// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Diolan DLN-2 USB-SPI adapter
 *
 * Copyright (c) 2014 Intel Corporation
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mfd/dln2.h>
#include <linux/spi/spi.h>
#include <linux/pm_runtime.h>
#include <asm/unaligned.h>

#define DLN2_SPI_MODULE_ID              0x02
#define DLN2_SPI_CMD(cmd)               DLN2_CMD(cmd, DLN2_SPI_MODULE_ID)

/* SPI commands */
#define DLN2_SPI_GET_PORT_COUNT                 DLN2_SPI_CMD(0x00)
#define DLN2_SPI_ENABLE                         DLN2_SPI_CMD(0x11)
#define DLN2_SPI_DISABLE                        DLN2_SPI_CMD(0x12)
#define DLN2_SPI_IS_ENABLED                     DLN2_SPI_CMD(0x13)
#define DLN2_SPI_SET_MODE                       DLN2_SPI_CMD(0x14)
#define DLN2_SPI_GET_MODE                       DLN2_SPI_CMD(0x15)
#define DLN2_SPI_SET_FRAME_SIZE                 DLN2_SPI_CMD(0x16)
#define DLN2_SPI_GET_FRAME_SIZE                 DLN2_SPI_CMD(0x17)
#define DLN2_SPI_SET_FREQUENCY                  DLN2_SPI_CMD(0x18)
#define DLN2_SPI_GET_FREQUENCY                  DLN2_SPI_CMD(0x19)
#define DLN2_SPI_READ_WRITE                     DLN2_SPI_CMD(0x1A)
#define DLN2_SPI_READ                           DLN2_SPI_CMD(0x1B)
#define DLN2_SPI_WRITE                          DLN2_SPI_CMD(0x1C)
#define DLN2_SPI_SET_DELAY_BETWEEN_SS           DLN2_SPI_CMD(0x20)
#define DLN2_SPI_GET_DELAY_BETWEEN_SS           DLN2_SPI_CMD(0x21)
#define DLN2_SPI_SET_DELAY_AFTER_SS             DLN2_SPI_CMD(0x22)
#define DLN2_SPI_GET_DELAY_AFTER_SS             DLN2_SPI_CMD(0x23)
#define DLN2_SPI_SET_DELAY_BETWEEN_FRAMES       DLN2_SPI_CMD(0x24)
#define DLN2_SPI_GET_DELAY_BETWEEN_FRAMES       DLN2_SPI_CMD(0x25)
#define DLN2_SPI_SET_SS                         DLN2_SPI_CMD(0x26)
#define DLN2_SPI_GET_SS                         DLN2_SPI_CMD(0x27)
#define DLN2_SPI_RELEASE_SS                     DLN2_SPI_CMD(0x28)
#define DLN2_SPI_SS_VARIABLE_ENABLE             DLN2_SPI_CMD(0x2B)
#define DLN2_SPI_SS_VARIABLE_DISABLE            DLN2_SPI_CMD(0x2C)
#define DLN2_SPI_SS_VARIABLE_IS_ENABLED         DLN2_SPI_CMD(0x2D)
#define DLN2_SPI_SS_AAT_ENABLE                  DLN2_SPI_CMD(0x2E)
#define DLN2_SPI_SS_AAT_DISABLE                 DLN2_SPI_CMD(0x2F)
#define DLN2_SPI_SS_AAT_IS_ENABLED              DLN2_SPI_CMD(0x30)
#define DLN2_SPI_SS_BETWEEN_FRAMES_ENABLE       DLN2_SPI_CMD(0x31)
#define DLN2_SPI_SS_BETWEEN_FRAMES_DISABLE      DLN2_SPI_CMD(0x32)
#define DLN2_SPI_SS_BETWEEN_FRAMES_IS_ENABLED   DLN2_SPI_CMD(0x33)
#define DLN2_SPI_SET_CPHA                       DLN2_SPI_CMD(0x34)
#define DLN2_SPI_GET_CPHA                       DLN2_SPI_CMD(0x35)
#define DLN2_SPI_SET_CPOL                       DLN2_SPI_CMD(0x36)
#define DLN2_SPI_GET_CPOL                       DLN2_SPI_CMD(0x37)
#define DLN2_SPI_SS_MULTI_ENABLE                DLN2_SPI_CMD(0x38)
#define DLN2_SPI_SS_MULTI_DISABLE               DLN2_SPI_CMD(0x39)
#define DLN2_SPI_SS_MULTI_IS_ENABLED            DLN2_SPI_CMD(0x3A)
#define DLN2_SPI_GET_SUPPORTED_MODES            DLN2_SPI_CMD(0x40)
#define DLN2_SPI_GET_SUPPORTED_CPHA_VALUES      DLN2_SPI_CMD(0x41)
#define DLN2_SPI_GET_SUPPORTED_CPOL_VALUES      DLN2_SPI_CMD(0x42)
#define DLN2_SPI_GET_SUPPORTED_FRAME_SIZES      DLN2_SPI_CMD(0x43)
#define DLN2_SPI_GET_SS_COUNT                   DLN2_SPI_CMD(0x44)
#define DLN2_SPI_GET_MIN_FREQUENCY              DLN2_SPI_CMD(0x45)
#define DLN2_SPI_GET_MAX_FREQUENCY              DLN2_SPI_CMD(0x46)
#define DLN2_SPI_GET_MIN_DELAY_BETWEEN_SS       DLN2_SPI_CMD(0x47)
#define DLN2_SPI_GET_MAX_DELAY_BETWEEN_SS       DLN2_SPI_CMD(0x48)
#define DLN2_SPI_GET_MIN_DELAY_AFTER_SS         DLN2_SPI_CMD(0x49)
#define DLN2_SPI_GET_MAX_DELAY_AFTER_SS         DLN2_SPI_CMD(0x4A)
#define DLN2_SPI_GET_MIN_DELAY_BETWEEN_FRAMES   DLN2_SPI_CMD(0x4B)
#define DLN2_SPI_GET_MAX_DELAY_BETWEEN_FRAMES   DLN2_SPI_CMD(0x4C)

#define DLN2_SPI_MAX_XFER_SIZE                  256
#define DLN2_SPI_BUF_SIZE                       (DLN2_SPI_MAX_XFER_SIZE + 16)
#define DLN2_SPI_ATTR_LEAVE_SS_LOW              BIT(0)
#define DLN2_TRANSFERS_WAIT_COMPLETE            1
#define DLN2_TRANSFERS_CANCEL                   0
#define DLN2_RPM_AUTOSUSPEND_TIMEOUT            2000

struct dln2_spi {
        struct platform_device *pdev;
        struct spi_master *master;
        u8 port;

        /*
         * This buffer will be used mainly for read/write operations. Since
         * they're quite large, we cannot use the stack. Protection is not
         * needed because all SPI communication is serialized by the SPI core.
         */
        void *buf;

        u8 bpw;
        u32 speed;
        u16 mode;
        u8 cs;
};

/*
 * Enable/Disable SPI module. The disable command will wait for transfers to
 * complete first.
 */
static int dln2_spi_enable(struct dln2_spi *dln2, bool enable)
{
        u16 cmd;
        struct {
                u8 port;
                u8 wait_for_completion;
        } tx;
        unsigned len = sizeof(tx);

        tx.port = dln2->port;

        if (enable) {
                cmd = DLN2_SPI_ENABLE;
                len -= sizeof(tx.wait_for_completion);
        } else {
                tx.wait_for_completion = DLN2_TRANSFERS_WAIT_COMPLETE;
                cmd = DLN2_SPI_DISABLE;
        }

        return dln2_transfer_tx(dln2->pdev, cmd, &tx, len);
}

/*
 * Select/unselect multiple CS lines. The selected lines will be automatically
 * toggled LOW/HIGH by the board firmware during transfers, provided they're
 * enabled first.
 *
 * Ex: cs_mask = 0x03 -> CS0 & CS1 will be selected and the next WR/RD operation
 *                       will toggle the lines LOW/HIGH automatically.
 */
static int dln2_spi_cs_set(struct dln2_spi *dln2, u8 cs_mask)
{
        struct {
                u8 port;
                u8 cs;
        } tx;

        tx.port = dln2->port;

        /*
         * According to Diolan docs, "a slave device can be selected by changing
         * the corresponding bit value to 0". The rest must be set to 1. Hence
         * the bitwise NOT in front.
         */
        tx.cs = ~cs_mask;

        return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_SS, &tx, sizeof(tx));
}

/*
 * Select one CS line. The other lines will be un-selected.
 */
static int dln2_spi_cs_set_one(struct dln2_spi *dln2, u8 cs)
{
        return dln2_spi_cs_set(dln2, BIT(cs));
}

/*
 * Enable/disable CS lines for usage. The module has to be disabled first.
 */
static int dln2_spi_cs_enable(struct dln2_spi *dln2, u8 cs_mask, bool enable)
{
        struct {
                u8 port;
                u8 cs;
        } tx;
        u16 cmd;

        tx.port = dln2->port;
        tx.cs = cs_mask;
        cmd = enable ? DLN2_SPI_SS_MULTI_ENABLE : DLN2_SPI_SS_MULTI_DISABLE;

        return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
}

static int dln2_spi_cs_enable_all(struct dln2_spi *dln2, bool enable)
{
        u8 cs_mask = GENMASK(dln2->master->num_chipselect - 1, 0);

        return dln2_spi_cs_enable(dln2, cs_mask, enable);
}

static int dln2_spi_get_cs_num(struct dln2_spi *dln2, u16 *cs_num)
{
        int ret;
        struct {
                u8 port;
        } tx;
        struct {
                __le16 cs_count;
        } rx;
        unsigned rx_len = sizeof(rx);

        tx.port = dln2->port;
        ret = dln2_transfer(dln2->pdev, DLN2_SPI_GET_SS_COUNT, &tx, sizeof(tx),
                            &rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx))
                return -EPROTO;

        *cs_num = le16_to_cpu(rx.cs_count);

        dev_dbg(&dln2->pdev->dev, "cs_num = %d\n", *cs_num);

        return 0;
}

static int dln2_spi_get_speed(struct dln2_spi *dln2, u16 cmd, u32 *freq)
{
        int ret;
        struct {
                u8 port;
        } tx;
        struct {
                __le32 speed;
        } rx;
        unsigned rx_len = sizeof(rx);

        tx.port = dln2->port;

        ret = dln2_transfer(dln2->pdev, cmd, &tx, sizeof(tx), &rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx))
                return -EPROTO;

        *freq = le32_to_cpu(rx.speed);

        return 0;
}

/*
 * Get bus min/max frequencies.
 */
static int dln2_spi_get_speed_range(struct dln2_spi *dln2, u32 *fmin, u32 *fmax)
{
        int ret;

        ret = dln2_spi_get_speed(dln2, DLN2_SPI_GET_MIN_FREQUENCY, fmin);
        if (ret < 0)
                return ret;

        ret = dln2_spi_get_speed(dln2, DLN2_SPI_GET_MAX_FREQUENCY, fmax);
        if (ret < 0)
                return ret;

        dev_dbg(&dln2->pdev->dev, "freq_min = %d, freq_max = %d\n",
                *fmin, *fmax);

        return 0;
}

/*
 * Set the bus speed. The module will automatically round down to the closest
 * available frequency and returns it. The module has to be disabled first.
 */
static int dln2_spi_set_speed(struct dln2_spi *dln2, u32 speed)
{
        int ret;
        struct {
                u8 port;
                __le32 speed;
        } __packed tx;
        struct {
                __le32 speed;
        } rx;
        int rx_len = sizeof(rx);

        tx.port = dln2->port;
        tx.speed = cpu_to_le32(speed);

        ret = dln2_transfer(dln2->pdev, DLN2_SPI_SET_FREQUENCY, &tx, sizeof(tx),
                            &rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx))
                return -EPROTO;

        return 0;
}

/*
 * Change CPOL & CPHA. The module has to be disabled first.
 */
static int dln2_spi_set_mode(struct dln2_spi *dln2, u8 mode)
{
        struct {
                u8 port;
                u8 mode;
        } tx;

        tx.port = dln2->port;
        tx.mode = mode;

        return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_MODE, &tx, sizeof(tx));
}

/*
 * Change frame size. The module has to be disabled first.
 */
static int dln2_spi_set_bpw(struct dln2_spi *dln2, u8 bpw)
{
        struct {
                u8 port;
                u8 bpw;
        } tx;

        tx.port = dln2->port;
        tx.bpw = bpw;

        return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_FRAME_SIZE,
                                &tx, sizeof(tx));
}

static int dln2_spi_get_supported_frame_sizes(struct dln2_spi *dln2,
                                              u32 *bpw_mask)
{
        int ret;
        struct {
                u8 port;
        } tx;
        struct {
                u8 count;
                u8 frame_sizes[36];
        } *rx = dln2->buf;
        unsigned rx_len = sizeof(*rx);
        int i;

        tx.port = dln2->port;

        ret = dln2_transfer(dln2->pdev, DLN2_SPI_GET_SUPPORTED_FRAME_SIZES,
                            &tx, sizeof(tx), rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(*rx))
                return -EPROTO;
        if (rx->count > ARRAY_SIZE(rx->frame_sizes))
                return -EPROTO;

        *bpw_mask = 0;
        for (i = 0; i < rx->count; i++)
                *bpw_mask |= BIT(rx->frame_sizes[i] - 1);

        dev_dbg(&dln2->pdev->dev, "bpw_mask = 0x%X\n", *bpw_mask);

        return 0;
}

/*
 * Copy the data to DLN2 buffer and change the byte order to LE, requested by
 * DLN2 module. SPI core makes sure that the data length is a multiple of word
 * size.
 */
static int dln2_spi_copy_to_buf(u8 *dln2_buf, const u8 *src, u16 len, u8 bpw)
{
#ifdef __LITTLE_ENDIAN
        memcpy(dln2_buf, src, len);
#else
        if (bpw <= 8) {
                memcpy(dln2_buf, src, len);
        } else if (bpw <= 16) {
                __le16 *d = (__le16 *)dln2_buf;
                u16 *s = (u16 *)src;

                len = len / 2;
                while (len--)
                        *d++ = cpu_to_le16p(s++);
        } else {
                __le32 *d = (__le32 *)dln2_buf;
                u32 *s = (u32 *)src;

                len = len / 4;
                while (len--)
                        *d++ = cpu_to_le32p(s++);
        }
#endif

        return 0;
}

/*
 * Copy the data from DLN2 buffer and convert to CPU byte order since the DLN2
 * buffer is LE ordered. SPI core makes sure that the data length is a multiple
 * of word size. The RX dln2_buf is 2 byte aligned so, for BE, we have to make
 * sure we avoid unaligned accesses for 32 bit case.
 */
static int dln2_spi_copy_from_buf(u8 *dest, const u8 *dln2_buf, u16 len, u8 bpw)
{
#ifdef __LITTLE_ENDIAN
        memcpy(dest, dln2_buf, len);
#else
        if (bpw <= 8) {
                memcpy(dest, dln2_buf, len);
        } else if (bpw <= 16) {
                u16 *d = (u16 *)dest;
                __le16 *s = (__le16 *)dln2_buf;

                len = len / 2;
                while (len--)
                        *d++ = le16_to_cpup(s++);
        } else {
                u32 *d = (u32 *)dest;
                __le32 *s = (__le32 *)dln2_buf;

                len = len / 4;
                while (len--)
                        *d++ = get_unaligned_le32(s++);
        }
#endif

        return 0;
}

/*
 * Perform one write operation.
 */
static int dln2_spi_write_one(struct dln2_spi *dln2, const u8 *data,
                              u16 data_len, u8 attr)
{
        struct {
                u8 port;
                __le16 size;
                u8 attr;
                u8 buf[DLN2_SPI_MAX_XFER_SIZE];
        } __packed *tx = dln2->buf;
        unsigned tx_len;

        BUILD_BUG_ON(sizeof(*tx) > DLN2_SPI_BUF_SIZE);

        if (data_len > DLN2_SPI_MAX_XFER_SIZE)
                return -EINVAL;

        tx->port = dln2->port;
        tx->size = cpu_to_le16(data_len);
        tx->attr = attr;

        dln2_spi_copy_to_buf(tx->buf, data, data_len, dln2->bpw);

        tx_len = sizeof(*tx) + data_len - DLN2_SPI_MAX_XFER_SIZE;
        return dln2_transfer_tx(dln2->pdev, DLN2_SPI_WRITE, tx, tx_len);
}

/*
 * Perform one read operation.
 */
static int dln2_spi_read_one(struct dln2_spi *dln2, u8 *data,
                             u16 data_len, u8 attr)
{
        int ret;
        struct {
                u8 port;
                __le16 size;
                u8 attr;
        } __packed tx;
        struct {
                __le16 size;
                u8 buf[DLN2_SPI_MAX_XFER_SIZE];
        } __packed *rx = dln2->buf;
        unsigned rx_len = sizeof(*rx);

        BUILD_BUG_ON(sizeof(*rx) > DLN2_SPI_BUF_SIZE);

        if (data_len > DLN2_SPI_MAX_XFER_SIZE)
                return -EINVAL;

        tx.port = dln2->port;
        tx.size = cpu_to_le16(data_len);
        tx.attr = attr;

        ret = dln2_transfer(dln2->pdev, DLN2_SPI_READ, &tx, sizeof(tx),
                            rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx->size) + data_len)
                return -EPROTO;
        if (le16_to_cpu(rx->size) != data_len)
                return -EPROTO;

        dln2_spi_copy_from_buf(data, rx->buf, data_len, dln2->bpw);

        return 0;
}

/*
 * Perform one write & read operation.
 */
static int dln2_spi_read_write_one(struct dln2_spi *dln2, const u8 *tx_data,
                                   u8 *rx_data, u16 data_len, u8 attr)
{
        int ret;
        struct {
                u8 port;
                __le16 size;
                u8 attr;
                u8 buf[DLN2_SPI_MAX_XFER_SIZE];
        } __packed *tx;
        struct {
                __le16 size;
                u8 buf[DLN2_SPI_MAX_XFER_SIZE];
        } __packed *rx;
        unsigned tx_len, rx_len;

        BUILD_BUG_ON(sizeof(*tx) > DLN2_SPI_BUF_SIZE ||
                     sizeof(*rx) > DLN2_SPI_BUF_SIZE);

        if (data_len > DLN2_SPI_MAX_XFER_SIZE)
                return -EINVAL;

        /*
         * Since this is a pseudo full-duplex communication, we're perfectly
         * safe to use the same buffer for both tx and rx. When DLN2 sends the
         * response back, with the rx data, we don't need the tx buffer anymore.
         */
        tx = dln2->buf;
        rx = dln2->buf;

        tx->port = dln2->port;
        tx->size = cpu_to_le16(data_len);
        tx->attr = attr;

        dln2_spi_copy_to_buf(tx->buf, tx_data, data_len, dln2->bpw);

        tx_len = sizeof(*tx) + data_len - DLN2_SPI_MAX_XFER_SIZE;
        rx_len = sizeof(*rx);

        ret = dln2_transfer(dln2->pdev, DLN2_SPI_READ_WRITE, tx, tx_len,
                            rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx->size) + data_len)
                return -EPROTO;
        if (le16_to_cpu(rx->size) != data_len)
                return -EPROTO;

        dln2_spi_copy_from_buf(rx_data, rx->buf, data_len, dln2->bpw);

        return 0;
}

/*
 * Read/Write wrapper. It will automatically split an operation into multiple
 * single ones due to device buffer constraints.
 */
static int dln2_spi_rdwr(struct dln2_spi *dln2, const u8 *tx_data,
                         u8 *rx_data, u16 data_len, u8 attr)
{
        int ret;
        u16 len;
        u8 temp_attr;
        u16 remaining = data_len;
        u16 offset;

        do {
                if (remaining > DLN2_SPI_MAX_XFER_SIZE) {
                        len = DLN2_SPI_MAX_XFER_SIZE;
                        temp_attr = DLN2_SPI_ATTR_LEAVE_SS_LOW;
                } else {
                        len = remaining;
                        temp_attr = attr;
                }

                offset = data_len - remaining;

                if (tx_data && rx_data) {
                        ret = dln2_spi_read_write_one(dln2,
                                                      tx_data + offset,
                                                      rx_data + offset,
                                                      len, temp_attr);
                } else if (tx_data) {
                        ret = dln2_spi_write_one(dln2,
                                                 tx_data + offset,
                                                 len, temp_attr);
                } else if (rx_data) {
                        ret = dln2_spi_read_one(dln2,
                                                rx_data + offset,
                                                len, temp_attr);
                 } else {
                        return -EINVAL;
                 }

                if (ret < 0)
                        return ret;

                remaining -= len;
        } while (remaining);

        return 0;
}

static int dln2_spi_prepare_message(struct spi_master *master,
                                    struct spi_message *message)
{
        int ret;
        struct dln2_spi *dln2 = spi_master_get_devdata(master);
        struct spi_device *spi = message->spi;

        if (dln2->cs != spi->chip_select) {
                ret = dln2_spi_cs_set_one(dln2, spi->chip_select);
                if (ret < 0)
                        return ret;

                dln2->cs = spi->chip_select;
        }

        return 0;
}

static int dln2_spi_transfer_setup(struct dln2_spi *dln2, u32 speed,
                                   u8 bpw, u8 mode)
{
        int ret;
        bool bus_setup_change;

        bus_setup_change = dln2->speed != speed || dln2->mode != mode ||
                           dln2->bpw != bpw;

        if (!bus_setup_change)
                return 0;

        ret = dln2_spi_enable(dln2, false);
        if (ret < 0)
                return ret;

        if (dln2->speed != speed) {
                ret = dln2_spi_set_speed(dln2, speed);
                if (ret < 0)
                        return ret;

                dln2->speed = speed;
        }

        if (dln2->mode != mode) {
                ret = dln2_spi_set_mode(dln2, mode & 0x3);
                if (ret < 0)
                        return ret;

                dln2->mode = mode;
        }

        if (dln2->bpw != bpw) {
                ret = dln2_spi_set_bpw(dln2, bpw);
                if (ret < 0)
                        return ret;

                dln2->bpw = bpw;
        }

        return dln2_spi_enable(dln2, true);
}

static int dln2_spi_transfer_one(struct spi_master *master,
                                 struct spi_device *spi,
                                 struct spi_transfer *xfer)
{
        struct dln2_spi *dln2 = spi_master_get_devdata(master);
        int status;
        u8 attr = 0;

        status = dln2_spi_transfer_setup(dln2, xfer->speed_hz,
                                         xfer->bits_per_word,
                                         spi->mode);
        if (status < 0) {
                dev_err(&dln2->pdev->dev, "Cannot setup transfer\n");
                return status;
        }

        if (!xfer->cs_change && !spi_transfer_is_last(master, xfer))
                attr = DLN2_SPI_ATTR_LEAVE_SS_LOW;

        status = dln2_spi_rdwr(dln2, xfer->tx_buf, xfer->rx_buf,
                               xfer->len, attr);
        if (status < 0)
                dev_err(&dln2->pdev->dev, "write/read failed!\n");

        return status;
}

static int dln2_spi_probe(struct platform_device *pdev)
{
        struct spi_master *master;
        struct dln2_spi *dln2;
        struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
        struct device *dev = &pdev->dev;
        int ret;

        master = spi_alloc_master(&pdev->dev, sizeof(*dln2));
        if (!master)
                return -ENOMEM;

        platform_set_drvdata(pdev, master);

        dln2 = spi_master_get_devdata(master);

        dln2->buf = devm_kmalloc(&pdev->dev, DLN2_SPI_BUF_SIZE, GFP_KERNEL);
        if (!dln2->buf) {
                ret = -ENOMEM;
                goto exit_free_master;
        }

        dln2->master = master;
        dln2->master->dev.of_node = dev->of_node;
        dln2->pdev = pdev;
        dln2->port = pdata->port;
        /* cs/mode can never be 0xff, so the first transfer will set them */
        dln2->cs = 0xff;
        dln2->mode = 0xff;

        /* disable SPI module before continuing with the setup */
        ret = dln2_spi_enable(dln2, false);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to disable SPI module\n");
                goto exit_free_master;
        }

        ret = dln2_spi_get_cs_num(dln2, &master->num_chipselect);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to get number of CS pins\n");
                goto exit_free_master;
        }

        ret = dln2_spi_get_speed_range(dln2,
                                       &master->min_speed_hz,
                                       &master->max_speed_hz);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to read bus min/max freqs\n");
                goto exit_free_master;
        }

        ret = dln2_spi_get_supported_frame_sizes(dln2,
                                                 &master->bits_per_word_mask);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to read supported frame sizes\n");
                goto exit_free_master;
        }

        ret = dln2_spi_cs_enable_all(dln2, true);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to enable CS pins\n");
                goto exit_free_master;
        }

        master->bus_num = -1;
        master->mode_bits = SPI_CPOL | SPI_CPHA;
        master->prepare_message = dln2_spi_prepare_message;
        master->transfer_one = dln2_spi_transfer_one;
        master->auto_runtime_pm = true;

        /* enable SPI module, we're good to go */
        ret = dln2_spi_enable(dln2, true);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to enable SPI module\n");
                goto exit_free_master;
        }

        pm_runtime_set_autosuspend_delay(&pdev->dev,
                                         DLN2_RPM_AUTOSUSPEND_TIMEOUT);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);

        ret = devm_spi_register_master(&pdev->dev, master);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to register master\n");
                goto exit_register;
        }

        return ret;

exit_register:
        pm_runtime_disable(&pdev->dev);
        pm_runtime_set_suspended(&pdev->dev);

        if (dln2_spi_enable(dln2, false) < 0)
                dev_err(&pdev->dev, "Failed to disable SPI module\n");
exit_free_master:
        spi_master_put(master);

        return ret;
}

static int dln2_spi_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct dln2_spi *dln2 = spi_master_get_devdata(master);

        pm_runtime_disable(&pdev->dev);

        if (dln2_spi_enable(dln2, false) < 0)
                dev_err(&pdev->dev, "Failed to disable SPI module\n");

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int dln2_spi_suspend(struct device *dev)
{
        int ret;
        struct spi_master *master = dev_get_drvdata(dev);
        struct dln2_spi *dln2 = spi_master_get_devdata(master);

        ret = spi_master_suspend(master);
        if (ret < 0)
                return ret;

        if (!pm_runtime_suspended(dev)) {
                ret = dln2_spi_enable(dln2, false);
                if (ret < 0)
                        return ret;
        }

        /*
         * USB power may be cut off during sleep. Resetting the following
         * parameters will force the board to be set up before first transfer.
         */
        dln2->cs = 0xff;
        dln2->speed = 0;
        dln2->bpw = 0;
        dln2->mode = 0xff;

        return 0;
}

static int dln2_spi_resume(struct device *dev)
{
        int ret;
        struct spi_master *master = dev_get_drvdata(dev);
        struct dln2_spi *dln2 = spi_master_get_devdata(master);

        if (!pm_runtime_suspended(dev)) {
                ret = dln2_spi_cs_enable_all(dln2, true);
                if (ret < 0)
                        return ret;

                ret = dln2_spi_enable(dln2, true);
                if (ret < 0)
                        return ret;
        }

        return spi_master_resume(master);
}
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM
static int dln2_spi_runtime_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct dln2_spi *dln2 = spi_master_get_devdata(master);

        return dln2_spi_enable(dln2, false);
}

static int dln2_spi_runtime_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct dln2_spi *dln2 = spi_master_get_devdata(master);

        return  dln2_spi_enable(dln2, true);
}
#endif /* CONFIG_PM */

static const struct dev_pm_ops dln2_spi_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(dln2_spi_suspend, dln2_spi_resume)
        SET_RUNTIME_PM_OPS(dln2_spi_runtime_suspend,
                           dln2_spi_runtime_resume, NULL)
};

static struct platform_driver spi_dln2_driver = {
        .driver = {
                .name   = "dln2-spi",
                .pm     = &dln2_spi_pm,
        },
        .probe          = dln2_spi_probe,
        .remove         = dln2_spi_remove,
};
module_platform_driver(spi_dln2_driver);

MODULE_DESCRIPTION("Driver for the Diolan DLN2 SPI master interface");
MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:dln2-spi");