/*
 * Atmel SDMMC controller driver.
 *
 * Copyright (C) 2015 Atmel,
 *               2015 Ludovic Desroches <ludovic.desroches@atmel.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mmc/host.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>

#include "sdhci-pltfm.h"

#define SDMMC_MC1R      0x204
#define         SDMMC_MC1R_DDR          BIT(3)
#define         SDMMC_MC1R_FCD          BIT(7)
#define SDMMC_CACR      0x230
#define         SDMMC_CACR_CAPWREN      BIT(0)
#define         SDMMC_CACR_KEY          (0x46 << 8)

#define SDHCI_AT91_PRESET_COMMON_CONF   0x400 /* drv type B, programmable clock mode */

struct sdhci_at91_priv {
        struct clk *hclock;
        struct clk *gck;
        struct clk *mainck;
        bool restore_needed;
};

static void sdhci_at91_set_force_card_detect(struct sdhci_host *host)
{
        u8 mc1r;

        mc1r = readb(host->ioaddr + SDMMC_MC1R);
        mc1r |= SDMMC_MC1R_FCD;
        writeb(mc1r, host->ioaddr + SDMMC_MC1R);
}

static void sdhci_at91_set_clock(struct sdhci_host *host, unsigned int clock)
{
        u16 clk;
        unsigned long timeout;

        host->mmc->actual_clock = 0;

        /*
         * There is no requirement to disable the internal clock before
         * changing the SD clock configuration. Moreover, disabling the
         * internal clock, changing the configuration and re-enabling the
         * internal clock causes some bugs. It can prevent to get the internal
         * clock stable flag ready and an unexpected switch to the base clock
         * when using presets.
         */
        clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
        clk &= SDHCI_CLOCK_INT_EN;
        sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);

        if (clock == 0)
                return;

        clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);

        clk |= SDHCI_CLOCK_INT_EN;
        sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);

        /* Wait max 20 ms */
        timeout = 20;
        while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
                & SDHCI_CLOCK_INT_STABLE)) {
                if (timeout == 0) {
                        pr_err("%s: Internal clock never stabilised.\n",
                               mmc_hostname(host->mmc));
                        return;
                }
                timeout--;
                mdelay(1);
        }

        clk |= SDHCI_CLOCK_CARD_EN;
        sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
}

/*
 * In this specific implementation of the SDHCI controller, the power register
 * needs to have a valid voltage set even when the power supply is managed by
 * an external regulator.
 */
static void sdhci_at91_set_power(struct sdhci_host *host, unsigned char mode,
                     unsigned short vdd)
{
        if (!IS_ERR(host->mmc->supply.vmmc)) {
                struct mmc_host *mmc = host->mmc;

                mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
        }
        sdhci_set_power_noreg(host, mode, vdd);
}

static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host,
                                         unsigned int timing)
{
        if (timing == MMC_TIMING_MMC_DDR52)
                sdhci_writeb(host, SDMMC_MC1R_DDR, SDMMC_MC1R);
        sdhci_set_uhs_signaling(host, timing);
}

static void sdhci_at91_reset(struct sdhci_host *host, u8 mask)
{
        sdhci_reset(host, mask);

        if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
                sdhci_at91_set_force_card_detect(host);
}

static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
        .set_clock              = sdhci_at91_set_clock,
        .set_bus_width          = sdhci_set_bus_width,
        .reset                  = sdhci_at91_reset,
        .set_uhs_signaling      = sdhci_at91_set_uhs_signaling,
        .set_power              = sdhci_at91_set_power,
};

static const struct sdhci_pltfm_data soc_data_sama5d2 = {
        .ops = &sdhci_at91_sama5d2_ops,
};

static const struct of_device_id sdhci_at91_dt_match[] = {
        { .compatible = "atmel,sama5d2-sdhci", .data = &soc_data_sama5d2 },
        {}
};
MODULE_DEVICE_TABLE(of, sdhci_at91_dt_match);

static int sdhci_at91_set_clks_presets(struct device *dev)
{
        struct sdhci_host *host = dev_get_drvdata(dev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
        int ret;
        unsigned int                    caps0, caps1;
        unsigned int                    clk_base, clk_mul;
        unsigned int                    gck_rate, real_gck_rate;
        unsigned int                    preset_div;

        /*
         * The mult clock is provided by as a generated clock by the PMC
         * controller. In order to set the rate of gck, we have to get the
         * base clock rate and the clock mult from capabilities.
         */
        clk_prepare_enable(priv->hclock);
        caps0 = readl(host->ioaddr + SDHCI_CAPABILITIES);
        caps1 = readl(host->ioaddr + SDHCI_CAPABILITIES_1);
        clk_base = (caps0 & SDHCI_CLOCK_V3_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
        clk_mul = (caps1 & SDHCI_CLOCK_MUL_MASK) >> SDHCI_CLOCK_MUL_SHIFT;
        gck_rate = clk_base * 1000000 * (clk_mul + 1);
        ret = clk_set_rate(priv->gck, gck_rate);
        if (ret < 0) {
                dev_err(dev, "failed to set gck");
                clk_disable_unprepare(priv->hclock);
                return ret;
        }
        /*
         * We need to check if we have the requested rate for gck because in
         * some cases this rate could be not supported. If it happens, the rate
         * is the closest one gck can provide. We have to update the value
         * of clk mul.
         */
        real_gck_rate = clk_get_rate(priv->gck);
        if (real_gck_rate != gck_rate) {
                clk_mul = real_gck_rate / (clk_base * 1000000) - 1;
                caps1 &= (~SDHCI_CLOCK_MUL_MASK);
                caps1 |= ((clk_mul << SDHCI_CLOCK_MUL_SHIFT) &
                          SDHCI_CLOCK_MUL_MASK);
                /* Set capabilities in r/w mode. */
                writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN,
                       host->ioaddr + SDMMC_CACR);
                writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
                /* Set capabilities in ro mode. */
                writel(0, host->ioaddr + SDMMC_CACR);
                dev_info(dev, "update clk mul to %u as gck rate is %u Hz\n",
                         clk_mul, real_gck_rate);
        }

        /*
         * We have to set preset values because it depends on the clk_mul
         * value. Moreover, SDR104 is supported in a degraded mode since the
         * maximum sd clock value is 120 MHz instead of 208 MHz. For that
         * reason, we need to use presets to support SDR104.
         */
        preset_div = DIV_ROUND_UP(real_gck_rate, 24000000) - 1;
        writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
               host->ioaddr + SDHCI_PRESET_FOR_SDR12);
        preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;
        writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
               host->ioaddr + SDHCI_PRESET_FOR_SDR25);
        preset_div = DIV_ROUND_UP(real_gck_rate, 100000000) - 1;
        writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
               host->ioaddr + SDHCI_PRESET_FOR_SDR50);
        preset_div = DIV_ROUND_UP(real_gck_rate, 120000000) - 1;
        writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
               host->ioaddr + SDHCI_PRESET_FOR_SDR104);
        preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;
        writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
               host->ioaddr + SDHCI_PRESET_FOR_DDR50);

        clk_prepare_enable(priv->mainck);
        clk_prepare_enable(priv->gck);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int sdhci_at91_suspend(struct device *dev)
{
        struct sdhci_host *host = dev_get_drvdata(dev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
        int ret;

        ret = pm_runtime_force_suspend(dev);

        priv->restore_needed = true;

        return ret;
}
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM
static int sdhci_at91_runtime_suspend(struct device *dev)
{
        struct sdhci_host *host = dev_get_drvdata(dev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
        int ret;

        ret = sdhci_runtime_suspend_host(host);

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

        clk_disable_unprepare(priv->gck);
        clk_disable_unprepare(priv->hclock);
        clk_disable_unprepare(priv->mainck);

        return ret;
}

static int sdhci_at91_runtime_resume(struct device *dev)
{
        struct sdhci_host *host = dev_get_drvdata(dev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
        int ret;

        if (priv->restore_needed) {
                ret = sdhci_at91_set_clks_presets(dev);
                if (ret)
                        return ret;

                priv->restore_needed = false;
                goto out;
        }

        ret = clk_prepare_enable(priv->mainck);
        if (ret) {
                dev_err(dev, "can't enable mainck\n");
                return ret;
        }

        ret = clk_prepare_enable(priv->hclock);
        if (ret) {
                dev_err(dev, "can't enable hclock\n");
                return ret;
        }

        ret = clk_prepare_enable(priv->gck);
        if (ret) {
                dev_err(dev, "can't enable gck\n");
                return ret;
        }

out:
        return sdhci_runtime_resume_host(host);
}
#endif /* CONFIG_PM */

static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(sdhci_at91_suspend, pm_runtime_force_resume)
        SET_RUNTIME_PM_OPS(sdhci_at91_runtime_suspend,
                           sdhci_at91_runtime_resume,
                           NULL)
};

static int sdhci_at91_probe(struct platform_device *pdev)
{
        const struct of_device_id       *match;
        const struct sdhci_pltfm_data   *soc_data;
        struct sdhci_host               *host;
        struct sdhci_pltfm_host         *pltfm_host;
        struct sdhci_at91_priv          *priv;
        int                             ret;

        match = of_match_device(sdhci_at91_dt_match, &pdev->dev);
        if (!match)
                return -EINVAL;
        soc_data = match->data;

        host = sdhci_pltfm_init(pdev, soc_data, sizeof(*priv));
        if (IS_ERR(host))
                return PTR_ERR(host);

        pltfm_host = sdhci_priv(host);
        priv = sdhci_pltfm_priv(pltfm_host);

        priv->mainck = devm_clk_get(&pdev->dev, "baseclk");
        if (IS_ERR(priv->mainck)) {
                dev_err(&pdev->dev, "failed to get baseclk\n");
                return PTR_ERR(priv->mainck);
        }

        priv->hclock = devm_clk_get(&pdev->dev, "hclock");
        if (IS_ERR(priv->hclock)) {
                dev_err(&pdev->dev, "failed to get hclock\n");
                return PTR_ERR(priv->hclock);
        }

        priv->gck = devm_clk_get(&pdev->dev, "multclk");
        if (IS_ERR(priv->gck)) {
                dev_err(&pdev->dev, "failed to get multclk\n");
                return PTR_ERR(priv->gck);
        }

        ret = sdhci_at91_set_clks_presets(&pdev->dev);
        if (ret)
                goto sdhci_pltfm_free;

        priv->restore_needed = false;

        ret = mmc_of_parse(host->mmc);
        if (ret)
                goto clocks_disable_unprepare;

        sdhci_get_of_property(pdev);

        pm_runtime_get_noresume(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
        pm_runtime_use_autosuspend(&pdev->dev);

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

        /*
         * When calling sdhci_runtime_suspend_host(), the sdhci layer makes
         * the assumption that all the clocks of the controller are disabled.
         * It means we can't get irq from it when it is runtime suspended.
         * For that reason, it is not planned to wake-up on a card detect irq
         * from the controller.
         * If we want to use runtime PM and to be able to wake-up on card
         * insertion, we have to use a GPIO for the card detection or we can
         * use polling. Be aware that using polling will resume/suspend the
         * controller between each attempt.
         * Disable SDHCI_QUIRK_BROKEN_CARD_DETECTION to be sure nobody tries
         * to enable polling via device tree with broken-cd property.
         */
        if (mmc_card_is_removable(host->mmc) &&
            mmc_gpio_get_cd(host->mmc) < 0) {
                host->mmc->caps |= MMC_CAP_NEEDS_POLL;
                host->quirks &= ~SDHCI_QUIRK_BROKEN_CARD_DETECTION;
        }

        /*
         * If the device attached to the MMC bus is not removable, it is safer
         * to set the Force Card Detect bit. People often don't connect the
         * card detect signal and use this pin for another purpose. If the card
         * detect pin is not muxed to SDHCI controller, a default value is
         * used. This value can be different from a SoC revision to another
         * one. Problems come when this default value is not card present. To
         * avoid this case, if the device is non removable then the card
         * detection procedure using the SDMCC_CD signal is bypassed.
         * This bit is reset when a software reset for all command is performed
         * so we need to implement our own reset function to set back this bit.
         */
        if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
                sdhci_at91_set_force_card_detect(host);

        pm_runtime_put_autosuspend(&pdev->dev);

        return 0;

pm_runtime_disable:
        pm_runtime_disable(&pdev->dev);
        pm_runtime_set_suspended(&pdev->dev);
        pm_runtime_put_noidle(&pdev->dev);
clocks_disable_unprepare:
        clk_disable_unprepare(priv->gck);
        clk_disable_unprepare(priv->mainck);
        clk_disable_unprepare(priv->hclock);
sdhci_pltfm_free:
        sdhci_pltfm_free(pdev);
        return ret;
}

static int sdhci_at91_remove(struct platform_device *pdev)
{
        struct sdhci_host       *host = platform_get_drvdata(pdev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct sdhci_at91_priv  *priv = sdhci_pltfm_priv(pltfm_host);
        struct clk *gck = priv->gck;
        struct clk *hclock = priv->hclock;
        struct clk *mainck = priv->mainck;

        pm_runtime_get_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
        pm_runtime_put_noidle(&pdev->dev);

        sdhci_pltfm_unregister(pdev);

        clk_disable_unprepare(gck);
        clk_disable_unprepare(hclock);
        clk_disable_unprepare(mainck);

        return 0;
}

static struct platform_driver sdhci_at91_driver = {
        .driver         = {
                .name   = "sdhci-at91",
                .of_match_table = sdhci_at91_dt_match,
                .pm     = &sdhci_at91_dev_pm_ops,
        },
        .probe          = sdhci_at91_probe,
        .remove         = sdhci_at91_remove,
};

module_platform_driver(sdhci_at91_driver);

MODULE_DESCRIPTION("SDHCI driver for at91");
MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@atmel.com>");
MODULE_LICENSE("GPL v2");