/*
 * Arasan Secure Digital Host Controller Interface.
 * Copyright (C) 2011 - 2012 Michal Simek <monstr@monstr.eu>
 * Copyright (c) 2012 Wind River Systems, Inc.
 * Copyright (C) 2013 Pengutronix e.K.
 * Copyright (C) 2013 Xilinx Inc.
 *
 * Based on sdhci-of-esdhc.c
 *
 * Copyright (c) 2007 Freescale Semiconductor, Inc.
 * Copyright (c) 2009 MontaVista Software, Inc.
 *
 * Authors: Xiaobo Xie <X.Xie@freescale.com>
 *          Anton Vorontsov <avorontsov@ru.mvista.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/clk-provider.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/phy/phy.h>
#include <linux/regmap.h>
#include "sdhci-pltfm.h"
#include <linux/of.h>

#define SDHCI_ARASAN_VENDOR_REGISTER    0x78

#define VENDOR_ENHANCED_STROBE          BIT(0)

#define PHY_CLK_TOO_SLOW_HZ             400000

/*
 * On some SoCs the syscon area has a feature where the upper 16-bits of
 * each 32-bit register act as a write mask for the lower 16-bits.  This allows
 * atomic updates of the register without locking.  This macro is used on SoCs
 * that have that feature.
 */
#define HIWORD_UPDATE(val, mask, shift) \
                ((val) << (shift) | (mask) << ((shift) + 16))

/**
 * struct sdhci_arasan_soc_ctl_field - Field used in sdhci_arasan_soc_ctl_map
 *
 * @reg:        Offset within the syscon of the register containing this field
 * @width:      Number of bits for this field
 * @shift:      Bit offset within @reg of this field (or -1 if not avail)
 */
struct sdhci_arasan_soc_ctl_field {
        u32 reg;
        u16 width;
        s16 shift;
};

/**
 * struct sdhci_arasan_soc_ctl_map - Map in syscon to corecfg registers
 *
 * It's up to the licensee of the Arsan IP block to make these available
 * somewhere if needed.  Presumably these will be scattered somewhere that's
 * accessible via the syscon API.
 *
 * @baseclkfreq:        Where to find corecfg_baseclkfreq
 * @clockmultiplier:    Where to find corecfg_clockmultiplier
 * @hiword_update:      If true, use HIWORD_UPDATE to access the syscon
 */
struct sdhci_arasan_soc_ctl_map {
        struct sdhci_arasan_soc_ctl_field       baseclkfreq;
        struct sdhci_arasan_soc_ctl_field       clockmultiplier;
        bool                                    hiword_update;
};

/**
 * struct sdhci_arasan_data
 * @host:               Pointer to the main SDHCI host structure.
 * @clk_ahb:            Pointer to the AHB clock
 * @phy:                Pointer to the generic phy
 * @is_phy_on:          True if the PHY is on; false if not.
 * @sdcardclk_hw:       Struct for the clock we might provide to a PHY.
 * @sdcardclk:          Pointer to normal 'struct clock' for sdcardclk_hw.
 * @soc_ctl_base:       Pointer to regmap for syscon for soc_ctl registers.
 * @soc_ctl_map:        Map to get offsets into soc_ctl registers.
 */
struct sdhci_arasan_data {
        struct sdhci_host *host;
        struct clk      *clk_ahb;
        struct phy      *phy;
        bool            is_phy_on;

        struct clk_hw   sdcardclk_hw;
        struct clk      *sdcardclk;

        struct regmap   *soc_ctl_base;
        const struct sdhci_arasan_soc_ctl_map *soc_ctl_map;
        unsigned int    quirks; /* Arasan deviations from spec */

/* Controller does not have CD wired and will not function normally without */
#define SDHCI_ARASAN_QUIRK_FORCE_CDTEST BIT(0)
};

static const struct sdhci_arasan_soc_ctl_map rk3399_soc_ctl_map = {
        .baseclkfreq = { .reg = 0xf000, .width = 8, .shift = 8 },
        .clockmultiplier = { .reg = 0xf02c, .width = 8, .shift = 0},
        .hiword_update = true,
};

/**
 * sdhci_arasan_syscon_write - Write to a field in soc_ctl registers
 *
 * This function allows writing to fields in sdhci_arasan_soc_ctl_map.
 * Note that if a field is specified as not available (shift < 0) then
 * this function will silently return an error code.  It will be noisy
 * and print errors for any other (unexpected) errors.
 *
 * @host:       The sdhci_host
 * @fld:        The field to write to
 * @val:        The value to write
 */
static int sdhci_arasan_syscon_write(struct sdhci_host *host,
                                   const struct sdhci_arasan_soc_ctl_field *fld,
                                   u32 val)
{
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        struct regmap *soc_ctl_base = sdhci_arasan->soc_ctl_base;
        u32 reg = fld->reg;
        u16 width = fld->width;
        s16 shift = fld->shift;
        int ret;

        /*
         * Silently return errors for shift < 0 so caller doesn't have
         * to check for fields which are optional.  For fields that
         * are required then caller needs to do something special
         * anyway.
         */
        if (shift < 0)
                return -EINVAL;

        if (sdhci_arasan->soc_ctl_map->hiword_update)
                ret = regmap_write(soc_ctl_base, reg,
                                   HIWORD_UPDATE(val, GENMASK(width, 0),
                                                 shift));
        else
                ret = regmap_update_bits(soc_ctl_base, reg,
                                         GENMASK(shift + width, shift),
                                         val << shift);

        /* Yell about (unexpected) regmap errors */
        if (ret)
                pr_warn("%s: Regmap write fail: %d\n",
                         mmc_hostname(host->mmc), ret);

        return ret;
}

static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock)
{
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        bool ctrl_phy = false;

        if (!IS_ERR(sdhci_arasan->phy)) {
                if (!sdhci_arasan->is_phy_on && clock <= PHY_CLK_TOO_SLOW_HZ) {
                        /*
                         * If PHY off, set clock to max speed and power PHY on.
                         *
                         * Although PHY docs apparently suggest power cycling
                         * when changing the clock the PHY doesn't like to be
                         * powered on while at low speeds like those used in ID
                         * mode.  Even worse is powering the PHY on while the
                         * clock is off.
                         *
                         * To workaround the PHY limitations, the best we can
                         * do is to power it on at a faster speed and then slam
                         * through low speeds without power cycling.
                         */
                        sdhci_set_clock(host, host->max_clk);
                        phy_power_on(sdhci_arasan->phy);
                        sdhci_arasan->is_phy_on = true;

                        /*
                         * We'll now fall through to the below case with
                         * ctrl_phy = false (so we won't turn off/on).  The
                         * sdhci_set_clock() will set the real clock.
                         */
                } else if (clock > PHY_CLK_TOO_SLOW_HZ) {
                        /*
                         * At higher clock speeds the PHY is fine being power
                         * cycled and docs say you _should_ power cycle when
                         * changing clock speeds.
                         */
                        ctrl_phy = true;
                }
        }

        if (ctrl_phy && sdhci_arasan->is_phy_on) {
                phy_power_off(sdhci_arasan->phy);
                sdhci_arasan->is_phy_on = false;
        }

        sdhci_set_clock(host, clock);

        if (ctrl_phy) {
                phy_power_on(sdhci_arasan->phy);
                sdhci_arasan->is_phy_on = true;
        }
}

static void sdhci_arasan_hs400_enhanced_strobe(struct mmc_host *mmc,
                                        struct mmc_ios *ios)
{
        u32 vendor;
        struct sdhci_host *host = mmc_priv(mmc);

        vendor = readl(host->ioaddr + SDHCI_ARASAN_VENDOR_REGISTER);
        if (ios->enhanced_strobe)
                vendor |= VENDOR_ENHANCED_STROBE;
        else
                vendor &= ~VENDOR_ENHANCED_STROBE;

        writel(vendor, host->ioaddr + SDHCI_ARASAN_VENDOR_REGISTER);
}

static void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
{
        u8 ctrl;
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);

        sdhci_reset(host, mask);

        if (sdhci_arasan->quirks & SDHCI_ARASAN_QUIRK_FORCE_CDTEST) {
                ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
                ctrl |= SDHCI_CTRL_CDTEST_INS | SDHCI_CTRL_CDTEST_EN;
                sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
        }
}

static int sdhci_arasan_voltage_switch(struct mmc_host *mmc,
                                       struct mmc_ios *ios)
{
        switch (ios->signal_voltage) {
        case MMC_SIGNAL_VOLTAGE_180:
                /*
                 * Plese don't switch to 1V8 as arasan,5.1 doesn't
                 * actually refer to this setting to indicate the
                 * signal voltage and the state machine will be broken
                 * actually if we force to enable 1V8. That's something
                 * like broken quirk but we could work around here.
                 */
                return 0;
        case MMC_SIGNAL_VOLTAGE_330:
        case MMC_SIGNAL_VOLTAGE_120:
                /* We don't support 3V3 and 1V2 */
                break;
        }

        return -EINVAL;
}

static struct sdhci_ops sdhci_arasan_ops = {
        .set_clock = sdhci_arasan_set_clock,
        .get_max_clock = sdhci_pltfm_clk_get_max_clock,
        .get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
        .set_bus_width = sdhci_set_bus_width,
        .reset = sdhci_arasan_reset,
        .set_uhs_signaling = sdhci_set_uhs_signaling,
};

static struct sdhci_pltfm_data sdhci_arasan_pdata = {
        .ops = &sdhci_arasan_ops,
        .quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
        .quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
                        SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN,
};

#ifdef CONFIG_PM_SLEEP
/**
 * sdhci_arasan_suspend - Suspend method for the driver
 * @dev:        Address of the device structure
 * Returns 0 on success and error value on error
 *
 * Put the device in a low power state.
 */
static int sdhci_arasan_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sdhci_host *host = platform_get_drvdata(pdev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        int ret;

        if (host->tuning_mode != SDHCI_TUNING_MODE_3)
                mmc_retune_needed(host->mmc);

        ret = sdhci_suspend_host(host);
        if (ret)
                return ret;

        if (!IS_ERR(sdhci_arasan->phy) && sdhci_arasan->is_phy_on) {
                ret = phy_power_off(sdhci_arasan->phy);
                if (ret) {
                        dev_err(dev, "Cannot power off phy.\n");
                        sdhci_resume_host(host);
                        return ret;
                }
                sdhci_arasan->is_phy_on = false;
        }

        clk_disable(pltfm_host->clk);
        clk_disable(sdhci_arasan->clk_ahb);

        return 0;
}

/**
 * sdhci_arasan_resume - Resume method for the driver
 * @dev:        Address of the device structure
 * Returns 0 on success and error value on error
 *
 * Resume operation after suspend
 */
static int sdhci_arasan_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sdhci_host *host = platform_get_drvdata(pdev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        int ret;

        ret = clk_enable(sdhci_arasan->clk_ahb);
        if (ret) {
                dev_err(dev, "Cannot enable AHB clock.\n");
                return ret;
        }

        ret = clk_enable(pltfm_host->clk);
        if (ret) {
                dev_err(dev, "Cannot enable SD clock.\n");
                return ret;
        }

        if (!IS_ERR(sdhci_arasan->phy) && host->mmc->actual_clock) {
                ret = phy_power_on(sdhci_arasan->phy);
                if (ret) {
                        dev_err(dev, "Cannot power on phy.\n");
                        return ret;
                }
                sdhci_arasan->is_phy_on = true;
        }

        return sdhci_resume_host(host);
}
#endif /* ! CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(sdhci_arasan_dev_pm_ops, sdhci_arasan_suspend,
                         sdhci_arasan_resume);

static const struct of_device_id sdhci_arasan_of_match[] = {
        /* SoC-specific compatible strings w/ soc_ctl_map */
        {
                .compatible = "rockchip,rk3399-sdhci-5.1",
                .data = &rk3399_soc_ctl_map,
        },

        /* Generic compatible below here */
        { .compatible = "arasan,sdhci-8.9a" },
        { .compatible = "arasan,sdhci-5.1" },
        { .compatible = "arasan,sdhci-4.9a" },

        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sdhci_arasan_of_match);

/**
 * sdhci_arasan_sdcardclk_recalc_rate - Return the card clock rate
 *
 * Return the current actual rate of the SD card clock.  This can be used
 * to communicate with out PHY.
 *
 * @hw:                 Pointer to the hardware clock structure.
 * @parent_rate         The parent rate (should be rate of clk_xin).
 * Returns the card clock rate.
 */
static unsigned long sdhci_arasan_sdcardclk_recalc_rate(struct clk_hw *hw,
                                                      unsigned long parent_rate)

{
        struct sdhci_arasan_data *sdhci_arasan =
                container_of(hw, struct sdhci_arasan_data, sdcardclk_hw);
        struct sdhci_host *host = sdhci_arasan->host;

        return host->mmc->actual_clock;
}

static const struct clk_ops arasan_sdcardclk_ops = {
        .recalc_rate = sdhci_arasan_sdcardclk_recalc_rate,
};

/**
 * sdhci_arasan_update_clockmultiplier - Set corecfg_clockmultiplier
 *
 * The corecfg_clockmultiplier is supposed to contain clock multiplier
 * value of programmable clock generator.
 *
 * NOTES:
 * - Many existing devices don't seem to do this and work fine.  To keep
 *   compatibility for old hardware where the device tree doesn't provide a
 *   register map, this function is a noop if a soc_ctl_map hasn't been provided
 *   for this platform.
 * - The value of corecfg_clockmultiplier should sync with that of corresponding
 *   value reading from sdhci_capability_register. So this function is called
 *   once at probe time and never called again.
 *
 * @host:               The sdhci_host
 */
static void sdhci_arasan_update_clockmultiplier(struct sdhci_host *host,
                                                u32 value)
{
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        const struct sdhci_arasan_soc_ctl_map *soc_ctl_map =
                sdhci_arasan->soc_ctl_map;

        /* Having a map is optional */
        if (!soc_ctl_map)
                return;

        /* If we have a map, we expect to have a syscon */
        if (!sdhci_arasan->soc_ctl_base) {
                pr_warn("%s: Have regmap, but no soc-ctl-syscon\n",
                        mmc_hostname(host->mmc));
                return;
        }

        sdhci_arasan_syscon_write(host, &soc_ctl_map->clockmultiplier, value);
}

/**
 * sdhci_arasan_update_baseclkfreq - Set corecfg_baseclkfreq
 *
 * The corecfg_baseclkfreq is supposed to contain the MHz of clk_xin.  This
 * function can be used to make that happen.
 *
 * NOTES:
 * - Many existing devices don't seem to do this and work fine.  To keep
 *   compatibility for old hardware where the device tree doesn't provide a
 *   register map, this function is a noop if a soc_ctl_map hasn't been provided
 *   for this platform.
 * - It's assumed that clk_xin is not dynamic and that we use the SDHCI divider
 *   to achieve lower clock rates.  That means that this function is called once
 *   at probe time and never called again.
 *
 * @host:               The sdhci_host
 */
static void sdhci_arasan_update_baseclkfreq(struct sdhci_host *host)
{
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        const struct sdhci_arasan_soc_ctl_map *soc_ctl_map =
                sdhci_arasan->soc_ctl_map;
        u32 mhz = DIV_ROUND_CLOSEST(clk_get_rate(pltfm_host->clk), 1000000);

        /* Having a map is optional */
        if (!soc_ctl_map)
                return;

        /* If we have a map, we expect to have a syscon */
        if (!sdhci_arasan->soc_ctl_base) {
                pr_warn("%s: Have regmap, but no soc-ctl-syscon\n",
                        mmc_hostname(host->mmc));
                return;
        }

        sdhci_arasan_syscon_write(host, &soc_ctl_map->baseclkfreq, mhz);
}

/**
 * sdhci_arasan_register_sdclk - Register the sdclk for a PHY to use
 *
 * Some PHY devices need to know what the actual card clock is.  In order for
 * them to find out, we'll provide a clock through the common clock framework
 * for them to query.
 *
 * Note: without seriously re-architecting SDHCI's clock code and testing on
 * all platforms, there's no way to create a totally beautiful clock here
 * with all clock ops implemented.  Instead, we'll just create a clock that can
 * be queried and set the CLK_GET_RATE_NOCACHE attribute to tell common clock
 * framework that we're doing things behind its back.  This should be sufficient
 * to create nice clean device tree bindings and later (if needed) we can try
 * re-architecting SDHCI if we see some benefit to it.
 *
 * @sdhci_arasan:       Our private data structure.
 * @clk_xin:            Pointer to the functional clock
 * @dev:                Pointer to our struct device.
 * Returns 0 on success and error value on error
 */
static int sdhci_arasan_register_sdclk(struct sdhci_arasan_data *sdhci_arasan,
                                       struct clk *clk_xin,
                                       struct device *dev)
{
        struct device_node *np = dev->of_node;
        struct clk_init_data sdcardclk_init;
        const char *parent_clk_name;
        int ret;

        /* Providing a clock to the PHY is optional; no error if missing */
        if (!of_find_property(np, "#clock-cells", NULL))
                return 0;

        ret = of_property_read_string_index(np, "clock-output-names", 0,
                                            &sdcardclk_init.name);
        if (ret) {
                dev_err(dev, "DT has #clock-cells but no clock-output-names\n");
                return ret;
        }

        parent_clk_name = __clk_get_name(clk_xin);
        sdcardclk_init.parent_names = &parent_clk_name;
        sdcardclk_init.num_parents = 1;
        sdcardclk_init.flags = CLK_GET_RATE_NOCACHE;
        sdcardclk_init.ops = &arasan_sdcardclk_ops;

        sdhci_arasan->sdcardclk_hw.init = &sdcardclk_init;
        sdhci_arasan->sdcardclk =
                devm_clk_register(dev, &sdhci_arasan->sdcardclk_hw);
        sdhci_arasan->sdcardclk_hw.init = NULL;

        ret = of_clk_add_provider(np, of_clk_src_simple_get,
                                  sdhci_arasan->sdcardclk);
        if (ret)
                dev_err(dev, "Failed to add clock provider\n");

        return ret;
}

/**
 * sdhci_arasan_unregister_sdclk - Undoes sdhci_arasan_register_sdclk()
 *
 * Should be called any time we're exiting and sdhci_arasan_register_sdclk()
 * returned success.
 *
 * @dev:                Pointer to our struct device.
 */
static void sdhci_arasan_unregister_sdclk(struct device *dev)
{
        struct device_node *np = dev->of_node;

        if (!of_find_property(np, "#clock-cells", NULL))
                return;

        of_clk_del_provider(dev->of_node);
}

static int sdhci_arasan_probe(struct platform_device *pdev)
{
        int ret;
        const struct of_device_id *match;
        struct device_node *node;
        struct clk *clk_xin;
        struct sdhci_host *host;
        struct sdhci_pltfm_host *pltfm_host;
        struct sdhci_arasan_data *sdhci_arasan;
        struct device_node *np = pdev->dev.of_node;

        host = sdhci_pltfm_init(pdev, &sdhci_arasan_pdata,
                                sizeof(*sdhci_arasan));
        if (IS_ERR(host))
                return PTR_ERR(host);

        pltfm_host = sdhci_priv(host);
        sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        sdhci_arasan->host = host;

        match = of_match_node(sdhci_arasan_of_match, pdev->dev.of_node);
        sdhci_arasan->soc_ctl_map = match->data;

        node = of_parse_phandle(pdev->dev.of_node, "arasan,soc-ctl-syscon", 0);
        if (node) {
                sdhci_arasan->soc_ctl_base = syscon_node_to_regmap(node);
                of_node_put(node);

                if (IS_ERR(sdhci_arasan->soc_ctl_base)) {
                        ret = PTR_ERR(sdhci_arasan->soc_ctl_base);
                        if (ret != -EPROBE_DEFER)
                                dev_err(&pdev->dev, "Can't get syscon: %d\n",
                                        ret);
                        goto err_pltfm_free;
                }
        }

        sdhci_arasan->clk_ahb = devm_clk_get(&pdev->dev, "clk_ahb");
        if (IS_ERR(sdhci_arasan->clk_ahb)) {
                dev_err(&pdev->dev, "clk_ahb clock not found.\n");
                ret = PTR_ERR(sdhci_arasan->clk_ahb);
                goto err_pltfm_free;
        }

        clk_xin = devm_clk_get(&pdev->dev, "clk_xin");
        if (IS_ERR(clk_xin)) {
                dev_err(&pdev->dev, "clk_xin clock not found.\n");
                ret = PTR_ERR(clk_xin);
                goto err_pltfm_free;
        }

        ret = clk_prepare_enable(sdhci_arasan->clk_ahb);
        if (ret) {
                dev_err(&pdev->dev, "Unable to enable AHB clock.\n");
                goto err_pltfm_free;
        }

        ret = clk_prepare_enable(clk_xin);
        if (ret) {
                dev_err(&pdev->dev, "Unable to enable SD clock.\n");
                goto clk_dis_ahb;
        }

        sdhci_get_of_property(pdev);

        if (of_property_read_bool(np, "xlnx,fails-without-test-cd"))
                sdhci_arasan->quirks |= SDHCI_ARASAN_QUIRK_FORCE_CDTEST;

        pltfm_host->clk = clk_xin;

        if (of_device_is_compatible(pdev->dev.of_node,
                                    "rockchip,rk3399-sdhci-5.1"))
                sdhci_arasan_update_clockmultiplier(host, 0x0);

        sdhci_arasan_update_baseclkfreq(host);

        ret = sdhci_arasan_register_sdclk(sdhci_arasan, clk_xin, &pdev->dev);
        if (ret)
                goto clk_disable_all;

        ret = mmc_of_parse(host->mmc);
        if (ret) {
                dev_err(&pdev->dev, "parsing dt failed (%d)\n", ret);
                goto unreg_clk;
        }

        sdhci_arasan->phy = ERR_PTR(-ENODEV);
        if (of_device_is_compatible(pdev->dev.of_node,
                                    "arasan,sdhci-5.1")) {
                sdhci_arasan->phy = devm_phy_get(&pdev->dev,
                                                 "phy_arasan");
                if (IS_ERR(sdhci_arasan->phy)) {
                        ret = PTR_ERR(sdhci_arasan->phy);
                        dev_err(&pdev->dev, "No phy for arasan,sdhci-5.1.\n");
                        goto unreg_clk;
                }

                ret = phy_init(sdhci_arasan->phy);
                if (ret < 0) {
                        dev_err(&pdev->dev, "phy_init err.\n");
                        goto unreg_clk;
                }

                host->mmc_host_ops.hs400_enhanced_strobe =
                                        sdhci_arasan_hs400_enhanced_strobe;
                host->mmc_host_ops.start_signal_voltage_switch =
                                        sdhci_arasan_voltage_switch;
        }

        ret = sdhci_add_host(host);
        if (ret)
                goto err_add_host;

        return 0;

err_add_host:
        if (!IS_ERR(sdhci_arasan->phy))
                phy_exit(sdhci_arasan->phy);
unreg_clk:
        sdhci_arasan_unregister_sdclk(&pdev->dev);
clk_disable_all:
        clk_disable_unprepare(clk_xin);
clk_dis_ahb:
        clk_disable_unprepare(sdhci_arasan->clk_ahb);
err_pltfm_free:
        sdhci_pltfm_free(pdev);
        return ret;
}

static int sdhci_arasan_remove(struct platform_device *pdev)
{
        int ret;
        struct sdhci_host *host = platform_get_drvdata(pdev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
        struct clk *clk_ahb = sdhci_arasan->clk_ahb;

        if (!IS_ERR(sdhci_arasan->phy)) {
                if (sdhci_arasan->is_phy_on)
                        phy_power_off(sdhci_arasan->phy);
                phy_exit(sdhci_arasan->phy);
        }

        sdhci_arasan_unregister_sdclk(&pdev->dev);

        ret = sdhci_pltfm_unregister(pdev);

        clk_disable_unprepare(clk_ahb);

        return ret;
}

static struct platform_driver sdhci_arasan_driver = {
        .driver = {
                .name = "sdhci-arasan",
                .of_match_table = sdhci_arasan_of_match,
                .pm = &sdhci_arasan_dev_pm_ops,
        },
        .probe = sdhci_arasan_probe,
        .remove = sdhci_arasan_remove,
};

module_platform_driver(sdhci_arasan_driver);

MODULE_DESCRIPTION("Driver for the Arasan SDHCI Controller");
MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com>");
MODULE_LICENSE("GPL");