/*
 * Broadcom BCM63XX High Speed SPI Controller driver
 *
 * Copyright 2000-2010 Broadcom Corporation
 * Copyright 2012-2013 Jonas Gorski <jonas.gorski@gmail.com>
 *
 * Licensed under the GNU/GPL. See COPYING for details.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/spi/spi.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/spi/spi-mem.h>
#include <linux/mtd/spi-nor.h>
#include <linux/reset.h>
#include <linux/pm_runtime.h>

#define HSSPI_GLOBAL_CTRL_REG                   0x0
#define GLOBAL_CTRL_CS_POLARITY_SHIFT           0
#define GLOBAL_CTRL_CS_POLARITY_MASK            0x000000ff
#define GLOBAL_CTRL_PLL_CLK_CTRL_SHIFT          8
#define GLOBAL_CTRL_PLL_CLK_CTRL_MASK           0x0000ff00
#define GLOBAL_CTRL_CLK_GATE_SSOFF              BIT(16)
#define GLOBAL_CTRL_CLK_POLARITY                BIT(17)
#define GLOBAL_CTRL_MOSI_IDLE                   BIT(18)

#define HSSPI_GLOBAL_EXT_TRIGGER_REG            0x4

#define HSSPI_INT_STATUS_REG                    0x8
#define HSSPI_INT_STATUS_MASKED_REG             0xc
#define HSSPI_INT_MASK_REG                      0x10

#define HSSPI_PINGx_CMD_DONE(i)                 BIT((i * 8) + 0)
#define HSSPI_PINGx_RX_OVER(i)                  BIT((i * 8) + 1)
#define HSSPI_PINGx_TX_UNDER(i)                 BIT((i * 8) + 2)
#define HSSPI_PINGx_POLL_TIMEOUT(i)             BIT((i * 8) + 3)
#define HSSPI_PINGx_CTRL_INVAL(i)               BIT((i * 8) + 4)

#define HSSPI_INT_CLEAR_ALL                     0xff001f1f

#define HSSPI_PINGPONG_COMMAND_REG(x)           (0x80 + (x) * 0x40)
#define PINGPONG_CMD_COMMAND_MASK               0xf
#define PINGPONG_COMMAND_NOOP                   0
#define PINGPONG_COMMAND_START_NOW              1
#define PINGPONG_COMMAND_START_TRIGGER          2
#define PINGPONG_COMMAND_HALT                   3
#define PINGPONG_COMMAND_FLUSH                  4
#define PINGPONG_CMD_PROFILE_SHIFT              8
#define PINGPONG_CMD_SS_SHIFT                   12

#define HSSPI_PINGPONG_STATUS_REG(x)            (0x84 + (x) * 0x40)
#define HSSPI_PINGPONG_STATUS_SRC_BUSY          BIT(1)

#define HSSPI_PROFILE_CLK_CTRL_REG(x)           (0x100 + (x) * 0x20)
#define CLK_CTRL_FREQ_CTRL_MASK                 0x0000ffff
#define CLK_CTRL_SPI_CLK_2X_SEL                 BIT(14)
#define CLK_CTRL_ACCUM_RST_ON_LOOP              BIT(15)

#define HSSPI_PROFILE_SIGNAL_CTRL_REG(x)        (0x104 + (x) * 0x20)
#define SIGNAL_CTRL_LATCH_RISING                BIT(12)
#define SIGNAL_CTRL_LAUNCH_RISING               BIT(13)
#define SIGNAL_CTRL_ASYNC_INPUT_PATH            BIT(16)

#define HSSPI_PROFILE_MODE_CTRL_REG(x)          (0x108 + (x) * 0x20)
#define MODE_CTRL_MULTIDATA_RD_STRT_SHIFT       8
#define MODE_CTRL_MULTIDATA_WR_STRT_SHIFT       12
#define MODE_CTRL_MULTIDATA_RD_SIZE_SHIFT       16
#define MODE_CTRL_MULTIDATA_WR_SIZE_SHIFT       18
#define MODE_CTRL_MODE_3WIRE                    BIT(20)
#define MODE_CTRL_PREPENDBYTE_CNT_SHIFT         24

#define HSSPI_FIFO_REG(x)                       (0x200 + (x) * 0x200)


#define HSSPI_OP_MULTIBIT                       BIT(11)
#define HSSPI_OP_CODE_SHIFT                     13
#define HSSPI_OP_SLEEP                          (0 << HSSPI_OP_CODE_SHIFT)
#define HSSPI_OP_READ_WRITE                     (1 << HSSPI_OP_CODE_SHIFT)
#define HSSPI_OP_WRITE                          (2 << HSSPI_OP_CODE_SHIFT)
#define HSSPI_OP_READ                           (3 << HSSPI_OP_CODE_SHIFT)
#define HSSPI_OP_SETIRQ                         (4 << HSSPI_OP_CODE_SHIFT)

#define HSSPI_BUFFER_LEN                        512
#define HSSPI_OPCODE_LEN                        2

#define HSSPI_MAX_PREPEND_LEN                   15

/*
 * Some chip require 30MHz but other require 25MHz. Use smaller value to cover
 * both cases.
 */
#define HSSPI_MAX_SYNC_CLOCK                    25000000

#define HSSPI_SPI_MAX_CS                        8
#define HSSPI_BUS_NUM                           1 /* 0 is legacy SPI */
#define HSSPI_POLL_STATUS_TIMEOUT_MS    100

#define HSSPI_WAIT_MODE_POLLING         0
#define HSSPI_WAIT_MODE_INTR            1
#define HSSPI_WAIT_MODE_MAX                     HSSPI_WAIT_MODE_INTR

/*
 * Default transfer mode is auto. If the msg is prependable, use the prepend
 * mode.  If not, falls back to use the dummy cs workaround mode but limit the
 * clock to 25MHz to make sure it works in all board design.
 */
#define HSSPI_XFER_MODE_AUTO            0
#define HSSPI_XFER_MODE_PREPEND         1
#define HSSPI_XFER_MODE_DUMMYCS         2
#define HSSPI_XFER_MODE_MAX                     HSSPI_XFER_MODE_DUMMYCS

#define bcm63xx_prepend_printk_on_checkfail(bs, fmt, ...)       \
do {                                                                            \
        if (bs->xfer_mode == HSSPI_XFER_MODE_AUTO)                              \
                dev_dbg(&bs->pdev->dev, fmt, ##__VA_ARGS__);            \
        else if (bs->xfer_mode == HSSPI_XFER_MODE_PREPEND)              \
                dev_err(&bs->pdev->dev, fmt, ##__VA_ARGS__);            \
} while (0)

struct bcm63xx_hsspi {
        struct completion done;
        struct mutex bus_mutex;
        struct mutex msg_mutex;
        struct platform_device *pdev;
        struct clk *clk;
        struct clk *pll_clk;
        void __iomem *regs;
        u8 __iomem *fifo;

        u32 speed_hz;
        u8 cs_polarity;
        u32 wait_mode;
        u32 xfer_mode;
        u32 prepend_cnt;
        u32 md_start;
        u8 *prepend_buf;
};

static ssize_t wait_mode_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct spi_controller *ctrl = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(ctrl);

        return sprintf(buf, "%d\n", bs->wait_mode);
}

static ssize_t wait_mode_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct spi_controller *ctrl = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(ctrl);
        u32 val;

        if (kstrtou32(buf, 10, &val))
                return -EINVAL;

        if (val > HSSPI_WAIT_MODE_MAX) {
                dev_warn(dev, "invalid wait mode %u\n", val);
                return -EINVAL;
        }

        mutex_lock(&bs->msg_mutex);
        bs->wait_mode = val;
        /* clear interrupt status to avoid spurious int on next transfer */
        if (val == HSSPI_WAIT_MODE_INTR)
                __raw_writel(HSSPI_INT_CLEAR_ALL, bs->regs + HSSPI_INT_STATUS_REG);
        mutex_unlock(&bs->msg_mutex);

        return count;
}

static DEVICE_ATTR_RW(wait_mode);

static ssize_t xfer_mode_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct spi_controller *ctrl = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(ctrl);

        return sprintf(buf, "%d\n", bs->xfer_mode);
}

static ssize_t xfer_mode_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct spi_controller *ctrl = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(ctrl);
        u32 val;

        if (kstrtou32(buf, 10, &val))
                return -EINVAL;

        if (val > HSSPI_XFER_MODE_MAX) {
                dev_warn(dev, "invalid xfer mode %u\n", val);
                return -EINVAL;
        }

        mutex_lock(&bs->msg_mutex);
        bs->xfer_mode = val;
        mutex_unlock(&bs->msg_mutex);

        return count;
}

static DEVICE_ATTR_RW(xfer_mode);

static struct attribute *bcm63xx_hsspi_attrs[] = {
        &dev_attr_wait_mode.attr,
        &dev_attr_xfer_mode.attr,
        NULL,
};

static const struct attribute_group bcm63xx_hsspi_group = {
        .attrs = bcm63xx_hsspi_attrs,
};

static void bcm63xx_hsspi_set_clk(struct bcm63xx_hsspi *bs,
                                  struct spi_device *spi, int hz);

static size_t bcm63xx_hsspi_max_message_size(struct spi_device *spi)
{
        return HSSPI_BUFFER_LEN - HSSPI_OPCODE_LEN;
}

static int bcm63xx_hsspi_wait_cmd(struct bcm63xx_hsspi *bs)
{
        unsigned long limit;
        u32 reg = 0;
        int rc = 0;

        if (bs->wait_mode == HSSPI_WAIT_MODE_INTR) {
                if (wait_for_completion_timeout(&bs->done, HZ) == 0)
                        rc = 1;
        } else {
                /* polling mode checks for status busy bit */
                limit = jiffies + msecs_to_jiffies(HSSPI_POLL_STATUS_TIMEOUT_MS);

                while (!time_after(jiffies, limit)) {
                        reg = __raw_readl(bs->regs + HSSPI_PINGPONG_STATUS_REG(0));
                        if (reg & HSSPI_PINGPONG_STATUS_SRC_BUSY)
                                cpu_relax();
                        else
                                break;
                }
                if (reg & HSSPI_PINGPONG_STATUS_SRC_BUSY)
                        rc = 1;
        }

        if (rc)
                dev_err(&bs->pdev->dev, "transfer timed out!\n");

        return rc;
}

static bool bcm63xx_prepare_prepend_transfer(struct spi_controller *host,
                                          struct spi_message *msg,
                                          struct spi_transfer *t_prepend)
{

        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(host);
        bool tx_only = false, multidata = false;
        struct spi_transfer *t;

        /*
         * Multiple transfers within a message may be combined into one transfer
         * to the controller using its prepend feature. A SPI message is prependable
         * only if the following are all true:
         *   1. One or more half duplex write transfers at the start
         *   2. Optional switch from single to dual bit within the write transfers
         *   3. Optional full duplex read/write at the end if all single bit
         *   4. No delay and cs_change between transfers
         */
        bs->prepend_cnt = 0;
        bs->md_start = 0;
        list_for_each_entry(t, &msg->transfers, transfer_list) {
                if ((spi_delay_to_ns(&t->delay, t) > 0) || t->cs_change) {
                        bcm63xx_prepend_printk_on_checkfail(bs,
                                 "Delay or cs change not supported in prepend mode!\n");
                        return false;
                }

                tx_only = false;
                if (t->tx_buf && !t->rx_buf) {
                        tx_only = true;
                        if (bs->prepend_cnt + t->len >
                                (HSSPI_BUFFER_LEN - HSSPI_OPCODE_LEN)) {
                                bcm63xx_prepend_printk_on_checkfail(bs,
                                         "exceed max buf len, abort prepending transfers!\n");
                                return false;
                        }

                        if (t->tx_nbits == SPI_NBITS_SINGLE &&
                            !list_is_last(&t->transfer_list, &msg->transfers) &&
                            multidata) {
                                bcm63xx_prepend_printk_on_checkfail(bs,
                                         "single-bit after multi-bit not supported!\n");
                                return false;
                        }

                        if (t->tx_nbits > SPI_NBITS_SINGLE)
                                multidata = true;

                        memcpy(bs->prepend_buf + bs->prepend_cnt, t->tx_buf, t->len);
                        bs->prepend_cnt += t->len;

                        if (t->tx_nbits == SPI_NBITS_SINGLE)
                                bs->md_start += t->len;

                } else {
                        if (!list_is_last(&t->transfer_list, &msg->transfers)) {
                                bcm63xx_prepend_printk_on_checkfail(bs,
                                         "rx/tx_rx transfer not supported when it is not last one!\n");
                                return false;
                        }

                        if (t->rx_buf && t->rx_nbits == SPI_NBITS_SINGLE &&
                            multidata) {
                                bcm63xx_prepend_printk_on_checkfail(bs,
                                         "single-bit after multi-bit not supported!\n");
                                return false;
                        }
                }

                if (list_is_last(&t->transfer_list, &msg->transfers)) {
                        memcpy(t_prepend, t, sizeof(struct spi_transfer));

                        if (tx_only) {
                                /*
                                 * if the last one is also a tx only transfer, merge
                                 * all of them into one single tx transfer
                                 */
                                t_prepend->len = bs->prepend_cnt;
                                t_prepend->tx_buf = bs->prepend_buf;
                                bs->prepend_cnt = 0;
                        } else {
                                /*
                                 * if the last one is not a tx only transfer, all
                                 * the previous transfers are sent through prepend bytes and
                                 * make sure it does not exceed the max prepend len
                                 */
                                if (bs->prepend_cnt > HSSPI_MAX_PREPEND_LEN) {
                                        bcm63xx_prepend_printk_on_checkfail(bs,
                                                "exceed max prepend len, abort prepending transfers!\n");
                                        return false;
                                }
                        }
                        /*
                         * If switching from single-bit to multi-bit, make sure
                         * the start offset does not exceed the maximum
                         */
                        if (multidata && bs->md_start > HSSPI_MAX_PREPEND_LEN) {
                                bcm63xx_prepend_printk_on_checkfail(bs,
                                        "exceed max multi-bit offset, abort prepending transfers!\n");
                                return false;
                        }
                }
        }

        return true;
}

static int bcm63xx_hsspi_do_prepend_txrx(struct spi_device *spi,
                                         struct spi_transfer *t)
{
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(spi->controller);
        unsigned int chip_select = spi_get_chipselect(spi, 0);
        u16 opcode = 0, val;
        const u8 *tx = t->tx_buf;
        u8 *rx = t->rx_buf;
        u32 reg = 0;

        /*
         * shouldn't happen as we set the max_message_size in the probe.
         * but check it again in case some driver does not honor the max size
         */
        if (t->len + bs->prepend_cnt > (HSSPI_BUFFER_LEN - HSSPI_OPCODE_LEN)) {
                dev_warn(&bs->pdev->dev,
                         "Prepend message large than fifo size len %d prepend %d\n",
                         t->len, bs->prepend_cnt);
                return -EINVAL;
        }

        bcm63xx_hsspi_set_clk(bs, spi, t->speed_hz);

        if (tx && rx)
                opcode = HSSPI_OP_READ_WRITE;
        else if (tx)
                opcode = HSSPI_OP_WRITE;
        else if (rx)
                opcode = HSSPI_OP_READ;

        if ((opcode == HSSPI_OP_READ && t->rx_nbits == SPI_NBITS_DUAL) ||
            (opcode == HSSPI_OP_WRITE && t->tx_nbits == SPI_NBITS_DUAL)) {
                opcode |= HSSPI_OP_MULTIBIT;

                if (t->rx_nbits == SPI_NBITS_DUAL) {
                        reg |= 1 << MODE_CTRL_MULTIDATA_RD_SIZE_SHIFT;
                        reg |= bs->md_start << MODE_CTRL_MULTIDATA_RD_STRT_SHIFT;
                }
                if (t->tx_nbits == SPI_NBITS_DUAL) {
                        reg |= 1 << MODE_CTRL_MULTIDATA_WR_SIZE_SHIFT;
                        reg |= bs->md_start << MODE_CTRL_MULTIDATA_WR_STRT_SHIFT;
                }
        }

        reg |= bs->prepend_cnt << MODE_CTRL_PREPENDBYTE_CNT_SHIFT;
        __raw_writel(reg | 0xff,
                     bs->regs + HSSPI_PROFILE_MODE_CTRL_REG(chip_select));

        reinit_completion(&bs->done);
        if (bs->prepend_cnt)
                memcpy_toio(bs->fifo + HSSPI_OPCODE_LEN, bs->prepend_buf,
                            bs->prepend_cnt);
        if (tx)
                memcpy_toio(bs->fifo + HSSPI_OPCODE_LEN + bs->prepend_cnt, tx,
                            t->len);

        *(__be16 *)(&val) = cpu_to_be16(opcode | t->len);
        __raw_writew(val, bs->fifo);
        /* enable interrupt */
        if (bs->wait_mode == HSSPI_WAIT_MODE_INTR)
                __raw_writel(HSSPI_PINGx_CMD_DONE(0), bs->regs + HSSPI_INT_MASK_REG);

        /* start the transfer */
        reg = chip_select << PINGPONG_CMD_SS_SHIFT |
            chip_select << PINGPONG_CMD_PROFILE_SHIFT |
            PINGPONG_COMMAND_START_NOW;
        __raw_writel(reg, bs->regs + HSSPI_PINGPONG_COMMAND_REG(0));

        if (bcm63xx_hsspi_wait_cmd(bs))
                return -ETIMEDOUT;

        if (rx)
                memcpy_fromio(rx, bs->fifo, t->len);

        return 0;
}

static void bcm63xx_hsspi_set_cs(struct bcm63xx_hsspi *bs, unsigned int cs,
                                 bool active)
{
        u32 reg;

        mutex_lock(&bs->bus_mutex);
        reg = __raw_readl(bs->regs + HSSPI_GLOBAL_CTRL_REG);

        reg &= ~BIT(cs);
        if (active == !(bs->cs_polarity & BIT(cs)))
                reg |= BIT(cs);

        __raw_writel(reg, bs->regs + HSSPI_GLOBAL_CTRL_REG);
        mutex_unlock(&bs->bus_mutex);
}

static void bcm63xx_hsspi_set_clk(struct bcm63xx_hsspi *bs,
                                  struct spi_device *spi, int hz)
{
        unsigned int profile = spi_get_chipselect(spi, 0);
        u32 reg;

        reg = DIV_ROUND_UP(2048, DIV_ROUND_UP(bs->speed_hz, hz));
        __raw_writel(CLK_CTRL_ACCUM_RST_ON_LOOP | reg,
                     bs->regs + HSSPI_PROFILE_CLK_CTRL_REG(profile));

        reg = __raw_readl(bs->regs + HSSPI_PROFILE_SIGNAL_CTRL_REG(profile));
        if (hz > HSSPI_MAX_SYNC_CLOCK)
                reg |= SIGNAL_CTRL_ASYNC_INPUT_PATH;
        else
                reg &= ~SIGNAL_CTRL_ASYNC_INPUT_PATH;
        __raw_writel(reg, bs->regs + HSSPI_PROFILE_SIGNAL_CTRL_REG(profile));

        mutex_lock(&bs->bus_mutex);
        /* setup clock polarity */
        reg = __raw_readl(bs->regs + HSSPI_GLOBAL_CTRL_REG);
        reg &= ~GLOBAL_CTRL_CLK_POLARITY;
        if (spi->mode & SPI_CPOL)
                reg |= GLOBAL_CTRL_CLK_POLARITY;
        __raw_writel(reg, bs->regs + HSSPI_GLOBAL_CTRL_REG);
        mutex_unlock(&bs->bus_mutex);
}

static int bcm63xx_hsspi_do_txrx(struct spi_device *spi, struct spi_transfer *t)
{
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(spi->controller);
        unsigned int chip_select = spi_get_chipselect(spi, 0);
        u16 opcode = 0, val;
        int pending = t->len;
        int step_size = HSSPI_BUFFER_LEN;
        const u8 *tx = t->tx_buf;
        u8 *rx = t->rx_buf;
        u32 reg = 0;

        bcm63xx_hsspi_set_clk(bs, spi, t->speed_hz);
        if (!t->cs_off)
                bcm63xx_hsspi_set_cs(bs, spi_get_chipselect(spi, 0), true);

        if (tx && rx)
                opcode = HSSPI_OP_READ_WRITE;
        else if (tx)
                opcode = HSSPI_OP_WRITE;
        else if (rx)
                opcode = HSSPI_OP_READ;

        if (opcode != HSSPI_OP_READ)
                step_size -= HSSPI_OPCODE_LEN;

        if ((opcode == HSSPI_OP_READ && t->rx_nbits == SPI_NBITS_DUAL) ||
            (opcode == HSSPI_OP_WRITE && t->tx_nbits == SPI_NBITS_DUAL)) {
                opcode |= HSSPI_OP_MULTIBIT;

                if (t->rx_nbits == SPI_NBITS_DUAL)
                        reg |= 1 << MODE_CTRL_MULTIDATA_RD_SIZE_SHIFT;
                if (t->tx_nbits == SPI_NBITS_DUAL)
                        reg |= 1 << MODE_CTRL_MULTIDATA_WR_SIZE_SHIFT;
        }

        __raw_writel(reg | 0xff,
                     bs->regs + HSSPI_PROFILE_MODE_CTRL_REG(chip_select));

        while (pending > 0) {
                int curr_step = min_t(int, step_size, pending);

                reinit_completion(&bs->done);
                if (tx) {
                        memcpy_toio(bs->fifo + HSSPI_OPCODE_LEN, tx, curr_step);
                        tx += curr_step;
                }

                *(__be16 *)(&val) = cpu_to_be16(opcode | curr_step);
                __raw_writew(val, bs->fifo);

                /* enable interrupt */
                if (bs->wait_mode == HSSPI_WAIT_MODE_INTR)
                        __raw_writel(HSSPI_PINGx_CMD_DONE(0),
                                     bs->regs + HSSPI_INT_MASK_REG);

                reg =  !chip_select << PINGPONG_CMD_SS_SHIFT |
                            chip_select << PINGPONG_CMD_PROFILE_SHIFT |
                            PINGPONG_COMMAND_START_NOW;
                __raw_writel(reg, bs->regs + HSSPI_PINGPONG_COMMAND_REG(0));

                if (bcm63xx_hsspi_wait_cmd(bs))
                        return -ETIMEDOUT;

                if (rx) {
                        memcpy_fromio(rx, bs->fifo, curr_step);
                        rx += curr_step;
                }

                pending -= curr_step;
        }

        return 0;
}

static int bcm63xx_hsspi_setup(struct spi_device *spi)
{
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(spi->controller);
        u32 reg;

        reg = __raw_readl(bs->regs +
                          HSSPI_PROFILE_SIGNAL_CTRL_REG(spi_get_chipselect(spi, 0)));
        reg &= ~(SIGNAL_CTRL_LAUNCH_RISING | SIGNAL_CTRL_LATCH_RISING);
        if (spi->mode & SPI_CPHA)
                reg |= SIGNAL_CTRL_LAUNCH_RISING;
        else
                reg |= SIGNAL_CTRL_LATCH_RISING;
        __raw_writel(reg, bs->regs +
                     HSSPI_PROFILE_SIGNAL_CTRL_REG(spi_get_chipselect(spi, 0)));

        mutex_lock(&bs->bus_mutex);
        reg = __raw_readl(bs->regs + HSSPI_GLOBAL_CTRL_REG);

        /* only change actual polarities if there is no transfer */
        if ((reg & GLOBAL_CTRL_CS_POLARITY_MASK) == bs->cs_polarity) {
                if (spi->mode & SPI_CS_HIGH)
                        reg |= BIT(spi_get_chipselect(spi, 0));
                else
                        reg &= ~BIT(spi_get_chipselect(spi, 0));
                __raw_writel(reg, bs->regs + HSSPI_GLOBAL_CTRL_REG);
        }

        if (spi->mode & SPI_CS_HIGH)
                bs->cs_polarity |= BIT(spi_get_chipselect(spi, 0));
        else
                bs->cs_polarity &= ~BIT(spi_get_chipselect(spi, 0));

        mutex_unlock(&bs->bus_mutex);

        return 0;
}

static int bcm63xx_hsspi_do_dummy_cs_txrx(struct spi_device *spi,
                                      struct spi_message *msg)
{
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(spi->controller);
        int status = -EINVAL;
        int dummy_cs;
        bool keep_cs = false;
        struct spi_transfer *t;

        /*
         * This controller does not support keeping CS active during idle.
         * To work around this, we use the following ugly hack:
         *
         * a. Invert the target chip select's polarity so it will be active.
         * b. Select a "dummy" chip select to use as the hardware target.
         * c. Invert the dummy chip select's polarity so it will be inactive
         *    during the actual transfers.
         * d. Tell the hardware to send to the dummy chip select. Thanks to
         *    the multiplexed nature of SPI the actual target will receive
         *    the transfer and we see its response.
         *
         * e. At the end restore the polarities again to their default values.
         */

        dummy_cs = !spi_get_chipselect(spi, 0);
        bcm63xx_hsspi_set_cs(bs, dummy_cs, true);

        list_for_each_entry(t, &msg->transfers, transfer_list) {
                /*
                 * We are here because one of reasons below:
                 * a. Message is not prependable and in default auto xfer mode. This mean
                 *    we fallback to dummy cs mode at maximum 25MHz safe clock rate.
                 * b. User set to use the dummy cs mode.
                 */
                if (bs->xfer_mode == HSSPI_XFER_MODE_AUTO) {
                        if (t->speed_hz > HSSPI_MAX_SYNC_CLOCK) {
                                t->speed_hz = HSSPI_MAX_SYNC_CLOCK;
                                dev_warn_once(&bs->pdev->dev,
                                        "Force to dummy cs mode. Reduce the speed to %dHz",
                                        t->speed_hz);
                        }
                }

                status = bcm63xx_hsspi_do_txrx(spi, t);
                if (status)
                        break;

                msg->actual_length += t->len;

                spi_transfer_delay_exec(t);

                /* use existing cs change logic from spi_transfer_one_message */
                if (t->cs_change) {
                        if (list_is_last(&t->transfer_list, &msg->transfers)) {
                                keep_cs = true;
                        } else {
                                if (!t->cs_off)
                                        bcm63xx_hsspi_set_cs(bs, spi_get_chipselect(spi, 0), false);

                                spi_transfer_cs_change_delay_exec(msg, t);

                                if (!list_next_entry(t, transfer_list)->cs_off)
                                        bcm63xx_hsspi_set_cs(bs, spi_get_chipselect(spi, 0), true);
                        }
                } else if (!list_is_last(&t->transfer_list, &msg->transfers) &&
                           t->cs_off != list_next_entry(t, transfer_list)->cs_off) {
                        bcm63xx_hsspi_set_cs(bs, spi_get_chipselect(spi, 0), t->cs_off);
                }
        }

        bcm63xx_hsspi_set_cs(bs, dummy_cs, false);
        if (status || !keep_cs)
                bcm63xx_hsspi_set_cs(bs, spi_get_chipselect(spi, 0), false);

        return status;
}

static int bcm63xx_hsspi_transfer_one(struct spi_controller *host,
                                      struct spi_message *msg)
{
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(host);
        struct spi_device *spi = msg->spi;
        int status = -EINVAL;
        bool prependable = false;
        struct spi_transfer t_prepend;

        mutex_lock(&bs->msg_mutex);

        if (bs->xfer_mode != HSSPI_XFER_MODE_DUMMYCS)
                prependable = bcm63xx_prepare_prepend_transfer(host, msg, &t_prepend);

        if (prependable) {
                status = bcm63xx_hsspi_do_prepend_txrx(spi, &t_prepend);
                msg->actual_length = (t_prepend.len + bs->prepend_cnt);
        } else {
                if (bs->xfer_mode == HSSPI_XFER_MODE_PREPEND) {
                        dev_err(&bs->pdev->dev,
                                "User sets prepend mode but msg not prependable! Abort transfer\n");
                        status = -EINVAL;
                } else
                        status = bcm63xx_hsspi_do_dummy_cs_txrx(spi, msg);
        }

        mutex_unlock(&bs->msg_mutex);
        msg->status = status;
        spi_finalize_current_message(host);

        return 0;
}

static bool bcm63xx_hsspi_mem_supports_op(struct spi_mem *mem,
                            const struct spi_mem_op *op)
{
        if (!spi_mem_default_supports_op(mem, op))
                return false;

        return true;
}

static const struct spi_controller_mem_ops bcm63xx_hsspi_mem_ops = {
        .supports_op = bcm63xx_hsspi_mem_supports_op,
};

static irqreturn_t bcm63xx_hsspi_interrupt(int irq, void *dev_id)
{
        struct bcm63xx_hsspi *bs = (struct bcm63xx_hsspi *)dev_id;

        if (__raw_readl(bs->regs + HSSPI_INT_STATUS_MASKED_REG) == 0)
                return IRQ_NONE;

        __raw_writel(HSSPI_INT_CLEAR_ALL, bs->regs + HSSPI_INT_STATUS_REG);
        __raw_writel(0, bs->regs + HSSPI_INT_MASK_REG);

        complete(&bs->done);

        return IRQ_HANDLED;
}

static int bcm63xx_hsspi_probe(struct platform_device *pdev)
{
        struct spi_controller *host;
        struct bcm63xx_hsspi *bs;
        void __iomem *regs;
        struct device *dev = &pdev->dev;
        struct clk *clk, *pll_clk = NULL;
        int irq, ret;
        u32 reg, rate, num_cs = HSSPI_SPI_MAX_CS;
        struct reset_control *reset;

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

        regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(regs))
                return PTR_ERR(regs);

        clk = devm_clk_get(dev, "hsspi");

        if (IS_ERR(clk))
                return PTR_ERR(clk);

        reset = devm_reset_control_get_optional_shared(dev, NULL);
        if (IS_ERR(reset))
                return PTR_ERR(reset);

        ret = clk_prepare_enable(clk);
        if (ret)
                return ret;

        ret = reset_control_reset(reset);
        if (ret) {
                dev_err(dev, "unable to reset device: %d\n", ret);
                goto out_disable_clk;
        }

        rate = clk_get_rate(clk);
        if (!rate) {
                pll_clk = devm_clk_get(dev, "pll");

                if (IS_ERR(pll_clk)) {
                        ret = PTR_ERR(pll_clk);
                        goto out_disable_clk;
                }

                ret = clk_prepare_enable(pll_clk);
                if (ret)
                        goto out_disable_clk;

                rate = clk_get_rate(pll_clk);
                if (!rate) {
                        ret = -EINVAL;
                        goto out_disable_pll_clk;
                }
        }

        host = spi_alloc_host(&pdev->dev, sizeof(*bs));
        if (!host) {
                ret = -ENOMEM;
                goto out_disable_pll_clk;
        }

        bs = spi_controller_get_devdata(host);
        bs->pdev = pdev;
        bs->clk = clk;
        bs->pll_clk = pll_clk;
        bs->regs = regs;
        bs->speed_hz = rate;
        bs->fifo = (u8 __iomem *)(bs->regs + HSSPI_FIFO_REG(0));
        bs->wait_mode = HSSPI_WAIT_MODE_POLLING;
        bs->prepend_buf = devm_kzalloc(dev, HSSPI_BUFFER_LEN, GFP_KERNEL);
        if (!bs->prepend_buf) {
                ret = -ENOMEM;
                goto out_put_host;
        }

        mutex_init(&bs->bus_mutex);
        mutex_init(&bs->msg_mutex);
        init_completion(&bs->done);

        host->mem_ops = &bcm63xx_hsspi_mem_ops;
        if (!dev->of_node)
                host->bus_num = HSSPI_BUS_NUM;

        of_property_read_u32(dev->of_node, "num-cs", &num_cs);
        if (num_cs > 8) {
                dev_warn(dev, "unsupported number of cs (%i), reducing to 8\n",
                         num_cs);
                num_cs = HSSPI_SPI_MAX_CS;
        }
        host->num_chipselect = num_cs;
        host->setup = bcm63xx_hsspi_setup;
        host->transfer_one_message = bcm63xx_hsspi_transfer_one;
        host->max_transfer_size = bcm63xx_hsspi_max_message_size;
        host->max_message_size = bcm63xx_hsspi_max_message_size;

        host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH |
                            SPI_RX_DUAL | SPI_TX_DUAL;
        host->bits_per_word_mask = SPI_BPW_MASK(8);
        host->auto_runtime_pm = true;

        platform_set_drvdata(pdev, host);

        /* Initialize the hardware */
        __raw_writel(0, bs->regs + HSSPI_INT_MASK_REG);

        /* clean up any pending interrupts */
        __raw_writel(HSSPI_INT_CLEAR_ALL, bs->regs + HSSPI_INT_STATUS_REG);

        /* read out default CS polarities */
        reg = __raw_readl(bs->regs + HSSPI_GLOBAL_CTRL_REG);
        bs->cs_polarity = reg & GLOBAL_CTRL_CS_POLARITY_MASK;
        __raw_writel(reg | GLOBAL_CTRL_CLK_GATE_SSOFF,
                     bs->regs + HSSPI_GLOBAL_CTRL_REG);

        if (irq > 0) {
                ret = devm_request_irq(dev, irq, bcm63xx_hsspi_interrupt, IRQF_SHARED,
                                       pdev->name, bs);

                if (ret)
                        goto out_put_host;
        }

        pm_runtime_enable(&pdev->dev);

        ret = sysfs_create_group(&pdev->dev.kobj, &bcm63xx_hsspi_group);
        if (ret) {
                dev_err(&pdev->dev, "couldn't register sysfs group\n");
                goto out_pm_disable;
        }

        /* register and we are done */
        ret = devm_spi_register_controller(dev, host);
        if (ret)
                goto out_sysgroup_disable;

        dev_info(dev, "Broadcom 63XX High Speed SPI Controller driver");

        return 0;

out_sysgroup_disable:
        sysfs_remove_group(&pdev->dev.kobj, &bcm63xx_hsspi_group);
out_pm_disable:
        pm_runtime_disable(&pdev->dev);
out_put_host:
        spi_controller_put(host);
out_disable_pll_clk:
        clk_disable_unprepare(pll_clk);
out_disable_clk:
        clk_disable_unprepare(clk);
        return ret;
}


static void bcm63xx_hsspi_remove(struct platform_device *pdev)
{
        struct spi_controller *host = platform_get_drvdata(pdev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(host);

        /* reset the hardware and block queue progress */
        __raw_writel(0, bs->regs + HSSPI_INT_MASK_REG);
        clk_disable_unprepare(bs->pll_clk);
        clk_disable_unprepare(bs->clk);
        sysfs_remove_group(&pdev->dev.kobj, &bcm63xx_hsspi_group);
}

#ifdef CONFIG_PM_SLEEP
static int bcm63xx_hsspi_suspend(struct device *dev)
{
        struct spi_controller *host = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(host);

        spi_controller_suspend(host);
        clk_disable_unprepare(bs->pll_clk);
        clk_disable_unprepare(bs->clk);

        return 0;
}

static int bcm63xx_hsspi_resume(struct device *dev)
{
        struct spi_controller *host = dev_get_drvdata(dev);
        struct bcm63xx_hsspi *bs = spi_controller_get_devdata(host);
        int ret;

        ret = clk_prepare_enable(bs->clk);
        if (ret)
                return ret;

        if (bs->pll_clk) {
                ret = clk_prepare_enable(bs->pll_clk);
                if (ret) {
                        clk_disable_unprepare(bs->clk);
                        return ret;
                }
        }

        spi_controller_resume(host);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(bcm63xx_hsspi_pm_ops, bcm63xx_hsspi_suspend,
                         bcm63xx_hsspi_resume);

static const struct of_device_id bcm63xx_hsspi_of_match[] = {
        { .compatible = "brcm,bcm6328-hsspi", },
        { .compatible = "brcm,bcmbca-hsspi-v1.0", },
        { },
};
MODULE_DEVICE_TABLE(of, bcm63xx_hsspi_of_match);

static struct platform_driver bcm63xx_hsspi_driver = {
        .driver = {
                .name   = "bcm63xx-hsspi",
                .pm     = &bcm63xx_hsspi_pm_ops,
                .of_match_table = bcm63xx_hsspi_of_match,
        },
        .probe          = bcm63xx_hsspi_probe,
        .remove         = bcm63xx_hsspi_remove,
};

module_platform_driver(bcm63xx_hsspi_driver);

MODULE_ALIAS("platform:bcm63xx_hsspi");
MODULE_DESCRIPTION("Broadcom BCM63xx High Speed SPI Controller driver");
MODULE_AUTHOR("Jonas Gorski <jogo@openwrt.org>");
MODULE_LICENSE("GPL");