/*
 * Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright (C) 2008 Juergen Beisert
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the
 * Free Software Foundation
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301, USA.
 */

#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/gpio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.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/of_gpio.h>

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

#define DRIVER_NAME "spi_imx"

#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 */

/* The maximum  bytes that a sdma BD can transfer.*/
#define MAX_SDMA_BD_BYTES  (1 << 15)
#define IMX_DMA_TIMEOUT (msecs_to_jiffies(3000))
struct spi_imx_config {
        unsigned int speed_hz;
        unsigned int bpw;
        unsigned int mode;
        u8 cs;
};

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 and later */
};

struct spi_imx_data;

struct spi_imx_devtype_data {
        void (*intctrl)(struct spi_imx_data *, int);
        int (*config)(struct spi_imx_data *, struct spi_imx_config *);
        void (*trigger)(struct spi_imx_data *);
        int (*rx_available)(struct spi_imx_data *);
        void (*reset)(struct spi_imx_data *);
        enum spi_imx_devtype devtype;
};

struct spi_imx_data {
        struct spi_bitbang bitbang;

        struct completion xfer_done;
        void __iomem *base;
        struct clk *clk_per;
        struct clk *clk_ipg;
        unsigned long spi_clk;

        unsigned int count;
        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 */

        /* DMA */
        unsigned int dma_is_inited;
        unsigned int dma_finished;
        bool usedma;
        u32 wml;
        struct completion dma_rx_completion;
        struct completion dma_tx_completion;

        const struct spi_imx_devtype_data *devtype_data;
        int chipselect[0];
};

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 unsigned spi_imx_get_fifosize(struct spi_imx_data *d)
{
        return is_imx51_ecspi(d) ? 64 : 8;
}

#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);                        \
        }                                                               \
}

#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)
{
        int i;

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

        return max;
}

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

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

        return 7;
}

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 (spi_imx->dma_is_inited && transfer->len >= spi_imx->wml &&
            (transfer->len % spi_imx->wml) == 0)
                return true;
        return false;
}

#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_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_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_DMA      0x14
#define MX51_ECSPI_DMA_TX_WML_OFFSET    0
#define MX51_ECSPI_DMA_TX_WML_MASK      0x3F
#define MX51_ECSPI_DMA_RX_WML_OFFSET    16
#define MX51_ECSPI_DMA_RX_WML_MASK      (0x3F << 16)
#define MX51_ECSPI_DMA_RXT_WML_OFFSET   24
#define MX51_ECSPI_DMA_RXT_WML_MASK     (0x3F << 24)

#define MX51_ECSPI_DMA_TEDEN_OFFSET     7
#define MX51_ECSPI_DMA_RXDEN_OFFSET     23
#define MX51_ECSPI_DMA_RXTDEN_OFFSET    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)

/* MX51 eCSPI */
static unsigned int mx51_ecspi_clkdiv(unsigned int fin, 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;

        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)) {
                pr_err("%s: cannot set clock freq: %u (base freq: %u)\n",
                                __func__, fspi, fin);
                return 0xff;
        }

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

        pr_debug("%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 __maybe_unused 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;

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

static void __maybe_unused mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
{
        u32 reg = readl(spi_imx->base + MX51_ECSPI_CTRL);

        if (!spi_imx->usedma)
                reg |= MX51_ECSPI_CTRL_XCH;
        else if (!spi_imx->dma_finished)
                reg |= MX51_ECSPI_CTRL_SMC;
        else
                reg &= ~MX51_ECSPI_CTRL_SMC;
        writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
}

static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
                struct spi_imx_config *config)
{
        u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0;
        u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg;
        u32 clk = config->speed_hz, delay, reg;

        /*
         * The hardware seems to have a race condition when changing modes. The
         * current assumption is that the selection of the channel arrives
         * earlier in the hardware than the mode bits when they are written at
         * the same time.
         * So set master mode for all channels as we do not support slave mode.
         */
        ctrl |= MX51_ECSPI_CTRL_MODE_MASK;

        /* set clock speed */
        ctrl |= mx51_ecspi_clkdiv(spi_imx->spi_clk, config->speed_hz, &clk);

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

        ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;

        cfg |= MX51_ECSPI_CONFIG_SBBCTRL(config->cs);

        if (config->mode & SPI_CPHA)
                cfg |= MX51_ECSPI_CONFIG_SCLKPHA(config->cs);
        else
                cfg &= ~MX51_ECSPI_CONFIG_SCLKPHA(config->cs);

        if (config->mode & SPI_CPOL) {
                cfg |= MX51_ECSPI_CONFIG_SCLKPOL(config->cs);
                cfg |= MX51_ECSPI_CONFIG_SCLKCTL(config->cs);
        } else {
                cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(config->cs);
                cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(config->cs);
        }
        if (config->mode & SPI_CS_HIGH)
                cfg |= MX51_ECSPI_CONFIG_SSBPOL(config->cs);
        else
                cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(config->cs);

        /* CTRL register always go first to bring out controller from reset */
        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);

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

        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.
         */
        delay = (2 * 1000000) / clk;
        if (likely(delay < 10)) /* SCLK is faster than 100 kHz */
                udelay(delay);
        else                    /* SCLK is _very_ slow */
                usleep_range(delay, delay + 10);

        /*
         * Configure the DMA register: setup the watermark
         * and enable DMA request.
         */
        if (spi_imx->dma_is_inited) {
                dma = readl(spi_imx->base + MX51_ECSPI_DMA);

                rx_wml_cfg = spi_imx->wml << MX51_ECSPI_DMA_RX_WML_OFFSET;
                tx_wml_cfg = spi_imx->wml << MX51_ECSPI_DMA_TX_WML_OFFSET;
                rxt_wml_cfg = spi_imx->wml << MX51_ECSPI_DMA_RXT_WML_OFFSET;
                dma = (dma & ~MX51_ECSPI_DMA_TX_WML_MASK
                           & ~MX51_ECSPI_DMA_RX_WML_MASK
                           & ~MX51_ECSPI_DMA_RXT_WML_MASK)
                           | rx_wml_cfg | tx_wml_cfg | rxt_wml_cfg
                           |(1 << MX51_ECSPI_DMA_TEDEN_OFFSET)
                           |(1 << MX51_ECSPI_DMA_RXDEN_OFFSET)
                           |(1 << MX51_ECSPI_DMA_RXTDEN_OFFSET);

                writel(dma, spi_imx->base + MX51_ECSPI_DMA);
        }

        return 0;
}

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

static void __maybe_unused 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_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_CSPISTATUS         0x14
#define MX31_STATUS_RR          (1 << 3)

/* 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 __maybe_unused 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 __maybe_unused 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 __maybe_unused mx31_config(struct spi_imx_data *spi_imx,
                struct spi_imx_config *config)
{
        unsigned int reg = MX31_CSPICTRL_ENABLE | MX31_CSPICTRL_MASTER;
        int cs = spi_imx->chipselect[config->cs];

        reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz) <<
                MX31_CSPICTRL_DR_SHIFT;

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

        if (config->mode & SPI_CPHA)
                reg |= MX31_CSPICTRL_PHA;
        if (config->mode & SPI_CPOL)
                reg |= MX31_CSPICTRL_POL;
        if (config->mode & SPI_CS_HIGH)
                reg |= MX31_CSPICTRL_SSPOL;
        if (cs < 0)
                reg |= (cs + 32) <<
                        (is_imx35_cspi(spi_imx) ? MX35_CSPICTRL_CS_SHIFT :
                                                  MX31_CSPICTRL_CS_SHIFT);

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

        return 0;
}

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

static void __maybe_unused 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 __maybe_unused 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 __maybe_unused 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 __maybe_unused mx21_config(struct spi_imx_data *spi_imx,
                struct spi_imx_config *config)
{
        unsigned int reg = MX21_CSPICTRL_ENABLE | MX21_CSPICTRL_MASTER;
        int cs = spi_imx->chipselect[config->cs];
        unsigned int max = is_imx27_cspi(spi_imx) ? 16 : 18;

        reg |= spi_imx_clkdiv_1(spi_imx->spi_clk, config->speed_hz, max) <<
                MX21_CSPICTRL_DR_SHIFT;
        reg |= config->bpw - 1;

        if (config->mode & SPI_CPHA)
                reg |= MX21_CSPICTRL_PHA;
        if (config->mode & SPI_CPOL)
                reg |= MX21_CSPICTRL_POL;
        if (config->mode & SPI_CS_HIGH)
                reg |= MX21_CSPICTRL_SSPOL;
        if (cs < 0)
                reg |= (cs + 32) << MX21_CSPICTRL_CS_SHIFT;

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

        return 0;
}

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

static void __maybe_unused 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 __maybe_unused 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 __maybe_unused 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 __maybe_unused mx1_config(struct spi_imx_data *spi_imx,
                struct spi_imx_config *config)
{
        unsigned int reg = MX1_CSPICTRL_ENABLE | MX1_CSPICTRL_MASTER;

        reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz) <<
                MX1_CSPICTRL_DR_SHIFT;
        reg |= config->bpw - 1;

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

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

        return 0;
}

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

static void __maybe_unused 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,
        .config = mx1_config,
        .trigger = mx1_trigger,
        .rx_available = mx1_rx_available,
        .reset = mx1_reset,
        .devtype = IMX1_CSPI,
};

static struct spi_imx_devtype_data imx21_cspi_devtype_data = {
        .intctrl = mx21_intctrl,
        .config = mx21_config,
        .trigger = mx21_trigger,
        .rx_available = mx21_rx_available,
        .reset = mx21_reset,
        .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,
        .config = mx21_config,
        .trigger = mx21_trigger,
        .rx_available = mx21_rx_available,
        .reset = mx21_reset,
        .devtype = IMX27_CSPI,
};

static struct spi_imx_devtype_data imx31_cspi_devtype_data = {
        .intctrl = mx31_intctrl,
        .config = mx31_config,
        .trigger = mx31_trigger,
        .rx_available = mx31_rx_available,
        .reset = mx31_reset,
        .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,
        .config = mx31_config,
        .trigger = mx31_trigger,
        .rx_available = mx31_rx_available,
        .reset = mx31_reset,
        .devtype = IMX35_CSPI,
};

static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
        .intctrl = mx51_ecspi_intctrl,
        .config = mx51_ecspi_config,
        .trigger = mx51_ecspi_trigger,
        .rx_available = mx51_ecspi_rx_available,
        .reset = mx51_ecspi_reset,
        .devtype = IMX51_ECSPI,
};

static const struct platform_device_id spi_imx_devtype[] = {
        {
                .name = "imx1-cspi",
                .driver_data = (kernel_ulong_t) &imx1_cspi_devtype_data,
        }, {
                .name = "imx21-cspi",
                .driver_data = (kernel_ulong_t) &imx21_cspi_devtype_data,
        }, {
                .name = "imx27-cspi",
                .driver_data = (kernel_ulong_t) &imx27_cspi_devtype_data,
        }, {
                .name = "imx31-cspi",
                .driver_data = (kernel_ulong_t) &imx31_cspi_devtype_data,
        }, {
                .name = "imx35-cspi",
                .driver_data = (kernel_ulong_t) &imx35_cspi_devtype_data,
        }, {
                .name = "imx51-ecspi",
                .driver_data = (kernel_ulong_t) &imx51_ecspi_devtype_data,
        }, {
                /* sentinel */
        }
};

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, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, spi_imx_dt_ids);

static void spi_imx_chipselect(struct spi_device *spi, int is_active)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
        int gpio = spi_imx->chipselect[spi->chip_select];
        int active = is_active != BITBANG_CS_INACTIVE;
        int dev_is_lowactive = !(spi->mode & SPI_CS_HIGH);

        if (!gpio_is_valid(gpio))
                return;

        gpio_set_value(gpio, dev_is_lowactive ^ active);
}

static void spi_imx_push(struct spi_imx_data *spi_imx)
{
        while (spi_imx->txfifo < spi_imx_get_fifosize(spi_imx)) {
                if (!spi_imx->count)
                        break;
                spi_imx->tx(spi_imx);
                spi_imx->txfifo++;
        }

        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->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_setupxfer(struct spi_device *spi,
                                 struct spi_transfer *t)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
        struct spi_imx_config config;

        config.bpw = t ? t->bits_per_word : spi->bits_per_word;
        config.speed_hz  = t ? t->speed_hz : spi->max_speed_hz;
        config.mode = spi->mode;
        config.cs = spi->chip_select;

        if (!config.speed_hz)
                config.speed_hz = spi->max_speed_hz;
        if (!config.bpw)
                config.bpw = spi->bits_per_word;

        /* Initialize the functions for transfer */
        if (config.bpw <= 8) {
                spi_imx->rx = spi_imx_buf_rx_u8;
                spi_imx->tx = spi_imx_buf_tx_u8;
        } else if (config.bpw <= 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->devtype_data->config(spi_imx, &config);

        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;
        }

        spi_imx->dma_is_inited = 0;
}

static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
                             struct spi_master *master,
                             const struct resource *res)
{
        struct dma_slave_config slave_config = {};
        int ret;

        /* use pio mode for i.mx6dl chip TKT238285 */
        if (of_machine_is_compatible("fsl,imx6dl"))
                return 0;

        spi_imx->wml = spi_imx_get_fifosize(spi_imx) / 2;

        /* Prepare for TX DMA: */
        master->dma_tx = dma_request_slave_channel_reason(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;
        }

        slave_config.direction = DMA_MEM_TO_DEV;
        slave_config.dst_addr = res->start + MXC_CSPITXDATA;
        slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        slave_config.dst_maxburst = spi_imx->wml;
        ret = dmaengine_slave_config(master->dma_tx, &slave_config);
        if (ret) {
                dev_err(dev, "error in TX dma configuration.\n");
                goto err;
        }

        /* Prepare for RX : */
        master->dma_rx = dma_request_slave_channel_reason(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;
        }

        slave_config.direction = DMA_DEV_TO_MEM;
        slave_config.src_addr = res->start + MXC_CSPIRXDATA;
        slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        slave_config.src_maxburst = spi_imx->wml;
        ret = dmaengine_slave_config(master->dma_rx, &slave_config);
        if (ret) {
                dev_err(dev, "error in RX dma configuration.\n");
                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;
        spi_imx->dma_is_inited = 1;

        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_dma_transfer(struct spi_imx_data *spi_imx,
                                struct spi_transfer *transfer)
{
        struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
        int ret;
        unsigned long timeout;
        struct spi_master *master = spi_imx->bitbang.master;
        struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;

        if (tx) {
                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)
                        goto tx_nodma;

                desc_tx->callback = spi_imx_dma_tx_callback;
                desc_tx->callback_param = (void *)spi_imx;
                dmaengine_submit(desc_tx);
        }

        if (rx) {
                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)
                        goto rx_nodma;

                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);
        reinit_completion(&spi_imx->dma_tx_completion);

        /* Trigger the cspi module. */
        spi_imx->dma_finished = 0;

        /*
         * Set these order to avoid potential RX overflow. The overflow may
         * happen if we enable SPI HW before starting RX DMA due to rescheduling
         * for another task and/or interrupt.
         * So RX DMA enabled first to make sure data would be read out from FIFO
         * ASAP. TX DMA enabled next to start filling TX FIFO with new data.
         * And finaly SPI HW enabled to start actual data transfer.
         */
        dma_async_issue_pending(master->dma_rx);
        dma_async_issue_pending(master->dma_tx);
        spi_imx->devtype_data->trigger(spi_imx);

        /* Wait SDMA to finish the data transfer.*/
        timeout = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
                                                IMX_DMA_TIMEOUT);
        if (!timeout) {
                pr_warn("%s %s: I/O Error in DMA TX\n",
                        dev_driver_string(&master->dev),
                        dev_name(&master->dev));
                dmaengine_terminate_all(master->dma_tx);
                dmaengine_terminate_all(master->dma_rx);
        } else {
                timeout = wait_for_completion_timeout(
                                &spi_imx->dma_rx_completion, IMX_DMA_TIMEOUT);
                if (!timeout) {
                        pr_warn("%s %s: I/O Error in DMA RX\n",
                                dev_driver_string(&master->dev),
                                dev_name(&master->dev));
                        spi_imx->devtype_data->reset(spi_imx);
                        dmaengine_terminate_all(master->dma_rx);
                }
        }

        spi_imx->dma_finished = 1;
        spi_imx->devtype_data->trigger(spi_imx);

        if (!timeout)
                ret = -ETIMEDOUT;
        else
                ret = transfer->len;

        return ret;

rx_nodma:
        dmaengine_terminate_all(master->dma_tx);
tx_nodma:

        pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
                     dev_driver_string(&master->dev),
                     dev_name(&master->dev));
        return -EAGAIN;
}

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);

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

        reinit_completion(&spi_imx->xfer_done);

        spi_imx_push(spi_imx);

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

        wait_for_completion(&spi_imx->xfer_done);

        return transfer->len;
}

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

        if (spi_imx->bitbang.master->can_dma &&
            spi_imx_can_dma(spi_imx->bitbang.master, spi, transfer)) {
                spi_imx->usedma = true;
                ret = spi_imx_dma_transfer(spi_imx, transfer);
                if (ret != -EAGAIN)
                        return ret;
        }
        spi_imx->usedma = false;

        return spi_imx_pio_transfer(spi, transfer);
}

static int spi_imx_setup(struct spi_device *spi)
{
        struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
        int gpio = spi_imx->chipselect[spi->chip_select];

        dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n", __func__,
                 spi->mode, spi->bits_per_word, spi->max_speed_hz);

        if (gpio_is_valid(gpio))
                gpio_direction_output(gpio, spi->mode & SPI_CS_HIGH ? 0 : 1);

        spi_imx_chipselect(spi, BITBANG_CS_INACTIVE);

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

        ret = clk_enable(spi_imx->clk_ipg);
        if (ret) {
                clk_disable(spi_imx->clk_per);
                return ret;
        }

        return 0;
}

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);

        clk_disable(spi_imx->clk_ipg);
        clk_disable(spi_imx->clk_per);
        return 0;
}

static int spi_imx_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        const struct of_device_id *of_id =
                        of_match_device(spi_imx_dt_ids, &pdev->dev);
        struct spi_imx_master *mxc_platform_info =
                        dev_get_platdata(&pdev->dev);
        struct spi_master *master;
        struct spi_imx_data *spi_imx;
        struct resource *res;
        int i, ret, num_cs, irq;

        if (!np && !mxc_platform_info) {
                dev_err(&pdev->dev, "can't get the platform data\n");
                return -EINVAL;
        }

        ret = of_property_read_u32(np, "fsl,spi-num-chipselects", &num_cs);
        if (ret < 0) {
                if (mxc_platform_info)
                        num_cs = mxc_platform_info->num_chipselect;
                else
                        return ret;
        }

        master = spi_alloc_master(&pdev->dev,
                        sizeof(struct spi_imx_data) + sizeof(int) * num_cs);
        if (!master)
                return -ENOMEM;

        platform_set_drvdata(pdev, master);

        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
        master->bus_num = pdev->id;
        master->num_chipselect = num_cs;

        spi_imx = spi_master_get_devdata(master);
        spi_imx->bitbang.master = master;

        spi_imx->devtype_data = of_id ? of_id->data :
                (struct spi_imx_devtype_data *)pdev->id_entry->driver_data;

        for (i = 0; i < master->num_chipselect; i++) {
                int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
                if (!gpio_is_valid(cs_gpio) && mxc_platform_info)
                        cs_gpio = mxc_platform_info->chipselect[i];

                spi_imx->chipselect[i] = cs_gpio;
                if (!gpio_is_valid(cs_gpio))
                        continue;

                ret = devm_gpio_request(&pdev->dev, spi_imx->chipselect[i],
                                        DRIVER_NAME);
                if (ret) {
                        dev_err(&pdev->dev, "can't get cs gpios\n");
                        goto out_master_put;
                }
        }

        spi_imx->bitbang.chipselect = spi_imx_chipselect;
        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->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
        if (is_imx51_ecspi(spi_imx))
                spi_imx->bitbang.master->mode_bits |= SPI_LOOP;

        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;
        }

        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;

        spi_imx->spi_clk = clk_get_rate(spi_imx->clk_per);
        /*
         * Only validated on i.mx6 now, can remove the constrain if validated on
         * other chips.
         */
        if (is_imx51_ecspi(spi_imx)) {
                ret = spi_imx_sdma_init(&pdev->dev, spi_imx, master, res);
                if (ret == -EPROBE_DEFER)
                        goto out_clk_put;

                if (ret < 0)
                        dev_err(&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(&pdev->dev, "bitbang start failed with %d\n", ret);
                goto out_clk_put;
        }

        dev_info(&pdev->dev, "probed\n");

        clk_disable(spi_imx->clk_ipg);
        clk_disable(spi_imx->clk_per);
        return ret;

out_clk_put:
        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);

        spi_bitbang_stop(&spi_imx->bitbang);

        writel(0, spi_imx->base + MXC_CSPICTRL);
        clk_unprepare(spi_imx->clk_ipg);
        clk_unprepare(spi_imx->clk_per);
        spi_imx_sdma_exit(spi_imx);
        spi_master_put(master);

        return 0;
}

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

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