sdhci-cns3xxx.c

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/*
 * SDHCI support for CNS3xxx SoC
 *
 * Copyright 2008 Cavium Networks
 * Copyright 2010 MontaVista Software, LLC.
 *
 * Authors: Scott Shu
 *      Anton Vorontsov <[email protected]>
 *
 * 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/delay.h>
#include <linux/device.h>
#include <linux/mmc/host.h>
#include <linux/module.h>
#include <mach/cns3xxx.h>
#include "sdhci-pltfm.h"

static unsigned int sdhci_cns3xxx_get_max_clk(struct sdhci_host *host)
{
    return 150000000;
}

static void sdhci_cns3xxx_set_clock(struct sdhci_host *host, unsigned int clock)
{
    struct device *dev = mmc_dev(host->mmc);
    int div = 1;
    u16 clk;
    unsigned long timeout;

    if (clock == host->clock)
        return;

    sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);

    if (clock == 0)
        goto out;

    while (host->max_clk / div > clock) {
        /*
         * On CNS3xxx divider grows linearly up to 4, and then
         * exponentially up to 256.
         */
        if (div < 4)
            div += 1;
        else if (div < 256)
            div *= 2;
        else
            break;
    }

    dev_dbg(dev, "desired SD clock: %d, actual: %d\n",
        clock, host->max_clk / div);

    /* Divide by 3 is special. */
    if (div != 3)
        div >>= 1;

    clk = div << SDHCI_DIVIDER_SHIFT;
    clk |= SDHCI_CLOCK_INT_EN;
    sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);

    timeout = 20;
    while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
            & SDHCI_CLOCK_INT_STABLE)) {
        if (timeout == 0) {
            dev_warn(dev, "clock is unstable");
            break;
        }
        timeout--;
        mdelay(1);
    }

    clk |= SDHCI_CLOCK_CARD_EN;
    sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
out:
    host->clock = clock;
}

static struct sdhci_ops sdhci_cns3xxx_ops = {
    .get_max_clock  = sdhci_cns3xxx_get_max_clk,
    .set_clock  = sdhci_cns3xxx_set_clock,
};

static struct sdhci_pltfm_data sdhci_cns3xxx_pdata = {
    .ops = &sdhci_cns3xxx_ops,
    .quirks = SDHCI_QUIRK_BROKEN_DMA |
          SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
          SDHCI_QUIRK_INVERTED_WRITE_PROTECT |
          SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
          SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
          SDHCI_QUIRK_NONSTANDARD_CLOCK,
};

static int __devinit sdhci_cns3xxx_probe(struct platform_device *pdev)
{
    return sdhci_pltfm_register(pdev, &sdhci_cns3xxx_pdata);
}

static int __devexit sdhci_cns3xxx_remove(struct platform_device *pdev)
{
    return sdhci_pltfm_unregister(pdev);
}

static struct platform_driver sdhci_cns3xxx_driver = {
    .driver     = {
        .name   = "sdhci-cns3xxx",
        .owner  = THIS_MODULE,
        .pm = SDHCI_PLTFM_PMOPS,
    },
    .probe      = sdhci_cns3xxx_probe,
    .remove     = __devexit_p(sdhci_cns3xxx_remove),
};

module_platform_driver(sdhci_cns3xxx_driver);

MODULE_DESCRIPTION("SDHCI driver for CNS3xxx");
MODULE_AUTHOR("Scott Shu, "
          "Anton Vorontsov <[email protected]>");
MODULE_LICENSE("GPL v2");