/* linux/drivers/mmc/host/sdhci-s3c.c
 *
 * Copyright 2008 Openmoko Inc.
 * Copyright 2008 Simtec Electronics
 *      Ben Dooks <ben@simtec.co.uk>
 *      http://armlinux.simtec.co.uk/
 *
 * SDHCI (HSMMC) support for Samsung SoC
 *
 * 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/dma-mapping.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <linux/mmc/host.h>

#include <plat/sdhci.h>
#include <plat/regs-sdhci.h>

#include "sdhci.h"

#define MAX_BUS_CLK     (4)

/**
 * struct sdhci_s3c - S3C SDHCI instance
 * @host: The SDHCI host created
 * @pdev: The platform device we where created from.
 * @ioarea: The resource created when we claimed the IO area.
 * @pdata: The platform data for this controller.
 * @cur_clk: The index of the current bus clock.
 * @clk_io: The clock for the internal bus interface.
 * @clk_bus: The clocks that are available for the SD/MMC bus clock.
 */
struct sdhci_s3c {
        struct sdhci_host       *host;
        struct platform_device  *pdev;
        struct resource         *ioarea;
        struct s3c_sdhci_platdata *pdata;
        unsigned int            cur_clk;

        struct clk              *clk_io;
        struct clk              *clk_bus[MAX_BUS_CLK];
};

static inline struct sdhci_s3c *to_s3c(struct sdhci_host *host)
{
        return sdhci_priv(host);
}

/**
 * get_curclk - convert ctrl2 register to clock source number
 * @ctrl2: Control2 register value.
 */
static u32 get_curclk(u32 ctrl2)
{
        ctrl2 &= S3C_SDHCI_CTRL2_SELBASECLK_MASK;
        ctrl2 >>= S3C_SDHCI_CTRL2_SELBASECLK_SHIFT;

        return ctrl2;
}

static void sdhci_s3c_check_sclk(struct sdhci_host *host)
{
        struct sdhci_s3c *ourhost = to_s3c(host);
        u32 tmp = readl(host->ioaddr + S3C_SDHCI_CONTROL2);

        if (get_curclk(tmp) != ourhost->cur_clk) {
                dev_dbg(&ourhost->pdev->dev, "restored ctrl2 clock setting\n");

                tmp &= ~S3C_SDHCI_CTRL2_SELBASECLK_MASK;
                tmp |= ourhost->cur_clk << S3C_SDHCI_CTRL2_SELBASECLK_SHIFT;
                writel(tmp, host->ioaddr + 0x80);
        }
}

/**
 * sdhci_s3c_get_max_clk - callback to get maximum clock frequency.
 * @host: The SDHCI host instance.
 *
 * Callback to return the maximum clock rate acheivable by the controller.
*/
static unsigned int sdhci_s3c_get_max_clk(struct sdhci_host *host)
{
        struct sdhci_s3c *ourhost = to_s3c(host);
        struct clk *busclk;
        unsigned int rate, max;
        int clk;

        /* note, a reset will reset the clock source */

        sdhci_s3c_check_sclk(host);

        for (max = 0, clk = 0; clk < MAX_BUS_CLK; clk++) {
                busclk = ourhost->clk_bus[clk];
                if (!busclk)
                        continue;

                rate = clk_get_rate(busclk);
                if (rate > max)
                        max = rate;
        }

        return max;
}

static unsigned int sdhci_s3c_get_timeout_clk(struct sdhci_host *host)
{
        return sdhci_s3c_get_max_clk(host) / 1000000;
}

/**
 * sdhci_s3c_consider_clock - consider one the bus clocks for current setting
 * @ourhost: Our SDHCI instance.
 * @src: The source clock index.
 * @wanted: The clock frequency wanted.
 */
static unsigned int sdhci_s3c_consider_clock(struct sdhci_s3c *ourhost,
                                             unsigned int src,
                                             unsigned int wanted)
{
        unsigned long rate;
        struct clk *clksrc = ourhost->clk_bus[src];
        int div;

        if (!clksrc)
                return UINT_MAX;

        rate = clk_get_rate(clksrc);

        for (div = 1; div < 256; div *= 2) {
                if ((rate / div) <= wanted)
                        break;
        }

        dev_dbg(&ourhost->pdev->dev, "clk %d: rate %ld, want %d, got %ld\n",
                src, rate, wanted, rate / div);

        return (wanted - (rate / div));
}

/**
 * sdhci_s3c_set_clock - callback on clock change
 * @host: The SDHCI host being changed
 * @clock: The clock rate being requested.
 *
 * When the card's clock is going to be changed, look at the new frequency
 * and find the best clock source to go with it.
*/
static void sdhci_s3c_set_clock(struct sdhci_host *host, unsigned int clock)
{
        struct sdhci_s3c *ourhost = to_s3c(host);
        unsigned int best = UINT_MAX;
        unsigned int delta;
        int best_src = 0;
        int src;
        u32 ctrl;

        /* don't bother if the clock is going off. */
        if (clock == 0)
                return;

        for (src = 0; src < MAX_BUS_CLK; src++) {
                delta = sdhci_s3c_consider_clock(ourhost, src, clock);
                if (delta < best) {
                        best = delta;
                        best_src = src;
                }
        }

        dev_dbg(&ourhost->pdev->dev,
                "selected source %d, clock %d, delta %d\n",
                 best_src, clock, best);

        /* select the new clock source */

        if (ourhost->cur_clk != best_src) {
                struct clk *clk = ourhost->clk_bus[best_src];

                /* turn clock off to card before changing clock source */
                writew(0, host->ioaddr + SDHCI_CLOCK_CONTROL);

                ourhost->cur_clk = best_src;
                host->max_clk = clk_get_rate(clk);
                host->timeout_clk = sdhci_s3c_get_timeout_clk(host);

                ctrl = readl(host->ioaddr + S3C_SDHCI_CONTROL2);
                ctrl &= ~S3C_SDHCI_CTRL2_SELBASECLK_MASK;
                ctrl |= best_src << S3C_SDHCI_CTRL2_SELBASECLK_SHIFT;
                writel(ctrl, host->ioaddr + S3C_SDHCI_CONTROL2);
        }

        /* reconfigure the hardware for new clock rate */

        {
                struct mmc_ios ios;

                ios.clock = clock;

                if (ourhost->pdata->cfg_card)
                        (ourhost->pdata->cfg_card)(ourhost->pdev, host->ioaddr,
                                                   &ios, NULL);
        }
}

static struct sdhci_ops sdhci_s3c_ops = {
        .get_max_clock          = sdhci_s3c_get_max_clk,
        .get_timeout_clock      = sdhci_s3c_get_timeout_clk,
        .set_clock              = sdhci_s3c_set_clock,
};

static int __devinit sdhci_s3c_probe(struct platform_device *pdev)
{
        struct s3c_sdhci_platdata *pdata = pdev->dev.platform_data;
        struct device *dev = &pdev->dev;
        struct sdhci_host *host;
        struct sdhci_s3c *sc;
        struct resource *res;
        int ret, irq, ptr, clks;

        if (!pdata) {
                dev_err(dev, "no device data specified\n");
                return -ENOENT;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(dev, "no irq specified\n");
                return irq;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(dev, "no memory specified\n");
                return -ENOENT;
        }

        host = sdhci_alloc_host(dev, sizeof(struct sdhci_s3c));
        if (IS_ERR(host)) {
                dev_err(dev, "sdhci_alloc_host() failed\n");
                return PTR_ERR(host);
        }

        sc = sdhci_priv(host);

        sc->host = host;
        sc->pdev = pdev;
        sc->pdata = pdata;

        platform_set_drvdata(pdev, host);

        sc->clk_io = clk_get(dev, "hsmmc");
        if (IS_ERR(sc->clk_io)) {
                dev_err(dev, "failed to get io clock\n");
                ret = PTR_ERR(sc->clk_io);
                goto err_io_clk;
        }

        /* enable the local io clock and keep it running for the moment. */
        clk_enable(sc->clk_io);

        for (clks = 0, ptr = 0; ptr < MAX_BUS_CLK; ptr++) {
                struct clk *clk;
                char *name = pdata->clocks[ptr];

                if (name == NULL)
                        continue;

                clk = clk_get(dev, name);
                if (IS_ERR(clk)) {
                        dev_err(dev, "failed to get clock %s\n", name);
                        continue;
                }

                clks++;
                sc->clk_bus[ptr] = clk;
                clk_enable(clk);

                dev_info(dev, "clock source %d: %s (%ld Hz)\n",
                         ptr, name, clk_get_rate(clk));
        }

        if (clks == 0) {
                dev_err(dev, "failed to find any bus clocks\n");
                ret = -ENOENT;
                goto err_no_busclks;
        }

        sc->ioarea = request_mem_region(res->start, resource_size(res),
                                        mmc_hostname(host->mmc));
        if (!sc->ioarea) {
                dev_err(dev, "failed to reserve register area\n");
                ret = -ENXIO;
                goto err_req_regs;
        }

        host->ioaddr = ioremap_nocache(res->start, resource_size(res));
        if (!host->ioaddr) {
                dev_err(dev, "failed to map registers\n");
                ret = -ENXIO;
                goto err_req_regs;
        }

        /* Ensure we have minimal gpio selected CMD/CLK/Detect */
        if (pdata->cfg_gpio)
                pdata->cfg_gpio(pdev, pdata->max_width);

        host->hw_name = "samsung-hsmmc";
        host->ops = &sdhci_s3c_ops;
        host->quirks = 0;
        host->irq = irq;

        /* Setup quirks for the controller */

        /* Currently with ADMA enabled we are getting some length
         * interrupts that are not being dealt with, do disable
         * ADMA until this is sorted out. */
        host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
        host->quirks |= SDHCI_QUIRK_32BIT_ADMA_SIZE;

#ifndef CONFIG_MMC_SDHCI_S3C_DMA

        /* we currently see overruns on errors, so disable the SDMA
         * support as well. */
        host->quirks |= SDHCI_QUIRK_BROKEN_DMA;

        /* PIO currently has problems with multi-block IO */
        host->quirks |= SDHCI_QUIRK_NO_MULTIBLOCK;

#endif /* CONFIG_MMC_SDHCI_S3C_DMA */

        /* It seems we do not get an DATA transfer complete on non-busy
         * transfers, not sure if this is a problem with this specific
         * SDHCI block, or a missing configuration that needs to be set. */
        host->quirks |= SDHCI_QUIRK_NO_BUSY_IRQ;

        host->quirks |= (SDHCI_QUIRK_32BIT_DMA_ADDR |
                         SDHCI_QUIRK_32BIT_DMA_SIZE);

        ret = sdhci_add_host(host);
        if (ret) {
                dev_err(dev, "sdhci_add_host() failed\n");
                goto err_add_host;
        }

        return 0;

 err_add_host:
        release_resource(sc->ioarea);
        kfree(sc->ioarea);

 err_req_regs:
        for (ptr = 0; ptr < MAX_BUS_CLK; ptr++) {
                clk_disable(sc->clk_bus[ptr]);
                clk_put(sc->clk_bus[ptr]);
        }

 err_no_busclks:
        clk_disable(sc->clk_io);
        clk_put(sc->clk_io);

 err_io_clk:
        sdhci_free_host(host);

        return ret;
}

static int __devexit sdhci_s3c_remove(struct platform_device *pdev)
{
        return 0;
}

#ifdef CONFIG_PM

static int sdhci_s3c_suspend(struct platform_device *dev, pm_message_t pm)
{
        struct sdhci_host *host = platform_get_drvdata(dev);

        sdhci_suspend_host(host, pm);
        return 0;
}

static int sdhci_s3c_resume(struct platform_device *dev)
{
        struct sdhci_host *host = platform_get_drvdata(dev);

        sdhci_resume_host(host);
        return 0;
}

#else
#define sdhci_s3c_suspend NULL
#define sdhci_s3c_resume NULL
#endif

static struct platform_driver sdhci_s3c_driver = {
        .probe          = sdhci_s3c_probe,
        .remove         = __devexit_p(sdhci_s3c_remove),
        .suspend        = sdhci_s3c_suspend,
        .resume         = sdhci_s3c_resume,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = "s3c-sdhci",
        },
};

static int __init sdhci_s3c_init(void)
{
        return platform_driver_register(&sdhci_s3c_driver);
}

static void __exit sdhci_s3c_exit(void)
{
        platform_driver_unregister(&sdhci_s3c_driver);
}

module_init(sdhci_s3c_init);
module_exit(sdhci_s3c_exit);

MODULE_DESCRIPTION("Samsung SDHCI (HSMMC) glue");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:s3c-sdhci");