/*
 * SH RSPI driver
 *
 * Copyright (C) 2012, 2013  Renesas Solutions Corp.
 * Copyright (C) 2014 Glider bvba
 *
 * Based on spi-sh.c:
 * Copyright (C) 2011 Renesas Solutions Corp.
 *
 * 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; version 2 of the License.
 *
 * 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, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/of_device.h>
#include <linux/pm_runtime.h>
#include <linux/sh_dma.h>
#include <linux/spi/spi.h>
#include <linux/spi/rspi.h>

#define RSPI_SPCR               0x00    /* Control Register */
#define RSPI_SSLP               0x01    /* Slave Select Polarity Register */
#define RSPI_SPPCR              0x02    /* Pin Control Register */
#define RSPI_SPSR               0x03    /* Status Register */
#define RSPI_SPDR               0x04    /* Data Register */
#define RSPI_SPSCR              0x08    /* Sequence Control Register */
#define RSPI_SPSSR              0x09    /* Sequence Status Register */
#define RSPI_SPBR               0x0a    /* Bit Rate Register */
#define RSPI_SPDCR              0x0b    /* Data Control Register */
#define RSPI_SPCKD              0x0c    /* Clock Delay Register */
#define RSPI_SSLND              0x0d    /* Slave Select Negation Delay Register */
#define RSPI_SPND               0x0e    /* Next-Access Delay Register */
#define RSPI_SPCR2              0x0f    /* Control Register 2 (SH only) */
#define RSPI_SPCMD0             0x10    /* Command Register 0 */
#define RSPI_SPCMD1             0x12    /* Command Register 1 */
#define RSPI_SPCMD2             0x14    /* Command Register 2 */
#define RSPI_SPCMD3             0x16    /* Command Register 3 */
#define RSPI_SPCMD4             0x18    /* Command Register 4 */
#define RSPI_SPCMD5             0x1a    /* Command Register 5 */
#define RSPI_SPCMD6             0x1c    /* Command Register 6 */
#define RSPI_SPCMD7             0x1e    /* Command Register 7 */
#define RSPI_SPCMD(i)           (RSPI_SPCMD0 + (i) * 2)
#define RSPI_NUM_SPCMD          8
#define RSPI_RZ_NUM_SPCMD       4
#define QSPI_NUM_SPCMD          4

/* RSPI on RZ only */
#define RSPI_SPBFCR             0x20    /* Buffer Control Register */
#define RSPI_SPBFDR             0x22    /* Buffer Data Count Setting Register */

/* QSPI only */
#define QSPI_SPBFCR             0x18    /* Buffer Control Register */
#define QSPI_SPBDCR             0x1a    /* Buffer Data Count Register */
#define QSPI_SPBMUL0            0x1c    /* Transfer Data Length Multiplier Setting Register 0 */
#define QSPI_SPBMUL1            0x20    /* Transfer Data Length Multiplier Setting Register 1 */
#define QSPI_SPBMUL2            0x24    /* Transfer Data Length Multiplier Setting Register 2 */
#define QSPI_SPBMUL3            0x28    /* Transfer Data Length Multiplier Setting Register 3 */
#define QSPI_SPBMUL(i)          (QSPI_SPBMUL0 + (i) * 4)

/* SPCR - Control Register */
#define SPCR_SPRIE              0x80    /* Receive Interrupt Enable */
#define SPCR_SPE                0x40    /* Function Enable */
#define SPCR_SPTIE              0x20    /* Transmit Interrupt Enable */
#define SPCR_SPEIE              0x10    /* Error Interrupt Enable */
#define SPCR_MSTR               0x08    /* Master/Slave Mode Select */
#define SPCR_MODFEN             0x04    /* Mode Fault Error Detection Enable */
/* RSPI on SH only */
#define SPCR_TXMD               0x02    /* TX Only Mode (vs. Full Duplex) */
#define SPCR_SPMS               0x01    /* 3-wire Mode (vs. 4-wire) */
/* QSPI on R-Car M2 only */
#define SPCR_WSWAP              0x02    /* Word Swap of read-data for DMAC */
#define SPCR_BSWAP              0x01    /* Byte Swap of read-data for DMAC */

/* SSLP - Slave Select Polarity Register */
#define SSLP_SSL1P              0x02    /* SSL1 Signal Polarity Setting */
#define SSLP_SSL0P              0x01    /* SSL0 Signal Polarity Setting */

/* SPPCR - Pin Control Register */
#define SPPCR_MOIFE             0x20    /* MOSI Idle Value Fixing Enable */
#define SPPCR_MOIFV             0x10    /* MOSI Idle Fixed Value */
#define SPPCR_SPOM              0x04
#define SPPCR_SPLP2             0x02    /* Loopback Mode 2 (non-inverting) */
#define SPPCR_SPLP              0x01    /* Loopback Mode (inverting) */

#define SPPCR_IO3FV             0x04    /* Single-/Dual-SPI Mode IO3 Output Fixed Value */
#define SPPCR_IO2FV             0x04    /* Single-/Dual-SPI Mode IO2 Output Fixed Value */

/* SPSR - Status Register */
#define SPSR_SPRF               0x80    /* Receive Buffer Full Flag */
#define SPSR_TEND               0x40    /* Transmit End */
#define SPSR_SPTEF              0x20    /* Transmit Buffer Empty Flag */
#define SPSR_PERF               0x08    /* Parity Error Flag */
#define SPSR_MODF               0x04    /* Mode Fault Error Flag */
#define SPSR_IDLNF              0x02    /* RSPI Idle Flag */
#define SPSR_OVRF               0x01    /* Overrun Error Flag (RSPI only) */

/* SPSCR - Sequence Control Register */
#define SPSCR_SPSLN_MASK        0x07    /* Sequence Length Specification */

/* SPSSR - Sequence Status Register */
#define SPSSR_SPECM_MASK        0x70    /* Command Error Mask */
#define SPSSR_SPCP_MASK         0x07    /* Command Pointer Mask */

/* SPDCR - Data Control Register */
#define SPDCR_TXDMY             0x80    /* Dummy Data Transmission Enable */
#define SPDCR_SPLW1             0x40    /* Access Width Specification (RZ) */
#define SPDCR_SPLW0             0x20    /* Access Width Specification (RZ) */
#define SPDCR_SPLLWORD          (SPDCR_SPLW1 | SPDCR_SPLW0)
#define SPDCR_SPLWORD           SPDCR_SPLW1
#define SPDCR_SPLBYTE           SPDCR_SPLW0
#define SPDCR_SPLW              0x20    /* Access Width Specification (SH) */
#define SPDCR_SPRDTD            0x10    /* Receive Transmit Data Select (SH) */
#define SPDCR_SLSEL1            0x08
#define SPDCR_SLSEL0            0x04
#define SPDCR_SLSEL_MASK        0x0c    /* SSL1 Output Select (SH) */
#define SPDCR_SPFC1             0x02
#define SPDCR_SPFC0             0x01
#define SPDCR_SPFC_MASK         0x03    /* Frame Count Setting (1-4) (SH) */

/* SPCKD - Clock Delay Register */
#define SPCKD_SCKDL_MASK        0x07    /* Clock Delay Setting (1-8) */

/* SSLND - Slave Select Negation Delay Register */
#define SSLND_SLNDL_MASK        0x07    /* SSL Negation Delay Setting (1-8) */

/* SPND - Next-Access Delay Register */
#define SPND_SPNDL_MASK         0x07    /* Next-Access Delay Setting (1-8) */

/* SPCR2 - Control Register 2 */
#define SPCR2_PTE               0x08    /* Parity Self-Test Enable */
#define SPCR2_SPIE              0x04    /* Idle Interrupt Enable */
#define SPCR2_SPOE              0x02    /* Odd Parity Enable (vs. Even) */
#define SPCR2_SPPE              0x01    /* Parity Enable */

/* SPCMDn - Command Registers */
#define SPCMD_SCKDEN            0x8000  /* Clock Delay Setting Enable */
#define SPCMD_SLNDEN            0x4000  /* SSL Negation Delay Setting Enable */
#define SPCMD_SPNDEN            0x2000  /* Next-Access Delay Enable */
#define SPCMD_LSBF              0x1000  /* LSB First */
#define SPCMD_SPB_MASK          0x0f00  /* Data Length Setting */
#define SPCMD_SPB_8_TO_16(bit)  (((bit - 1) << 8) & SPCMD_SPB_MASK)
#define SPCMD_SPB_8BIT          0x0000  /* QSPI only */
#define SPCMD_SPB_16BIT         0x0100
#define SPCMD_SPB_20BIT         0x0000
#define SPCMD_SPB_24BIT         0x0100
#define SPCMD_SPB_32BIT         0x0200
#define SPCMD_SSLKP             0x0080  /* SSL Signal Level Keeping */
#define SPCMD_SPIMOD_MASK       0x0060  /* SPI Operating Mode (QSPI only) */
#define SPCMD_SPIMOD1           0x0040
#define SPCMD_SPIMOD0           0x0020
#define SPCMD_SPIMOD_SINGLE     0
#define SPCMD_SPIMOD_DUAL       SPCMD_SPIMOD0
#define SPCMD_SPIMOD_QUAD       SPCMD_SPIMOD1
#define SPCMD_SPRW              0x0010  /* SPI Read/Write Access (Dual/Quad) */
#define SPCMD_SSLA_MASK         0x0030  /* SSL Assert Signal Setting (RSPI) */
#define SPCMD_BRDV_MASK         0x000c  /* Bit Rate Division Setting */
#define SPCMD_CPOL              0x0002  /* Clock Polarity Setting */
#define SPCMD_CPHA              0x0001  /* Clock Phase Setting */

/* SPBFCR - Buffer Control Register */
#define SPBFCR_TXRST            0x80    /* Transmit Buffer Data Reset */
#define SPBFCR_RXRST            0x40    /* Receive Buffer Data Reset */
#define SPBFCR_TXTRG_MASK       0x30    /* Transmit Buffer Data Triggering Number */
#define SPBFCR_RXTRG_MASK       0x07    /* Receive Buffer Data Triggering Number */

struct rspi_data {
        void __iomem *addr;
        u32 max_speed_hz;
        struct spi_master *master;
        wait_queue_head_t wait;
        struct clk *clk;
        u16 spcmd;
        u8 spsr;
        u8 sppcr;
        int rx_irq, tx_irq;
        const struct spi_ops *ops;

        unsigned dma_callbacked:1;
        unsigned byte_access:1;
};

static void rspi_write8(const struct rspi_data *rspi, u8 data, u16 offset)
{
        iowrite8(data, rspi->addr + offset);
}

static void rspi_write16(const struct rspi_data *rspi, u16 data, u16 offset)
{
        iowrite16(data, rspi->addr + offset);
}

static void rspi_write32(const struct rspi_data *rspi, u32 data, u16 offset)
{
        iowrite32(data, rspi->addr + offset);
}

static u8 rspi_read8(const struct rspi_data *rspi, u16 offset)
{
        return ioread8(rspi->addr + offset);
}

static u16 rspi_read16(const struct rspi_data *rspi, u16 offset)
{
        return ioread16(rspi->addr + offset);
}

static void rspi_write_data(const struct rspi_data *rspi, u16 data)
{
        if (rspi->byte_access)
                rspi_write8(rspi, data, RSPI_SPDR);
        else /* 16 bit */
                rspi_write16(rspi, data, RSPI_SPDR);
}

static u16 rspi_read_data(const struct rspi_data *rspi)
{
        if (rspi->byte_access)
                return rspi_read8(rspi, RSPI_SPDR);
        else /* 16 bit */
                return rspi_read16(rspi, RSPI_SPDR);
}

/* optional functions */
struct spi_ops {
        int (*set_config_register)(struct rspi_data *rspi, int access_size);
        int (*transfer_one)(struct spi_master *master, struct spi_device *spi,
                            struct spi_transfer *xfer);
        u16 mode_bits;
        u16 flags;
        u16 fifo_size;
};

/*
 * functions for RSPI on legacy SH
 */
static int rspi_set_config_register(struct rspi_data *rspi, int access_size)
{
        int spbr;

        /* Sets output mode, MOSI signal, and (optionally) loopback */
        rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);

        /* Sets transfer bit rate */
        spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk),
                            2 * rspi->max_speed_hz) - 1;
        rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);

        /* Disable dummy transmission, set 16-bit word access, 1 frame */
        rspi_write8(rspi, 0, RSPI_SPDCR);
        rspi->byte_access = 0;

        /* Sets RSPCK, SSL, next-access delay value */
        rspi_write8(rspi, 0x00, RSPI_SPCKD);
        rspi_write8(rspi, 0x00, RSPI_SSLND);
        rspi_write8(rspi, 0x00, RSPI_SPND);

        /* Sets parity, interrupt mask */
        rspi_write8(rspi, 0x00, RSPI_SPCR2);

        /* Sets SPCMD */
        rspi->spcmd |= SPCMD_SPB_8_TO_16(access_size);
        rspi_write16(rspi, rspi->spcmd, RSPI_SPCMD0);

        /* Sets RSPI mode */
        rspi_write8(rspi, SPCR_MSTR, RSPI_SPCR);

        return 0;
}

/*
 * functions for RSPI on RZ
 */
static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size)
{
        int spbr;

        /* Sets output mode, MOSI signal, and (optionally) loopback */
        rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);

        /* Sets transfer bit rate */
        spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk),
                            2 * rspi->max_speed_hz) - 1;
        rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);

        /* Disable dummy transmission, set byte access */
        rspi_write8(rspi, SPDCR_SPLBYTE, RSPI_SPDCR);
        rspi->byte_access = 1;

        /* Sets RSPCK, SSL, next-access delay value */
        rspi_write8(rspi, 0x00, RSPI_SPCKD);
        rspi_write8(rspi, 0x00, RSPI_SSLND);
        rspi_write8(rspi, 0x00, RSPI_SPND);

        /* Sets SPCMD */
        rspi->spcmd |= SPCMD_SPB_8_TO_16(access_size);
        rspi_write16(rspi, rspi->spcmd, RSPI_SPCMD0);

        /* Sets RSPI mode */
        rspi_write8(rspi, SPCR_MSTR, RSPI_SPCR);

        return 0;
}

/*
 * functions for QSPI
 */
static int qspi_set_config_register(struct rspi_data *rspi, int access_size)
{
        int spbr;

        /* Sets output mode, MOSI signal, and (optionally) loopback */
        rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);

        /* Sets transfer bit rate */
        spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->max_speed_hz);
        rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);

        /* Disable dummy transmission, set byte access */
        rspi_write8(rspi, 0, RSPI_SPDCR);
        rspi->byte_access = 1;

        /* Sets RSPCK, SSL, next-access delay value */
        rspi_write8(rspi, 0x00, RSPI_SPCKD);
        rspi_write8(rspi, 0x00, RSPI_SSLND);
        rspi_write8(rspi, 0x00, RSPI_SPND);

        /* Data Length Setting */
        if (access_size == 8)
                rspi->spcmd |= SPCMD_SPB_8BIT;
        else if (access_size == 16)
                rspi->spcmd |= SPCMD_SPB_16BIT;
        else
                rspi->spcmd |= SPCMD_SPB_32BIT;

        rspi->spcmd |= SPCMD_SCKDEN | SPCMD_SLNDEN | SPCMD_SPNDEN;

        /* Resets transfer data length */
        rspi_write32(rspi, 0, QSPI_SPBMUL0);

        /* Resets transmit and receive buffer */
        rspi_write8(rspi, SPBFCR_TXRST | SPBFCR_RXRST, QSPI_SPBFCR);
        /* Sets buffer to allow normal operation */
        rspi_write8(rspi, 0x00, QSPI_SPBFCR);

        /* Sets SPCMD */
        rspi_write16(rspi, rspi->spcmd, RSPI_SPCMD0);

        /* Enables SPI function in master mode */
        rspi_write8(rspi, SPCR_SPE | SPCR_MSTR, RSPI_SPCR);

        return 0;
}

#define set_config_register(spi, n) spi->ops->set_config_register(spi, n)

static void rspi_enable_irq(const struct rspi_data *rspi, u8 enable)
{
        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) | enable, RSPI_SPCR);
}

static void rspi_disable_irq(const struct rspi_data *rspi, u8 disable)
{
        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) & ~disable, RSPI_SPCR);
}

static int rspi_wait_for_interrupt(struct rspi_data *rspi, u8 wait_mask,
                                   u8 enable_bit)
{
        int ret;

        rspi->spsr = rspi_read8(rspi, RSPI_SPSR);
        if (rspi->spsr & wait_mask)
                return 0;

        rspi_enable_irq(rspi, enable_bit);
        ret = wait_event_timeout(rspi->wait, rspi->spsr & wait_mask, HZ);
        if (ret == 0 && !(rspi->spsr & wait_mask))
                return -ETIMEDOUT;

        return 0;
}

static inline int rspi_wait_for_tx_empty(struct rspi_data *rspi)
{
        return rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE);
}

static inline int rspi_wait_for_rx_full(struct rspi_data *rspi)
{
        return rspi_wait_for_interrupt(rspi, SPSR_SPRF, SPCR_SPRIE);
}

static int rspi_data_out(struct rspi_data *rspi, u8 data)
{
        int error = rspi_wait_for_tx_empty(rspi);
        if (error < 0) {
                dev_err(&rspi->master->dev, "transmit timeout\n");
                return error;
        }
        rspi_write_data(rspi, data);
        return 0;
}

static int rspi_data_in(struct rspi_data *rspi)
{
        int error;
        u8 data;

        error = rspi_wait_for_rx_full(rspi);
        if (error < 0) {
                dev_err(&rspi->master->dev, "receive timeout\n");
                return error;
        }
        data = rspi_read_data(rspi);
        return data;
}

static int rspi_pio_transfer(struct rspi_data *rspi, const u8 *tx, u8 *rx,
                             unsigned int n)
{
        while (n-- > 0) {
                if (tx) {
                        int ret = rspi_data_out(rspi, *tx++);
                        if (ret < 0)
                                return ret;
                }
                if (rx) {
                        int ret = rspi_data_in(rspi);
                        if (ret < 0)
                                return ret;
                        *rx++ = ret;
                }
        }

        return 0;
}

static void rspi_dma_complete(void *arg)
{
        struct rspi_data *rspi = arg;

        rspi->dma_callbacked = 1;
        wake_up_interruptible(&rspi->wait);
}

static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
                             struct sg_table *rx)
{
        struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
        u8 irq_mask = 0;
        unsigned int other_irq = 0;
        dma_cookie_t cookie;
        int ret;

        /* First prepare and submit the DMA request(s), as this may fail */
        if (rx) {
                desc_rx = dmaengine_prep_slave_sg(rspi->master->dma_rx,
                                        rx->sgl, rx->nents, DMA_FROM_DEVICE,
                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                if (!desc_rx) {
                        ret = -EAGAIN;
                        goto no_dma_rx;
                }

                desc_rx->callback = rspi_dma_complete;
                desc_rx->callback_param = rspi;
                cookie = dmaengine_submit(desc_rx);
                if (dma_submit_error(cookie)) {
                        ret = cookie;
                        goto no_dma_rx;
                }

                irq_mask |= SPCR_SPRIE;
        }

        if (tx) {
                desc_tx = dmaengine_prep_slave_sg(rspi->master->dma_tx,
                                        tx->sgl, tx->nents, 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 = rspi_dma_complete;
                        desc_tx->callback_param = rspi;
                }
                cookie = dmaengine_submit(desc_tx);
                if (dma_submit_error(cookie)) {
                        ret = cookie;
                        goto no_dma_tx;
                }

                irq_mask |= SPCR_SPTIE;
        }

        /*
         * DMAC needs SPxIE, but if SPxIE is set, the IRQ routine will be
         * called. So, this driver disables the IRQ while DMA transfer.
         */
        if (tx)
                disable_irq(other_irq = rspi->tx_irq);
        if (rx && rspi->rx_irq != other_irq)
                disable_irq(rspi->rx_irq);

        rspi_enable_irq(rspi, irq_mask);
        rspi->dma_callbacked = 0;

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

        ret = wait_event_interruptible_timeout(rspi->wait,
                                               rspi->dma_callbacked, HZ);
        if (ret > 0 && rspi->dma_callbacked)
                ret = 0;
        else if (!ret) {
                dev_err(&rspi->master->dev, "DMA timeout\n");
                ret = -ETIMEDOUT;
                if (tx)
                        dmaengine_terminate_all(rspi->master->dma_tx);
                if (rx)
                        dmaengine_terminate_all(rspi->master->dma_rx);
        }

        rspi_disable_irq(rspi, irq_mask);

        if (tx)
                enable_irq(rspi->tx_irq);
        if (rx && rspi->rx_irq != other_irq)
                enable_irq(rspi->rx_irq);

        return ret;

no_dma_tx:
        if (rx)
                dmaengine_terminate_all(rspi->master->dma_rx);
no_dma_rx:
        if (ret == -EAGAIN) {
                pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
                             dev_driver_string(&rspi->master->dev),
                             dev_name(&rspi->master->dev));
        }
        return ret;
}

static void rspi_receive_init(const struct rspi_data *rspi)
{
        u8 spsr;

        spsr = rspi_read8(rspi, RSPI_SPSR);
        if (spsr & SPSR_SPRF)
                rspi_read_data(rspi);   /* dummy read */
        if (spsr & SPSR_OVRF)
                rspi_write8(rspi, rspi_read8(rspi, RSPI_SPSR) & ~SPSR_OVRF,
                            RSPI_SPSR);
}

static void rspi_rz_receive_init(const struct rspi_data *rspi)
{
        rspi_receive_init(rspi);
        rspi_write8(rspi, SPBFCR_TXRST | SPBFCR_RXRST, RSPI_SPBFCR);
        rspi_write8(rspi, 0, RSPI_SPBFCR);
}

static void qspi_receive_init(const struct rspi_data *rspi)
{
        u8 spsr;

        spsr = rspi_read8(rspi, RSPI_SPSR);
        if (spsr & SPSR_SPRF)
                rspi_read_data(rspi);   /* dummy read */
        rspi_write8(rspi, SPBFCR_TXRST | SPBFCR_RXRST, QSPI_SPBFCR);
        rspi_write8(rspi, 0, QSPI_SPBFCR);
}

static bool __rspi_can_dma(const struct rspi_data *rspi,
                           const struct spi_transfer *xfer)
{
        return xfer->len > rspi->ops->fifo_size;
}

static bool rspi_can_dma(struct spi_master *master, struct spi_device *spi,
                         struct spi_transfer *xfer)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);

        return __rspi_can_dma(rspi, xfer);
}

static int rspi_common_transfer(struct rspi_data *rspi,
                                struct spi_transfer *xfer)
{
        int ret;

        if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
                /* rx_buf can be NULL on RSPI on SH in TX-only Mode */
                ret = rspi_dma_transfer(rspi, &xfer->tx_sg,
                                        xfer->rx_buf ? &xfer->rx_sg : NULL);
                if (ret != -EAGAIN)
                        return ret;
        }

        ret = rspi_pio_transfer(rspi, xfer->tx_buf, xfer->rx_buf, xfer->len);
        if (ret < 0)
                return ret;

        /* Wait for the last transmission */
        rspi_wait_for_tx_empty(rspi);

        return 0;
}

static int rspi_transfer_one(struct spi_master *master, struct spi_device *spi,
                             struct spi_transfer *xfer)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);
        u8 spcr;

        spcr = rspi_read8(rspi, RSPI_SPCR);
        if (xfer->rx_buf) {
                rspi_receive_init(rspi);
                spcr &= ~SPCR_TXMD;
        } else {
                spcr |= SPCR_TXMD;
        }
        rspi_write8(rspi, spcr, RSPI_SPCR);

        return rspi_common_transfer(rspi, xfer);
}

static int rspi_rz_transfer_one(struct spi_master *master,
                                struct spi_device *spi,
                                struct spi_transfer *xfer)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);

        rspi_rz_receive_init(rspi);

        return rspi_common_transfer(rspi, xfer);
}

static int qspi_transfer_out_in(struct rspi_data *rspi,
                                struct spi_transfer *xfer)
{
        qspi_receive_init(rspi);

        return rspi_common_transfer(rspi, xfer);
}

static int qspi_transfer_out(struct rspi_data *rspi, struct spi_transfer *xfer)
{
        int ret;

        if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
                ret = rspi_dma_transfer(rspi, &xfer->tx_sg, NULL);
                if (ret != -EAGAIN)
                        return ret;
        }

        ret = rspi_pio_transfer(rspi, xfer->tx_buf, NULL, xfer->len);
        if (ret < 0)
                return ret;

        /* Wait for the last transmission */
        rspi_wait_for_tx_empty(rspi);

        return 0;
}

static int qspi_transfer_in(struct rspi_data *rspi, struct spi_transfer *xfer)
{
        if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
                int ret = rspi_dma_transfer(rspi, NULL, &xfer->rx_sg);
                if (ret != -EAGAIN)
                        return ret;
        }

        return rspi_pio_transfer(rspi, NULL, xfer->rx_buf, xfer->len);
}

static int qspi_transfer_one(struct spi_master *master, struct spi_device *spi,
                             struct spi_transfer *xfer)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);

        if (spi->mode & SPI_LOOP) {
                return qspi_transfer_out_in(rspi, xfer);
        } else if (xfer->tx_nbits > SPI_NBITS_SINGLE) {
                /* Quad or Dual SPI Write */
                return qspi_transfer_out(rspi, xfer);
        } else if (xfer->rx_nbits > SPI_NBITS_SINGLE) {
                /* Quad or Dual SPI Read */
                return qspi_transfer_in(rspi, xfer);
        } else {
                /* Single SPI Transfer */
                return qspi_transfer_out_in(rspi, xfer);
        }
}

static int rspi_setup(struct spi_device *spi)
{
        struct rspi_data *rspi = spi_master_get_devdata(spi->master);

        rspi->max_speed_hz = spi->max_speed_hz;

        rspi->spcmd = SPCMD_SSLKP;
        if (spi->mode & SPI_CPOL)
                rspi->spcmd |= SPCMD_CPOL;
        if (spi->mode & SPI_CPHA)
                rspi->spcmd |= SPCMD_CPHA;

        /* CMOS output mode and MOSI signal from previous transfer */
        rspi->sppcr = 0;
        if (spi->mode & SPI_LOOP)
                rspi->sppcr |= SPPCR_SPLP;

        set_config_register(rspi, 8);

        return 0;
}

static u16 qspi_transfer_mode(const struct spi_transfer *xfer)
{
        if (xfer->tx_buf)
                switch (xfer->tx_nbits) {
                case SPI_NBITS_QUAD:
                        return SPCMD_SPIMOD_QUAD;
                case SPI_NBITS_DUAL:
                        return SPCMD_SPIMOD_DUAL;
                default:
                        return 0;
                }
        if (xfer->rx_buf)
                switch (xfer->rx_nbits) {
                case SPI_NBITS_QUAD:
                        return SPCMD_SPIMOD_QUAD | SPCMD_SPRW;
                case SPI_NBITS_DUAL:
                        return SPCMD_SPIMOD_DUAL | SPCMD_SPRW;
                default:
                        return 0;
                }

        return 0;
}

static int qspi_setup_sequencer(struct rspi_data *rspi,
                                const struct spi_message *msg)
{
        const struct spi_transfer *xfer;
        unsigned int i = 0, len = 0;
        u16 current_mode = 0xffff, mode;

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                mode = qspi_transfer_mode(xfer);
                if (mode == current_mode) {
                        len += xfer->len;
                        continue;
                }

                /* Transfer mode change */
                if (i) {
                        /* Set transfer data length of previous transfer */
                        rspi_write32(rspi, len, QSPI_SPBMUL(i - 1));
                }

                if (i >= QSPI_NUM_SPCMD) {
                        dev_err(&msg->spi->dev,
                                "Too many different transfer modes");
                        return -EINVAL;
                }

                /* Program transfer mode for this transfer */
                rspi_write16(rspi, rspi->spcmd | mode, RSPI_SPCMD(i));
                current_mode = mode;
                len = xfer->len;
                i++;
        }
        if (i) {
                /* Set final transfer data length and sequence length */
                rspi_write32(rspi, len, QSPI_SPBMUL(i - 1));
                rspi_write8(rspi, i - 1, RSPI_SPSCR);
        }

        return 0;
}

static int rspi_prepare_message(struct spi_master *master,
                                struct spi_message *msg)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);
        int ret;

        if (msg->spi->mode &
            (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)) {
                /* Setup sequencer for messages with multiple transfer modes */
                ret = qspi_setup_sequencer(rspi, msg);
                if (ret < 0)
                        return ret;
        }

        /* Enable SPI function in master mode */
        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) | SPCR_SPE, RSPI_SPCR);
        return 0;
}

static int rspi_unprepare_message(struct spi_master *master,
                                  struct spi_message *msg)
{
        struct rspi_data *rspi = spi_master_get_devdata(master);

        /* Disable SPI function */
        rspi_write8(rspi, rspi_read8(rspi, RSPI_SPCR) & ~SPCR_SPE, RSPI_SPCR);

        /* Reset sequencer for Single SPI Transfers */
        rspi_write16(rspi, rspi->spcmd, RSPI_SPCMD0);
        rspi_write8(rspi, 0, RSPI_SPSCR);
        return 0;
}

static irqreturn_t rspi_irq_mux(int irq, void *_sr)
{
        struct rspi_data *rspi = _sr;
        u8 spsr;
        irqreturn_t ret = IRQ_NONE;
        u8 disable_irq = 0;

        rspi->spsr = spsr = rspi_read8(rspi, RSPI_SPSR);
        if (spsr & SPSR_SPRF)
                disable_irq |= SPCR_SPRIE;
        if (spsr & SPSR_SPTEF)
                disable_irq |= SPCR_SPTIE;

        if (disable_irq) {
                ret = IRQ_HANDLED;
                rspi_disable_irq(rspi, disable_irq);
                wake_up(&rspi->wait);
        }

        return ret;
}

static irqreturn_t rspi_irq_rx(int irq, void *_sr)
{
        struct rspi_data *rspi = _sr;
        u8 spsr;

        rspi->spsr = spsr = rspi_read8(rspi, RSPI_SPSR);
        if (spsr & SPSR_SPRF) {
                rspi_disable_irq(rspi, SPCR_SPRIE);
                wake_up(&rspi->wait);
                return IRQ_HANDLED;
        }

        return 0;
}

static irqreturn_t rspi_irq_tx(int irq, void *_sr)
{
        struct rspi_data *rspi = _sr;
        u8 spsr;

        rspi->spsr = spsr = rspi_read8(rspi, RSPI_SPSR);
        if (spsr & SPSR_SPTEF) {
                rspi_disable_irq(rspi, SPCR_SPTIE);
                wake_up(&rspi->wait);
                return IRQ_HANDLED;
        }

        return 0;
}

static struct dma_chan *rspi_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_channel(mask, shdma_chan_filter,
                                   (void *)(unsigned long)id);
        if (!chan) {
                dev_warn(dev, "dma_request_channel failed\n");
                return NULL;
        }

        memset(&cfg, 0, sizeof(cfg));
        cfg.slave_id = id;
        cfg.direction = dir;
        if (dir == DMA_MEM_TO_DEV)
                cfg.dst_addr = port_addr;
        else
                cfg.src_addr = port_addr;

        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 rspi_request_dma(struct device *dev, struct spi_master *master,
                            const struct resource *res)
{
        const struct rspi_plat_data *rspi_pd = dev_get_platdata(dev);

        if (!rspi_pd || !rspi_pd->dma_rx_id || !rspi_pd->dma_tx_id)
                return 0;       /* The driver assumes no error. */

        master->dma_rx = rspi_request_dma_chan(dev, DMA_DEV_TO_MEM,
                                               rspi_pd->dma_rx_id,
                                               res->start + RSPI_SPDR);
        if (!master->dma_rx)
                return -ENODEV;

        master->dma_tx = rspi_request_dma_chan(dev, DMA_MEM_TO_DEV,
                                               rspi_pd->dma_tx_id,
                                               res->start + RSPI_SPDR);
        if (!master->dma_tx) {
                dma_release_channel(master->dma_rx);
                master->dma_rx = NULL;
                return -ENODEV;
        }

        master->can_dma = rspi_can_dma;
        dev_info(dev, "DMA available");
        return 0;
}

static void rspi_release_dma(struct spi_master *master)
{
        if (master->dma_tx)
                dma_release_channel(master->dma_tx);
        if (master->dma_rx)
                dma_release_channel(master->dma_rx);
}

static int rspi_remove(struct platform_device *pdev)
{
        struct rspi_data *rspi = platform_get_drvdata(pdev);

        rspi_release_dma(rspi->master);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

static const struct spi_ops rspi_ops = {
        .set_config_register =  rspi_set_config_register,
        .transfer_one =         rspi_transfer_one,
        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP,
        .flags =                SPI_MASTER_MUST_TX,
        .fifo_size =            8,
};

static const struct spi_ops rspi_rz_ops = {
        .set_config_register =  rspi_rz_set_config_register,
        .transfer_one =         rspi_rz_transfer_one,
        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP,
        .flags =                SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
        .fifo_size =            8,      /* 8 for TX, 32 for RX */
};

static const struct spi_ops qspi_ops = {
        .set_config_register =  qspi_set_config_register,

        .transfer_one =         qspi_transfer_one,
        .mode_bits =            SPI_CPHA | SPI_CPOL | SPI_LOOP |
                                SPI_TX_DUAL | SPI_TX_QUAD |
                                SPI_RX_DUAL | SPI_RX_QUAD,
        .flags =                SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
        .fifo_size =            32,
};

#ifdef CONFIG_OF
static const struct of_device_id rspi_of_match[] = {
        /* RSPI on legacy SH */
        { .compatible = "renesas,rspi", .data = &rspi_ops },
        /* RSPI on RZ/A1H */
        { .compatible = "renesas,rspi-rz", .data = &rspi_rz_ops },
        /* QSPI on R-Car Gen2 */
        { .compatible = "renesas,qspi", .data = &qspi_ops },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, rspi_of_match);

static int rspi_parse_dt(struct device *dev, struct spi_master *master)
{
        u32 num_cs;
        int error;

        /* Parse DT properties */
        error = of_property_read_u32(dev->of_node, "num-cs", &num_cs);
        if (error) {
                dev_err(dev, "of_property_read_u32 num-cs failed %d\n", error);
                return error;
        }

        master->num_chipselect = num_cs;
        return 0;
}
#else
#define rspi_of_match   NULL
static inline int rspi_parse_dt(struct device *dev, struct spi_master *master)
{
        return -EINVAL;
}
#endif /* CONFIG_OF */

static int rspi_request_irq(struct device *dev, unsigned int irq,
                            irq_handler_t handler, const char *suffix,
                            void *dev_id)
{
        const char *base = dev_name(dev);
        size_t len = strlen(base) + strlen(suffix) + 2;
        char *name = devm_kzalloc(dev, len, GFP_KERNEL);
        if (!name)
                return -ENOMEM;
        snprintf(name, len, "%s:%s", base, suffix);
        return devm_request_irq(dev, irq, handler, 0, name, dev_id);
}

static int rspi_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct spi_master *master;
        struct rspi_data *rspi;
        int ret;
        const struct of_device_id *of_id;
        const struct rspi_plat_data *rspi_pd;
        const struct spi_ops *ops;

        master = spi_alloc_master(&pdev->dev, sizeof(struct rspi_data));
        if (master == NULL) {
                dev_err(&pdev->dev, "spi_alloc_master error.\n");
                return -ENOMEM;
        }

        of_id = of_match_device(rspi_of_match, &pdev->dev);
        if (of_id) {
                ops = of_id->data;
                ret = rspi_parse_dt(&pdev->dev, master);
                if (ret)
                        goto error1;
        } else {
                ops = (struct spi_ops *)pdev->id_entry->driver_data;
                rspi_pd = dev_get_platdata(&pdev->dev);
                if (rspi_pd && rspi_pd->num_chipselect)
                        master->num_chipselect = rspi_pd->num_chipselect;
                else
                        master->num_chipselect = 2; /* default */
        };

        /* ops parameter check */
        if (!ops->set_config_register) {
                dev_err(&pdev->dev, "there is no set_config_register\n");
                ret = -ENODEV;
                goto error1;
        }

        rspi = spi_master_get_devdata(master);
        platform_set_drvdata(pdev, rspi);
        rspi->ops = ops;
        rspi->master = master;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        rspi->addr = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(rspi->addr)) {
                ret = PTR_ERR(rspi->addr);
                goto error1;
        }

        rspi->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(rspi->clk)) {
                dev_err(&pdev->dev, "cannot get clock\n");
                ret = PTR_ERR(rspi->clk);
                goto error1;
        }

        pm_runtime_enable(&pdev->dev);

        init_waitqueue_head(&rspi->wait);

        master->bus_num = pdev->id;
        master->setup = rspi_setup;
        master->auto_runtime_pm = true;
        master->transfer_one = ops->transfer_one;
        master->prepare_message = rspi_prepare_message;
        master->unprepare_message = rspi_unprepare_message;
        master->mode_bits = ops->mode_bits;
        master->flags = ops->flags;
        master->dev.of_node = pdev->dev.of_node;

        ret = platform_get_irq_byname(pdev, "rx");
        if (ret < 0) {
                ret = platform_get_irq_byname(pdev, "mux");
                if (ret < 0)
                        ret = platform_get_irq(pdev, 0);
                if (ret >= 0)
                        rspi->rx_irq = rspi->tx_irq = ret;
        } else {
                rspi->rx_irq = ret;
                ret = platform_get_irq_byname(pdev, "tx");
                if (ret >= 0)
                        rspi->tx_irq = ret;
        }
        if (ret < 0) {
                dev_err(&pdev->dev, "platform_get_irq error\n");
                goto error2;
        }

        if (rspi->rx_irq == rspi->tx_irq) {
                /* Single multiplexed interrupt */
                ret = rspi_request_irq(&pdev->dev, rspi->rx_irq, rspi_irq_mux,
                                       "mux", rspi);
        } else {
                /* Multi-interrupt mode, only SPRI and SPTI are used */
                ret = rspi_request_irq(&pdev->dev, rspi->rx_irq, rspi_irq_rx,
                                       "rx", rspi);
                if (!ret)
                        ret = rspi_request_irq(&pdev->dev, rspi->tx_irq,
                                               rspi_irq_tx, "tx", rspi);
        }
        if (ret < 0) {
                dev_err(&pdev->dev, "request_irq error\n");
                goto error2;
        }

        ret = rspi_request_dma(&pdev->dev, master, res);
        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 error3;
        }

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

        return 0;

error3:
        rspi_release_dma(master);
error2:
        pm_runtime_disable(&pdev->dev);
error1:
        spi_master_put(master);

        return ret;
}

static struct platform_device_id spi_driver_ids[] = {
        { "rspi",       (kernel_ulong_t)&rspi_ops },
        { "rspi-rz",    (kernel_ulong_t)&rspi_rz_ops },
        { "qspi",       (kernel_ulong_t)&qspi_ops },
        {},
};

MODULE_DEVICE_TABLE(platform, spi_driver_ids);

static struct platform_driver rspi_driver = {
        .probe =        rspi_probe,
        .remove =       rspi_remove,
        .id_table =     spi_driver_ids,
        .driver         = {
                .name = "renesas_spi",
                .owner  = THIS_MODULE,
                .of_match_table = of_match_ptr(rspi_of_match),
        },
};
module_platform_driver(rspi_driver);

MODULE_DESCRIPTION("Renesas RSPI bus driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Yoshihiro Shimoda");
MODULE_ALIAS("platform:rspi");