mmdc.c

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/*
 * Copyright 2011 Freescale Semiconductor, Inc.
 * Copyright 2011 Linaro Ltd.
 *
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>

#define MMDC_MAPSR      0x404
#define BP_MMDC_MAPSR_PSD   0
#define BP_MMDC_MAPSR_PSS   4

static int __devinit imx_mmdc_probe(struct platform_device *pdev)
{
    struct device_node *np = pdev->dev.of_node;
    void __iomem *mmdc_base, *reg;
    u32 val;
    int timeout = 0x400;

    mmdc_base = of_iomap(np, 0);
    WARN_ON(!mmdc_base);

    reg = mmdc_base + MMDC_MAPSR;

    /* Enable automatic power saving */
    val = readl_relaxed(reg);
    val &= ~(1 << BP_MMDC_MAPSR_PSD);
    writel_relaxed(val, reg);

    /* Ensure it's successfully enabled */
    while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
        cpu_relax();

    if (unlikely(!timeout)) {
        pr_warn("%s: failed to enable automatic power saving\n",
            __func__);
        return -EBUSY;
    }

    return 0;
}

static struct of_device_id imx_mmdc_dt_ids[] = {
    { .compatible = "fsl,imx6q-mmdc", },
    { /* sentinel */ }
};

static struct platform_driver imx_mmdc_driver = {
    .driver     = {
        .name   = "imx-mmdc",
        .owner  = THIS_MODULE,
        .of_match_table = imx_mmdc_dt_ids,
    },
    .probe      = imx_mmdc_probe,
};

static int __init imx_mmdc_init(void)
{
    return platform_driver_register(&imx_mmdc_driver);
}
postcore_initcall(imx_mmdc_init);