// SPDX-License-Identifier: GPL-2.0+
// Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
// Copyright (C) 2008 Juergen Beisert

#include <linux/clk.h>
#include <linux/completion.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/kernel.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/property.h>

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

#define DRIVER_NAME "spi_imx"

static bool use_dma = true;
module_param(use_dma, bool, 0644);
MODULE_PARM_DESC(use_dma, "Enable usage of DMA when available (default)");

#define MXC_RPM_TIMEOUT         2000 /* 2000ms */

#define MXC_CSPIRXDATA          0x00
#define MXC_CSPITXDATA          0x04
#define MXC_CSPICTRL            0x08
#define MXC_CSPIINT             0x0c
#define MXC_RESET               0x1c

/* generic defines to abstract from the different register layouts */
#define MXC_INT_RR      (1 << 0) /* Receive data ready interrupt */
#define MXC_INT_TE      (1 << 1) /* Transmit FIFO empty interrupt */
#define MXC_INT_RDR     BIT(4) /* Receive date threshold interrupt */

/* The maximum bytes that a sdma BD can transfer. */
#define MAX_SDMA_BD_BYTES (1 << 15)
#define MX51_ECSPI_CTRL_MAX_BURST       512
/* The maximum bytes that IMX53_ECSPI can transfer in slave mode.*/
#define MX53_MAX_TRANSFER_BYTES         512

enum spi_imx_devtype {
        IMX1_CSPI,
        IMX21_CSPI,
        IMX27_CSPI,
        IMX31_CSPI,
        IMX35_CSPI,     /* CSPI on all i.mx except above */
        IMX51_ECSPI,    /* ECSPI on i.mx51 */
        IMX53_ECSPI,    /* ECSPI on i.mx53 and later */
};

struct spi_imx_data;

struct spi_imx_devtype_data {
        void (*intctrl)(struct spi_imx_data *, int);
        int (*prepare_message)(struct spi_imx_data *, struct spi_message *);
        int (*prepare_transfer)(struct spi_imx_data *, struct spi_device *);
        void (*trigger)(struct spi_imx_data *);
        int (*rx_available)(struct spi_imx_data *);
        void (*reset)(struct spi_imx_data *);
        void (*setup_wml)(struct spi_imx_data *);
        void (*disable)(struct spi_imx_data *);
        void (*disable_dma)(struct spi_imx_data *);
        bool has_dmamode;
        bool has_slavemode;
        unsigned int fifo_size;
        bool dynamic_burst;
        /*
         * ERR009165 fixed or not:
         * https://www.nxp.com/docs/en/errata/IMX6DQCE.pdf
         */
        bool tx_glitch_fixed;
        enum spi_imx_devtype devtype;
};

struct spi_imx_data {
        struct spi_bitbang bitbang;
        struct device *dev;

        struct completion xfer_done;
        void __iomem *base;
        unsigned long base_phys;

        struct clk *clk_per;
        struct clk *clk_ipg;
        unsigned long spi_clk;
        unsigned int spi_bus_clk;

        unsigned int bits_per_word;
        unsigned int spi_drctl;

        unsigned int count, remainder;
        void (*tx)(struct spi_imx_data *);
        void (*rx)(struct spi_imx_data *);
        void *rx_buf;
        const void *tx_buf;
        unsigned int txfifo; /* number of words pushed in tx FIFO */
        unsigned int dynamic_burst;

        /* Slave mode */
        bool slave_mode;
        bool slave_aborted;
        unsigned int slave_burst;

        /* DMA */
        bool usedma;
        u32 wml;
        struct completion dma_rx_completion;
        struct completion dma_tx_completion;

        const struct spi_imx_devtype_data *devtype_data;
};

static inline int is_imx27_cspi(struct spi_imx_data *d)
{
        return d->devtype_data->devtype == IMX27_CSPI;
}

static inline int is_imx35_cspi(struct spi_imx_data *d)
{
        return d->devtype_data->devtype == IMX35_CSPI;
}

static inline int is_imx51_ecspi(struct spi_imx_data *d)
{
        return d->devtype_data->devtype == IMX51_ECSPI;
}

static inline int is_imx53_ecspi(struct spi_imx_data *d)
{
        return d->devtype_data->devtype == IMX53_ECSPI;
}

#define MXC_SPI_BUF_RX(type)                                            \
static void spi_imx_buf_rx_##type(struct spi_imx_data *spi_imx)         \
{                                                                       \
        unsigned int val = readl(spi_imx->base + MXC_CSPIRXDATA);       \
                                                                        \
        if (spi_imx->rx_buf) {                                          \
                *(type *)spi_imx->rx_buf = val;                         \
                spi_imx->rx_buf += sizeof(type);                        \
        }                                                               \
                                                                        \
        spi_imx->remainder -= sizeof(type);                             \
}

#define MXC_SPI_BUF_TX(type)                                            \
static void spi_imx_buf_tx_##type(struct spi_imx_data *spi_imx)         \
{                                                                       \
        type val = 0;                                                   \
                                                                        \
        if (spi_imx->tx_buf) {                                          \
                val = *(type *)spi_imx->tx_buf;                         \
                spi_imx->tx_buf += sizeof(type);                        \
        }                                                               \
                                                                        \
        spi_imx->count -= sizeof(type);                                 \
                                                                        \
        writel(val, spi_imx->base + MXC_CSPITXDATA);                    \
}

MXC_SPI_BUF_RX(u8)
MXC_SPI_BUF_TX(u8)
MXC_SPI_BUF_RX(u16)
MXC_SPI_BUF_TX(u16)
MXC_SPI_BUF_RX(u32)
MXC_SPI_BUF_TX(u32)

/* First entry is reserved, second entry is valid only if SDHC_SPIEN is set
 * (which is currently not the case in this driver)
 */
static int mxc_clkdivs[] = {0, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128, 192,
        256, 384, 512, 768, 1024};

/* MX21, MX27 */
static unsigned int spi_imx_clkdiv_1(unsigned int fin,
                unsigned int fspi, unsigned int max, unsigned int *fres)
{
        int i;

        for (i = 2; i < max; i++)
                if (fspi * mxc_clkdivs[i] >= fin)
                        break;

        *fres = fin / mxc_clkdivs[i];
        return i;
}

/* MX1, MX31, MX35, MX51 CSPI */
static unsigned int spi_imx_clkdiv_2(unsigned int fin,
                unsigned int fspi, unsigned int *fres)
{
        int i, div = 4;

        for (i = 0; i < 7; i++) {
                if (fspi * div >= fin)
                        goto out;
                div <<= 1;
        }

out:
        *fres = fin / div;
        return i;
}

static int spi_imx_bytes_per_word(const int bits_per_word)
{
        if (bits_per_word <= 8)
                return 1;
        else if (bits_per_word <= 16)
                return 2;
        else
                return 4;
}

static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
                         struct spi_transfer *transfer)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);

        if (!use_dma || master->fallback)
                return false;

        if (!master->dma_rx)
                return false;

        if (spi_imx->slave_mode)
                return false;

        if (transfer->len < spi_imx->devtype_data->fifo_size)
                return false;

        spi_imx->dynamic_burst = 0;

        return true;
}

#define MX51_ECSPI_CTRL         0x08
#define MX51_ECSPI_CTRL_ENABLE          (1 <<  0)
#define MX51_ECSPI_CTRL_XCH             (1 <<  2)
#define MX51_ECSPI_CTRL_SMC             (1 << 3)
#define MX51_ECSPI_CTRL_MODE_MASK       (0xf << 4)
#define MX51_ECSPI_CTRL_DRCTL(drctl)    ((drctl) << 16)
#define MX51_ECSPI_CTRL_POSTDIV_OFFSET  8
#define MX51_ECSPI_CTRL_PREDIV_OFFSET   12
#define MX51_ECSPI_CTRL_CS(cs)          ((cs) << 18)
#define MX51_ECSPI_CTRL_BL_OFFSET       20
#define MX51_ECSPI_CTRL_BL_MASK         (0xfff << 20)

#define MX51_ECSPI_CONFIG       0x0c
#define MX51_ECSPI_CONFIG_SCLKPHA(cs)   (1 << ((cs) +  0))
#define MX51_ECSPI_CONFIG_SCLKPOL(cs)   (1 << ((cs) +  4))
#define MX51_ECSPI_CONFIG_SBBCTRL(cs)   (1 << ((cs) +  8))
#define MX51_ECSPI_CONFIG_SSBPOL(cs)    (1 << ((cs) + 12))
#define MX51_ECSPI_CONFIG_SCLKCTL(cs)   (1 << ((cs) + 20))

#define MX51_ECSPI_INT          0x10
#define MX51_ECSPI_INT_TEEN             (1 <<  0)
#define MX51_ECSPI_INT_RREN             (1 <<  3)
#define MX51_ECSPI_INT_RDREN            (1 <<  4)

#define MX51_ECSPI_DMA          0x14
#define MX51_ECSPI_DMA_TX_WML(wml)      ((wml) & 0x3f)
#define MX51_ECSPI_DMA_RX_WML(wml)      (((wml) & 0x3f) << 16)
#define MX51_ECSPI_DMA_RXT_WML(wml)     (((wml) & 0x3f) << 24)

#define MX51_ECSPI_DMA_TEDEN            (1 << 7)
#define MX51_ECSPI_DMA_RXDEN            (1 << 23)
#define MX51_ECSPI_DMA_RXTDEN           (1 << 31)

#define MX51_ECSPI_STAT         0x18
#define MX51_ECSPI_STAT_RR              (1 <<  3)

#define MX51_ECSPI_TESTREG      0x20
#define MX51_ECSPI_TESTREG_LBC  BIT(31)

static void spi_imx_buf_rx_swap_u32(struct spi_imx_data *spi_imx)
{
        unsigned int val = readl(spi_imx->base + MXC_CSPIRXDATA);
#ifdef __LITTLE_ENDIAN
        unsigned int bytes_per_word;
#endif

        if (spi_imx->rx_buf) {
#ifdef __LITTLE_ENDIAN
                bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);
                if (bytes_per_word == 1)
                        val = cpu_to_be32(val);
                else if (bytes_per_word == 2)
                        val = (val << 16) | (val >> 16);
#endif
                *(u32 *)spi_imx->rx_buf = val;
                spi_imx->rx_buf += sizeof(u32);
        }

        spi_imx->remainder -= sizeof(u32);
}

static void spi_imx_buf_rx_swap(struct spi_imx_data *spi_imx)
{
        int unaligned;
        u32 val;

        unaligned = spi_imx->remainder % 4;

        if (!unaligned) {
                spi_imx_buf_rx_swap_u32(spi_imx);
                return;
        }

        if (spi_imx_bytes_per_word(spi_imx->bits_per_word) == 2) {
                spi_imx_buf_rx_u16(spi_imx);
                return;
        }

        val = readl(spi_imx->base + MXC_CSPIRXDATA);

        while (unaligned--) {
                if (spi_imx->rx_buf) {
                        *(u8 *)spi_imx->rx_buf = (val >> (8 * unaligned)) & 0xff;
                        spi_imx->rx_buf++;
                }
                spi_imx->remainder--;
        }
}

static void spi_imx_buf_tx_swap_u32(struct spi_imx_data *spi_imx)
{
        u32 val = 0;
#ifdef __LITTLE_ENDIAN
        unsigned int bytes_per_word;
#endif

        if (spi_imx->tx_buf) {
                val = *(u32 *)spi_imx->tx_buf;
                spi_imx->tx_buf += sizeof(u32);
        }

        spi_imx->count -= sizeof(u32);
#ifdef __LITTLE_ENDIAN
        bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);

        if (bytes_per_word == 1)
                val = cpu_to_be32(val);
        else if (bytes_per_word == 2)
                val = (val << 16) | (val >> 16);
#endif
        writel(val, spi_imx->base + MXC_CSPITXDATA);
}

static void spi_imx_buf_tx_swap(struct spi_imx_data *spi_imx)
{
        int unaligned;
        u32 val = 0;

        unaligned = spi_imx->count % 4;

        if (!unaligned) {
                spi_imx_buf_tx_swap_u32(spi_imx);
                return;
        }

        if (spi_imx_bytes_per_word(spi_imx->bits_per_word) == 2) {
                spi_imx_buf_tx_u16(spi_imx);
                return;
        }

        while (unaligned--) {
                if (spi_imx->tx_buf) {
                        val |= *(u8 *)spi_imx->tx_buf << (8 * unaligned);
                        spi_imx->tx_buf++;
                }
                spi_imx->count--;
        }

        writel(val, spi_imx->base + MXC_CSPITXDATA);
}

static void mx53_ecspi_rx_slave(struct spi_imx_data *spi_imx)
{
        u32 val = be32_to_cpu(readl(spi_imx->base + MXC_CSPIRXDATA));

        if (spi_imx->rx_buf) {
                int n_bytes = spi_imx->slave_burst % sizeof(val);

                if (!n_bytes)
                        n_bytes = sizeof(val);

                memcpy(spi_imx->rx_buf,
                       ((u8 *)&val) + sizeof(val) - n_bytes, n_bytes);

                spi_imx->rx_buf += n_bytes;
                spi_imx->slave_burst -= n_bytes;
        }

        spi_imx->remainder -= sizeof(u32);
}

static void mx53_ecspi_tx_slave(struct spi_imx_data *spi_imx)
{
        u32 val = 0;
        int n_bytes = spi_imx->count % sizeof(val);

        if (!n_bytes)
                n_bytes = sizeof(val);

        if (spi_imx->tx_buf) {
                memcpy(((u8 *)&val) + sizeof(val) - n_bytes,
                       spi_imx->tx_buf, n_bytes);
                val = cpu_to_be32(val);
                spi_imx->tx_buf += n_bytes;
        }

        spi_imx->count -= n_bytes;

        writel(val, spi_imx->base + MXC_CSPITXDATA);
}

/* MX51 eCSPI */
static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx,
                                      unsigned int fspi, unsigned int *fres)
{
        /*
         * there are two 4-bit dividers, the pre-divider divides by
         * $pre, the post-divider by 2^$post
         */
        unsigned int pre, post;
        unsigned int fin = spi_imx->spi_clk;

        if (unlikely(fspi > fin))
                return 0;

        post = fls(fin) - fls(fspi);
        if (fin > fspi << post)
                post++;

        /* now we have: (fin <= fspi << post) with post being minimal */

        post = max(4U, post) - 4;
        if (unlikely(post > 0xf)) {
                dev_err(spi_imx->dev, "cannot set clock freq: %u (base freq: %u)\n",
                                fspi, fin);
                return 0xff;
        }

        pre = DIV_ROUND_UP(fin, fspi << post) - 1;

        dev_dbg(spi_imx->dev, "%s: fin: %u, fspi: %u, post: %u, pre: %u\n",
                        __func__, fin, fspi, post, pre);

        /* Resulting frequency for the SCLK line. */
        *fres = (fin / (pre + 1)) >> post;

        return (pre << MX51_ECSPI_CTRL_PREDIV_OFFSET) |
                (post << MX51_ECSPI_CTRL_POSTDIV_OFFSET);
}

static void mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int enable)
{
        unsigned val = 0;

        if (enable & MXC_INT_TE)
                val |= MX51_ECSPI_INT_TEEN;

        if (enable & MXC_INT_RR)
                val |= MX51_ECSPI_INT_RREN;

        if (enable & MXC_INT_RDR)
                val |= MX51_ECSPI_INT_RDREN;

        writel(val, spi_imx->base + MX51_ECSPI_INT);
}

static void mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
{
        u32 reg;

        reg = readl(spi_imx->base + MX51_ECSPI_CTRL);
        reg |= MX51_ECSPI_CTRL_XCH;
        writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
}

static void mx51_disable_dma(struct spi_imx_data *spi_imx)
{
        writel(0, spi_imx->base + MX51_ECSPI_DMA);
}

static void mx51_ecspi_disable(struct spi_imx_data *spi_imx)
{
        u32 ctrl;

        ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
        ctrl &= ~MX51_ECSPI_CTRL_ENABLE;
        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
}

static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
                                      struct spi_message *msg)
{
        struct spi_device *spi = msg->spi;
        struct spi_transfer *xfer;
        u32 ctrl = MX51_ECSPI_CTRL_ENABLE;
        u32 min_speed_hz = ~0U;
        u32 testreg, delay;
        u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);

        /* set Master or Slave mode */
        if (spi_imx->slave_mode)
                ctrl &= ~MX51_ECSPI_CTRL_MODE_MASK;
        else
                ctrl |= MX51_ECSPI_CTRL_MODE_MASK;

        /*
         * Enable SPI_RDY handling (falling edge/level triggered).
         */
        if (spi->mode & SPI_READY)
                ctrl |= MX51_ECSPI_CTRL_DRCTL(spi_imx->spi_drctl);

        /* set chip select to use */
        ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);

        /*
         * The ctrl register must be written first, with the EN bit set other
         * registers must not be written to.
         */
        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);

        testreg = readl(spi_imx->base + MX51_ECSPI_TESTREG);
        if (spi->mode & SPI_LOOP)
                testreg |= MX51_ECSPI_TESTREG_LBC;
        else
                testreg &= ~MX51_ECSPI_TESTREG_LBC;
        writel(testreg, spi_imx->base + MX51_ECSPI_TESTREG);

        /*
         * eCSPI burst completion by Chip Select signal in Slave mode
         * is not functional for imx53 Soc, config SPI burst completed when
         * BURST_LENGTH + 1 bits are received
         */
        if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
                cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
        else
                cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);

        if (spi->mode & SPI_CPHA)
                cfg |= MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
        else
                cfg &= ~MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);

        if (spi->mode & SPI_CPOL) {
                cfg |= MX51_ECSPI_CONFIG_SCLKPOL(spi->chip_select);
                cfg |= MX51_ECSPI_CONFIG_SCLKCTL(spi->chip_select);
        } else {
                cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(spi->chip_select);
                cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(spi->chip_select);
        }

        if (spi->mode & SPI_CS_HIGH)
                cfg |= MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);
        else
                cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);

        writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);

        /*
         * Wait until the changes in the configuration register CONFIGREG
         * propagate into the hardware. It takes exactly one tick of the
         * SCLK clock, but we will wait two SCLK clock just to be sure. The
         * effect of the delay it takes for the hardware to apply changes
         * is noticable if the SCLK clock run very slow. In such a case, if
         * the polarity of SCLK should be inverted, the GPIO ChipSelect might
         * be asserted before the SCLK polarity changes, which would disrupt
         * the SPI communication as the device on the other end would consider
         * the change of SCLK polarity as a clock tick already.
         *
         * Because spi_imx->spi_bus_clk is only set in bitbang prepare_message
         * callback, iterate over all the transfers in spi_message, find the
         * one with lowest bus frequency, and use that bus frequency for the
         * delay calculation. In case all transfers have speed_hz == 0, then
         * min_speed_hz is ~0 and the resulting delay is zero.
         */
        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                if (!xfer->speed_hz)
                        continue;
                min_speed_hz = min(xfer->speed_hz, min_speed_hz);
        }

        delay = (2 * 1000000) / min_speed_hz;
        if (likely(delay < 10)) /* SCLK is faster than 200 kHz */
                udelay(delay);
        else                    /* SCLK is _very_ slow */
                usleep_range(delay, delay + 10);

        return 0;
}

static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
                                       struct spi_device *spi)
{
        u32 ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
        u32 clk;

        /* Clear BL field and set the right value */
        ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
        if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
                ctrl |= (spi_imx->slave_burst * 8 - 1)
                        << MX51_ECSPI_CTRL_BL_OFFSET;
        else
                ctrl |= (spi_imx->bits_per_word - 1)
                        << MX51_ECSPI_CTRL_BL_OFFSET;

        /* set clock speed */
        ctrl &= ~(0xf << MX51_ECSPI_CTRL_POSTDIV_OFFSET |
                  0xf << MX51_ECSPI_CTRL_PREDIV_OFFSET);
        ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
        spi_imx->spi_bus_clk = clk;

        /*
         * ERR009165: work in XHC mode instead of SMC as PIO on the chips
         * before i.mx6ul.
         */
        if (spi_imx->usedma && spi_imx->devtype_data->tx_glitch_fixed)
                ctrl |= MX51_ECSPI_CTRL_SMC;
        else
                ctrl &= ~MX51_ECSPI_CTRL_SMC;

        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);

        return 0;
}

static void mx51_setup_wml(struct spi_imx_data *spi_imx)
{
        u32 tx_wml = 0;

        if (spi_imx->devtype_data->tx_glitch_fixed)
                tx_wml = spi_imx->wml;
        /*
         * Configure the DMA register: setup the watermark
         * and enable DMA request.
         */
        writel(MX51_ECSPI_DMA_RX_WML(spi_imx->wml - 1) |
                MX51_ECSPI_DMA_TX_WML(tx_wml) |
                MX51_ECSPI_DMA_RXT_WML(spi_imx->wml) |
                MX51_ECSPI_DMA_TEDEN | MX51_ECSPI_DMA_RXDEN |
                MX51_ECSPI_DMA_RXTDEN, spi_imx->base + MX51_ECSPI_DMA);
}

static int mx51_ecspi_rx_available(struct spi_imx_data *spi_imx)
{
        return readl(spi_imx->base + MX51_ECSPI_STAT) & MX51_ECSPI_STAT_RR;
}

static void mx51_ecspi_reset(struct spi_imx_data *spi_imx)
{
        /* drain receive buffer */
        while (mx51_ecspi_rx_available(spi_imx))
                readl(spi_imx->base + MXC_CSPIRXDATA);
}

#define MX31_INTREG_TEEN        (1 << 0)
#define MX31_INTREG_RREN        (1 << 3)

#define MX31_CSPICTRL_ENABLE    (1 << 0)
#define MX31_CSPICTRL_MASTER    (1 << 1)
#define MX31_CSPICTRL_XCH       (1 << 2)
#define MX31_CSPICTRL_SMC       (1 << 3)
#define MX31_CSPICTRL_POL       (1 << 4)
#define MX31_CSPICTRL_PHA       (1 << 5)
#define MX31_CSPICTRL_SSCTL     (1 << 6)
#define MX31_CSPICTRL_SSPOL     (1 << 7)
#define MX31_CSPICTRL_BC_SHIFT  8
#define MX35_CSPICTRL_BL_SHIFT  20
#define MX31_CSPICTRL_CS_SHIFT  24
#define MX35_CSPICTRL_CS_SHIFT  12
#define MX31_CSPICTRL_DR_SHIFT  16

#define MX31_CSPI_DMAREG        0x10
#define MX31_DMAREG_RH_DEN      (1<<4)
#define MX31_DMAREG_TH_DEN      (1<<1)

#define MX31_CSPISTATUS         0x14
#define MX31_STATUS_RR          (1 << 3)

#define MX31_CSPI_TESTREG       0x1C
#define MX31_TEST_LBC           (1 << 14)

/* These functions also work for the i.MX35, but be aware that
 * the i.MX35 has a slightly different register layout for bits
 * we do not use here.
 */
static void mx31_intctrl(struct spi_imx_data *spi_imx, int enable)
{
        unsigned int val = 0;

        if (enable & MXC_INT_TE)
                val |= MX31_INTREG_TEEN;
        if (enable & MXC_INT_RR)
                val |= MX31_INTREG_RREN;

        writel(val, spi_imx->base + MXC_CSPIINT);
}

static void mx31_trigger(struct spi_imx_data *spi_imx)
{
        unsigned int reg;

        reg = readl(spi_imx->base + MXC_CSPICTRL);
        reg |= MX31_CSPICTRL_XCH;
        writel(reg, spi_imx->base + MXC_CSPICTRL);
}

static int mx31_prepare_message(struct spi_imx_data *spi_imx,
                                struct spi_message *msg)
{
        return 0;
}

static int mx31_prepare_transfer(struct spi_imx_data *spi_imx,
                                 struct spi_device *spi)
{
        unsigned int reg = MX31_CSPICTRL_ENABLE | MX31_CSPICTRL_MASTER;
        unsigned int clk;

        reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, spi_imx->spi_bus_clk, &clk) <<
                MX31_CSPICTRL_DR_SHIFT;
        spi_imx->spi_bus_clk = clk;

        if (is_imx35_cspi(spi_imx)) {
                reg |= (spi_imx->bits_per_word - 1) << MX35_CSPICTRL_BL_SHIFT;
                reg |= MX31_CSPICTRL_SSCTL;
        } else {
                reg |= (spi_imx->bits_per_word - 1) << MX31_CSPICTRL_BC_SHIFT;
        }

        if (spi->mode & SPI_CPHA)
                reg |= MX31_CSPICTRL_PHA;
        if (spi->mode & SPI_CPOL)
                reg |= MX31_CSPICTRL_POL;
        if (spi->mode & SPI_CS_HIGH)
                reg |= MX31_CSPICTRL_SSPOL;
        if (!spi->cs_gpiod)
                reg |= (spi->chip_select) <<
                        (is_imx35_cspi(spi_imx) ? MX35_CSPICTRL_CS_SHIFT :
                                                  MX31_CSPICTRL_CS_SHIFT);

        if (spi_imx->usedma)
                reg |= MX31_CSPICTRL_SMC;

        writel(reg, spi_imx->base + MXC_CSPICTRL);

        reg = readl(spi_imx->base + MX31_CSPI_TESTREG);
        if (spi->mode & SPI_LOOP)
                reg |= MX31_TEST_LBC;
        else
                reg &= ~MX31_TEST_LBC;
        writel(reg, spi_imx->base + MX31_CSPI_TESTREG);

        if (spi_imx->usedma) {
                /*
                 * configure DMA requests when RXFIFO is half full and
                 * when TXFIFO is half empty
                 */
                writel(MX31_DMAREG_RH_DEN | MX31_DMAREG_TH_DEN,
                        spi_imx->base + MX31_CSPI_DMAREG);
        }

        return 0;
}

static int mx31_rx_available(struct spi_imx_data *spi_imx)
{
        return readl(spi_imx->base + MX31_CSPISTATUS) & MX31_STATUS_RR;
}

static void mx31_reset(struct spi_imx_data *spi_imx)
{
        /* drain receive buffer */
        while (readl(spi_imx->base + MX31_CSPISTATUS) & MX31_STATUS_RR)
                readl(spi_imx->base + MXC_CSPIRXDATA);
}

#define MX21_INTREG_RR          (1 << 4)
#define MX21_INTREG_TEEN        (1 << 9)
#define MX21_INTREG_RREN        (1 << 13)

#define MX21_CSPICTRL_POL       (1 << 5)
#define MX21_CSPICTRL_PHA       (1 << 6)
#define MX21_CSPICTRL_SSPOL     (1 << 8)
#define MX21_CSPICTRL_XCH       (1 << 9)
#define MX21_CSPICTRL_ENABLE    (1 << 10)
#define MX21_CSPICTRL_MASTER    (1 << 11)
#define MX21_CSPICTRL_DR_SHIFT  14
#define MX21_CSPICTRL_CS_SHIFT  19

static void mx21_intctrl(struct spi_imx_data *spi_imx, int enable)
{
        unsigned int val = 0;

        if (enable & MXC_INT_TE)
                val |= MX21_INTREG_TEEN;
        if (enable & MXC_INT_RR)
                val |= MX21_INTREG_RREN;

        writel(val, spi_imx->base + MXC_CSPIINT);
}

static void mx21_trigger(struct spi_imx_data *spi_imx)
{
        unsigned int reg;

        reg = readl(spi_imx->base + MXC_CSPICTRL);
        reg |= MX21_CSPICTRL_XCH;
        writel(reg, spi_imx->base + MXC_CSPICTRL);
}

static int mx21_prepare_message(struct spi_imx_data *spi_imx,
                                struct spi_message *msg)
{
        return 0;
}

static int mx21_prepare_transfer(struct spi_imx_data *spi_imx,
                                 struct spi_device *spi)
{
        unsigned int reg = MX21_CSPICTRL_ENABLE | MX21_CSPICTRL_MASTER;
        unsigned int max = is_imx27_cspi(spi_imx) ? 16 : 18;
        unsigned int clk;

        reg |= spi_imx_clkdiv_1(spi_imx->spi_clk, spi_imx->spi_bus_clk, max, &clk)
                << MX21_CSPICTRL_DR_SHIFT;
        spi_imx->spi_bus_clk = clk;

        reg |= spi_imx->bits_per_word - 1;

        if (spi->mode & SPI_CPHA)
                reg |= MX21_CSPICTRL_PHA;
        if (spi->mode & SPI_CPOL)
                reg |= MX21_CSPICTRL_POL;
        if (spi->mode & SPI_CS_HIGH)
                reg |= MX21_CSPICTRL_SSPOL;
        if (!spi->cs_gpiod)
                reg |= spi->chip_select << MX21_CSPICTRL_CS_SHIFT;

        writel(reg, spi_imx->base + MXC_CSPICTRL);

        return 0;
}

static int mx21_rx_available(struct spi_imx_data *spi_imx)
{
        return readl(spi_imx->base + MXC_CSPIINT) & MX21_INTREG_RR;
}

static void mx21_reset(struct spi_imx_data *spi_imx)
{
        writel(1, spi_imx->base + MXC_RESET);
}

#define MX1_INTREG_RR           (1 << 3)
#define MX1_INTREG_TEEN         (1 << 8)
#define MX1_INTREG_RREN         (1 << 11)

#define MX1_CSPICTRL_POL        (1 << 4)
#define MX1_CSPICTRL_PHA        (1 << 5)
#define MX1_CSPICTRL_XCH        (1 << 8)
#define MX1_CSPICTRL_ENABLE     (1 << 9)
#define MX1_CSPICTRL_MASTER     (1 << 10)
#define MX1_CSPICTRL_DR_SHIFT   13

static void mx1_intctrl(struct spi_imx_data *spi_imx, int enable)
{
        unsigned int val = 0;

        if (enable & MXC_INT_TE)
                val |= MX1_INTREG_TEEN;
        if (enable & MXC_INT_RR)
                val |= MX1_INTREG_RREN;

        writel(val, spi_imx->base + MXC_CSPIINT);
}

static void mx1_trigger(struct spi_imx_data *spi_imx)
{
        unsigned int reg;

        reg = readl(spi_imx->base + MXC_CSPICTRL);
        reg |= MX1_CSPICTRL_XCH;
        writel(reg, spi_imx->base + MXC_CSPICTRL);
}

static int mx1_prepare_message(struct spi_imx_data *spi_imx,
                               struct spi_message *msg)
{
        return 0;
}

static int mx1_prepare_transfer(struct spi_imx_data *spi_imx,
                                struct spi_device *spi)
{
        unsigned int reg = MX1_CSPICTRL_ENABLE | MX1_CSPICTRL_MASTER;
        unsigned int clk;

        reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, spi_imx->spi_bus_clk, &clk) <<
                MX1_CSPICTRL_DR_SHIFT;
        spi_imx->spi_bus_clk = clk;

        reg |= spi_imx->bits_per_word - 1;

        if (spi->mode & SPI_CPHA)
                reg |= MX1_CSPICTRL_PHA;
        if (spi->mode & SPI_CPOL)
                reg |= MX1_CSPICTRL_POL;

        writel(reg, spi_imx->base + MXC_CSPICTRL);

        return 0;
}

static int mx1_rx_available(struct spi_imx_data *spi_imx)
{
        return readl(spi_imx->base + MXC_CSPIINT) & MX1_INTREG_RR;
}

static void mx1_reset(struct spi_imx_data *spi_imx)
{
        writel(1, spi_imx->base + MXC_RESET);
}

static struct spi_imx_devtype_data imx1_cspi_devtype_data = {
        .intctrl = mx1_intctrl,
        .prepare_message = mx1_prepare_message,
        .prepare_transfer = mx1_prepare_transfer,
        .trigger = mx1_trigger,
        .rx_available = mx1_rx_available,
        .reset = mx1_reset,
        .fifo_size = 8,
        .has_dmamode = false,
        .dynamic_burst = false,
        .has_slavemode = false,
        .devtype = IMX1_CSPI,
};

static struct spi_imx_devtype_data imx21_cspi_devtype_data = {
        .intctrl = mx21_intctrl,
        .prepare_message = mx21_prepare_message,
        .prepare_transfer = mx21_prepare_transfer,
        .trigger = mx21_trigger,
        .rx_available = mx21_rx_available,
        .reset = mx21_reset,
        .fifo_size = 8,
        .has_dmamode = false,
        .dynamic_burst = false,
        .has_slavemode = false,
        .devtype = IMX21_CSPI,
};

static struct spi_imx_devtype_data imx27_cspi_devtype_data = {
        /* i.mx27 cspi shares the functions with i.mx21 one */
        .intctrl = mx21_intctrl,
        .prepare_message = mx21_prepare_message,
        .prepare_transfer = mx21_prepare_transfer,
        .trigger = mx21_trigger,
        .rx_available = mx21_rx_available,
        .reset = mx21_reset,
        .fifo_size = 8,
        .has_dmamode = false,
        .dynamic_burst = false,
        .has_slavemode = false,
        .devtype = IMX27_CSPI,
};

static struct spi_imx_devtype_data imx31_cspi_devtype_data = {
        .intctrl = mx31_intctrl,
        .prepare_message = mx31_prepare_message,
        .prepare_transfer = mx31_prepare_transfer,
        .trigger = mx31_trigger,
        .rx_available = mx31_rx_available,
        .reset = mx31_reset,
        .fifo_size = 8,
        .has_dmamode = false,
        .dynamic_burst = false,
        .has_slavemode = false,
        .devtype = IMX31_CSPI,
};

static struct spi_imx_devtype_data imx35_cspi_devtype_data = {
        /* i.mx35 and later cspi shares the functions with i.mx31 one */

        .intctrl = mx31_intctrl,
        .prepare_message = mx31_prepare_message,
        .prepare_transfer = mx31_prepare_transfer,
        .trigger = mx31_trigger,
        .rx_available = mx31_rx_available,
        .reset = mx31_reset,
        .fifo_size = 8,
        .has_dmamode = true,
        .dynamic_burst = false,
        .has_slavemode = false,
        .devtype = IMX35_CSPI,
};

static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
        .intctrl = mx51_ecspi_intctrl,
        .prepare_message = mx51_ecspi_prepare_message,
        .prepare_transfer = mx51_ecspi_prepare_transfer,
        .trigger = mx51_ecspi_trigger,
        .rx_available = mx51_ecspi_rx_available,
        .reset = mx51_ecspi_reset,
        .setup_wml = mx51_setup_wml,
        .disable_dma = mx51_disable_dma,
        .fifo_size = 64,
        .has_dmamode = true,
        .dynamic_burst = true,
        .has_slavemode = true,
        .disable = mx51_ecspi_disable,
        .devtype = IMX51_ECSPI,
};

static struct spi_imx_devtype_data imx53_ecspi_devtype_data = {
        .intctrl = mx51_ecspi_intctrl,
        .prepare_message = mx51_ecspi_prepare_message,
        .prepare_transfer = mx51_ecspi_prepare_transfer,
        .trigger = mx51_ecspi_trigger,
        .rx_available = mx51_ecspi_rx_available,
        .disable_dma = mx51_disable_dma,
        .reset = mx51_ecspi_reset,
        .fifo_size = 64,
        .has_dmamode = true,
        .has_slavemode = true,
        .disable = mx51_ecspi_disable,
        .devtype = IMX53_ECSPI,
};

static struct spi_imx_devtype_data imx6ul_ecspi_devtype_data = {
        .intctrl = mx51_ecspi_intctrl,
        .prepare_message = mx51_ecspi_prepare_message,
        .prepare_transfer = mx51_ecspi_prepare_transfer,
        .trigger = mx51_ecspi_trigger,
        .rx_available = mx51_ecspi_rx_available,
        .reset = mx51_ecspi_reset,
        .setup_wml = mx51_setup_wml,
        .fifo_size = 64,
        .has_dmamode = true,
        .dynamic_burst = true,
        .has_slavemode = true,
        .tx_glitch_fixed = true,
        .disable = mx51_ecspi_disable,
        .devtype = IMX51_ECSPI,
};

static const struct of_device_id spi_imx_dt_ids[] = {
        { .compatible = "fsl,imx1-cspi", .data = &imx1_cspi_devtype_data, },
        { .compatible = "fsl,imx21-cspi", .data = &imx21_cspi_devtype_data, },
        { .compatible = "fsl,imx27-cspi", .data = &imx27_cspi_devtype_data, },
        { .compatible = "fsl,imx31-cspi", .data = &imx31_cspi_devtype_data, },
        { .compatible = "fsl,imx35-cspi", .data = &imx35_cspi_devtype_data, },
        { .compatible = "fsl,imx51-ecspi", .data = &imx51_ecspi_devtype_data, },
        { .compatible = "fsl,imx53-ecspi", .data = &imx53_ecspi_devtype_data, },
        { .compatible = "fsl,imx6ul-ecspi", .data = &imx6ul_ecspi_devtype_data, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, spi_imx_dt_ids);

static void spi_imx_set_burst_len(struct spi_imx_data *spi_imx, int n_bits)
{
        u32 ctrl;

        ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
        ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
        ctrl |= ((n_bits - 1) << MX51_ECSPI_CTRL_BL_OFFSET);
        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
}

static void spi_imx_push(struct spi_imx_data *spi_imx)
{
        unsigned int burst_len;

        /*
         * Reload the FIFO when the remaining bytes to be transferred in the
         * current burst is 0. This only applies when bits_per_word is a
         * multiple of 8.
         */
        if (!spi_imx->remainder) {
                if (spi_imx->dynamic_burst) {

                        /* We need to deal unaligned data first */
                        burst_len = spi_imx->count % MX51_ECSPI_CTRL_MAX_BURST;

                        if (!burst_len)
                                burst_len = MX51_ECSPI_CTRL_MAX_BURST;

                        spi_imx_set_burst_len(spi_imx, burst_len * 8);

                        spi_imx->remainder = burst_len;
                } else {
                        spi_imx->remainder = spi_imx_bytes_per_word(spi_imx->bits_per_word);
                }
        }

        while (spi_imx->txfifo < spi_imx->devtype_data->fifo_size) {
                if (!spi_imx->count)
                        break;
                if (spi_imx->dynamic_burst &&
                    spi_imx->txfifo >= DIV_ROUND_UP(spi_imx->remainder, 4))
                        break;
                spi_imx->tx(spi_imx);
                spi_imx->txfifo++;
        }

        if (!spi_imx->slave_mode)
                spi_imx->devtype_data->trigger(spi_imx);
}

static irqreturn_t spi_imx_isr(int irq, void *dev_id)
{
        struct spi_imx_data *spi_imx = dev_id;

        while (spi_imx->txfifo &&
               spi_imx->devtype_data->rx_available(spi_imx)) {
                spi_imx->rx(spi_imx);
                spi_imx->txfifo--;
        }

        if (spi_imx->count) {
                spi_imx_push(spi_imx);
                return IRQ_HANDLED;
        }

        if (spi_imx->txfifo) {
                /* No data left to push, but still waiting for rx data,
                 * enable receive data available interrupt.
                 */
                spi_imx->devtype_data->intctrl(
                                spi_imx, MXC_INT_RR);
                return IRQ_HANDLED;
        }

        spi_imx->devtype_data->intctrl(spi_imx, 0);
        complete(&spi_imx->xfer_done);

        return IRQ_HANDLED;
}

static int spi_imx_dma_configure(struct spi_master *master)
{
        int ret;
        enum dma_slave_buswidth buswidth;
        struct dma_slave_config rx = {}, tx = {};
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);

        switch (spi_imx_bytes_per_word(spi_imx->bits_per_word)) {
        case 4:
                buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
                break;
        case 2:
                buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
                break;
        case 1:
                buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
                break;
        default:
                return -EINVAL;
        }

        tx.direction = DMA_MEM_TO_DEV;
        tx.dst_addr = spi_imx->base_phys + MXC_CSPITXDATA;
        tx.dst_addr_width = buswidth;
        tx.dst_maxburst = spi_imx->wml;
        ret = dmaengine_slave_config(master->dma_tx, &tx);
        if (ret) {
                dev_err(spi_imx->dev, "TX dma configuration failed with %d\n", ret);
                return ret;
        }

        rx.direction = DMA_DEV_TO_MEM;
        rx.src_addr = spi_imx->base_phys + MXC_CSPIRXDATA;
        rx.src_addr_width = buswidth;
        rx.src_maxburst = spi_imx->wml;
        ret = dmaengine_slave_config(master->dma_rx, &rx);
        if (ret) {
                dev_err(spi_imx->dev, "RX dma configuration failed with %d\n", ret);
                return ret;
        }

        return 0;
}

static int spi_imx_setupxfer(struct spi_device *spi,
                                 struct spi_transfer *t)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);

        if (!t)
                return 0;

        if (!t->speed_hz) {
                if (!spi->max_speed_hz) {
                        dev_err(&spi->dev, "no speed_hz provided!\n");
                        return -EINVAL;
                }
                dev_dbg(&spi->dev, "using spi->max_speed_hz!\n");
                spi_imx->spi_bus_clk = spi->max_speed_hz;
        } else
                spi_imx->spi_bus_clk = t->speed_hz;

        spi_imx->bits_per_word = t->bits_per_word;

        /*
         * Initialize the functions for transfer. To transfer non byte-aligned
         * words, we have to use multiple word-size bursts, we can't use
         * dynamic_burst in that case.
         */
        if (spi_imx->devtype_data->dynamic_burst && !spi_imx->slave_mode &&
            !(spi->mode & SPI_CS_WORD) &&
            (spi_imx->bits_per_word == 8 ||
            spi_imx->bits_per_word == 16 ||
            spi_imx->bits_per_word == 32)) {

                spi_imx->rx = spi_imx_buf_rx_swap;
                spi_imx->tx = spi_imx_buf_tx_swap;
                spi_imx->dynamic_burst = 1;

        } else {
                if (spi_imx->bits_per_word <= 8) {
                        spi_imx->rx = spi_imx_buf_rx_u8;
                        spi_imx->tx = spi_imx_buf_tx_u8;
                } else if (spi_imx->bits_per_word <= 16) {
                        spi_imx->rx = spi_imx_buf_rx_u16;
                        spi_imx->tx = spi_imx_buf_tx_u16;
                } else {
                        spi_imx->rx = spi_imx_buf_rx_u32;
                        spi_imx->tx = spi_imx_buf_tx_u32;
                }
                spi_imx->dynamic_burst = 0;
        }

        if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
                spi_imx->usedma = true;
        else
                spi_imx->usedma = false;

        if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode) {
                spi_imx->rx = mx53_ecspi_rx_slave;
                spi_imx->tx = mx53_ecspi_tx_slave;
                spi_imx->slave_burst = t->len;
        }

        spi_imx->devtype_data->prepare_transfer(spi_imx, spi);

        return 0;
}

static void spi_imx_sdma_exit(struct spi_imx_data *spi_imx)
{
        struct spi_master *master = spi_imx->bitbang.master;

        if (master->dma_rx) {
                dma_release_channel(master->dma_rx);
                master->dma_rx = NULL;
        }

        if (master->dma_tx) {
                dma_release_channel(master->dma_tx);
                master->dma_tx = NULL;
        }
}

static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
                             struct spi_master *master)
{
        int ret;

        spi_imx->wml = spi_imx->devtype_data->fifo_size / 2;

        /* Prepare for TX DMA: */
        master->dma_tx = dma_request_chan(dev, "tx");
        if (IS_ERR(master->dma_tx)) {
                ret = PTR_ERR(master->dma_tx);
                dev_dbg(dev, "can't get the TX DMA channel, error %d!\n", ret);
                master->dma_tx = NULL;
                goto err;
        }

        /* Prepare for RX : */
        master->dma_rx = dma_request_chan(dev, "rx");
        if (IS_ERR(master->dma_rx)) {
                ret = PTR_ERR(master->dma_rx);
                dev_dbg(dev, "can't get the RX DMA channel, error %d\n", ret);
                master->dma_rx = NULL;
                goto err;
        }

        init_completion(&spi_imx->dma_rx_completion);
        init_completion(&spi_imx->dma_tx_completion);
        master->can_dma = spi_imx_can_dma;
        master->max_dma_len = MAX_SDMA_BD_BYTES;
        spi_imx->bitbang.master->flags = SPI_MASTER_MUST_RX |
                                         SPI_MASTER_MUST_TX;

        return 0;
err:
        spi_imx_sdma_exit(spi_imx);
        return ret;
}

static void spi_imx_dma_rx_callback(void *cookie)
{
        struct spi_imx_data *spi_imx = (struct spi_imx_data *)cookie;

        complete(&spi_imx->dma_rx_completion);
}

static void spi_imx_dma_tx_callback(void *cookie)
{
        struct spi_imx_data *spi_imx = (struct spi_imx_data *)cookie;

        complete(&spi_imx->dma_tx_completion);
}

static int spi_imx_calculate_timeout(struct spi_imx_data *spi_imx, int size)
{
        unsigned long timeout = 0;

        /* Time with actual data transfer and CS change delay related to HW */
        timeout = (8 + 4) * size / spi_imx->spi_bus_clk;

        /* Add extra second for scheduler related activities */
        timeout += 1;

        /* Double calculated timeout */
        return msecs_to_jiffies(2 * timeout * MSEC_PER_SEC);
}

static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
                                struct spi_transfer *transfer)
{
        struct dma_async_tx_descriptor *desc_tx, *desc_rx;
        unsigned long transfer_timeout;
        unsigned long timeout;
        struct spi_master *master = spi_imx->bitbang.master;
        struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;
        struct scatterlist *last_sg = sg_last(rx->sgl, rx->nents);
        unsigned int bytes_per_word, i;
        int ret;

        /* Get the right burst length from the last sg to ensure no tail data */
        bytes_per_word = spi_imx_bytes_per_word(transfer->bits_per_word);
        for (i = spi_imx->devtype_data->fifo_size / 2; i > 0; i--) {
                if (!(sg_dma_len(last_sg) % (i * bytes_per_word)))
                        break;
        }
        /* Use 1 as wml in case no available burst length got */
        if (i == 0)
                i = 1;

        spi_imx->wml =  i;

        ret = spi_imx_dma_configure(master);
        if (ret)
                goto dma_failure_no_start;

        if (!spi_imx->devtype_data->setup_wml) {
                dev_err(spi_imx->dev, "No setup_wml()?\n");
                ret = -EINVAL;
                goto dma_failure_no_start;
        }
        spi_imx->devtype_data->setup_wml(spi_imx);

        /*
         * The TX DMA setup starts the transfer, so make sure RX is configured
         * before TX.
         */
        desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
                                rx->sgl, rx->nents, DMA_DEV_TO_MEM,
                                DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!desc_rx) {
                ret = -EINVAL;
                goto dma_failure_no_start;
        }

        desc_rx->callback = spi_imx_dma_rx_callback;
        desc_rx->callback_param = (void *)spi_imx;
        dmaengine_submit(desc_rx);
        reinit_completion(&spi_imx->dma_rx_completion);
        dma_async_issue_pending(master->dma_rx);

        desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
                                tx->sgl, tx->nents, DMA_MEM_TO_DEV,
                                DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!desc_tx) {
                dmaengine_terminate_all(master->dma_tx);
                dmaengine_terminate_all(master->dma_rx);
                return -EINVAL;
        }

        desc_tx->callback = spi_imx_dma_tx_callback;
        desc_tx->callback_param = (void *)spi_imx;
        dmaengine_submit(desc_tx);
        reinit_completion(&spi_imx->dma_tx_completion);
        dma_async_issue_pending(master->dma_tx);

        transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);

        /* Wait SDMA to finish the data transfer.*/
        timeout = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
                                                transfer_timeout);
        if (!timeout) {
                dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
                dmaengine_terminate_all(master->dma_tx);
                dmaengine_terminate_all(master->dma_rx);
                return -ETIMEDOUT;
        }

        timeout = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
                                              transfer_timeout);
        if (!timeout) {
                dev_err(&master->dev, "I/O Error in DMA RX\n");
                spi_imx->devtype_data->reset(spi_imx);
                dmaengine_terminate_all(master->dma_rx);
                return -ETIMEDOUT;
        }

        return transfer->len;
/* fallback to pio */
dma_failure_no_start:
        transfer->error |= SPI_TRANS_FAIL_NO_START;
        return ret;
}

static int spi_imx_pio_transfer(struct spi_device *spi,
                                struct spi_transfer *transfer)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
        unsigned long transfer_timeout;
        unsigned long timeout;

        spi_imx->tx_buf = transfer->tx_buf;
        spi_imx->rx_buf = transfer->rx_buf;
        spi_imx->count = transfer->len;
        spi_imx->txfifo = 0;
        spi_imx->remainder = 0;

        reinit_completion(&spi_imx->xfer_done);

        spi_imx_push(spi_imx);

        spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE);

        transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);

        timeout = wait_for_completion_timeout(&spi_imx->xfer_done,
                                              transfer_timeout);
        if (!timeout) {
                dev_err(&spi->dev, "I/O Error in PIO\n");
                spi_imx->devtype_data->reset(spi_imx);
                return -ETIMEDOUT;
        }

        return transfer->len;
}

static int spi_imx_pio_transfer_slave(struct spi_device *spi,
                                      struct spi_transfer *transfer)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
        int ret = transfer->len;

        if (is_imx53_ecspi(spi_imx) &&
            transfer->len > MX53_MAX_TRANSFER_BYTES) {
                dev_err(&spi->dev, "Transaction too big, max size is %d bytes\n",
                        MX53_MAX_TRANSFER_BYTES);
                return -EMSGSIZE;
        }

        spi_imx->tx_buf = transfer->tx_buf;
        spi_imx->rx_buf = transfer->rx_buf;
        spi_imx->count = transfer->len;
        spi_imx->txfifo = 0;
        spi_imx->remainder = 0;

        reinit_completion(&spi_imx->xfer_done);
        spi_imx->slave_aborted = false;

        spi_imx_push(spi_imx);

        spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE | MXC_INT_RDR);

        if (wait_for_completion_interruptible(&spi_imx->xfer_done) ||
            spi_imx->slave_aborted) {
                dev_dbg(&spi->dev, "interrupted\n");
                ret = -EINTR;
        }

        /* ecspi has a HW issue when works in Slave mode,
         * after 64 words writtern to TXFIFO, even TXFIFO becomes empty,
         * ECSPI_TXDATA keeps shift out the last word data,
         * so we have to disable ECSPI when in slave mode after the
         * transfer completes
         */
        if (spi_imx->devtype_data->disable)
                spi_imx->devtype_data->disable(spi_imx);

        return ret;
}

static int spi_imx_transfer(struct spi_device *spi,
                                struct spi_transfer *transfer)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);

        transfer->effective_speed_hz = spi_imx->spi_bus_clk;

        /* flush rxfifo before transfer */
        while (spi_imx->devtype_data->rx_available(spi_imx))
                readl(spi_imx->base + MXC_CSPIRXDATA);

        if (spi_imx->slave_mode)
                return spi_imx_pio_transfer_slave(spi, transfer);

        if (spi_imx->usedma)
                return spi_imx_dma_transfer(spi_imx, transfer);

        return spi_imx_pio_transfer(spi, transfer);
}

static int spi_imx_setup(struct spi_device *spi)
{
        dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n", __func__,
                 spi->mode, spi->bits_per_word, spi->max_speed_hz);

        return 0;
}

static void spi_imx_cleanup(struct spi_device *spi)
{
}

static int
spi_imx_prepare_message(struct spi_master *master, struct spi_message *msg)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
        int ret;

        ret = pm_runtime_get_sync(spi_imx->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(spi_imx->dev);
                dev_err(spi_imx->dev, "failed to enable clock\n");
                return ret;
        }

        ret = spi_imx->devtype_data->prepare_message(spi_imx, msg);
        if (ret) {
                pm_runtime_mark_last_busy(spi_imx->dev);
                pm_runtime_put_autosuspend(spi_imx->dev);
        }

        return ret;
}

static int
spi_imx_unprepare_message(struct spi_master *master, struct spi_message *msg)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);

        pm_runtime_mark_last_busy(spi_imx->dev);
        pm_runtime_put_autosuspend(spi_imx->dev);
        return 0;
}

static int spi_imx_slave_abort(struct spi_master *master)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);

        spi_imx->slave_aborted = true;
        complete(&spi_imx->xfer_done);

        return 0;
}

static int spi_imx_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct spi_master *master;
        struct spi_imx_data *spi_imx;
        struct resource *res;
        int ret, irq, spi_drctl;
        const struct spi_imx_devtype_data *devtype_data =
                        of_device_get_match_data(&pdev->dev);
        bool slave_mode;
        u32 val;

        slave_mode = devtype_data->has_slavemode &&
                        of_property_read_bool(np, "spi-slave");
        if (slave_mode)
                master = spi_alloc_slave(&pdev->dev,
                                         sizeof(struct spi_imx_data));
        else
                master = spi_alloc_master(&pdev->dev,
                                          sizeof(struct spi_imx_data));
        if (!master)
                return -ENOMEM;

        ret = of_property_read_u32(np, "fsl,spi-rdy-drctl", &spi_drctl);
        if ((ret < 0) || (spi_drctl >= 0x3)) {
                /* '11' is reserved */
                spi_drctl = 0;
        }

        platform_set_drvdata(pdev, master);

        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
        master->bus_num = np ? -1 : pdev->id;
        master->use_gpio_descriptors = true;

        spi_imx = spi_master_get_devdata(master);
        spi_imx->bitbang.master = master;
        spi_imx->dev = &pdev->dev;
        spi_imx->slave_mode = slave_mode;

        spi_imx->devtype_data = devtype_data;

        /*
         * Get number of chip selects from device properties. This can be
         * coming from device tree or boardfiles, if it is not defined,
         * a default value of 3 chip selects will be used, as all the legacy
         * board files have <= 3 chip selects.
         */
        if (!device_property_read_u32(&pdev->dev, "num-cs", &val))
                master->num_chipselect = val;
        else
                master->num_chipselect = 3;

        spi_imx->bitbang.setup_transfer = spi_imx_setupxfer;
        spi_imx->bitbang.txrx_bufs = spi_imx_transfer;
        spi_imx->bitbang.master->setup = spi_imx_setup;
        spi_imx->bitbang.master->cleanup = spi_imx_cleanup;
        spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
        spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
        spi_imx->bitbang.master->slave_abort = spi_imx_slave_abort;
        spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
                                             | SPI_NO_CS;
        if (is_imx35_cspi(spi_imx) || is_imx51_ecspi(spi_imx) ||
            is_imx53_ecspi(spi_imx))
                spi_imx->bitbang.master->mode_bits |= SPI_LOOP | SPI_READY;

        if (is_imx51_ecspi(spi_imx) &&
            device_property_read_u32(&pdev->dev, "cs-gpios", NULL))
                /*
                 * When using HW-CS implementing SPI_CS_WORD can be done by just
                 * setting the burst length to the word size. This is
                 * considerably faster than manually controlling the CS.
                 */
                spi_imx->bitbang.master->mode_bits |= SPI_CS_WORD;

        spi_imx->spi_drctl = spi_drctl;

        init_completion(&spi_imx->xfer_done);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        spi_imx->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(spi_imx->base)) {
                ret = PTR_ERR(spi_imx->base);
                goto out_master_put;
        }
        spi_imx->base_phys = res->start;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                ret = irq;
                goto out_master_put;
        }

        ret = devm_request_irq(&pdev->dev, irq, spi_imx_isr, 0,
                               dev_name(&pdev->dev), spi_imx);
        if (ret) {
                dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
                goto out_master_put;
        }

        spi_imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
        if (IS_ERR(spi_imx->clk_ipg)) {
                ret = PTR_ERR(spi_imx->clk_ipg);
                goto out_master_put;
        }

        spi_imx->clk_per = devm_clk_get(&pdev->dev, "per");
        if (IS_ERR(spi_imx->clk_per)) {
                ret = PTR_ERR(spi_imx->clk_per);
                goto out_master_put;
        }

        ret = clk_prepare_enable(spi_imx->clk_per);
        if (ret)
                goto out_master_put;

        ret = clk_prepare_enable(spi_imx->clk_ipg);
        if (ret)
                goto out_put_per;

        pm_runtime_set_autosuspend_delay(spi_imx->dev, MXC_RPM_TIMEOUT);
        pm_runtime_use_autosuspend(spi_imx->dev);
        pm_runtime_get_noresume(spi_imx->dev);
        pm_runtime_set_active(spi_imx->dev);
        pm_runtime_enable(spi_imx->dev);

        spi_imx->spi_clk = clk_get_rate(spi_imx->clk_per);
        /*
         * Only validated on i.mx35 and i.mx6 now, can remove the constraint
         * if validated on other chips.
         */
        if (spi_imx->devtype_data->has_dmamode) {
                ret = spi_imx_sdma_init(&pdev->dev, spi_imx, master);
                if (ret == -EPROBE_DEFER)
                        goto out_runtime_pm_put;

                if (ret < 0)
                        dev_dbg(&pdev->dev, "dma setup error %d, use pio\n",
                                ret);
        }

        spi_imx->devtype_data->reset(spi_imx);

        spi_imx->devtype_data->intctrl(spi_imx, 0);

        master->dev.of_node = pdev->dev.of_node;
        ret = spi_bitbang_start(&spi_imx->bitbang);
        if (ret) {
                dev_err_probe(&pdev->dev, ret, "bitbang start failed\n");
                goto out_bitbang_start;
        }

        pm_runtime_mark_last_busy(spi_imx->dev);
        pm_runtime_put_autosuspend(spi_imx->dev);

        return ret;

out_bitbang_start:
        if (spi_imx->devtype_data->has_dmamode)
                spi_imx_sdma_exit(spi_imx);
out_runtime_pm_put:
        pm_runtime_dont_use_autosuspend(spi_imx->dev);
        pm_runtime_set_suspended(&pdev->dev);
        pm_runtime_disable(spi_imx->dev);

        clk_disable_unprepare(spi_imx->clk_ipg);
out_put_per:
        clk_disable_unprepare(spi_imx->clk_per);
out_master_put:
        spi_master_put(master);

        return ret;
}

static int spi_imx_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
        int ret;

        spi_bitbang_stop(&spi_imx->bitbang);

        ret = pm_runtime_get_sync(spi_imx->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(spi_imx->dev);
                dev_err(spi_imx->dev, "failed to enable clock\n");
                return ret;
        }

        writel(0, spi_imx->base + MXC_CSPICTRL);

        pm_runtime_dont_use_autosuspend(spi_imx->dev);
        pm_runtime_put_sync(spi_imx->dev);
        pm_runtime_disable(spi_imx->dev);

        spi_imx_sdma_exit(spi_imx);
        spi_master_put(master);

        return 0;
}

static int __maybe_unused spi_imx_runtime_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct spi_imx_data *spi_imx;
        int ret;

        spi_imx = spi_master_get_devdata(master);

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

        ret = clk_prepare_enable(spi_imx->clk_ipg);
        if (ret) {
                clk_disable_unprepare(spi_imx->clk_per);
                return ret;
        }

        return 0;
}

static int __maybe_unused spi_imx_runtime_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct spi_imx_data *spi_imx;

        spi_imx = spi_master_get_devdata(master);

        clk_disable_unprepare(spi_imx->clk_per);
        clk_disable_unprepare(spi_imx->clk_ipg);

        return 0;
}

static int __maybe_unused spi_imx_suspend(struct device *dev)
{
        pinctrl_pm_select_sleep_state(dev);
        return 0;
}

static int __maybe_unused spi_imx_resume(struct device *dev)
{
        pinctrl_pm_select_default_state(dev);
        return 0;
}

static const struct dev_pm_ops imx_spi_pm = {
        SET_RUNTIME_PM_OPS(spi_imx_runtime_suspend,
                                spi_imx_runtime_resume, NULL)
        SET_SYSTEM_SLEEP_PM_OPS(spi_imx_suspend, spi_imx_resume)
};

static struct platform_driver spi_imx_driver = {
        .driver = {
                   .name = DRIVER_NAME,
                   .of_match_table = spi_imx_dt_ids,
                   .pm = &imx_spi_pm,
        },
        .probe = spi_imx_probe,
        .remove = spi_imx_remove,
};
module_platform_driver(spi_imx_driver);

MODULE_DESCRIPTION("i.MX SPI Controller driver");
MODULE_AUTHOR("Sascha Hauer, Pengutronix");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);