root/drivers/mmc/host/mxcmmc.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/drivers/mmc/host/mxcmmc.c - Freescale i.MX MMCI driver
 *
 *  This is a driver for the SDHC controller found in Freescale MX2/MX3
 *  SoCs. It is basically the same hardware as found on MX1 (imxmmc.c).
 *  Unlike the hardware found on MX1, this hardware just works and does
 *  not need all the quirks found in imxmmc.c, hence the separate driver.
 *
 *  Copyright (C) 2008 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
 *  Copyright (C) 2006 Pavel Pisa, PiKRON <ppisa@pikron.com>
 *
 *  derived from pxamci.c by Russell King
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/highmem.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/blkdev.h>
#include <linux/dma-mapping.h>
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/regulator/consumer.h>
#include <linux/dmaengine.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_dma.h>
#include <linux/mmc/slot-gpio.h>

#include <asm/dma.h>
#include <asm/irq.h>
#include <linux/platform_data/mmc-mxcmmc.h>

#include <linux/dma/imx-dma.h>

#define DRIVER_NAME "mxc-mmc"
#define MXCMCI_TIMEOUT_MS 10000

#define MMC_REG_STR_STP_CLK             0x00
#define MMC_REG_STATUS                  0x04
#define MMC_REG_CLK_RATE                0x08
#define MMC_REG_CMD_DAT_CONT            0x0C
#define MMC_REG_RES_TO                  0x10
#define MMC_REG_READ_TO                 0x14
#define MMC_REG_BLK_LEN                 0x18
#define MMC_REG_NOB                     0x1C
#define MMC_REG_REV_NO                  0x20
#define MMC_REG_INT_CNTR                0x24
#define MMC_REG_CMD                     0x28
#define MMC_REG_ARG                     0x2C
#define MMC_REG_RES_FIFO                0x34
#define MMC_REG_BUFFER_ACCESS           0x38

#define STR_STP_CLK_RESET               (1 << 3)
#define STR_STP_CLK_START_CLK           (1 << 1)
#define STR_STP_CLK_STOP_CLK            (1 << 0)

#define STATUS_CARD_INSERTION           (1 << 31)
#define STATUS_CARD_REMOVAL             (1 << 30)
#define STATUS_YBUF_EMPTY               (1 << 29)
#define STATUS_XBUF_EMPTY               (1 << 28)
#define STATUS_YBUF_FULL                (1 << 27)
#define STATUS_XBUF_FULL                (1 << 26)
#define STATUS_BUF_UND_RUN              (1 << 25)
#define STATUS_BUF_OVFL                 (1 << 24)
#define STATUS_SDIO_INT_ACTIVE          (1 << 14)
#define STATUS_END_CMD_RESP             (1 << 13)
#define STATUS_WRITE_OP_DONE            (1 << 12)
#define STATUS_DATA_TRANS_DONE          (1 << 11)
#define STATUS_READ_OP_DONE             (1 << 11)
#define STATUS_WR_CRC_ERROR_CODE_MASK   (3 << 10)
#define STATUS_CARD_BUS_CLK_RUN         (1 << 8)
#define STATUS_BUF_READ_RDY             (1 << 7)
#define STATUS_BUF_WRITE_RDY            (1 << 6)
#define STATUS_RESP_CRC_ERR             (1 << 5)
#define STATUS_CRC_READ_ERR             (1 << 3)
#define STATUS_CRC_WRITE_ERR            (1 << 2)
#define STATUS_TIME_OUT_RESP            (1 << 1)
#define STATUS_TIME_OUT_READ            (1 << 0)
#define STATUS_ERR_MASK                 0x2f

#define CMD_DAT_CONT_CMD_RESP_LONG_OFF  (1 << 12)
#define CMD_DAT_CONT_STOP_READWAIT      (1 << 11)
#define CMD_DAT_CONT_START_READWAIT     (1 << 10)
#define CMD_DAT_CONT_BUS_WIDTH_4        (2 << 8)
#define CMD_DAT_CONT_INIT               (1 << 7)
#define CMD_DAT_CONT_WRITE              (1 << 4)
#define CMD_DAT_CONT_DATA_ENABLE        (1 << 3)
#define CMD_DAT_CONT_RESPONSE_48BIT_CRC (1 << 0)
#define CMD_DAT_CONT_RESPONSE_136BIT    (2 << 0)
#define CMD_DAT_CONT_RESPONSE_48BIT     (3 << 0)

#define INT_SDIO_INT_WKP_EN             (1 << 18)
#define INT_CARD_INSERTION_WKP_EN       (1 << 17)
#define INT_CARD_REMOVAL_WKP_EN         (1 << 16)
#define INT_CARD_INSERTION_EN           (1 << 15)
#define INT_CARD_REMOVAL_EN             (1 << 14)
#define INT_SDIO_IRQ_EN                 (1 << 13)
#define INT_DAT0_EN                     (1 << 12)
#define INT_BUF_READ_EN                 (1 << 4)
#define INT_BUF_WRITE_EN                (1 << 3)
#define INT_END_CMD_RES_EN              (1 << 2)
#define INT_WRITE_OP_DONE_EN            (1 << 1)
#define INT_READ_OP_EN                  (1 << 0)

enum mxcmci_type {
        IMX21_MMC,
        IMX31_MMC,
        MPC512X_MMC,
};

struct mxcmci_host {
        struct mmc_host         *mmc;
        void __iomem            *base;
        dma_addr_t              phys_base;
        int                     detect_irq;
        struct dma_chan         *dma;
        struct dma_async_tx_descriptor *desc;
        int                     do_dma;
        int                     default_irq_mask;
        int                     use_sdio;
        unsigned int            power_mode;
        struct imxmmc_platform_data *pdata;

        struct mmc_request      *req;
        struct mmc_command      *cmd;
        struct mmc_data         *data;

        unsigned int            datasize;
        unsigned int            dma_dir;

        u16                     rev_no;
        unsigned int            cmdat;

        struct clk              *clk_ipg;
        struct clk              *clk_per;

        int                     clock;

        struct work_struct      datawork;
        spinlock_t              lock;

        int                     burstlen;
        int                     dmareq;
        struct dma_slave_config dma_slave_config;
        struct imx_dma_data     dma_data;

        struct timer_list       watchdog;
        enum mxcmci_type        devtype;
};

static const struct of_device_id mxcmci_of_match[] = {
        {
                .compatible = "fsl,imx21-mmc",
                .data = (void *) IMX21_MMC,
        }, {
                .compatible = "fsl,imx31-mmc",
                .data = (void *) IMX31_MMC,
        }, {
                .compatible = "fsl,mpc5121-sdhc",
                .data = (void *) MPC512X_MMC,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(of, mxcmci_of_match);

static inline int is_imx31_mmc(struct mxcmci_host *host)
{
        return host->devtype == IMX31_MMC;
}

static inline int is_mpc512x_mmc(struct mxcmci_host *host)
{
        return host->devtype == MPC512X_MMC;
}

static inline u32 mxcmci_readl(struct mxcmci_host *host, int reg)
{
        if (IS_ENABLED(CONFIG_PPC_MPC512x))
                return ioread32be(host->base + reg);
        else
                return readl(host->base + reg);
}

static inline void mxcmci_writel(struct mxcmci_host *host, u32 val, int reg)
{
        if (IS_ENABLED(CONFIG_PPC_MPC512x))
                iowrite32be(val, host->base + reg);
        else
                writel(val, host->base + reg);
}

static inline u16 mxcmci_readw(struct mxcmci_host *host, int reg)
{
        if (IS_ENABLED(CONFIG_PPC_MPC512x))
                return ioread32be(host->base + reg);
        else
                return readw(host->base + reg);
}

static inline void mxcmci_writew(struct mxcmci_host *host, u16 val, int reg)
{
        if (IS_ENABLED(CONFIG_PPC_MPC512x))
                iowrite32be(val, host->base + reg);
        else
                writew(val, host->base + reg);
}

static void mxcmci_set_clk_rate(struct mxcmci_host *host, unsigned int clk_ios);

static void mxcmci_set_power(struct mxcmci_host *host, unsigned int vdd)
{
        if (!IS_ERR(host->mmc->supply.vmmc)) {
                if (host->power_mode == MMC_POWER_UP)
                        mmc_regulator_set_ocr(host->mmc,
                                              host->mmc->supply.vmmc, vdd);
                else if (host->power_mode == MMC_POWER_OFF)
                        mmc_regulator_set_ocr(host->mmc,
                                              host->mmc->supply.vmmc, 0);
        }

        if (host->pdata && host->pdata->setpower)
                host->pdata->setpower(mmc_dev(host->mmc), vdd);
}

static inline int mxcmci_use_dma(struct mxcmci_host *host)
{
        return host->do_dma;
}

static void mxcmci_softreset(struct mxcmci_host *host)
{
        int i;

        dev_dbg(mmc_dev(host->mmc), "mxcmci_softreset\n");

        /* reset sequence */
        mxcmci_writew(host, STR_STP_CLK_RESET, MMC_REG_STR_STP_CLK);
        mxcmci_writew(host, STR_STP_CLK_RESET | STR_STP_CLK_START_CLK,
                        MMC_REG_STR_STP_CLK);

        for (i = 0; i < 8; i++)
                mxcmci_writew(host, STR_STP_CLK_START_CLK, MMC_REG_STR_STP_CLK);

        mxcmci_writew(host, 0xff, MMC_REG_RES_TO);
}

#if IS_ENABLED(CONFIG_PPC_MPC512x)
static inline void buffer_swap32(u32 *buf, int len)
{
        int i;

        for (i = 0; i < ((len + 3) / 4); i++) {
                *buf = swab32(*buf);
                buf++;
        }
}

static void mxcmci_swap_buffers(struct mmc_data *data)
{
        struct sg_mapping_iter sgm;
        u32 *buf;

        sg_miter_start(&sgm, data->sg, data->sg_len,
                       SG_MITER_TO_SG | SG_MITER_FROM_SG);

        while (sg_miter_next(&sgm)) {
                buf = sgm.addr;
                buffer_swap32(buf, sgm.length);
        }

        sg_miter_stop(&sgm);
}
#else
static inline void mxcmci_swap_buffers(struct mmc_data *data) {}
#endif

static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
{
        unsigned int nob = data->blocks;
        unsigned int blksz = data->blksz;
        unsigned int datasize = nob * blksz;
        struct scatterlist *sg;
        enum dma_transfer_direction slave_dirn;
        int i, nents;

        host->data = data;
        data->bytes_xfered = 0;

        mxcmci_writew(host, nob, MMC_REG_NOB);
        mxcmci_writew(host, blksz, MMC_REG_BLK_LEN);
        host->datasize = datasize;

        if (!mxcmci_use_dma(host))
                return 0;

        for_each_sg(data->sg, sg, data->sg_len, i) {
                if (sg->offset & 3 || sg->length & 3 || sg->length < 512) {
                        host->do_dma = 0;
                        return 0;
                }
        }

        if (data->flags & MMC_DATA_READ) {
                host->dma_dir = DMA_FROM_DEVICE;
                slave_dirn = DMA_DEV_TO_MEM;
        } else {
                host->dma_dir = DMA_TO_DEVICE;
                slave_dirn = DMA_MEM_TO_DEV;

                mxcmci_swap_buffers(data);
        }

        nents = dma_map_sg(host->dma->device->dev, data->sg,
                                     data->sg_len,  host->dma_dir);
        if (nents != data->sg_len)
                return -EINVAL;

        host->desc = dmaengine_prep_slave_sg(host->dma,
                data->sg, data->sg_len, slave_dirn,
                DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

        if (!host->desc) {
                dma_unmap_sg(host->dma->device->dev, data->sg, data->sg_len,
                                host->dma_dir);
                host->do_dma = 0;
                return 0; /* Fall back to PIO */
        }
        wmb();

        dmaengine_submit(host->desc);
        dma_async_issue_pending(host->dma);

        mod_timer(&host->watchdog, jiffies + msecs_to_jiffies(MXCMCI_TIMEOUT_MS));

        return 0;
}

static void mxcmci_cmd_done(struct mxcmci_host *host, unsigned int stat);
static void mxcmci_data_done(struct mxcmci_host *host, unsigned int stat);

static void mxcmci_dma_callback(void *data)
{
        struct mxcmci_host *host = data;
        u32 stat;

        timer_delete(&host->watchdog);

        stat = mxcmci_readl(host, MMC_REG_STATUS);

        dev_dbg(mmc_dev(host->mmc), "%s: 0x%08x\n", __func__, stat);

        mxcmci_data_done(host, stat);
}

static int mxcmci_start_cmd(struct mxcmci_host *host, struct mmc_command *cmd,
                unsigned int cmdat)
{
        u32 int_cntr = host->default_irq_mask;
        unsigned long flags;

        WARN_ON(host->cmd != NULL);
        host->cmd = cmd;

        switch (mmc_resp_type(cmd)) {
        case MMC_RSP_R1: /* short CRC, OPCODE */
        case MMC_RSP_R1B:/* short CRC, OPCODE, BUSY */
                cmdat |= CMD_DAT_CONT_RESPONSE_48BIT_CRC;
                break;
        case MMC_RSP_R2: /* long 136 bit + CRC */
                cmdat |= CMD_DAT_CONT_RESPONSE_136BIT;
                break;
        case MMC_RSP_R3: /* short */
                cmdat |= CMD_DAT_CONT_RESPONSE_48BIT;
                break;
        case MMC_RSP_NONE:
                break;
        default:
                dev_err(mmc_dev(host->mmc), "unhandled response type 0x%x\n",
                                mmc_resp_type(cmd));
                cmd->error = -EINVAL;
                return -EINVAL;
        }

        int_cntr = INT_END_CMD_RES_EN;

        if (mxcmci_use_dma(host)) {
                if (host->dma_dir == DMA_FROM_DEVICE) {
                        host->desc->callback = mxcmci_dma_callback;
                        host->desc->callback_param = host;
                } else {
                        int_cntr |= INT_WRITE_OP_DONE_EN;
                }
        }

        spin_lock_irqsave(&host->lock, flags);
        if (host->use_sdio)
                int_cntr |= INT_SDIO_IRQ_EN;
        mxcmci_writel(host, int_cntr, MMC_REG_INT_CNTR);
        spin_unlock_irqrestore(&host->lock, flags);

        mxcmci_writew(host, cmd->opcode, MMC_REG_CMD);
        mxcmci_writel(host, cmd->arg, MMC_REG_ARG);
        mxcmci_writew(host, cmdat, MMC_REG_CMD_DAT_CONT);

        return 0;
}

static void mxcmci_finish_request(struct mxcmci_host *host,
                struct mmc_request *req)
{
        u32 int_cntr = host->default_irq_mask;
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        if (host->use_sdio)
                int_cntr |= INT_SDIO_IRQ_EN;
        mxcmci_writel(host, int_cntr, MMC_REG_INT_CNTR);
        spin_unlock_irqrestore(&host->lock, flags);

        host->req = NULL;
        host->cmd = NULL;
        host->data = NULL;

        mmc_request_done(host->mmc, req);
}

static int mxcmci_finish_data(struct mxcmci_host *host, unsigned int stat)
{
        struct mmc_data *data = host->data;
        int data_error;

        if (mxcmci_use_dma(host)) {
                dma_unmap_sg(host->dma->device->dev, data->sg, data->sg_len,
                                host->dma_dir);
                mxcmci_swap_buffers(data);
        }

        if (stat & STATUS_ERR_MASK) {
                dev_dbg(mmc_dev(host->mmc), "request failed. status: 0x%08x\n",
                                stat);
                if (stat & STATUS_CRC_READ_ERR) {
                        dev_err(mmc_dev(host->mmc), "%s: -EILSEQ\n", __func__);
                        data->error = -EILSEQ;
                } else if (stat & STATUS_CRC_WRITE_ERR) {
                        u32 err_code = (stat >> 9) & 0x3;
                        if (err_code == 2) { /* No CRC response */
                                dev_err(mmc_dev(host->mmc),
                                        "%s: No CRC -ETIMEDOUT\n", __func__);
                                data->error = -ETIMEDOUT;
                        } else {
                                dev_err(mmc_dev(host->mmc),
                                        "%s: -EILSEQ\n", __func__);
                                data->error = -EILSEQ;
                        }
                } else if (stat & STATUS_TIME_OUT_READ) {
                        dev_err(mmc_dev(host->mmc),
                                "%s: read -ETIMEDOUT\n", __func__);
                        data->error = -ETIMEDOUT;
                } else {
                        dev_err(mmc_dev(host->mmc), "%s: -EIO\n", __func__);
                        data->error = -EIO;
                }
        } else {
                data->bytes_xfered = host->datasize;
        }

        data_error = data->error;

        host->data = NULL;

        return data_error;
}

static void mxcmci_read_response(struct mxcmci_host *host, unsigned int stat)
{
        struct mmc_command *cmd = host->cmd;
        int i;
        u32 a, b, c;

        if (!cmd)
                return;

        if (stat & STATUS_TIME_OUT_RESP) {
                dev_dbg(mmc_dev(host->mmc), "CMD TIMEOUT\n");
                cmd->error = -ETIMEDOUT;
        } else if (stat & STATUS_RESP_CRC_ERR && cmd->flags & MMC_RSP_CRC) {
                dev_dbg(mmc_dev(host->mmc), "cmd crc error\n");
                cmd->error = -EILSEQ;
        }

        if (cmd->flags & MMC_RSP_PRESENT) {
                if (cmd->flags & MMC_RSP_136) {
                        for (i = 0; i < 4; i++) {
                                a = mxcmci_readw(host, MMC_REG_RES_FIFO);
                                b = mxcmci_readw(host, MMC_REG_RES_FIFO);
                                cmd->resp[i] = a << 16 | b;
                        }
                } else {
                        a = mxcmci_readw(host, MMC_REG_RES_FIFO);
                        b = mxcmci_readw(host, MMC_REG_RES_FIFO);
                        c = mxcmci_readw(host, MMC_REG_RES_FIFO);
                        cmd->resp[0] = a << 24 | b << 8 | c >> 8;
                }
        }
}

static int mxcmci_poll_status(struct mxcmci_host *host, u32 mask)
{
        u32 stat;
        unsigned long timeout = jiffies + HZ;

        do {
                stat = mxcmci_readl(host, MMC_REG_STATUS);
                if (stat & STATUS_ERR_MASK)
                        return stat;
                if (time_after(jiffies, timeout)) {
                        mxcmci_softreset(host);
                        mxcmci_set_clk_rate(host, host->clock);
                        return STATUS_TIME_OUT_READ;
                }
                if (stat & mask)
                        return 0;
                cpu_relax();
        } while (1);
}

static int mxcmci_pull(struct mxcmci_host *host, u32 *buf, int bytes)
{
        unsigned int stat;

        while (bytes > 3) {
                stat = mxcmci_poll_status(host,
                                STATUS_BUF_READ_RDY | STATUS_READ_OP_DONE);
                if (stat)
                        return stat;
                *buf++ = cpu_to_le32(mxcmci_readl(host, MMC_REG_BUFFER_ACCESS));
                bytes -= 4;
        }

        if (bytes) {
                u8 *b = (u8 *)buf;
                u32 tmp;

                stat = mxcmci_poll_status(host,
                                STATUS_BUF_READ_RDY | STATUS_READ_OP_DONE);
                if (stat)
                        return stat;
                tmp = cpu_to_le32(mxcmci_readl(host, MMC_REG_BUFFER_ACCESS));
                memcpy(b, &tmp, bytes);
        }

        return 0;
}

static int mxcmci_push(struct mxcmci_host *host, u32 *buf, int bytes)
{
        unsigned int stat;

        while (bytes > 3) {
                stat = mxcmci_poll_status(host, STATUS_BUF_WRITE_RDY);
                if (stat)
                        return stat;
                mxcmci_writel(host, cpu_to_le32(*buf++), MMC_REG_BUFFER_ACCESS);
                bytes -= 4;
        }

        if (bytes) {
                u8 *b = (u8 *)buf;
                u32 tmp;

                stat = mxcmci_poll_status(host, STATUS_BUF_WRITE_RDY);
                if (stat)
                        return stat;

                memcpy(&tmp, b, bytes);
                mxcmci_writel(host, cpu_to_le32(tmp), MMC_REG_BUFFER_ACCESS);
        }

        return mxcmci_poll_status(host, STATUS_BUF_WRITE_RDY);
}

static int mxcmci_transfer_data(struct mxcmci_host *host)
{
        struct mmc_data *data = host->req->data;
        struct sg_mapping_iter sgm;
        int stat;
        u32 *buf;

        host->data = data;
        host->datasize = 0;
        sg_miter_start(&sgm, data->sg, data->sg_len,
                       (data->flags & MMC_DATA_READ) ? SG_MITER_TO_SG : SG_MITER_FROM_SG);

        if (data->flags & MMC_DATA_READ) {
                while (sg_miter_next(&sgm)) {
                        buf = sgm.addr;
                        stat = mxcmci_pull(host, buf, sgm.length);
                        if (stat)
                                goto transfer_error;
                        host->datasize += sgm.length;
                }
        } else {
                while (sg_miter_next(&sgm)) {
                        buf = sgm.addr;
                        stat = mxcmci_push(host, buf, sgm.length);
                        if (stat)
                                goto transfer_error;
                        host->datasize += sgm.length;
                }
                stat = mxcmci_poll_status(host, STATUS_WRITE_OP_DONE);
                if (stat)
                        goto transfer_error;
        }

transfer_error:
        sg_miter_stop(&sgm);
        return stat;
}

static void mxcmci_datawork(struct work_struct *work)
{
        struct mxcmci_host *host = container_of(work, struct mxcmci_host,
                                                  datawork);
        int datastat = mxcmci_transfer_data(host);

        mxcmci_writel(host, STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE,
                MMC_REG_STATUS);
        mxcmci_finish_data(host, datastat);

        if (host->req->stop) {
                if (mxcmci_start_cmd(host, host->req->stop, 0)) {
                        mxcmci_finish_request(host, host->req);
                        return;
                }
        } else {
                mxcmci_finish_request(host, host->req);
        }
}

static void mxcmci_data_done(struct mxcmci_host *host, unsigned int stat)
{
        struct mmc_request *req;
        int data_error;
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);

        if (!host->data) {
                spin_unlock_irqrestore(&host->lock, flags);
                return;
        }

        if (!host->req) {
                spin_unlock_irqrestore(&host->lock, flags);
                return;
        }

        req = host->req;
        if (!req->stop)
                host->req = NULL; /* we will handle finish req below */

        data_error = mxcmci_finish_data(host, stat);

        spin_unlock_irqrestore(&host->lock, flags);

        if (data_error)
                return;

        mxcmci_read_response(host, stat);
        host->cmd = NULL;

        if (req->stop) {
                if (mxcmci_start_cmd(host, req->stop, 0)) {
                        mxcmci_finish_request(host, req);
                        return;
                }
        } else {
                mxcmci_finish_request(host, req);
        }
}

static void mxcmci_cmd_done(struct mxcmci_host *host, unsigned int stat)
{
        mxcmci_read_response(host, stat);
        host->cmd = NULL;

        if (!host->data && host->req) {
                mxcmci_finish_request(host, host->req);
                return;
        }

        /* For the DMA case the DMA engine handles the data transfer
         * automatically. For non DMA we have to do it ourselves.
         * Don't do it in interrupt context though.
         */
        if (!mxcmci_use_dma(host) && host->data)
                schedule_work(&host->datawork);

}

static irqreturn_t mxcmci_irq(int irq, void *devid)
{
        struct mxcmci_host *host = devid;
        bool sdio_irq;
        u32 stat;

        stat = mxcmci_readl(host, MMC_REG_STATUS);
        mxcmci_writel(host,
                stat & ~(STATUS_SDIO_INT_ACTIVE | STATUS_DATA_TRANS_DONE |
                         STATUS_WRITE_OP_DONE),
                MMC_REG_STATUS);

        dev_dbg(mmc_dev(host->mmc), "%s: 0x%08x\n", __func__, stat);

        spin_lock(&host->lock);
        sdio_irq = (stat & STATUS_SDIO_INT_ACTIVE) && host->use_sdio;
        spin_unlock(&host->lock);

        if (mxcmci_use_dma(host) && (stat & (STATUS_WRITE_OP_DONE)))
                mxcmci_writel(host, STATUS_WRITE_OP_DONE, MMC_REG_STATUS);

        if (sdio_irq) {
                mxcmci_writel(host, STATUS_SDIO_INT_ACTIVE, MMC_REG_STATUS);
                mmc_signal_sdio_irq(host->mmc);
        }

        if (stat & STATUS_END_CMD_RESP)
                mxcmci_cmd_done(host, stat);

        if (mxcmci_use_dma(host) && (stat & STATUS_WRITE_OP_DONE)) {
                timer_delete(&host->watchdog);
                mxcmci_data_done(host, stat);
        }

        if (host->default_irq_mask &&
                  (stat & (STATUS_CARD_INSERTION | STATUS_CARD_REMOVAL)))
                mmc_detect_change(host->mmc, msecs_to_jiffies(200));

        return IRQ_HANDLED;
}

static void mxcmci_request(struct mmc_host *mmc, struct mmc_request *req)
{
        struct mxcmci_host *host = mmc_priv(mmc);
        unsigned int cmdat = host->cmdat;
        int error;

        WARN_ON(host->req != NULL);

        host->req = req;
        host->cmdat &= ~CMD_DAT_CONT_INIT;

        if (host->dma)
                host->do_dma = 1;

        if (req->data) {
                error = mxcmci_setup_data(host, req->data);
                if (error) {
                        req->cmd->error = error;
                        goto out;
                }


                cmdat |= CMD_DAT_CONT_DATA_ENABLE;

                if (req->data->flags & MMC_DATA_WRITE)
                        cmdat |= CMD_DAT_CONT_WRITE;
        }

        error = mxcmci_start_cmd(host, req->cmd, cmdat);

out:
        if (error)
                mxcmci_finish_request(host, req);
}

static void mxcmci_set_clk_rate(struct mxcmci_host *host, unsigned int clk_ios)
{
        unsigned int divider;
        int prescaler = 0;
        unsigned int clk_in = clk_get_rate(host->clk_per);

        while (prescaler <= 0x800) {
                for (divider = 1; divider <= 0xF; divider++) {
                        int x;

                        x = (clk_in / (divider + 1));

                        if (prescaler)
                                x /= (prescaler * 2);

                        if (x <= clk_ios)
                                break;
                }
                if (divider < 0x10)
                        break;

                if (prescaler == 0)
                        prescaler = 1;
                else
                        prescaler <<= 1;
        }

        mxcmci_writew(host, (prescaler << 4) | divider, MMC_REG_CLK_RATE);

        dev_dbg(mmc_dev(host->mmc), "scaler: %d divider: %d in: %d out: %d\n",
                        prescaler, divider, clk_in, clk_ios);
}

static int mxcmci_setup_dma(struct mmc_host *mmc)
{
        struct mxcmci_host *host = mmc_priv(mmc);
        struct dma_slave_config *config = &host->dma_slave_config;

        config->dst_addr = host->phys_base + MMC_REG_BUFFER_ACCESS;
        config->src_addr = host->phys_base + MMC_REG_BUFFER_ACCESS;
        config->dst_addr_width = 4;
        config->src_addr_width = 4;
        config->dst_maxburst = host->burstlen;
        config->src_maxburst = host->burstlen;
        config->device_fc = false;

        return dmaengine_slave_config(host->dma, config);
}

static void mxcmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
        struct mxcmci_host *host = mmc_priv(mmc);
        int burstlen, ret;

        /*
         * use burstlen of 64 (16 words) in 4 bit mode (--> reg value  0)
         * use burstlen of 16 (4 words) in 1 bit mode (--> reg value 16)
         */
        if (ios->bus_width == MMC_BUS_WIDTH_4)
                burstlen = 16;
        else
                burstlen = 4;

        if (mxcmci_use_dma(host) && burstlen != host->burstlen) {
                host->burstlen = burstlen;
                ret = mxcmci_setup_dma(mmc);
                if (ret) {
                        dev_err(mmc_dev(host->mmc),
                                "failed to config DMA channel. Falling back to PIO\n");
                        dma_release_channel(host->dma);
                        host->do_dma = 0;
                        host->dma = NULL;
                }
        }

        if (ios->bus_width == MMC_BUS_WIDTH_4)
                host->cmdat |= CMD_DAT_CONT_BUS_WIDTH_4;
        else
                host->cmdat &= ~CMD_DAT_CONT_BUS_WIDTH_4;

        if (host->power_mode != ios->power_mode) {
                host->power_mode = ios->power_mode;
                mxcmci_set_power(host, ios->vdd);

                if (ios->power_mode == MMC_POWER_ON)
                        host->cmdat |= CMD_DAT_CONT_INIT;
        }

        if (ios->clock) {
                mxcmci_set_clk_rate(host, ios->clock);
                mxcmci_writew(host, STR_STP_CLK_START_CLK, MMC_REG_STR_STP_CLK);
        } else {
                mxcmci_writew(host, STR_STP_CLK_STOP_CLK, MMC_REG_STR_STP_CLK);
        }

        host->clock = ios->clock;
}

static irqreturn_t mxcmci_detect_irq(int irq, void *data)
{
        struct mmc_host *mmc = data;

        dev_dbg(mmc_dev(mmc), "%s\n", __func__);

        mmc_detect_change(mmc, msecs_to_jiffies(250));
        return IRQ_HANDLED;
}

static int mxcmci_get_ro(struct mmc_host *mmc)
{
        struct mxcmci_host *host = mmc_priv(mmc);

        if (host->pdata && host->pdata->get_ro)
                return !!host->pdata->get_ro(mmc_dev(mmc));
        /*
         * If board doesn't support read only detection (no mmc_gpio
         * context or gpio is invalid), then let the mmc core decide
         * what to do.
         */
        return mmc_gpio_get_ro(mmc);
}

static void mxcmci_enable_sdio_irq(struct mmc_host *mmc, int enable)
{
        struct mxcmci_host *host = mmc_priv(mmc);
        unsigned long flags;
        u32 int_cntr;

        spin_lock_irqsave(&host->lock, flags);
        host->use_sdio = enable;
        int_cntr = mxcmci_readl(host, MMC_REG_INT_CNTR);

        if (enable)
                int_cntr |= INT_SDIO_IRQ_EN;
        else
                int_cntr &= ~INT_SDIO_IRQ_EN;

        mxcmci_writel(host, int_cntr, MMC_REG_INT_CNTR);
        spin_unlock_irqrestore(&host->lock, flags);
}

static void mxcmci_init_card(struct mmc_host *host, struct mmc_card *card)
{
        struct mxcmci_host *mxcmci = mmc_priv(host);

        /*
         * MX3 SoCs have a silicon bug which corrupts CRC calculation of
         * multi-block transfers when connected SDIO peripheral doesn't
         * drive the BUSY line as required by the specs.
         * One way to prevent this is to only allow 1-bit transfers.
         */

        if (is_imx31_mmc(mxcmci) && mmc_card_sdio(card))
                host->caps &= ~MMC_CAP_4_BIT_DATA;
        else
                host->caps |= MMC_CAP_4_BIT_DATA;
}

static bool filter(struct dma_chan *chan, void *param)
{
        struct mxcmci_host *host = param;

        if (!imx_dma_is_general_purpose(chan))
                return false;

        chan->private = &host->dma_data;

        return true;
}

static void mxcmci_watchdog(struct timer_list *t)
{
        struct mxcmci_host *host = timer_container_of(host, t, watchdog);
        struct mmc_request *req = host->req;
        unsigned int stat = mxcmci_readl(host, MMC_REG_STATUS);

        if (host->dma_dir == DMA_FROM_DEVICE) {
                dmaengine_terminate_all(host->dma);
                dev_err(mmc_dev(host->mmc),
                        "%s: read time out (status = 0x%08x)\n",
                        __func__, stat);
        } else {
                dev_err(mmc_dev(host->mmc),
                        "%s: write time out (status = 0x%08x)\n",
                        __func__, stat);
                mxcmci_softreset(host);
        }

        /* Mark transfer as erroneus and inform the upper layers */

        if (host->data)
                host->data->error = -ETIMEDOUT;
        host->req = NULL;
        host->cmd = NULL;
        host->data = NULL;
        mmc_request_done(host->mmc, req);
}

static const struct mmc_host_ops mxcmci_ops = {
        .request                = mxcmci_request,
        .set_ios                = mxcmci_set_ios,
        .get_ro                 = mxcmci_get_ro,
        .enable_sdio_irq        = mxcmci_enable_sdio_irq,
        .init_card              = mxcmci_init_card,
};

static int mxcmci_probe(struct platform_device *pdev)
{
        struct mmc_host *mmc;
        struct mxcmci_host *host;
        struct resource *res;
        int ret = 0, irq;
        bool dat3_card_detect;
        dma_cap_mask_t mask;
        struct imxmmc_platform_data *pdata = pdev->dev.platform_data;

        pr_info("i.MX/MPC512x SDHC driver\n");

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        mmc = devm_mmc_alloc_host(&pdev->dev, sizeof(*host));
        if (!mmc)
                return -ENOMEM;

        host = mmc_priv(mmc);

        host->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(host->base))
                return PTR_ERR(host->base);

        host->phys_base = res->start;

        ret = mmc_of_parse(mmc);
        if (ret)
                return ret;
        mmc->ops = &mxcmci_ops;

        /* For devicetree parsing, the bus width is read from devicetree */
        if (pdata)
                mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_SDIO_IRQ;
        else
                mmc->caps |= MMC_CAP_SDIO_IRQ;

        /* MMC core transfer sizes tunable parameters */
        mmc->max_blk_size = 2048;
        mmc->max_blk_count = 65535;
        mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
        mmc->max_seg_size = mmc->max_req_size;

        host->devtype = (uintptr_t)of_device_get_match_data(&pdev->dev);

        /* adjust max_segs after devtype detection */
        if (!is_mpc512x_mmc(host))
                mmc->max_segs = 64;

        host->mmc = mmc;
        host->pdata = pdata;
        spin_lock_init(&host->lock);

        if (pdata)
                dat3_card_detect = pdata->dat3_card_detect;
        else
                dat3_card_detect = mmc_card_is_removable(mmc) &&
                                   !of_property_present(pdev->dev.of_node, "cd-gpios");

        ret = mmc_regulator_get_supply(mmc);
        if (ret)
                return ret;

        if (!mmc->ocr_avail) {
                if (pdata && pdata->ocr_avail)
                        mmc->ocr_avail = pdata->ocr_avail;
                else
                        mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
        }

        if (dat3_card_detect)
                host->default_irq_mask =
                        INT_CARD_INSERTION_EN | INT_CARD_REMOVAL_EN;
        else
                host->default_irq_mask = 0;

        host->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
        if (IS_ERR(host->clk_ipg))
                return PTR_ERR(host->clk_ipg);

        host->clk_per = devm_clk_get(&pdev->dev, "per");
        if (IS_ERR(host->clk_per))
                return PTR_ERR(host->clk_per);

        ret = clk_prepare_enable(host->clk_per);
        if (ret)
                return ret;

        ret = clk_prepare_enable(host->clk_ipg);
        if (ret)
                goto out_clk_per_put;

        mxcmci_softreset(host);

        host->rev_no = mxcmci_readw(host, MMC_REG_REV_NO);
        if (host->rev_no != 0x400) {
                ret = -ENODEV;
                dev_err(mmc_dev(host->mmc), "wrong rev.no. 0x%08x. aborting.\n",
                        host->rev_no);
                goto out_clk_put;
        }

        mmc->f_min = clk_get_rate(host->clk_per) >> 16;
        mmc->f_max = clk_get_rate(host->clk_per) >> 1;

        /* recommended in data sheet */
        mxcmci_writew(host, 0x2db4, MMC_REG_READ_TO);

        mxcmci_writel(host, host->default_irq_mask, MMC_REG_INT_CNTR);

        if (!host->pdata) {
                host->dma = dma_request_chan(&pdev->dev, "rx-tx");
                if (IS_ERR(host->dma)) {
                        if (PTR_ERR(host->dma) == -EPROBE_DEFER) {
                                ret = -EPROBE_DEFER;
                                goto out_clk_put;
                        }

                        /* Ignore errors to fall back to PIO mode */
                        host->dma = NULL;
                }
        } else {
                res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
                if (res) {
                        host->dmareq = res->start;
                        host->dma_data.peripheral_type = IMX_DMATYPE_SDHC;
                        host->dma_data.priority = DMA_PRIO_LOW;
                        host->dma_data.dma_request = host->dmareq;
                        dma_cap_zero(mask);
                        dma_cap_set(DMA_SLAVE, mask);
                        host->dma = dma_request_channel(mask, filter, host);
                }
        }
        if (host->dma)
                mmc->max_seg_size = dma_get_max_seg_size(
                                host->dma->device->dev);
        else
                dev_info(mmc_dev(host->mmc), "dma not available. Using PIO\n");

        INIT_WORK(&host->datawork, mxcmci_datawork);

        ret = devm_request_irq(&pdev->dev, irq, mxcmci_irq, 0,
                               dev_name(&pdev->dev), host);
        if (ret)
                goto out_free_dma;

        platform_set_drvdata(pdev, mmc);

        if (host->pdata && host->pdata->init) {
                ret = host->pdata->init(&pdev->dev, mxcmci_detect_irq,
                                host->mmc);
                if (ret)
                        goto out_free_dma;
        }

        timer_setup(&host->watchdog, mxcmci_watchdog, 0);

        ret = mmc_add_host(mmc);
        if (ret)
                goto out_free_dma;

        return 0;

out_free_dma:
        if (host->dma)
                dma_release_channel(host->dma);

out_clk_put:
        clk_disable_unprepare(host->clk_ipg);
out_clk_per_put:
        clk_disable_unprepare(host->clk_per);

        return ret;
}

static void mxcmci_remove(struct platform_device *pdev)
{
        struct mmc_host *mmc = platform_get_drvdata(pdev);
        struct mxcmci_host *host = mmc_priv(mmc);

        mmc_remove_host(mmc);

        if (host->pdata && host->pdata->exit)
                host->pdata->exit(&pdev->dev, mmc);

        if (host->dma)
                dma_release_channel(host->dma);

        clk_disable_unprepare(host->clk_per);
        clk_disable_unprepare(host->clk_ipg);
}

static int mxcmci_suspend(struct device *dev)
{
        struct mmc_host *mmc = dev_get_drvdata(dev);
        struct mxcmci_host *host = mmc_priv(mmc);

        clk_disable_unprepare(host->clk_per);
        clk_disable_unprepare(host->clk_ipg);
        return 0;
}

static int mxcmci_resume(struct device *dev)
{
        struct mmc_host *mmc = dev_get_drvdata(dev);
        struct mxcmci_host *host = mmc_priv(mmc);
        int ret;

        ret = clk_prepare_enable(host->clk_per);
        if (ret)
                return ret;

        ret = clk_prepare_enable(host->clk_ipg);
        if (ret)
                clk_disable_unprepare(host->clk_per);

        return ret;
}

static DEFINE_SIMPLE_DEV_PM_OPS(mxcmci_pm_ops, mxcmci_suspend, mxcmci_resume);

static struct platform_driver mxcmci_driver = {
        .probe          = mxcmci_probe,
        .remove         = mxcmci_remove,
        .driver         = {
                .name           = DRIVER_NAME,
                .probe_type     = PROBE_PREFER_ASYNCHRONOUS,
                .pm     = pm_sleep_ptr(&mxcmci_pm_ops),
                .of_match_table = mxcmci_of_match,
        }
};

module_platform_driver(mxcmci_driver);

MODULE_DESCRIPTION("i.MX Multimedia Card Interface Driver");
MODULE_AUTHOR("Sascha Hauer, Pengutronix");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:mxc-mmc");