)
{
    struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
    struct davinci_ops *ops = cpuidle_get_statedata(state_usage);

    if (ops && ops->enter)
        ops->enter(ops->flags);

    index = cpuidle_wrap_enter(dev, drv, index,
                arm_cpuidle_simple_enter);

    if (ops && ops->exit)
        ops->exit(ops->flags);

    return index;
}

/* fields in davinci_ops.flags */
#define DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN BIT(0)

static struct cpuidle_driver davinci_idle_driver = {
    .name           = "cpuidle-davinci",
    .owner          = THIS_MODULE,
    .en_core_tk_irqen   = 1,
    .states[0]      = ARM_CPUIDLE_WFI_STATE,
    .states[1]      = {
        .enter          = davinci_enter_idle,
        .exit_latency       = 10,
        .target_residency   = 100000,
        .flags          = CPUIDLE_FLAG_TIME_VALID,
        .name           = "DDR SR",
        .desc           = "WFI and DDR Self Refresh",
    },
    .state_count = DAVINCI_CPUIDLE_MAX_STATES,
};

static DEFINE_PER_CPU(struct cpuidle_device, davinci_cpuidle_device);
static void __iomem *ddr2_reg_base;

static void davinci_save_ddr_power(int enter, bool pdown)
{
    u32 val;

    val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);

    if (enter) {
        if (pdown)
            val |= DDR2_SRPD_BIT;
        else
            val &= ~DDR2_SRPD_BIT;
        val |= DDR2_LPMODEN_BIT;
    } else {
        val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
    }

    __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
}

static void davinci_c2state_enter(u32 flags)
{
    davinci_save_ddr_power(1, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
}

static void davinci_c2state_exit(u32 flags)
{
    davinci_save_ddr_power(0, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
}

static struct davinci_ops davinci_states[DAVINCI_CPUIDLE_MAX_STATES] = {
    [1] = {
        .enter  = davinci_c2state_enter,
        .exit   = davinci_c2state_exit,
    },
};

static int __init davinci_cpuidle_probe(struct platform_device *pdev)
{
    int ret;
    struct cpuidle_device *device;
    struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;

    device = &per_cpu(davinci_cpuidle_device, smp_processor_id());

    if (!pdata) {
        dev_err(&pdev->dev, "cannot get platform data\n");
        return -ENOENT;
    }

    ddr2_reg_base = pdata->ddr2_ctlr_base;

    if (pdata->ddr2_pdown)
        davinci_states[1].flags |= DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN;
    cpuidle_set_statedata(&device->states_usage[1], &davinci_states[1]);

    device->state_count = DAVINCI_CPUIDLE_MAX_STATES;

    ret = cpuidle_register_driver(&davinci_idle_driver);
    if (ret) {
        dev_err(&pdev->dev, "failed to register driver\n");
        return ret;
    }

    ret = cpuidle_register_device(device);
    if (ret) {
        dev_err(&pdev->dev, "failed to register device\n");
        cpuidle_unregister_driver(&davinci_idle_driver);
        return ret;
    }

    return 0;
}

static struct platform_driver davinci_cpuidle_driver = {
    .driver = {
        .name   = "cpuidle-davinci",
        .owner  = THIS_MODULE,
    },
};

static int __init davinci_cpuidle_init(void)
{
    return platform_driver_probe(&davinci_cpuidle_driver,
                        davinci_cpuidle_probe);
}
device_initcall(davinci_cpuidle_init);