/*
 * SuperH MSIOF SPI Master Interface
 *
 * Copyright (c) 2009 Magnus Damm
 * Copyright (C) 2014 Glider bvba
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/bitmap.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/sh_dma.h>

#include <linux/spi/sh_msiof.h>
#include <linux/spi/spi.h>

#include <asm/unaligned.h>


struct sh_msiof_chipdata {
        u16 tx_fifo_size;
        u16 rx_fifo_size;
        u16 master_flags;
};

struct sh_msiof_spi_priv {
        struct spi_master *master;
        void __iomem *mapbase;
        struct clk *clk;
        struct platform_device *pdev;
        struct sh_msiof_spi_info *info;
        struct completion done;
        unsigned int tx_fifo_size;
        unsigned int rx_fifo_size;
        void *tx_dma_page;
        void *rx_dma_page;
        dma_addr_t tx_dma_addr;
        dma_addr_t rx_dma_addr;
};

#define TMDR1   0x00    /* Transmit Mode Register 1 */
#define TMDR2   0x04    /* Transmit Mode Register 2 */
#define TMDR3   0x08    /* Transmit Mode Register 3 */
#define RMDR1   0x10    /* Receive Mode Register 1 */
#define RMDR2   0x14    /* Receive Mode Register 2 */
#define RMDR3   0x18    /* Receive Mode Register 3 */
#define TSCR    0x20    /* Transmit Clock Select Register */
#define RSCR    0x22    /* Receive Clock Select Register (SH, A1, APE6) */
#define CTR     0x28    /* Control Register */
#define FCTR    0x30    /* FIFO Control Register */
#define STR     0x40    /* Status Register */
#define IER     0x44    /* Interrupt Enable Register */
#define TDR1    0x48    /* Transmit Control Data Register 1 (SH, A1) */
#define TDR2    0x4c    /* Transmit Control Data Register 2 (SH, A1) */
#define TFDR    0x50    /* Transmit FIFO Data Register */
#define RDR1    0x58    /* Receive Control Data Register 1 (SH, A1) */
#define RDR2    0x5c    /* Receive Control Data Register 2 (SH, A1) */
#define RFDR    0x60    /* Receive FIFO Data Register */

/* TMDR1 and RMDR1 */
#define MDR1_TRMD        0x80000000 /* Transfer Mode (1 = Master mode) */
#define MDR1_SYNCMD_MASK 0x30000000 /* SYNC Mode */
#define MDR1_SYNCMD_SPI  0x20000000 /*   Level mode/SPI */
#define MDR1_SYNCMD_LR   0x30000000 /*   L/R mode */
#define MDR1_SYNCAC_SHIFT        25 /* Sync Polarity (1 = Active-low) */
#define MDR1_BITLSB_SHIFT        24 /* MSB/LSB First (1 = LSB first) */
#define MDR1_DTDL_SHIFT          20 /* Data Pin Bit Delay for MSIOF_SYNC */
#define MDR1_SYNCDL_SHIFT        16 /* Frame Sync Signal Timing Delay */
#define MDR1_FLD_MASK    0x0000000c /* Frame Sync Signal Interval (0-3) */
#define MDR1_FLD_SHIFT            2
#define MDR1_XXSTP       0x00000001 /* Transmission/Reception Stop on FIFO */
/* TMDR1 */
#define TMDR1_PCON       0x40000000 /* Transfer Signal Connection */

/* TMDR2 and RMDR2 */
#define MDR2_BITLEN1(i) (((i) - 1) << 24) /* Data Size (8-32 bits) */
#define MDR2_WDLEN1(i)  (((i) - 1) << 16) /* Word Count (1-64/256 (SH, A1))) */
#define MDR2_GRPMASK1   0x00000001 /* Group Output Mask 1 (SH, A1) */

/* TSCR and RSCR */
#define SCR_BRPS_MASK       0x1f00 /* Prescaler Setting (1-32) */
#define SCR_BRPS(i)     (((i) - 1) << 8)
#define SCR_BRDV_MASK       0x0007 /* Baud Rate Generator's Division Ratio */
#define SCR_BRDV_DIV_2      0x0000
#define SCR_BRDV_DIV_4      0x0001
#define SCR_BRDV_DIV_8      0x0002
#define SCR_BRDV_DIV_16     0x0003
#define SCR_BRDV_DIV_32     0x0004
#define SCR_BRDV_DIV_1      0x0007

/* CTR */
#define CTR_TSCKIZ_MASK 0xc0000000 /* Transmit Clock I/O Polarity Select */
#define CTR_TSCKIZ_SCK  0x80000000 /*   Disable SCK when TX disabled */
#define CTR_TSCKIZ_POL_SHIFT    30 /*   Transmit Clock Polarity */
#define CTR_RSCKIZ_MASK 0x30000000 /* Receive Clock Polarity Select */
#define CTR_RSCKIZ_SCK  0x20000000 /*   Must match CTR_TSCKIZ_SCK */
#define CTR_RSCKIZ_POL_SHIFT    28 /*   Receive Clock Polarity */
#define CTR_TEDG_SHIFT          27 /* Transmit Timing (1 = falling edge) */
#define CTR_REDG_SHIFT          26 /* Receive Timing (1 = falling edge) */
#define CTR_TXDIZ_MASK  0x00c00000 /* Pin Output When TX is Disabled */
#define CTR_TXDIZ_LOW   0x00000000 /*   0 */
#define CTR_TXDIZ_HIGH  0x00400000 /*   1 */
#define CTR_TXDIZ_HIZ   0x00800000 /*   High-impedance */
#define CTR_TSCKE       0x00008000 /* Transmit Serial Clock Output Enable */
#define CTR_TFSE        0x00004000 /* Transmit Frame Sync Signal Output Enable */
#define CTR_TXE         0x00000200 /* Transmit Enable */
#define CTR_RXE         0x00000100 /* Receive Enable */

/* FCTR */
#define FCTR_TFWM_MASK  0xe0000000 /* Transmit FIFO Watermark */
#define FCTR_TFWM_64    0x00000000 /*  Transfer Request when 64 empty stages */
#define FCTR_TFWM_32    0x20000000 /*  Transfer Request when 32 empty stages */
#define FCTR_TFWM_24    0x40000000 /*  Transfer Request when 24 empty stages */
#define FCTR_TFWM_16    0x60000000 /*  Transfer Request when 16 empty stages */
#define FCTR_TFWM_12    0x80000000 /*  Transfer Request when 12 empty stages */
#define FCTR_TFWM_8     0xa0000000 /*  Transfer Request when 8 empty stages */
#define FCTR_TFWM_4     0xc0000000 /*  Transfer Request when 4 empty stages */
#define FCTR_TFWM_1     0xe0000000 /*  Transfer Request when 1 empty stage */
#define FCTR_TFUA_MASK  0x07f00000 /* Transmit FIFO Usable Area */
#define FCTR_TFUA_SHIFT         20
#define FCTR_TFUA(i)    ((i) << FCTR_TFUA_SHIFT)
#define FCTR_RFWM_MASK  0x0000e000 /* Receive FIFO Watermark */
#define FCTR_RFWM_1     0x00000000 /*  Transfer Request when 1 valid stages */
#define FCTR_RFWM_4     0x00002000 /*  Transfer Request when 4 valid stages */
#define FCTR_RFWM_8     0x00004000 /*  Transfer Request when 8 valid stages */
#define FCTR_RFWM_16    0x00006000 /*  Transfer Request when 16 valid stages */
#define FCTR_RFWM_32    0x00008000 /*  Transfer Request when 32 valid stages */
#define FCTR_RFWM_64    0x0000a000 /*  Transfer Request when 64 valid stages */
#define FCTR_RFWM_128   0x0000c000 /*  Transfer Request when 128 valid stages */
#define FCTR_RFWM_256   0x0000e000 /*  Transfer Request when 256 valid stages */
#define FCTR_RFUA_MASK  0x00001ff0 /* Receive FIFO Usable Area (0x40 = full) */
#define FCTR_RFUA_SHIFT          4
#define FCTR_RFUA(i)    ((i) << FCTR_RFUA_SHIFT)

/* STR */
#define STR_TFEMP       0x20000000 /* Transmit FIFO Empty */
#define STR_TDREQ       0x10000000 /* Transmit Data Transfer Request */
#define STR_TEOF        0x00800000 /* Frame Transmission End */
#define STR_TFSERR      0x00200000 /* Transmit Frame Synchronization Error */
#define STR_TFOVF       0x00100000 /* Transmit FIFO Overflow */
#define STR_TFUDF       0x00080000 /* Transmit FIFO Underflow */
#define STR_RFFUL       0x00002000 /* Receive FIFO Full */
#define STR_RDREQ       0x00001000 /* Receive Data Transfer Request */
#define STR_REOF        0x00000080 /* Frame Reception End */
#define STR_RFSERR      0x00000020 /* Receive Frame Synchronization Error */
#define STR_RFUDF       0x00000010 /* Receive FIFO Underflow */
#define STR_RFOVF       0x00000008 /* Receive FIFO Overflow */

/* IER */
#define IER_TDMAE       0x80000000 /* Transmit Data DMA Transfer Req. Enable */
#define IER_TFEMPE      0x20000000 /* Transmit FIFO Empty Enable */
#define IER_TDREQE      0x10000000 /* Transmit Data Transfer Request Enable */
#define IER_TEOFE       0x00800000 /* Frame Transmission End Enable */
#define IER_TFSERRE     0x00200000 /* Transmit Frame Sync Error Enable */
#define IER_TFOVFE      0x00100000 /* Transmit FIFO Overflow Enable */
#define IER_TFUDFE      0x00080000 /* Transmit FIFO Underflow Enable */
#define IER_RDMAE       0x00008000 /* Receive Data DMA Transfer Req. Enable */
#define IER_RFFULE      0x00002000 /* Receive FIFO Full Enable */
#define IER_RDREQE      0x00001000 /* Receive Data Transfer Request Enable */
#define IER_REOFE       0x00000080 /* Frame Reception End Enable */
#define IER_RFSERRE     0x00000020 /* Receive Frame Sync Error Enable */
#define IER_RFUDFE      0x00000010 /* Receive FIFO Underflow Enable */
#define IER_RFOVFE      0x00000008 /* Receive FIFO Overflow Enable */


static u32 sh_msiof_read(struct sh_msiof_spi_priv *p, int reg_offs)
{
        switch (reg_offs) {
        case TSCR:
        case RSCR:
                return ioread16(p->mapbase + reg_offs);
        default:
                return ioread32(p->mapbase + reg_offs);
        }
}

static void sh_msiof_write(struct sh_msiof_spi_priv *p, int reg_offs,
                           u32 value)
{
        switch (reg_offs) {
        case TSCR:
        case RSCR:
                iowrite16(value, p->mapbase + reg_offs);
                break;
        default:
                iowrite32(value, p->mapbase + reg_offs);
                break;
        }
}

static int sh_msiof_modify_ctr_wait(struct sh_msiof_spi_priv *p,
                                    u32 clr, u32 set)
{
        u32 mask = clr | set;
        u32 data;
        int k;

        data = sh_msiof_read(p, CTR);
        data &= ~clr;
        data |= set;
        sh_msiof_write(p, CTR, data);

        for (k = 100; k > 0; k--) {
                if ((sh_msiof_read(p, CTR) & mask) == set)
                        break;

                udelay(10);
        }

        return k > 0 ? 0 : -ETIMEDOUT;
}

static irqreturn_t sh_msiof_spi_irq(int irq, void *data)
{
        struct sh_msiof_spi_priv *p = data;

        /* just disable the interrupt and wake up */
        sh_msiof_write(p, IER, 0);
        complete(&p->done);

        return IRQ_HANDLED;
}

static struct {
        unsigned short div;
        unsigned short brdv;
} const sh_msiof_spi_div_table[] = {
        { 1,    SCR_BRDV_DIV_1 },
        { 2,    SCR_BRDV_DIV_2 },
        { 4,    SCR_BRDV_DIV_4 },
        { 8,    SCR_BRDV_DIV_8 },
        { 16,   SCR_BRDV_DIV_16 },
        { 32,   SCR_BRDV_DIV_32 },
};

static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
                                      unsigned long parent_rate, u32 spi_hz)
{
        unsigned long div = 1024;
        u32 brps, scr;
        size_t k;

        if (!WARN_ON(!spi_hz || !parent_rate))
                div = DIV_ROUND_UP(parent_rate, spi_hz);

        for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_div_table); k++) {
                brps = DIV_ROUND_UP(div, sh_msiof_spi_div_table[k].div);
                /* SCR_BRDV_DIV_1 is valid only if BRPS is x 1/1 or x 1/2 */
                if (sh_msiof_spi_div_table[k].div == 1 && brps > 2)
                        continue;
                if (brps <= 32) /* max of brdv is 32 */
                        break;
        }

        k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_div_table) - 1);

        scr = sh_msiof_spi_div_table[k].brdv | SCR_BRPS(brps);
        sh_msiof_write(p, TSCR, scr);
        if (!(p->master->flags & SPI_MASTER_MUST_TX))
                sh_msiof_write(p, RSCR, scr);
}

static u32 sh_msiof_get_delay_bit(u32 dtdl_or_syncdl)
{
        /*
         * DTDL/SYNCDL bit      : p->info->dtdl or p->info->syncdl
         * b'000                : 0
         * b'001                : 100
         * b'010                : 200
         * b'011 (SYNCDL only)  : 300
         * b'101                : 50
         * b'110                : 150
         */
        if (dtdl_or_syncdl % 100)
                return dtdl_or_syncdl / 100 + 5;
        else
                return dtdl_or_syncdl / 100;
}

static u32 sh_msiof_spi_get_dtdl_and_syncdl(struct sh_msiof_spi_priv *p)
{
        u32 val;

        if (!p->info)
                return 0;

        /* check if DTDL and SYNCDL is allowed value */
        if (p->info->dtdl > 200 || p->info->syncdl > 300) {
                dev_warn(&p->pdev->dev, "DTDL or SYNCDL is too large\n");
                return 0;
        }

        /* check if the sum of DTDL and SYNCDL becomes an integer value  */
        if ((p->info->dtdl + p->info->syncdl) % 100) {
                dev_warn(&p->pdev->dev, "the sum of DTDL/SYNCDL is not good\n");
                return 0;
        }

        val = sh_msiof_get_delay_bit(p->info->dtdl) << MDR1_DTDL_SHIFT;
        val |= sh_msiof_get_delay_bit(p->info->syncdl) << MDR1_SYNCDL_SHIFT;

        return val;
}

static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
                                      u32 cpol, u32 cpha,
                                      u32 tx_hi_z, u32 lsb_first, u32 cs_high)
{
        u32 tmp;
        int edge;

        /*
         * CPOL CPHA     TSCKIZ RSCKIZ TEDG REDG
         *    0    0         10     10    1    1
         *    0    1         10     10    0    0
         *    1    0         11     11    0    0
         *    1    1         11     11    1    1
         */
        tmp = MDR1_SYNCMD_SPI | 1 << MDR1_FLD_SHIFT | MDR1_XXSTP;
        tmp |= !cs_high << MDR1_SYNCAC_SHIFT;
        tmp |= lsb_first << MDR1_BITLSB_SHIFT;
        tmp |= sh_msiof_spi_get_dtdl_and_syncdl(p);
        sh_msiof_write(p, TMDR1, tmp | MDR1_TRMD | TMDR1_PCON);
        if (p->master->flags & SPI_MASTER_MUST_TX) {
                /* These bits are reserved if RX needs TX */
                tmp &= ~0x0000ffff;
        }
        sh_msiof_write(p, RMDR1, tmp);

        tmp = 0;
        tmp |= CTR_TSCKIZ_SCK | cpol << CTR_TSCKIZ_POL_SHIFT;
        tmp |= CTR_RSCKIZ_SCK | cpol << CTR_RSCKIZ_POL_SHIFT;

        edge = cpol ^ !cpha;

        tmp |= edge << CTR_TEDG_SHIFT;
        tmp |= edge << CTR_REDG_SHIFT;
        tmp |= tx_hi_z ? CTR_TXDIZ_HIZ : CTR_TXDIZ_LOW;
        sh_msiof_write(p, CTR, tmp);
}

static void sh_msiof_spi_set_mode_regs(struct sh_msiof_spi_priv *p,
                                       const void *tx_buf, void *rx_buf,
                                       u32 bits, u32 words)
{
        u32 dr2 = MDR2_BITLEN1(bits) | MDR2_WDLEN1(words);

        if (tx_buf || (p->master->flags & SPI_MASTER_MUST_TX))
                sh_msiof_write(p, TMDR2, dr2);
        else
                sh_msiof_write(p, TMDR2, dr2 | MDR2_GRPMASK1);

        if (rx_buf)
                sh_msiof_write(p, RMDR2, dr2);
}

static void sh_msiof_reset_str(struct sh_msiof_spi_priv *p)
{
        sh_msiof_write(p, STR, sh_msiof_read(p, STR));
}

static void sh_msiof_spi_write_fifo_8(struct sh_msiof_spi_priv *p,
                                      const void *tx_buf, int words, int fs)
{
        const u8 *buf_8 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, buf_8[k] << fs);
}

static void sh_msiof_spi_write_fifo_16(struct sh_msiof_spi_priv *p,
                                       const void *tx_buf, int words, int fs)
{
        const u16 *buf_16 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, buf_16[k] << fs);
}

static void sh_msiof_spi_write_fifo_16u(struct sh_msiof_spi_priv *p,
                                        const void *tx_buf, int words, int fs)
{
        const u16 *buf_16 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, get_unaligned(&buf_16[k]) << fs);
}

static void sh_msiof_spi_write_fifo_32(struct sh_msiof_spi_priv *p,
                                       const void *tx_buf, int words, int fs)
{
        const u32 *buf_32 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, buf_32[k] << fs);
}

static void sh_msiof_spi_write_fifo_32u(struct sh_msiof_spi_priv *p,
                                        const void *tx_buf, int words, int fs)
{
        const u32 *buf_32 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, get_unaligned(&buf_32[k]) << fs);
}

static void sh_msiof_spi_write_fifo_s32(struct sh_msiof_spi_priv *p,
                                        const void *tx_buf, int words, int fs)
{
        const u32 *buf_32 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, swab32(buf_32[k] << fs));
}

static void sh_msiof_spi_write_fifo_s32u(struct sh_msiof_spi_priv *p,
                                         const void *tx_buf, int words, int fs)
{
        const u32 *buf_32 = tx_buf;
        int k;

        for (k = 0; k < words; k++)
                sh_msiof_write(p, TFDR, swab32(get_unaligned(&buf_32[k]) << fs));
}

static void sh_msiof_spi_read_fifo_8(struct sh_msiof_spi_priv *p,
                                     void *rx_buf, int words, int fs)
{
        u8 *buf_8 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                buf_8[k] = sh_msiof_read(p, RFDR) >> fs;
}

static void sh_msiof_spi_read_fifo_16(struct sh_msiof_spi_priv *p,
                                      void *rx_buf, int words, int fs)
{
        u16 *buf_16 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                buf_16[k] = sh_msiof_read(p, RFDR) >> fs;
}

static void sh_msiof_spi_read_fifo_16u(struct sh_msiof_spi_priv *p,
                                       void *rx_buf, int words, int fs)
{
        u16 *buf_16 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                put_unaligned(sh_msiof_read(p, RFDR) >> fs, &buf_16[k]);
}

static void sh_msiof_spi_read_fifo_32(struct sh_msiof_spi_priv *p,
                                      void *rx_buf, int words, int fs)
{
        u32 *buf_32 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                buf_32[k] = sh_msiof_read(p, RFDR) >> fs;
}

static void sh_msiof_spi_read_fifo_32u(struct sh_msiof_spi_priv *p,
                                       void *rx_buf, int words, int fs)
{
        u32 *buf_32 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                put_unaligned(sh_msiof_read(p, RFDR) >> fs, &buf_32[k]);
}

static void sh_msiof_spi_read_fifo_s32(struct sh_msiof_spi_priv *p,
                                       void *rx_buf, int words, int fs)
{
        u32 *buf_32 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                buf_32[k] = swab32(sh_msiof_read(p, RFDR) >> fs);
}

static void sh_msiof_spi_read_fifo_s32u(struct sh_msiof_spi_priv *p,
                                       void *rx_buf, int words, int fs)
{
        u32 *buf_32 = rx_buf;
        int k;

        for (k = 0; k < words; k++)
                put_unaligned(swab32(sh_msiof_read(p, RFDR) >> fs), &buf_32[k]);
}

static int sh_msiof_spi_setup(struct spi_device *spi)
{
        struct device_node      *np = spi->master->dev.of_node;
        struct sh_msiof_spi_priv *p = spi_master_get_devdata(spi->master);

        pm_runtime_get_sync(&p->pdev->dev);

        if (!np) {
                /*
                 * Use spi->controller_data for CS (same strategy as spi_gpio),
                 * if any. otherwise let HW control CS
                 */
                spi->cs_gpio = (uintptr_t)spi->controller_data;
        }

        /* Configure pins before deasserting CS */
        sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
                                  !!(spi->mode & SPI_CPHA),
                                  !!(spi->mode & SPI_3WIRE),
                                  !!(spi->mode & SPI_LSB_FIRST),
                                  !!(spi->mode & SPI_CS_HIGH));

        if (spi->cs_gpio >= 0)
                gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));


        pm_runtime_put(&p->pdev->dev);

        return 0;
}

static int sh_msiof_prepare_message(struct spi_master *master,
                                    struct spi_message *msg)
{
        struct sh_msiof_spi_priv *p = spi_master_get_devdata(master);
        const struct spi_device *spi = msg->spi;

        /* Configure pins before asserting CS */
        sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
                                  !!(spi->mode & SPI_CPHA),
                                  !!(spi->mode & SPI_3WIRE),
                                  !!(spi->mode & SPI_LSB_FIRST),
                                  !!(spi->mode & SPI_CS_HIGH));
        return 0;
}

static int sh_msiof_spi_start(struct sh_msiof_spi_priv *p, void *rx_buf)
{
        int ret;

        /* setup clock and rx/tx signals */
        ret = sh_msiof_modify_ctr_wait(p, 0, CTR_TSCKE);
        if (rx_buf && !ret)
                ret = sh_msiof_modify_ctr_wait(p, 0, CTR_RXE);
        if (!ret)
                ret = sh_msiof_modify_ctr_wait(p, 0, CTR_TXE);

        /* start by setting frame bit */
        if (!ret)
                ret = sh_msiof_modify_ctr_wait(p, 0, CTR_TFSE);

        return ret;
}

static int sh_msiof_spi_stop(struct sh_msiof_spi_priv *p, void *rx_buf)
{
        int ret;

        /* shut down frame, rx/tx and clock signals */
        ret = sh_msiof_modify_ctr_wait(p, CTR_TFSE, 0);
        if (!ret)
                ret = sh_msiof_modify_ctr_wait(p, CTR_TXE, 0);
        if (rx_buf && !ret)
                ret = sh_msiof_modify_ctr_wait(p, CTR_RXE, 0);
        if (!ret)
                ret = sh_msiof_modify_ctr_wait(p, CTR_TSCKE, 0);

        return ret;
}

static int sh_msiof_spi_txrx_once(struct sh_msiof_spi_priv *p,
                                  void (*tx_fifo)(struct sh_msiof_spi_priv *,
                                                  const void *, int, int),
                                  void (*rx_fifo)(struct sh_msiof_spi_priv *,
                                                  void *, int, int),
                                  const void *tx_buf, void *rx_buf,
                                  int words, int bits)
{
        int fifo_shift;
        int ret;

        /* limit maximum word transfer to rx/tx fifo size */
        if (tx_buf)
                words = min_t(int, words, p->tx_fifo_size);
        if (rx_buf)
                words = min_t(int, words, p->rx_fifo_size);

        /* the fifo contents need shifting */
        fifo_shift = 32 - bits;

        /* default FIFO watermarks for PIO */
        sh_msiof_write(p, FCTR, 0);

        /* setup msiof transfer mode registers */
        sh_msiof_spi_set_mode_regs(p, tx_buf, rx_buf, bits, words);
        sh_msiof_write(p, IER, IER_TEOFE | IER_REOFE);

        /* write tx fifo */
        if (tx_buf)
                tx_fifo(p, tx_buf, words, fifo_shift);

        reinit_completion(&p->done);

        ret = sh_msiof_spi_start(p, rx_buf);
        if (ret) {
                dev_err(&p->pdev->dev, "failed to start hardware\n");
                goto stop_ier;
        }

        /* wait for tx fifo to be emptied / rx fifo to be filled */
        if (!wait_for_completion_timeout(&p->done, HZ)) {
                dev_err(&p->pdev->dev, "PIO timeout\n");
                ret = -ETIMEDOUT;
                goto stop_reset;
        }

        /* read rx fifo */
        if (rx_buf)
                rx_fifo(p, rx_buf, words, fifo_shift);

        /* clear status bits */
        sh_msiof_reset_str(p);

        ret = sh_msiof_spi_stop(p, rx_buf);
        if (ret) {
                dev_err(&p->pdev->dev, "failed to shut down hardware\n");
                return ret;
        }

        return words;

stop_reset:
        sh_msiof_reset_str(p);
        sh_msiof_spi_stop(p, rx_buf);
stop_ier:
        sh_msiof_write(p, IER, 0);
        return ret;
}

static void sh_msiof_dma_complete(void *arg)
{
        struct sh_msiof_spi_priv *p = arg;

        sh_msiof_write(p, IER, 0);
        complete(&p->done);
}

static int sh_msiof_dma_once(struct sh_msiof_spi_priv *p, const void *tx,
                             void *rx, unsigned int len)
{
        u32 ier_bits = 0;
        struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
        dma_cookie_t cookie;
        int ret;

        /* First prepare and submit the DMA request(s), as this may fail */
        if (rx) {
                ier_bits |= IER_RDREQE | IER_RDMAE;
                desc_rx = dmaengine_prep_slave_single(p->master->dma_rx,
                                        p->rx_dma_addr, len, DMA_FROM_DEVICE,
                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                if (!desc_rx)
                        return -EAGAIN;

                desc_rx->callback = sh_msiof_dma_complete;
                desc_rx->callback_param = p;
                cookie = dmaengine_submit(desc_rx);
                if (dma_submit_error(cookie))
                        return cookie;
        }

        if (tx) {
                ier_bits |= IER_TDREQE | IER_TDMAE;
                dma_sync_single_for_device(p->master->dma_tx->device->dev,
                                           p->tx_dma_addr, len, DMA_TO_DEVICE);
                desc_tx = dmaengine_prep_slave_single(p->master->dma_tx,
                                        p->tx_dma_addr, len, DMA_TO_DEVICE,
                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                if (!desc_tx) {
                        ret = -EAGAIN;
                        goto no_dma_tx;
                }

                if (rx) {
                        /* No callback */
                        desc_tx->callback = NULL;
                } else {
                        desc_tx->callback = sh_msiof_dma_complete;
                        desc_tx->callback_param = p;
                }
                cookie = dmaengine_submit(desc_tx);
                if (dma_submit_error(cookie)) {
                        ret = cookie;
                        goto no_dma_tx;
                }
        }

        /* 1 stage FIFO watermarks for DMA */
        sh_msiof_write(p, FCTR, FCTR_TFWM_1 | FCTR_RFWM_1);

        /* setup msiof transfer mode registers (32-bit words) */
        sh_msiof_spi_set_mode_regs(p, tx, rx, 32, len / 4);

        sh_msiof_write(p, IER, ier_bits);

        reinit_completion(&p->done);

        /* Now start DMA */
        if (rx)
                dma_async_issue_pending(p->master->dma_rx);
        if (tx)
                dma_async_issue_pending(p->master->dma_tx);

        ret = sh_msiof_spi_start(p, rx);
        if (ret) {
                dev_err(&p->pdev->dev, "failed to start hardware\n");
                goto stop_dma;
        }

        /* wait for tx fifo to be emptied / rx fifo to be filled */
        if (!wait_for_completion_timeout(&p->done, HZ)) {
                dev_err(&p->pdev->dev, "DMA timeout\n");
                ret = -ETIMEDOUT;
                goto stop_reset;
        }

        /* clear status bits */
        sh_msiof_reset_str(p);

        ret = sh_msiof_spi_stop(p, rx);
        if (ret) {
                dev_err(&p->pdev->dev, "failed to shut down hardware\n");
                return ret;
        }

        if (rx)
                dma_sync_single_for_cpu(p->master->dma_rx->device->dev,
                                        p->rx_dma_addr, len,
                                        DMA_FROM_DEVICE);

        return 0;

stop_reset:
        sh_msiof_reset_str(p);
        sh_msiof_spi_stop(p, rx);
stop_dma:
        if (tx)
                dmaengine_terminate_all(p->master->dma_tx);
no_dma_tx:
        if (rx)
                dmaengine_terminate_all(p->master->dma_rx);
        sh_msiof_write(p, IER, 0);
        return ret;
}

static void copy_bswap32(u32 *dst, const u32 *src, unsigned int words)
{
        /* src or dst can be unaligned, but not both */
        if ((unsigned long)src & 3) {
                while (words--) {
                        *dst++ = swab32(get_unaligned(src));
                        src++;
                }
        } else if ((unsigned long)dst & 3) {
                while (words--) {
                        put_unaligned(swab32(*src++), dst);
                        dst++;
                }
        } else {
                while (words--)
                        *dst++ = swab32(*src++);
        }
}

static void copy_wswap32(u32 *dst, const u32 *src, unsigned int words)
{
        /* src or dst can be unaligned, but not both */
        if ((unsigned long)src & 3) {
                while (words--) {
                        *dst++ = swahw32(get_unaligned(src));
                        src++;
                }
        } else if ((unsigned long)dst & 3) {
                while (words--) {
                        put_unaligned(swahw32(*src++), dst);
                        dst++;
                }
        } else {
                while (words--)
                        *dst++ = swahw32(*src++);
        }
}

static void copy_plain32(u32 *dst, const u32 *src, unsigned int words)
{
        memcpy(dst, src, words * 4);
}

static int sh_msiof_transfer_one(struct spi_master *master,
                                 struct spi_device *spi,
                                 struct spi_transfer *t)
{
        struct sh_msiof_spi_priv *p = spi_master_get_devdata(master);
        void (*copy32)(u32 *, const u32 *, unsigned int);
        void (*tx_fifo)(struct sh_msiof_spi_priv *, const void *, int, int);
        void (*rx_fifo)(struct sh_msiof_spi_priv *, void *, int, int);
        const void *tx_buf = t->tx_buf;
        void *rx_buf = t->rx_buf;
        unsigned int len = t->len;
        unsigned int bits = t->bits_per_word;
        unsigned int bytes_per_word;
        unsigned int words;
        int n;
        bool swab;
        int ret;

        /* setup clocks (clock already enabled in chipselect()) */
        sh_msiof_spi_set_clk_regs(p, clk_get_rate(p->clk), t->speed_hz);

        while (master->dma_tx && len > 15) {
                /*
                 *  DMA supports 32-bit words only, hence pack 8-bit and 16-bit
                 *  words, with byte resp. word swapping.
                 */
                unsigned int l = 0;

                if (tx_buf)
                        l = min(len, p->tx_fifo_size * 4);
                if (rx_buf)
                        l = min(len, p->rx_fifo_size * 4);

                if (bits <= 8) {
                        if (l & 3)
                                break;
                        copy32 = copy_bswap32;
                } else if (bits <= 16) {
                        if (l & 1)
                                break;
                        copy32 = copy_wswap32;
                } else {
                        copy32 = copy_plain32;
                }

                if (tx_buf)
                        copy32(p->tx_dma_page, tx_buf, l / 4);

                ret = sh_msiof_dma_once(p, tx_buf, rx_buf, l);
                if (ret == -EAGAIN) {
                        pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
                                     dev_driver_string(&p->pdev->dev),
                                     dev_name(&p->pdev->dev));
                        break;
                }
                if (ret)
                        return ret;

                if (rx_buf) {
                        copy32(rx_buf, p->rx_dma_page, l / 4);
                        rx_buf += l;
                }
                if (tx_buf)
                        tx_buf += l;

                len -= l;
                if (!len)
                        return 0;
        }

        if (bits <= 8 && len > 15 && !(len & 3)) {
                bits = 32;
                swab = true;
        } else {
                swab = false;
        }

        /* setup bytes per word and fifo read/write functions */
        if (bits <= 8) {
                bytes_per_word = 1;
                tx_fifo = sh_msiof_spi_write_fifo_8;
                rx_fifo = sh_msiof_spi_read_fifo_8;
        } else if (bits <= 16) {
                bytes_per_word = 2;
                if ((unsigned long)tx_buf & 0x01)
                        tx_fifo = sh_msiof_spi_write_fifo_16u;
                else
                        tx_fifo = sh_msiof_spi_write_fifo_16;

                if ((unsigned long)rx_buf & 0x01)
                        rx_fifo = sh_msiof_spi_read_fifo_16u;
                else
                        rx_fifo = sh_msiof_spi_read_fifo_16;
        } else if (swab) {
                bytes_per_word = 4;
                if ((unsigned long)tx_buf & 0x03)
                        tx_fifo = sh_msiof_spi_write_fifo_s32u;
                else
                        tx_fifo = sh_msiof_spi_write_fifo_s32;

                if ((unsigned long)rx_buf & 0x03)
                        rx_fifo = sh_msiof_spi_read_fifo_s32u;
                else
                        rx_fifo = sh_msiof_spi_read_fifo_s32;
        } else {
                bytes_per_word = 4;
                if ((unsigned long)tx_buf & 0x03)
                        tx_fifo = sh_msiof_spi_write_fifo_32u;
                else
                        tx_fifo = sh_msiof_spi_write_fifo_32;

                if ((unsigned long)rx_buf & 0x03)
                        rx_fifo = sh_msiof_spi_read_fifo_32u;
                else
                        rx_fifo = sh_msiof_spi_read_fifo_32;
        }

        /* transfer in fifo sized chunks */
        words = len / bytes_per_word;

        while (words > 0) {
                n = sh_msiof_spi_txrx_once(p, tx_fifo, rx_fifo, tx_buf, rx_buf,
                                           words, bits);
                if (n < 0)
                        return n;

                if (tx_buf)
                        tx_buf += n * bytes_per_word;
                if (rx_buf)
                        rx_buf += n * bytes_per_word;
                words -= n;
        }

        return 0;
}

static const struct sh_msiof_chipdata sh_data = {
        .tx_fifo_size = 64,
        .rx_fifo_size = 64,
        .master_flags = 0,
};

static const struct sh_msiof_chipdata r8a779x_data = {
        .tx_fifo_size = 64,
        .rx_fifo_size = 64,
        .master_flags = SPI_MASTER_MUST_TX,
};

static const struct of_device_id sh_msiof_match[] = {
        { .compatible = "renesas,sh-mobile-msiof", .data = &sh_data },
        { .compatible = "renesas,msiof-r8a7790",   .data = &r8a779x_data },
        { .compatible = "renesas,msiof-r8a7791",   .data = &r8a779x_data },
        { .compatible = "renesas,msiof-r8a7792",   .data = &r8a779x_data },
        { .compatible = "renesas,msiof-r8a7793",   .data = &r8a779x_data },
        { .compatible = "renesas,msiof-r8a7794",   .data = &r8a779x_data },
        { .compatible = "renesas,rcar-gen2-msiof", .data = &r8a779x_data },
        { .compatible = "renesas,msiof-r8a7796",   .data = &r8a779x_data },
        { .compatible = "renesas,rcar-gen3-msiof", .data = &r8a779x_data },
        { .compatible = "renesas,sh-msiof",        .data = &sh_data }, /* Deprecated */
        {},
};
MODULE_DEVICE_TABLE(of, sh_msiof_match);

#ifdef CONFIG_OF
static struct sh_msiof_spi_info *sh_msiof_spi_parse_dt(struct device *dev)
{
        struct sh_msiof_spi_info *info;
        struct device_node *np = dev->of_node;
        u32 num_cs = 1;

        info = devm_kzalloc(dev, sizeof(struct sh_msiof_spi_info), GFP_KERNEL);
        if (!info)
                return NULL;

        /* Parse the MSIOF properties */
        of_property_read_u32(np, "num-cs", &num_cs);
        of_property_read_u32(np, "renesas,tx-fifo-size",
                                        &info->tx_fifo_override);
        of_property_read_u32(np, "renesas,rx-fifo-size",
                                        &info->rx_fifo_override);
        of_property_read_u32(np, "renesas,dtdl", &info->dtdl);
        of_property_read_u32(np, "renesas,syncdl", &info->syncdl);

        info->num_chipselect = num_cs;

        return info;
}
#else
static struct sh_msiof_spi_info *sh_msiof_spi_parse_dt(struct device *dev)
{
        return NULL;
}
#endif

static struct dma_chan *sh_msiof_request_dma_chan(struct device *dev,
        enum dma_transfer_direction dir, unsigned int id, dma_addr_t port_addr)
{
        dma_cap_mask_t mask;
        struct dma_chan *chan;
        struct dma_slave_config cfg;
        int ret;

        dma_cap_zero(mask);
        dma_cap_set(DMA_SLAVE, mask);

        chan = dma_request_slave_channel_compat(mask, shdma_chan_filter,
                                (void *)(unsigned long)id, dev,
                                dir == DMA_MEM_TO_DEV ? "tx" : "rx");
        if (!chan) {
                dev_warn(dev, "dma_request_slave_channel_compat failed\n");
                return NULL;
        }

        memset(&cfg, 0, sizeof(cfg));
        cfg.direction = dir;
        if (dir == DMA_MEM_TO_DEV) {
                cfg.dst_addr = port_addr;
                cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
        } else {
                cfg.src_addr = port_addr;
                cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
        }

        ret = dmaengine_slave_config(chan, &cfg);
        if (ret) {
                dev_warn(dev, "dmaengine_slave_config failed %d\n", ret);
                dma_release_channel(chan);
                return NULL;
        }

        return chan;
}

static int sh_msiof_request_dma(struct sh_msiof_spi_priv *p)
{
        struct platform_device *pdev = p->pdev;
        struct device *dev = &pdev->dev;
        const struct sh_msiof_spi_info *info = dev_get_platdata(dev);
        unsigned int dma_tx_id, dma_rx_id;
        const struct resource *res;
        struct spi_master *master;
        struct device *tx_dev, *rx_dev;

        if (dev->of_node) {
                /* In the OF case we will get the slave IDs from the DT */
                dma_tx_id = 0;
                dma_rx_id = 0;
        } else if (info && info->dma_tx_id && info->dma_rx_id) {
                dma_tx_id = info->dma_tx_id;
                dma_rx_id = info->dma_rx_id;
        } else {
                /* The driver assumes no error */
                return 0;
        }

        /* The DMA engine uses the second register set, if present */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res)
                res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        master = p->master;
        master->dma_tx = sh_msiof_request_dma_chan(dev, DMA_MEM_TO_DEV,
                                                   dma_tx_id,
                                                   res->start + TFDR);
        if (!master->dma_tx)
                return -ENODEV;

        master->dma_rx = sh_msiof_request_dma_chan(dev, DMA_DEV_TO_MEM,
                                                   dma_rx_id,
                                                   res->start + RFDR);
        if (!master->dma_rx)
                goto free_tx_chan;

        p->tx_dma_page = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
        if (!p->tx_dma_page)
                goto free_rx_chan;

        p->rx_dma_page = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
        if (!p->rx_dma_page)
                goto free_tx_page;

        tx_dev = master->dma_tx->device->dev;
        p->tx_dma_addr = dma_map_single(tx_dev, p->tx_dma_page, PAGE_SIZE,
                                        DMA_TO_DEVICE);
        if (dma_mapping_error(tx_dev, p->tx_dma_addr))
                goto free_rx_page;

        rx_dev = master->dma_rx->device->dev;
        p->rx_dma_addr = dma_map_single(rx_dev, p->rx_dma_page, PAGE_SIZE,
                                        DMA_FROM_DEVICE);
        if (dma_mapping_error(rx_dev, p->rx_dma_addr))
                goto unmap_tx_page;

        dev_info(dev, "DMA available");
        return 0;

unmap_tx_page:
        dma_unmap_single(tx_dev, p->tx_dma_addr, PAGE_SIZE, DMA_TO_DEVICE);
free_rx_page:
        free_page((unsigned long)p->rx_dma_page);
free_tx_page:
        free_page((unsigned long)p->tx_dma_page);
free_rx_chan:
        dma_release_channel(master->dma_rx);
free_tx_chan:
        dma_release_channel(master->dma_tx);
        master->dma_tx = NULL;
        return -ENODEV;
}

static void sh_msiof_release_dma(struct sh_msiof_spi_priv *p)
{
        struct spi_master *master = p->master;
        struct device *dev;

        if (!master->dma_tx)
                return;

        dev = &p->pdev->dev;
        dma_unmap_single(master->dma_rx->device->dev, p->rx_dma_addr,
                         PAGE_SIZE, DMA_FROM_DEVICE);
        dma_unmap_single(master->dma_tx->device->dev, p->tx_dma_addr,
                         PAGE_SIZE, DMA_TO_DEVICE);
        free_page((unsigned long)p->rx_dma_page);
        free_page((unsigned long)p->tx_dma_page);
        dma_release_channel(master->dma_rx);
        dma_release_channel(master->dma_tx);
}

static int sh_msiof_spi_probe(struct platform_device *pdev)
{
        struct resource *r;
        struct spi_master *master;
        const struct sh_msiof_chipdata *chipdata;
        const struct of_device_id *of_id;
        struct sh_msiof_spi_priv *p;
        int i;
        int ret;

        master = spi_alloc_master(&pdev->dev, sizeof(struct sh_msiof_spi_priv));
        if (master == NULL) {
                dev_err(&pdev->dev, "failed to allocate spi master\n");
                return -ENOMEM;
        }

        p = spi_master_get_devdata(master);

        platform_set_drvdata(pdev, p);
        p->master = master;

        of_id = of_match_device(sh_msiof_match, &pdev->dev);
        if (of_id) {
                chipdata = of_id->data;
                p->info = sh_msiof_spi_parse_dt(&pdev->dev);
        } else {
                chipdata = (const void *)pdev->id_entry->driver_data;
                p->info = dev_get_platdata(&pdev->dev);
        }

        if (!p->info) {
                dev_err(&pdev->dev, "failed to obtain device info\n");
                ret = -ENXIO;
                goto err1;
        }

        init_completion(&p->done);

        p->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(p->clk)) {
                dev_err(&pdev->dev, "cannot get clock\n");
                ret = PTR_ERR(p->clk);
                goto err1;
        }

        i = platform_get_irq(pdev, 0);
        if (i < 0) {
                dev_err(&pdev->dev, "cannot get platform IRQ\n");
                ret = -ENOENT;
                goto err1;
        }

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        p->mapbase = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(p->mapbase)) {
                ret = PTR_ERR(p->mapbase);
                goto err1;
        }

        ret = devm_request_irq(&pdev->dev, i, sh_msiof_spi_irq, 0,
                               dev_name(&pdev->dev), p);
        if (ret) {
                dev_err(&pdev->dev, "unable to request irq\n");
                goto err1;
        }

        p->pdev = pdev;
        pm_runtime_enable(&pdev->dev);

        /* Platform data may override FIFO sizes */
        p->tx_fifo_size = chipdata->tx_fifo_size;
        p->rx_fifo_size = chipdata->rx_fifo_size;
        if (p->info->tx_fifo_override)
                p->tx_fifo_size = p->info->tx_fifo_override;
        if (p->info->rx_fifo_override)
                p->rx_fifo_size = p->info->rx_fifo_override;

        /* init master code */
        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
        master->mode_bits |= SPI_LSB_FIRST | SPI_3WIRE;
        master->flags = chipdata->master_flags;
        master->bus_num = pdev->id;
        master->dev.of_node = pdev->dev.of_node;
        master->num_chipselect = p->info->num_chipselect;
        master->setup = sh_msiof_spi_setup;
        master->prepare_message = sh_msiof_prepare_message;
        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
        master->auto_runtime_pm = true;
        master->transfer_one = sh_msiof_transfer_one;

        ret = sh_msiof_request_dma(p);
        if (ret < 0)
                dev_warn(&pdev->dev, "DMA not available, using PIO\n");

        ret = devm_spi_register_master(&pdev->dev, master);
        if (ret < 0) {
                dev_err(&pdev->dev, "spi_register_master error.\n");
                goto err2;
        }

        return 0;

 err2:
        sh_msiof_release_dma(p);
        pm_runtime_disable(&pdev->dev);
 err1:
        spi_master_put(master);
        return ret;
}

static int sh_msiof_spi_remove(struct platform_device *pdev)
{
        struct sh_msiof_spi_priv *p = platform_get_drvdata(pdev);

        sh_msiof_release_dma(p);
        pm_runtime_disable(&pdev->dev);
        return 0;
}

static const struct platform_device_id spi_driver_ids[] = {
        { "spi_sh_msiof",       (kernel_ulong_t)&sh_data },
        {},
};
MODULE_DEVICE_TABLE(platform, spi_driver_ids);

static struct platform_driver sh_msiof_spi_drv = {
        .probe          = sh_msiof_spi_probe,
        .remove         = sh_msiof_spi_remove,
        .id_table       = spi_driver_ids,
        .driver         = {
                .name           = "spi_sh_msiof",
                .of_match_table = of_match_ptr(sh_msiof_match),
        },
};
module_platform_driver(sh_msiof_spi_drv);

MODULE_DESCRIPTION("SuperH MSIOF SPI Master Interface Driver");
MODULE_AUTHOR("Magnus Damm");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:spi_sh_msiof");