// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
 *  Copyright (C) 2013, Imagination Technologies
 *
 *  JZ4740 SD/MMC controller driver
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/mmc/host.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/scatterlist.h>

#include <asm/cacheflush.h>

#define JZ_REG_MMC_STRPCL       0x00
#define JZ_REG_MMC_STATUS       0x04
#define JZ_REG_MMC_CLKRT        0x08
#define JZ_REG_MMC_CMDAT        0x0C
#define JZ_REG_MMC_RESTO        0x10
#define JZ_REG_MMC_RDTO         0x14
#define JZ_REG_MMC_BLKLEN       0x18
#define JZ_REG_MMC_NOB          0x1C
#define JZ_REG_MMC_SNOB         0x20
#define JZ_REG_MMC_IMASK        0x24
#define JZ_REG_MMC_IREG         0x28
#define JZ_REG_MMC_CMD          0x2C
#define JZ_REG_MMC_ARG          0x30
#define JZ_REG_MMC_RESP_FIFO    0x34
#define JZ_REG_MMC_RXFIFO       0x38
#define JZ_REG_MMC_TXFIFO       0x3C
#define JZ_REG_MMC_LPM          0x40
#define JZ_REG_MMC_DMAC         0x44

#define JZ_MMC_STRPCL_EXIT_MULTIPLE BIT(7)
#define JZ_MMC_STRPCL_EXIT_TRANSFER BIT(6)
#define JZ_MMC_STRPCL_START_READWAIT BIT(5)
#define JZ_MMC_STRPCL_STOP_READWAIT BIT(4)
#define JZ_MMC_STRPCL_RESET BIT(3)
#define JZ_MMC_STRPCL_START_OP BIT(2)
#define JZ_MMC_STRPCL_CLOCK_CONTROL (BIT(1) | BIT(0))
#define JZ_MMC_STRPCL_CLOCK_STOP BIT(0)
#define JZ_MMC_STRPCL_CLOCK_START BIT(1)


#define JZ_MMC_STATUS_IS_RESETTING BIT(15)
#define JZ_MMC_STATUS_SDIO_INT_ACTIVE BIT(14)
#define JZ_MMC_STATUS_PRG_DONE BIT(13)
#define JZ_MMC_STATUS_DATA_TRAN_DONE BIT(12)
#define JZ_MMC_STATUS_END_CMD_RES BIT(11)
#define JZ_MMC_STATUS_DATA_FIFO_AFULL BIT(10)
#define JZ_MMC_STATUS_IS_READWAIT BIT(9)
#define JZ_MMC_STATUS_CLK_EN BIT(8)
#define JZ_MMC_STATUS_DATA_FIFO_FULL BIT(7)
#define JZ_MMC_STATUS_DATA_FIFO_EMPTY BIT(6)
#define JZ_MMC_STATUS_CRC_RES_ERR BIT(5)
#define JZ_MMC_STATUS_CRC_READ_ERROR BIT(4)
#define JZ_MMC_STATUS_TIMEOUT_WRITE BIT(3)
#define JZ_MMC_STATUS_CRC_WRITE_ERROR BIT(2)
#define JZ_MMC_STATUS_TIMEOUT_RES BIT(1)
#define JZ_MMC_STATUS_TIMEOUT_READ BIT(0)

#define JZ_MMC_STATUS_READ_ERROR_MASK (BIT(4) | BIT(0))
#define JZ_MMC_STATUS_WRITE_ERROR_MASK (BIT(3) | BIT(2))


#define JZ_MMC_CMDAT_IO_ABORT BIT(11)
#define JZ_MMC_CMDAT_BUS_WIDTH_4BIT BIT(10)
#define JZ_MMC_CMDAT_BUS_WIDTH_8BIT (BIT(10) | BIT(9))
#define JZ_MMC_CMDAT_BUS_WIDTH_MASK (BIT(10) | BIT(9))
#define JZ_MMC_CMDAT_DMA_EN BIT(8)
#define JZ_MMC_CMDAT_INIT BIT(7)
#define JZ_MMC_CMDAT_BUSY BIT(6)
#define JZ_MMC_CMDAT_STREAM BIT(5)
#define JZ_MMC_CMDAT_WRITE BIT(4)
#define JZ_MMC_CMDAT_DATA_EN BIT(3)
#define JZ_MMC_CMDAT_RESPONSE_FORMAT (BIT(2) | BIT(1) | BIT(0))
#define JZ_MMC_CMDAT_RSP_R1 1
#define JZ_MMC_CMDAT_RSP_R2 2
#define JZ_MMC_CMDAT_RSP_R3 3

#define JZ_MMC_IRQ_SDIO BIT(7)
#define JZ_MMC_IRQ_TXFIFO_WR_REQ BIT(6)
#define JZ_MMC_IRQ_RXFIFO_RD_REQ BIT(5)
#define JZ_MMC_IRQ_END_CMD_RES BIT(2)
#define JZ_MMC_IRQ_PRG_DONE BIT(1)
#define JZ_MMC_IRQ_DATA_TRAN_DONE BIT(0)

#define JZ_MMC_DMAC_DMA_SEL BIT(1)
#define JZ_MMC_DMAC_DMA_EN BIT(0)

#define JZ_MMC_LPM_DRV_RISING BIT(31)
#define JZ_MMC_LPM_DRV_RISING_QTR_PHASE_DLY BIT(31)
#define JZ_MMC_LPM_DRV_RISING_1NS_DLY BIT(30)
#define JZ_MMC_LPM_SMP_RISING_QTR_OR_HALF_PHASE_DLY BIT(29)
#define JZ_MMC_LPM_LOW_POWER_MODE_EN BIT(0)

#define JZ_MMC_CLK_RATE 24000000
#define JZ_MMC_REQ_TIMEOUT_MS 5000

enum jz4740_mmc_version {
        JZ_MMC_JZ4740,
        JZ_MMC_JZ4725B,
        JZ_MMC_JZ4760,
        JZ_MMC_JZ4780,
        JZ_MMC_X1000,
};

enum jz4740_mmc_state {
        JZ4740_MMC_STATE_READ_RESPONSE,
        JZ4740_MMC_STATE_TRANSFER_DATA,
        JZ4740_MMC_STATE_SEND_STOP,
        JZ4740_MMC_STATE_DONE,
};

/*
 * The MMC core allows to prepare a mmc_request while another mmc_request
 * is in-flight. This is used via the pre_req/post_req hooks.
 * This driver uses the pre_req/post_req hooks to map/unmap the mmc_request.
 * Following what other drivers do (sdhci, dw_mmc) we use the following cookie
 * flags to keep track of the mmc_request mapping state.
 *
 * COOKIE_UNMAPPED: the request is not mapped.
 * COOKIE_PREMAPPED: the request was mapped in pre_req,
 * and should be unmapped in post_req.
 * COOKIE_MAPPED: the request was mapped in the irq handler,
 * and should be unmapped before mmc_request_done is called..
 */
enum jz4780_cookie {
        COOKIE_UNMAPPED = 0,
        COOKIE_PREMAPPED,
        COOKIE_MAPPED,
};

struct jz4740_mmc_host {
        struct mmc_host *mmc;
        struct platform_device *pdev;
        struct clk *clk;

        enum jz4740_mmc_version version;

        int irq;

        void __iomem *base;
        struct resource *mem_res;
        struct mmc_request *req;
        struct mmc_command *cmd;

        bool vqmmc_enabled;

        unsigned long waiting;

        uint32_t cmdat;

        uint32_t irq_mask;

        spinlock_t lock;

        struct timer_list timeout_timer;
        struct sg_mapping_iter miter;
        enum jz4740_mmc_state state;

        /* DMA support */
        struct dma_chan *dma_rx;
        struct dma_chan *dma_tx;
        bool use_dma;

/* The DMA trigger level is 8 words, that is to say, the DMA read
 * trigger is when data words in MSC_RXFIFO is >= 8 and the DMA write
 * trigger is when data words in MSC_TXFIFO is < 8.
 */
#define JZ4740_MMC_FIFO_HALF_SIZE 8
};

static void jz4740_mmc_write_irq_mask(struct jz4740_mmc_host *host,
                                      uint32_t val)
{
        if (host->version >= JZ_MMC_JZ4725B)
                return writel(val, host->base + JZ_REG_MMC_IMASK);
        else
                return writew(val, host->base + JZ_REG_MMC_IMASK);
}

static void jz4740_mmc_write_irq_reg(struct jz4740_mmc_host *host,
                                     uint32_t val)
{
        if (host->version >= JZ_MMC_JZ4780)
                writel(val, host->base + JZ_REG_MMC_IREG);
        else
                writew(val, host->base + JZ_REG_MMC_IREG);
}

static uint32_t jz4740_mmc_read_irq_reg(struct jz4740_mmc_host *host)
{
        if (host->version >= JZ_MMC_JZ4780)
                return readl(host->base + JZ_REG_MMC_IREG);
        else
                return readw(host->base + JZ_REG_MMC_IREG);
}

/*----------------------------------------------------------------------------*/
/* DMA infrastructure */

static void jz4740_mmc_release_dma_channels(struct jz4740_mmc_host *host)
{
        if (!host->use_dma)
                return;

        dma_release_channel(host->dma_tx);
        if (host->dma_rx)
                dma_release_channel(host->dma_rx);
}

static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
{
        struct device *dev = mmc_dev(host->mmc);

        host->dma_tx = dma_request_chan(dev, "tx-rx");
        if (!IS_ERR(host->dma_tx))
                return 0;

        if (PTR_ERR(host->dma_tx) != -ENODEV) {
                dev_err(dev, "Failed to get dma tx-rx channel\n");
                return PTR_ERR(host->dma_tx);
        }

        host->dma_tx = dma_request_chan(mmc_dev(host->mmc), "tx");
        if (IS_ERR(host->dma_tx)) {
                dev_err(mmc_dev(host->mmc), "Failed to get dma_tx channel\n");
                return PTR_ERR(host->dma_tx);
        }

        host->dma_rx = dma_request_chan(mmc_dev(host->mmc), "rx");
        if (IS_ERR(host->dma_rx)) {
                dev_err(mmc_dev(host->mmc), "Failed to get dma_rx channel\n");
                dma_release_channel(host->dma_tx);
                return PTR_ERR(host->dma_rx);
        }

        /*
         * Limit the maximum segment size in any SG entry according to
         * the parameters of the DMA engine device.
         */
        if (host->dma_tx) {
                struct device *dev = host->dma_tx->device->dev;
                unsigned int max_seg_size = dma_get_max_seg_size(dev);

                if (max_seg_size < host->mmc->max_seg_size)
                        host->mmc->max_seg_size = max_seg_size;
        }

        if (host->dma_rx) {
                struct device *dev = host->dma_rx->device->dev;
                unsigned int max_seg_size = dma_get_max_seg_size(dev);

                if (max_seg_size < host->mmc->max_seg_size)
                        host->mmc->max_seg_size = max_seg_size;
        }

        return 0;
}

static inline struct dma_chan *jz4740_mmc_get_dma_chan(struct jz4740_mmc_host *host,
                                                       struct mmc_data *data)
{
        if ((data->flags & MMC_DATA_READ) && host->dma_rx)
                return host->dma_rx;
        else
                return host->dma_tx;
}

static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
                                 struct mmc_data *data)
{
        struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
        enum dma_data_direction dir = mmc_get_dma_dir(data);

        dma_unmap_sg(chan->device->dev, data->sg, data->sg_len, dir);
        data->host_cookie = COOKIE_UNMAPPED;
}

/* Prepares DMA data for current or next transfer.
 * A request can be in-flight when this is called.
 */
static int jz4740_mmc_prepare_dma_data(struct jz4740_mmc_host *host,
                                       struct mmc_data *data,
                                       int cookie)
{
        struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
        enum dma_data_direction dir = mmc_get_dma_dir(data);
        unsigned int sg_count;

        if (data->host_cookie == COOKIE_PREMAPPED)
                return data->sg_count;

        sg_count = dma_map_sg(chan->device->dev,
                        data->sg,
                        data->sg_len,
                        dir);

        if (!sg_count) {
                dev_err(mmc_dev(host->mmc),
                        "Failed to map scatterlist for DMA operation\n");
                return -EINVAL;
        }

        data->sg_count = sg_count;
        data->host_cookie = cookie;

        return data->sg_count;
}

static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
                                         struct mmc_data *data)
{
        struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
        struct dma_async_tx_descriptor *desc;
        struct dma_slave_config conf = {
                .src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
                .dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
                .src_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
                .dst_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
        };
        int sg_count;

        if (data->flags & MMC_DATA_WRITE) {
                conf.direction = DMA_MEM_TO_DEV;
                conf.dst_addr = host->mem_res->start + JZ_REG_MMC_TXFIFO;
        } else {
                conf.direction = DMA_DEV_TO_MEM;
                conf.src_addr = host->mem_res->start + JZ_REG_MMC_RXFIFO;
        }

        sg_count = jz4740_mmc_prepare_dma_data(host, data, COOKIE_MAPPED);
        if (sg_count < 0)
                return sg_count;

        dmaengine_slave_config(chan, &conf);
        desc = dmaengine_prep_slave_sg(chan, data->sg, sg_count,
                        conf.direction,
                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!desc) {
                dev_err(mmc_dev(host->mmc),
                        "Failed to allocate DMA %s descriptor",
                         conf.direction == DMA_MEM_TO_DEV ? "TX" : "RX");
                goto dma_unmap;
        }

        dmaengine_submit(desc);
        dma_async_issue_pending(chan);

        return 0;

dma_unmap:
        if (data->host_cookie == COOKIE_MAPPED)
                jz4740_mmc_dma_unmap(host, data);
        return -ENOMEM;
}

static void jz4740_mmc_pre_request(struct mmc_host *mmc,
                                   struct mmc_request *mrq)
{
        struct jz4740_mmc_host *host = mmc_priv(mmc);
        struct mmc_data *data = mrq->data;

        if (!host->use_dma)
                return;

        data->host_cookie = COOKIE_UNMAPPED;
        if (jz4740_mmc_prepare_dma_data(host, data, COOKIE_PREMAPPED) < 0)
                data->host_cookie = COOKIE_UNMAPPED;
}

static void jz4740_mmc_post_request(struct mmc_host *mmc,
                                    struct mmc_request *mrq,
                                    int err)
{
        struct jz4740_mmc_host *host = mmc_priv(mmc);
        struct mmc_data *data = mrq->data;

        if (data && data->host_cookie != COOKIE_UNMAPPED)
                jz4740_mmc_dma_unmap(host, data);

        if (err) {
                struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);

                dmaengine_terminate_all(chan);
        }
}

/*----------------------------------------------------------------------------*/

static void jz4740_mmc_set_irq_enabled(struct jz4740_mmc_host *host,
        unsigned int irq, bool enabled)
{
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        if (enabled)
                host->irq_mask &= ~irq;
        else
                host->irq_mask |= irq;

        jz4740_mmc_write_irq_mask(host, host->irq_mask);
        spin_unlock_irqrestore(&host->lock, flags);
}

static void jz4740_mmc_clock_enable(struct jz4740_mmc_host *host,
        bool start_transfer)
{
        uint16_t val = JZ_MMC_STRPCL_CLOCK_START;

        if (start_transfer)
                val |= JZ_MMC_STRPCL_START_OP;

        writew(val, host->base + JZ_REG_MMC_STRPCL);
}

static void jz4740_mmc_clock_disable(struct jz4740_mmc_host *host)
{
        uint32_t status;
        unsigned int timeout = 1000;

        writew(JZ_MMC_STRPCL_CLOCK_STOP, host->base + JZ_REG_MMC_STRPCL);
        do {
                status = readl(host->base + JZ_REG_MMC_STATUS);
        } while (status & JZ_MMC_STATUS_CLK_EN && --timeout);
}

static void jz4740_mmc_reset(struct jz4740_mmc_host *host)
{
        uint32_t status;
        unsigned int timeout = 1000;

        writew(JZ_MMC_STRPCL_RESET, host->base + JZ_REG_MMC_STRPCL);
        udelay(10);
        do {
                status = readl(host->base + JZ_REG_MMC_STATUS);
        } while (status & JZ_MMC_STATUS_IS_RESETTING && --timeout);
}

static void jz4740_mmc_request_done(struct jz4740_mmc_host *host)
{
        struct mmc_request *req;
        struct mmc_data *data;

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

        if (data && data->host_cookie == COOKIE_MAPPED)
                jz4740_mmc_dma_unmap(host, data);
        mmc_request_done(host->mmc, req);
}

static unsigned int jz4740_mmc_poll_irq(struct jz4740_mmc_host *host,
        unsigned int irq)
{
        unsigned int timeout = 0x800;
        uint32_t status;

        do {
                status = jz4740_mmc_read_irq_reg(host);
        } while (!(status & irq) && --timeout);

        if (timeout == 0) {
                set_bit(0, &host->waiting);
                mod_timer(&host->timeout_timer,
                          jiffies + msecs_to_jiffies(JZ_MMC_REQ_TIMEOUT_MS));
                jz4740_mmc_set_irq_enabled(host, irq, true);
                return true;
        }

        return false;
}

static void jz4740_mmc_transfer_check_state(struct jz4740_mmc_host *host,
        struct mmc_data *data)
{
        int status;

        status = readl(host->base + JZ_REG_MMC_STATUS);
        if (status & JZ_MMC_STATUS_WRITE_ERROR_MASK) {
                if (status & (JZ_MMC_STATUS_TIMEOUT_WRITE)) {
                        host->req->cmd->error = -ETIMEDOUT;
                        data->error = -ETIMEDOUT;
                } else {
                        host->req->cmd->error = -EIO;
                        data->error = -EIO;
                }
        } else if (status & JZ_MMC_STATUS_READ_ERROR_MASK) {
                if (status & (JZ_MMC_STATUS_TIMEOUT_READ)) {
                        host->req->cmd->error = -ETIMEDOUT;
                        data->error = -ETIMEDOUT;
                } else {
                        host->req->cmd->error = -EIO;
                        data->error = -EIO;
                }
        }
}

static bool jz4740_mmc_write_data(struct jz4740_mmc_host *host,
        struct mmc_data *data)
{
        struct sg_mapping_iter *miter = &host->miter;
        void __iomem *fifo_addr = host->base + JZ_REG_MMC_TXFIFO;
        uint32_t *buf;
        bool timeout;
        size_t i, j;

        while (sg_miter_next(miter)) {
                buf = miter->addr;
                i = miter->length / 4;
                j = i / 8;
                i = i & 0x7;
                while (j) {
                        timeout = jz4740_mmc_poll_irq(host, JZ_MMC_IRQ_TXFIFO_WR_REQ);
                        if (unlikely(timeout))
                                goto poll_timeout;

                        writel(buf[0], fifo_addr);
                        writel(buf[1], fifo_addr);
                        writel(buf[2], fifo_addr);
                        writel(buf[3], fifo_addr);
                        writel(buf[4], fifo_addr);
                        writel(buf[5], fifo_addr);
                        writel(buf[6], fifo_addr);
                        writel(buf[7], fifo_addr);
                        buf += 8;
                        --j;
                }
                if (unlikely(i)) {
                        timeout = jz4740_mmc_poll_irq(host, JZ_MMC_IRQ_TXFIFO_WR_REQ);
                        if (unlikely(timeout))
                                goto poll_timeout;

                        while (i) {
                                writel(*buf, fifo_addr);
                                ++buf;
                                --i;
                        }
                }
                data->bytes_xfered += miter->length;
        }
        sg_miter_stop(miter);

        return false;

poll_timeout:
        miter->consumed = (void *)buf - miter->addr;
        data->bytes_xfered += miter->consumed;
        sg_miter_stop(miter);

        return true;
}

static bool jz4740_mmc_read_data(struct jz4740_mmc_host *host,
                                struct mmc_data *data)
{
        struct sg_mapping_iter *miter = &host->miter;
        void __iomem *fifo_addr = host->base + JZ_REG_MMC_RXFIFO;
        uint32_t *buf;
        uint32_t d;
        uint32_t status;
        size_t i, j;
        unsigned int timeout;

        while (sg_miter_next(miter)) {
                buf = miter->addr;
                i = miter->length;
                j = i / 32;
                i = i & 0x1f;
                while (j) {
                        timeout = jz4740_mmc_poll_irq(host, JZ_MMC_IRQ_RXFIFO_RD_REQ);
                        if (unlikely(timeout))
                                goto poll_timeout;

                        buf[0] = readl(fifo_addr);
                        buf[1] = readl(fifo_addr);
                        buf[2] = readl(fifo_addr);
                        buf[3] = readl(fifo_addr);
                        buf[4] = readl(fifo_addr);
                        buf[5] = readl(fifo_addr);
                        buf[6] = readl(fifo_addr);
                        buf[7] = readl(fifo_addr);

                        buf += 8;
                        --j;
                }

                if (unlikely(i)) {
                        timeout = jz4740_mmc_poll_irq(host, JZ_MMC_IRQ_RXFIFO_RD_REQ);
                        if (unlikely(timeout))
                                goto poll_timeout;

                        while (i >= 4) {
                                *buf++ = readl(fifo_addr);
                                i -= 4;
                        }
                        if (unlikely(i > 0)) {
                                d = readl(fifo_addr);
                                memcpy(buf, &d, i);
                        }
                }
                data->bytes_xfered += miter->length;
        }
        sg_miter_stop(miter);

        /* For whatever reason there is sometime one word more in the fifo then
         * requested */
        timeout = 1000;
        status = readl(host->base + JZ_REG_MMC_STATUS);
        while (!(status & JZ_MMC_STATUS_DATA_FIFO_EMPTY) && --timeout) {
                d = readl(fifo_addr);
                status = readl(host->base + JZ_REG_MMC_STATUS);
        }

        return false;

poll_timeout:
        miter->consumed = (void *)buf - miter->addr;
        data->bytes_xfered += miter->consumed;
        sg_miter_stop(miter);

        return true;
}

static void jz4740_mmc_timeout(struct timer_list *t)
{
        struct jz4740_mmc_host *host = timer_container_of(host, t,
                                                          timeout_timer);

        if (!test_and_clear_bit(0, &host->waiting))
                return;

        jz4740_mmc_set_irq_enabled(host, JZ_MMC_IRQ_END_CMD_RES, false);

        host->req->cmd->error = -ETIMEDOUT;
        jz4740_mmc_request_done(host);
}

static void jz4740_mmc_read_response(struct jz4740_mmc_host *host,
        struct mmc_command *cmd)
{
        int i;
        uint16_t tmp;
        void __iomem *fifo_addr = host->base + JZ_REG_MMC_RESP_FIFO;

        if (cmd->flags & MMC_RSP_136) {
                tmp = readw(fifo_addr);
                for (i = 0; i < 4; ++i) {
                        cmd->resp[i] = tmp << 24;
                        tmp = readw(fifo_addr);
                        cmd->resp[i] |= tmp << 8;
                        tmp = readw(fifo_addr);
                        cmd->resp[i] |= tmp >> 8;
                }
        } else {
                cmd->resp[0] = readw(fifo_addr) << 24;
                cmd->resp[0] |= readw(fifo_addr) << 8;
                cmd->resp[0] |= readw(fifo_addr) & 0xff;
        }
}

static void jz4740_mmc_send_command(struct jz4740_mmc_host *host,
        struct mmc_command *cmd)
{
        uint32_t cmdat = host->cmdat;

        host->cmdat &= ~JZ_MMC_CMDAT_INIT;
        jz4740_mmc_clock_disable(host);

        host->cmd = cmd;

        if (cmd->flags & MMC_RSP_BUSY)
                cmdat |= JZ_MMC_CMDAT_BUSY;

        switch (mmc_resp_type(cmd)) {
        case MMC_RSP_R1B:
        case MMC_RSP_R1:
                cmdat |= JZ_MMC_CMDAT_RSP_R1;
                break;
        case MMC_RSP_R2:
                cmdat |= JZ_MMC_CMDAT_RSP_R2;
                break;
        case MMC_RSP_R3:
                cmdat |= JZ_MMC_CMDAT_RSP_R3;
                break;
        default:
                break;
        }

        if (cmd->data) {
                cmdat |= JZ_MMC_CMDAT_DATA_EN;
                if (cmd->data->flags & MMC_DATA_WRITE)
                        cmdat |= JZ_MMC_CMDAT_WRITE;
                if (host->use_dma) {
                        /*
                         * The JZ4780's MMC controller has integrated DMA ability
                         * in addition to being able to use the external DMA
                         * controller. It moves DMA control bits to a separate
                         * register. The DMA_SEL bit chooses the external
                         * controller over the integrated one. Earlier SoCs
                         * can only use the external controller, and have a
                         * single DMA enable bit in CMDAT.
                         */
                        if (host->version >= JZ_MMC_JZ4780) {
                                writel(JZ_MMC_DMAC_DMA_EN | JZ_MMC_DMAC_DMA_SEL,
                                       host->base + JZ_REG_MMC_DMAC);
                        } else {
                                cmdat |= JZ_MMC_CMDAT_DMA_EN;
                        }
                } else if (host->version >= JZ_MMC_JZ4780) {
                        writel(0, host->base + JZ_REG_MMC_DMAC);
                }

                writew(cmd->data->blksz, host->base + JZ_REG_MMC_BLKLEN);
                writew(cmd->data->blocks, host->base + JZ_REG_MMC_NOB);
        }

        writeb(cmd->opcode, host->base + JZ_REG_MMC_CMD);
        writel(cmd->arg, host->base + JZ_REG_MMC_ARG);
        writel(cmdat, host->base + JZ_REG_MMC_CMDAT);

        jz4740_mmc_clock_enable(host, 1);
}

static void jz_mmc_prepare_data_transfer(struct jz4740_mmc_host *host)
{
        struct mmc_command *cmd = host->req->cmd;
        struct mmc_data *data = cmd->data;
        int direction;

        if (data->flags & MMC_DATA_READ)
                direction = SG_MITER_TO_SG;
        else
                direction = SG_MITER_FROM_SG;

        sg_miter_start(&host->miter, data->sg, data->sg_len, direction);
}


static irqreturn_t jz_mmc_irq_worker(int irq, void *devid)
{
        struct jz4740_mmc_host *host = (struct jz4740_mmc_host *)devid;
        struct mmc_command *cmd = host->req->cmd;
        struct mmc_request *req = host->req;
        struct mmc_data *data = cmd->data;
        bool timeout = false;

        if (cmd->error)
                host->state = JZ4740_MMC_STATE_DONE;

        switch (host->state) {
        case JZ4740_MMC_STATE_READ_RESPONSE:
                if (cmd->flags & MMC_RSP_PRESENT)
                        jz4740_mmc_read_response(host, cmd);

                if (!data)
                        break;

                jz_mmc_prepare_data_transfer(host);
                fallthrough;

        case JZ4740_MMC_STATE_TRANSFER_DATA:
                if (host->use_dma) {
                        /* Use DMA if enabled.
                         * Data transfer direction is defined later by
                         * relying on data flags in
                         * jz4740_mmc_prepare_dma_data() and
                         * jz4740_mmc_start_dma_transfer().
                         */
                        timeout = jz4740_mmc_start_dma_transfer(host, data);
                        data->bytes_xfered = data->blocks * data->blksz;
                } else if (data->flags & MMC_DATA_READ)
                        /* Use PIO if DMA is not enabled.
                         * Data transfer direction was defined before
                         * by relying on data flags in
                         * jz_mmc_prepare_data_transfer().
                         */
                        timeout = jz4740_mmc_read_data(host, data);
                else
                        timeout = jz4740_mmc_write_data(host, data);

                if (unlikely(timeout)) {
                        host->state = JZ4740_MMC_STATE_TRANSFER_DATA;
                        break;
                }

                jz4740_mmc_transfer_check_state(host, data);

                timeout = jz4740_mmc_poll_irq(host, JZ_MMC_IRQ_DATA_TRAN_DONE);
                if (unlikely(timeout)) {
                        host->state = JZ4740_MMC_STATE_SEND_STOP;
                        break;
                }
                jz4740_mmc_write_irq_reg(host, JZ_MMC_IRQ_DATA_TRAN_DONE);
                fallthrough;

        case JZ4740_MMC_STATE_SEND_STOP:
                if (!req->stop)
                        break;

                jz4740_mmc_send_command(host, req->stop);

                if (mmc_resp_type(req->stop) & MMC_RSP_BUSY) {
                        timeout = jz4740_mmc_poll_irq(host,
                                                      JZ_MMC_IRQ_PRG_DONE);
                        if (timeout) {
                                host->state = JZ4740_MMC_STATE_DONE;
                                break;
                        }
                }
                fallthrough;

        case JZ4740_MMC_STATE_DONE:
                break;
        }

        if (!timeout)
                jz4740_mmc_request_done(host);

        return IRQ_HANDLED;
}

static irqreturn_t jz_mmc_irq(int irq, void *devid)
{
        struct jz4740_mmc_host *host = devid;
        struct mmc_command *cmd = host->cmd;
        uint32_t irq_reg, status, tmp;

        status = readl(host->base + JZ_REG_MMC_STATUS);
        irq_reg = jz4740_mmc_read_irq_reg(host);

        tmp = irq_reg;
        irq_reg &= ~host->irq_mask;

        tmp &= ~(JZ_MMC_IRQ_TXFIFO_WR_REQ | JZ_MMC_IRQ_RXFIFO_RD_REQ |
                JZ_MMC_IRQ_PRG_DONE | JZ_MMC_IRQ_DATA_TRAN_DONE);

        if (tmp != irq_reg)
                jz4740_mmc_write_irq_reg(host, tmp & ~irq_reg);

        if (irq_reg & JZ_MMC_IRQ_SDIO) {
                jz4740_mmc_write_irq_reg(host, JZ_MMC_IRQ_SDIO);
                mmc_signal_sdio_irq(host->mmc);
                irq_reg &= ~JZ_MMC_IRQ_SDIO;
        }

        if (host->req && cmd && irq_reg) {
                if (test_and_clear_bit(0, &host->waiting)) {
                        timer_delete(&host->timeout_timer);

                        if (status & JZ_MMC_STATUS_TIMEOUT_RES) {
                                cmd->error = -ETIMEDOUT;
                        } else if (status & JZ_MMC_STATUS_CRC_RES_ERR) {
                                cmd->error = -EIO;
                        } else if (status & (JZ_MMC_STATUS_CRC_READ_ERROR |
                                    JZ_MMC_STATUS_CRC_WRITE_ERROR)) {
                                if (cmd->data)
                                        cmd->data->error = -EIO;
                                cmd->error = -EIO;
                        }

                        jz4740_mmc_set_irq_enabled(host, irq_reg, false);
                        jz4740_mmc_write_irq_reg(host, irq_reg);

                        return IRQ_WAKE_THREAD;
                }
        }

        return IRQ_HANDLED;
}

static int jz4740_mmc_set_clock_rate(struct jz4740_mmc_host *host, int rate)
{
        int div = 0;
        int real_rate;

        jz4740_mmc_clock_disable(host);
        clk_set_rate(host->clk, host->mmc->f_max);

        real_rate = clk_get_rate(host->clk);

        while (real_rate > rate && div < 7) {
                ++div;
                real_rate >>= 1;
        }

        writew(div, host->base + JZ_REG_MMC_CLKRT);

        if (real_rate > 25000000) {
                if (host->version >= JZ_MMC_JZ4780) {
                        writel(JZ_MMC_LPM_DRV_RISING_QTR_PHASE_DLY |
                                   JZ_MMC_LPM_SMP_RISING_QTR_OR_HALF_PHASE_DLY |
                                   JZ_MMC_LPM_LOW_POWER_MODE_EN,
                                   host->base + JZ_REG_MMC_LPM);
                } else if (host->version >= JZ_MMC_JZ4760) {
                        writel(JZ_MMC_LPM_DRV_RISING |
                                   JZ_MMC_LPM_LOW_POWER_MODE_EN,
                                   host->base + JZ_REG_MMC_LPM);
                } else if (host->version >= JZ_MMC_JZ4725B)
                        writel(JZ_MMC_LPM_LOW_POWER_MODE_EN,
                                   host->base + JZ_REG_MMC_LPM);
        }

        return real_rate;
}

static void jz4740_mmc_request(struct mmc_host *mmc, struct mmc_request *req)
{
        struct jz4740_mmc_host *host = mmc_priv(mmc);

        host->req = req;

        jz4740_mmc_write_irq_reg(host, ~0);
        jz4740_mmc_set_irq_enabled(host, JZ_MMC_IRQ_END_CMD_RES, true);

        host->state = JZ4740_MMC_STATE_READ_RESPONSE;
        set_bit(0, &host->waiting);
        mod_timer(&host->timeout_timer,
                  jiffies + msecs_to_jiffies(JZ_MMC_REQ_TIMEOUT_MS));
        jz4740_mmc_send_command(host, req->cmd);
}

static void jz4740_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
        struct jz4740_mmc_host *host = mmc_priv(mmc);
        int ret;

        if (ios->clock)
                jz4740_mmc_set_clock_rate(host, ios->clock);

        switch (ios->power_mode) {
        case MMC_POWER_UP:
                jz4740_mmc_reset(host);
                if (!IS_ERR(mmc->supply.vmmc))
                        mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, ios->vdd);
                host->cmdat |= JZ_MMC_CMDAT_INIT;
                clk_prepare_enable(host->clk);
                break;
        case MMC_POWER_ON:
                if (!IS_ERR(mmc->supply.vqmmc) && !host->vqmmc_enabled) {
                        ret = regulator_enable(mmc->supply.vqmmc);
                        if (ret)
                                dev_err(&host->pdev->dev, "Failed to set vqmmc power!\n");
                        else
                                host->vqmmc_enabled = true;
                }
                break;
        case MMC_POWER_OFF:
                if (!IS_ERR(mmc->supply.vmmc))
                        mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
                if (!IS_ERR(mmc->supply.vqmmc) && host->vqmmc_enabled) {
                        regulator_disable(mmc->supply.vqmmc);
                        host->vqmmc_enabled = false;
                }
                clk_disable_unprepare(host->clk);
                break;
        default:
                break;
        }

        switch (ios->bus_width) {
        case MMC_BUS_WIDTH_1:
                host->cmdat &= ~JZ_MMC_CMDAT_BUS_WIDTH_MASK;
                break;
        case MMC_BUS_WIDTH_4:
                host->cmdat &= ~JZ_MMC_CMDAT_BUS_WIDTH_MASK;
                host->cmdat |= JZ_MMC_CMDAT_BUS_WIDTH_4BIT;
                break;
        case MMC_BUS_WIDTH_8:
                host->cmdat &= ~JZ_MMC_CMDAT_BUS_WIDTH_MASK;
                host->cmdat |= JZ_MMC_CMDAT_BUS_WIDTH_8BIT;
                break;
        default:
                break;
        }
}

static void jz4740_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
{
        struct jz4740_mmc_host *host = mmc_priv(mmc);
        jz4740_mmc_set_irq_enabled(host, JZ_MMC_IRQ_SDIO, enable);
}

static int jz4740_voltage_switch(struct mmc_host *mmc, struct mmc_ios *ios)
{
        int ret;

        /* vqmmc regulator is available */
        if (!IS_ERR(mmc->supply.vqmmc)) {
                ret = mmc_regulator_set_vqmmc(mmc, ios);
                return ret < 0 ? ret : 0;
        }

        /* no vqmmc regulator, assume fixed regulator at 3/3.3V */
        if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330)
                return 0;

        return -EINVAL;
}

static const struct mmc_host_ops jz4740_mmc_ops = {
        .request        = jz4740_mmc_request,
        .pre_req        = jz4740_mmc_pre_request,
        .post_req       = jz4740_mmc_post_request,
        .set_ios        = jz4740_mmc_set_ios,
        .get_ro         = mmc_gpio_get_ro,
        .get_cd         = mmc_gpio_get_cd,
        .enable_sdio_irq = jz4740_mmc_enable_sdio_irq,
        .start_signal_voltage_switch = jz4740_voltage_switch,
};

static const struct of_device_id jz4740_mmc_of_match[] = {
        { .compatible = "ingenic,jz4740-mmc", .data = (void *) JZ_MMC_JZ4740 },
        { .compatible = "ingenic,jz4725b-mmc", .data = (void *)JZ_MMC_JZ4725B },
        { .compatible = "ingenic,jz4760-mmc", .data = (void *) JZ_MMC_JZ4760 },
        { .compatible = "ingenic,jz4775-mmc", .data = (void *) JZ_MMC_JZ4780 },
        { .compatible = "ingenic,jz4780-mmc", .data = (void *) JZ_MMC_JZ4780 },
        { .compatible = "ingenic,x1000-mmc", .data = (void *) JZ_MMC_X1000 },
        {},
};
MODULE_DEVICE_TABLE(of, jz4740_mmc_of_match);

static int jz4740_mmc_probe(struct platform_device* pdev)
{
        int ret;
        struct mmc_host *mmc;
        struct jz4740_mmc_host *host;

        mmc = devm_mmc_alloc_host(&pdev->dev, sizeof(*host));
        if (!mmc) {
                dev_err(&pdev->dev, "Failed to alloc mmc host structure\n");
                return -ENOMEM;
        }

        host = mmc_priv(mmc);

        /* Default if no match is JZ4740 */
        host->version = (enum jz4740_mmc_version)device_get_match_data(&pdev->dev);

        ret = mmc_of_parse(mmc);
        if (ret)
                return dev_err_probe(&pdev->dev, ret,
                                     "could not parse device properties\n");

        mmc_regulator_get_supply(mmc);

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

        host->clk = devm_clk_get(&pdev->dev, "mmc");
        if (IS_ERR(host->clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(host->clk),
                                     "Failed to get mmc clock\n");

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

        mmc->ops = &jz4740_mmc_ops;
        if (!mmc->f_max)
                mmc->f_max = JZ_MMC_CLK_RATE;

        /*
         * There seems to be a problem with this driver on the JZ4760 and
         * JZ4760B SoCs. There, when using the maximum rate supported (50 MHz),
         * the communication fails with many SD cards.
         * Until this bug is sorted out, limit the maximum rate to 24 MHz.
         */
        if (host->version == JZ_MMC_JZ4760 && mmc->f_max > JZ_MMC_CLK_RATE)
                mmc->f_max = JZ_MMC_CLK_RATE;

        mmc->f_min = mmc->f_max / 128;
        mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;

        /*
         * We use a fixed timeout of 5s, hence inform the core about it. A
         * future improvement should instead respect the cmd->busy_timeout.
         */
        mmc->max_busy_timeout = JZ_MMC_REQ_TIMEOUT_MS;

        mmc->max_blk_size = (1 << 10) - 1;
        mmc->max_blk_count = (1 << 15) - 1;
        mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;

        mmc->max_segs = 128;
        mmc->max_seg_size = mmc->max_req_size;

        host->mmc = mmc;
        host->pdev = pdev;
        spin_lock_init(&host->lock);
        host->irq_mask = ~0;

        jz4740_mmc_reset(host);

        ret = request_threaded_irq(host->irq, jz_mmc_irq, jz_mmc_irq_worker, 0,
                        dev_name(&pdev->dev), host);
        if (ret)
                return dev_err_probe(&pdev->dev, ret, "Failed to request irq\n");

        jz4740_mmc_clock_disable(host);
        timer_setup(&host->timeout_timer, jz4740_mmc_timeout, 0);

        ret = jz4740_mmc_acquire_dma_channels(host);
        if (ret == -EPROBE_DEFER)
                goto err_free_irq;
        host->use_dma = !ret;

        platform_set_drvdata(pdev, host);
        ret = mmc_add_host(mmc);

        if (ret) {
                dev_err(&pdev->dev, "Failed to add mmc host: %d\n", ret);
                goto err_release_dma;
        }
        dev_info(&pdev->dev, "Ingenic SD/MMC card driver registered\n");

        dev_info(&pdev->dev, "Using %s, %d-bit mode\n",
                 host->use_dma ? "DMA" : "PIO",
                 (mmc->caps & MMC_CAP_8_BIT_DATA) ? 8 :
                 ((mmc->caps & MMC_CAP_4_BIT_DATA) ? 4 : 1));

        return 0;

err_release_dma:
        if (host->use_dma)
                jz4740_mmc_release_dma_channels(host);
err_free_irq:
        free_irq(host->irq, host);
        return ret;
}

static void jz4740_mmc_remove(struct platform_device *pdev)
{
        struct jz4740_mmc_host *host = platform_get_drvdata(pdev);

        timer_delete_sync(&host->timeout_timer);
        jz4740_mmc_set_irq_enabled(host, 0xff, false);
        jz4740_mmc_reset(host);

        mmc_remove_host(host->mmc);

        free_irq(host->irq, host);

        if (host->use_dma)
                jz4740_mmc_release_dma_channels(host);
}

static int jz4740_mmc_suspend(struct device *dev)
{
        return pinctrl_pm_select_sleep_state(dev);
}

static int jz4740_mmc_resume(struct device *dev)
{
        return pinctrl_select_default_state(dev);
}

static DEFINE_SIMPLE_DEV_PM_OPS(jz4740_mmc_pm_ops, jz4740_mmc_suspend,
                                jz4740_mmc_resume);

static struct platform_driver jz4740_mmc_driver = {
        .probe = jz4740_mmc_probe,
        .remove = jz4740_mmc_remove,
        .driver = {
                .name = "jz4740-mmc",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = jz4740_mmc_of_match,
                .pm = pm_sleep_ptr(&jz4740_mmc_pm_ops),
        },
};

module_platform_driver(jz4740_mmc_driver);

MODULE_DESCRIPTION("JZ4740 SD/MMC controller driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");