Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[mirror_ubuntu-jammy-kernel.git] / drivers / spi / spi-zynq-qspi.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2019 Xilinx, Inc.
 *
 * Author: Naga Sureshkumar Relli <nagasure@xilinx.com>
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/workqueue.h>
#include <linux/spi/spi-mem.h>

/* Register offset definitions */
#define ZYNQ_QSPI_CONFIG_OFFSET         0x00 /* Configuration  Register, RW */
#define ZYNQ_QSPI_STATUS_OFFSET         0x04 /* Interrupt Status Register, RO */
#define ZYNQ_QSPI_IEN_OFFSET            0x08 /* Interrupt Enable Register, WO */
#define ZYNQ_QSPI_IDIS_OFFSET           0x0C /* Interrupt Disable Reg, WO */
#define ZYNQ_QSPI_IMASK_OFFSET          0x10 /* Interrupt Enabled Mask Reg,RO */
#define ZYNQ_QSPI_ENABLE_OFFSET         0x14 /* Enable/Disable Register, RW */
#define ZYNQ_QSPI_DELAY_OFFSET          0x18 /* Delay Register, RW */
#define ZYNQ_QSPI_TXD_00_00_OFFSET      0x1C /* Transmit 4-byte inst, WO */
#define ZYNQ_QSPI_TXD_00_01_OFFSET      0x80 /* Transmit 1-byte inst, WO */
#define ZYNQ_QSPI_TXD_00_10_OFFSET      0x84 /* Transmit 2-byte inst, WO */
#define ZYNQ_QSPI_TXD_00_11_OFFSET      0x88 /* Transmit 3-byte inst, WO */
#define ZYNQ_QSPI_RXD_OFFSET            0x20 /* Data Receive Register, RO */
#define ZYNQ_QSPI_SIC_OFFSET            0x24 /* Slave Idle Count Register, RW */
#define ZYNQ_QSPI_TX_THRESH_OFFSET      0x28 /* TX FIFO Watermark Reg, RW */
#define ZYNQ_QSPI_RX_THRESH_OFFSET      0x2C /* RX FIFO Watermark Reg, RW */
#define ZYNQ_QSPI_GPIO_OFFSET           0x30 /* GPIO Register, RW */
#define ZYNQ_QSPI_LINEAR_CFG_OFFSET     0xA0 /* Linear Adapter Config Ref, RW */
#define ZYNQ_QSPI_MOD_ID_OFFSET         0xFC /* Module ID Register, RO */

/*
 * QSPI Configuration Register bit Masks
 *
 * This register contains various control bits that effect the operation
 * of the QSPI controller
 */
#define ZYNQ_QSPI_CONFIG_IFMODE_MASK    BIT(31) /* Flash Memory Interface */
#define ZYNQ_QSPI_CONFIG_MANSRT_MASK    BIT(16) /* Manual TX Start */
#define ZYNQ_QSPI_CONFIG_MANSRTEN_MASK  BIT(15) /* Enable Manual TX Mode */
#define ZYNQ_QSPI_CONFIG_SSFORCE_MASK   BIT(14) /* Manual Chip Select */
#define ZYNQ_QSPI_CONFIG_BDRATE_MASK    GENMASK(5, 3) /* Baud Rate Mask */
#define ZYNQ_QSPI_CONFIG_CPHA_MASK      BIT(2) /* Clock Phase Control */
#define ZYNQ_QSPI_CONFIG_CPOL_MASK      BIT(1) /* Clock Polarity Control */
#define ZYNQ_QSPI_CONFIG_FWIDTH_MASK    GENMASK(7, 6) /* FIFO width */
#define ZYNQ_QSPI_CONFIG_MSTREN_MASK    BIT(0) /* Master Mode */

/*
 * QSPI Configuration Register - Baud rate and slave select
 *
 * These are the values used in the calculation of baud rate divisor and
 * setting the slave select.
 */
#define ZYNQ_QSPI_CONFIG_BAUD_DIV_MAX   GENMASK(2, 0) /* Baud rate maximum */
#define ZYNQ_QSPI_CONFIG_BAUD_DIV_SHIFT 3 /* Baud rate divisor shift */
#define ZYNQ_QSPI_CONFIG_PCS            BIT(10) /* Peripheral Chip Select */

/*
 * QSPI Interrupt Registers bit Masks
 *
 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
 * bit definitions.
 */
#define ZYNQ_QSPI_IXR_RX_OVERFLOW_MASK  BIT(0) /* QSPI RX FIFO Overflow */
#define ZYNQ_QSPI_IXR_TXNFULL_MASK      BIT(2) /* QSPI TX FIFO Overflow */
#define ZYNQ_QSPI_IXR_TXFULL_MASK       BIT(3) /* QSPI TX FIFO is full */
#define ZYNQ_QSPI_IXR_RXNEMTY_MASK      BIT(4) /* QSPI RX FIFO Not Empty */
#define ZYNQ_QSPI_IXR_RXF_FULL_MASK     BIT(5) /* QSPI RX FIFO is full */
#define ZYNQ_QSPI_IXR_TXF_UNDRFLOW_MASK BIT(6) /* QSPI TX FIFO Underflow */
#define ZYNQ_QSPI_IXR_ALL_MASK          (ZYNQ_QSPI_IXR_RX_OVERFLOW_MASK | \
                                        ZYNQ_QSPI_IXR_TXNFULL_MASK | \
                                        ZYNQ_QSPI_IXR_TXFULL_MASK | \
                                        ZYNQ_QSPI_IXR_RXNEMTY_MASK | \
                                        ZYNQ_QSPI_IXR_RXF_FULL_MASK | \
                                        ZYNQ_QSPI_IXR_TXF_UNDRFLOW_MASK)
#define ZYNQ_QSPI_IXR_RXTX_MASK         (ZYNQ_QSPI_IXR_TXNFULL_MASK | \
                                        ZYNQ_QSPI_IXR_RXNEMTY_MASK)

/*
 * QSPI Enable Register bit Masks
 *
 * This register is used to enable or disable the QSPI controller
 */
#define ZYNQ_QSPI_ENABLE_ENABLE_MASK    BIT(0) /* QSPI Enable Bit Mask */

/*
 * QSPI Linear Configuration Register
 *
 * It is named Linear Configuration but it controls other modes when not in
 * linear mode also.
 */
#define ZYNQ_QSPI_LCFG_TWO_MEM          BIT(30) /* LQSPI Two memories */
#define ZYNQ_QSPI_LCFG_SEP_BUS          BIT(29) /* LQSPI Separate bus */
#define ZYNQ_QSPI_LCFG_U_PAGE           BIT(28) /* LQSPI Upper Page */

#define ZYNQ_QSPI_LCFG_DUMMY_SHIFT      8

#define ZYNQ_QSPI_FAST_READ_QOUT_CODE   0x6B /* read instruction code */
#define ZYNQ_QSPI_FIFO_DEPTH            63 /* FIFO depth in words */
#define ZYNQ_QSPI_RX_THRESHOLD          32 /* Rx FIFO threshold level */
#define ZYNQ_QSPI_TX_THRESHOLD          1 /* Tx FIFO threshold level */

/*
 * The modebits configurable by the driver to make the SPI support different
 * data formats
 */
#define ZYNQ_QSPI_MODEBITS                      (SPI_CPOL | SPI_CPHA)

/* Maximum number of chip selects */
#define ZYNQ_QSPI_MAX_NUM_CS            2

/**
 * struct zynq_qspi - Defines qspi driver instance
 * @dev:                Pointer to the this device's information
 * @regs:               Virtual address of the QSPI controller registers
 * @refclk:             Pointer to the peripheral clock
 * @pclk:               Pointer to the APB clock
 * @irq:                IRQ number
 * @txbuf:              Pointer to the TX buffer
 * @rxbuf:              Pointer to the RX buffer
 * @tx_bytes:           Number of bytes left to transfer
 * @rx_bytes:           Number of bytes left to receive
 * @data_completion:    completion structure
 */
struct zynq_qspi {
        struct device *dev;
        void __iomem *regs;
        struct clk *refclk;
        struct clk *pclk;
        int irq;
        u8 *txbuf;
        u8 *rxbuf;
        int tx_bytes;
        int rx_bytes;
        struct completion data_completion;
};

/*
 * Inline functions for the QSPI controller read/write
 */
static inline u32 zynq_qspi_read(struct zynq_qspi *xqspi, u32 offset)
{
        return readl_relaxed(xqspi->regs + offset);
}

static inline void zynq_qspi_write(struct zynq_qspi *xqspi, u32 offset,
                                   u32 val)
{
        writel_relaxed(val, xqspi->regs + offset);
}

/**
 * zynq_qspi_init_hw - Initialize the hardware
 * @xqspi:      Pointer to the zynq_qspi structure
 * @num_cs:     Number of connected CS (to enable dual memories if needed)
 *
 * The default settings of the QSPI controller's configurable parameters on
 * reset are
 *      - Master mode
 *      - Baud rate divisor is set to 2
 *      - Tx threshold set to 1l Rx threshold set to 32
 *      - Flash memory interface mode enabled
 *      - Size of the word to be transferred as 8 bit
 * This function performs the following actions
 *      - Disable and clear all the interrupts
 *      - Enable manual slave select
 *      - Enable manual start
 *      - Deselect all the chip select lines
 *      - Set the size of the word to be transferred as 32 bit
 *      - Set the little endian mode of TX FIFO and
 *      - Enable the QSPI controller
 */
static void zynq_qspi_init_hw(struct zynq_qspi *xqspi, unsigned int num_cs)
{
        u32 config_reg;

        zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
        zynq_qspi_write(xqspi, ZYNQ_QSPI_IDIS_OFFSET, ZYNQ_QSPI_IXR_ALL_MASK);

        /* Disable linear mode as the boot loader may have used it */
        config_reg = 0;
        /* At the same time, enable dual mode if more than 1 CS is available */
        if (num_cs > 1)
                config_reg |= ZYNQ_QSPI_LCFG_TWO_MEM;

        zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET, config_reg);

        /* Clear the RX FIFO */
        while (zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET) &
                              ZYNQ_QSPI_IXR_RXNEMTY_MASK)
                zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);

        zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET, ZYNQ_QSPI_IXR_ALL_MASK);
        config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
        config_reg &= ~(ZYNQ_QSPI_CONFIG_MSTREN_MASK |
                        ZYNQ_QSPI_CONFIG_CPOL_MASK |
                        ZYNQ_QSPI_CONFIG_CPHA_MASK |
                        ZYNQ_QSPI_CONFIG_BDRATE_MASK |
                        ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
                        ZYNQ_QSPI_CONFIG_MANSRTEN_MASK |
                        ZYNQ_QSPI_CONFIG_MANSRT_MASK);
        config_reg |= (ZYNQ_QSPI_CONFIG_MSTREN_MASK |
                       ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
                       ZYNQ_QSPI_CONFIG_FWIDTH_MASK |
                       ZYNQ_QSPI_CONFIG_IFMODE_MASK);
        zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);

        zynq_qspi_write(xqspi, ZYNQ_QSPI_RX_THRESH_OFFSET,
                        ZYNQ_QSPI_RX_THRESHOLD);
        zynq_qspi_write(xqspi, ZYNQ_QSPI_TX_THRESH_OFFSET,
                        ZYNQ_QSPI_TX_THRESHOLD);

        zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET,
                        ZYNQ_QSPI_ENABLE_ENABLE_MASK);
}

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

        /*
         * The number of address bytes should be equal to or less than 3 bytes.
         */
        if (op->addr.nbytes > 3)
                return false;

        return true;
}

/**
 * zynq_qspi_rxfifo_op - Read 1..4 bytes from RxFIFO to RX buffer
 * @xqspi:      Pointer to the zynq_qspi structure
 * @size:       Number of bytes to be read (1..4)
 */
static void zynq_qspi_rxfifo_op(struct zynq_qspi *xqspi, unsigned int size)
{
        u32 data;

        data = zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);

        if (xqspi->rxbuf) {
                memcpy(xqspi->rxbuf, ((u8 *)&data) + 4 - size, size);
                xqspi->rxbuf += size;
        }

        xqspi->rx_bytes -= size;
        if (xqspi->rx_bytes < 0)
                xqspi->rx_bytes = 0;
}

/**
 * zynq_qspi_txfifo_op - Write 1..4 bytes from TX buffer to TxFIFO
 * @xqspi:      Pointer to the zynq_qspi structure
 * @size:       Number of bytes to be written (1..4)
 */
static void zynq_qspi_txfifo_op(struct zynq_qspi *xqspi, unsigned int size)
{
        static const unsigned int offset[4] = {
                ZYNQ_QSPI_TXD_00_01_OFFSET, ZYNQ_QSPI_TXD_00_10_OFFSET,
                ZYNQ_QSPI_TXD_00_11_OFFSET, ZYNQ_QSPI_TXD_00_00_OFFSET };
        u32 data;

        if (xqspi->txbuf) {
                data = 0xffffffff;
                memcpy(&data, xqspi->txbuf, size);
                xqspi->txbuf += size;
        } else {
                data = 0;
        }

        xqspi->tx_bytes -= size;
        zynq_qspi_write(xqspi, offset[size - 1], data);
}

/**
 * zynq_qspi_chipselect - Select or deselect the chip select line
 * @spi:        Pointer to the spi_device structure
 * @assert:     1 for select or 0 for deselect the chip select line
 */
static void zynq_qspi_chipselect(struct spi_device *spi, bool assert)
{
        struct spi_controller *ctlr = spi->master;
        struct zynq_qspi *xqspi = spi_controller_get_devdata(ctlr);
        u32 config_reg;

        /* Select the lower (CS0) or upper (CS1) memory */
        if (ctlr->num_chipselect > 1) {
                config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET);
                if (!spi->chip_select)
                        config_reg &= ~ZYNQ_QSPI_LCFG_U_PAGE;
                else
                        config_reg |= ZYNQ_QSPI_LCFG_U_PAGE;

                zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET, config_reg);
        }

        /* Ground the line to assert the CS */
        config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
        if (assert)
                config_reg &= ~ZYNQ_QSPI_CONFIG_PCS;
        else
                config_reg |= ZYNQ_QSPI_CONFIG_PCS;

        zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
}

/**
 * zynq_qspi_config_op - Configure QSPI controller for specified transfer
 * @xqspi:      Pointer to the zynq_qspi structure
 * @spi:        Pointer to the spi_device structure
 *
 * Sets the operational mode of QSPI controller for the next QSPI transfer and
 * sets the requested clock frequency.
 *
 * Return:      0 on success and -EINVAL on invalid input parameter
 *
 * Note: If the requested frequency is not an exact match with what can be
 * obtained using the prescalar value, the driver sets the clock frequency which
 * is lower than the requested frequency (maximum lower) for the transfer. If
 * the requested frequency is higher or lower than that is supported by the QSPI
 * controller the driver will set the highest or lowest frequency supported by
 * controller.
 */
static int zynq_qspi_config_op(struct zynq_qspi *xqspi, struct spi_device *spi)
{
        u32 config_reg, baud_rate_val = 0;

        /*
         * Set the clock frequency
         * The baud rate divisor is not a direct mapping to the value written
         * into the configuration register (config_reg[5:3])
         * i.e. 000 - divide by 2
         *      001 - divide by 4
         *      ----------------
         *      111 - divide by 256
         */
        while ((baud_rate_val < ZYNQ_QSPI_CONFIG_BAUD_DIV_MAX)  &&
               (clk_get_rate(xqspi->refclk) / (2 << baud_rate_val)) >
                spi->max_speed_hz)
                baud_rate_val++;

        config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);

        /* Set the QSPI clock phase and clock polarity */
        config_reg &= (~ZYNQ_QSPI_CONFIG_CPHA_MASK) &
                      (~ZYNQ_QSPI_CONFIG_CPOL_MASK);
        if (spi->mode & SPI_CPHA)
                config_reg |= ZYNQ_QSPI_CONFIG_CPHA_MASK;
        if (spi->mode & SPI_CPOL)
                config_reg |= ZYNQ_QSPI_CONFIG_CPOL_MASK;

        config_reg &= ~ZYNQ_QSPI_CONFIG_BDRATE_MASK;
        config_reg |= (baud_rate_val << ZYNQ_QSPI_CONFIG_BAUD_DIV_SHIFT);
        zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);

        return 0;
}

/**
 * zynq_qspi_setup - Configure the QSPI controller
 * @spi:        Pointer to the spi_device structure
 *
 * Sets the operational mode of QSPI controller for the next QSPI transfer, baud
 * rate and divisor value to setup the requested qspi clock.
 *
 * Return:      0 on success and error value on failure
 */
static int zynq_qspi_setup_op(struct spi_device *spi)
{
        struct spi_controller *ctlr = spi->master;
        struct zynq_qspi *qspi = spi_controller_get_devdata(ctlr);

        if (ctlr->busy)
                return -EBUSY;

        clk_enable(qspi->refclk);
        clk_enable(qspi->pclk);
        zynq_qspi_write(qspi, ZYNQ_QSPI_ENABLE_OFFSET,
                        ZYNQ_QSPI_ENABLE_ENABLE_MASK);

        return 0;
}

/**
 * zynq_qspi_write_op - Fills the TX FIFO with as many bytes as possible
 * @xqspi:      Pointer to the zynq_qspi structure
 * @txcount:    Maximum number of words to write
 * @txempty:    Indicates that TxFIFO is empty
 */
static void zynq_qspi_write_op(struct zynq_qspi *xqspi, int txcount,
                               bool txempty)
{
        int count, len, k;

        len = xqspi->tx_bytes;
        if (len && len < 4) {
                /*
                 * We must empty the TxFIFO between accesses to TXD0,
                 * TXD1, TXD2, TXD3.
                 */
                if (txempty)
                        zynq_qspi_txfifo_op(xqspi, len);

                return;
        }

        count = len / 4;
        if (count > txcount)
                count = txcount;

        if (xqspi->txbuf) {
                iowrite32_rep(xqspi->regs + ZYNQ_QSPI_TXD_00_00_OFFSET,
                              xqspi->txbuf, count);
                xqspi->txbuf += count * 4;
        } else {
                for (k = 0; k < count; k++)
                        writel_relaxed(0, xqspi->regs +
                                          ZYNQ_QSPI_TXD_00_00_OFFSET);
        }

        xqspi->tx_bytes -= count * 4;
}

/**
 * zynq_qspi_read_op - Drains the RX FIFO by as many bytes as possible
 * @xqspi:      Pointer to the zynq_qspi structure
 * @rxcount:    Maximum number of words to read
 */
static void zynq_qspi_read_op(struct zynq_qspi *xqspi, int rxcount)
{
        int count, len, k;

        len = xqspi->rx_bytes - xqspi->tx_bytes;
        count = len / 4;
        if (count > rxcount)
                count = rxcount;
        if (xqspi->rxbuf) {
                ioread32_rep(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET,
                             xqspi->rxbuf, count);
                xqspi->rxbuf += count * 4;
        } else {
                for (k = 0; k < count; k++)
                        readl_relaxed(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET);
        }
        xqspi->rx_bytes -= count * 4;
        len -= count * 4;

        if (len && len < 4 && count < rxcount)
                zynq_qspi_rxfifo_op(xqspi, len);
}

/**
 * zynq_qspi_irq - Interrupt service routine of the QSPI controller
 * @irq:        IRQ number
 * @dev_id:     Pointer to the xqspi structure
 *
 * This function handles TX empty only.
 * On TX empty interrupt this function reads the received data from RX FIFO and
 * fills the TX FIFO if there is any data remaining to be transferred.
 *
 * Return:      IRQ_HANDLED when interrupt is handled; IRQ_NONE otherwise.
 */
static irqreturn_t zynq_qspi_irq(int irq, void *dev_id)
{
        u32 intr_status;
        bool txempty;
        struct zynq_qspi *xqspi = (struct zynq_qspi *)dev_id;

        intr_status = zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET);
        zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET, intr_status);

        if ((intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK) ||
            (intr_status & ZYNQ_QSPI_IXR_RXNEMTY_MASK)) {
                /*
                 * This bit is set when Tx FIFO has < THRESHOLD entries.
                 * We have the THRESHOLD value set to 1,
                 * so this bit indicates Tx FIFO is empty.
                 */
                txempty = !!(intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK);
                /* Read out the data from the RX FIFO */
                zynq_qspi_read_op(xqspi, ZYNQ_QSPI_RX_THRESHOLD);
                if (xqspi->tx_bytes) {
                        /* There is more data to send */
                        zynq_qspi_write_op(xqspi, ZYNQ_QSPI_RX_THRESHOLD,
                                           txempty);
                } else {
                        /*
                         * If transfer and receive is completed then only send
                         * complete signal.
                         */
                        if (!xqspi->rx_bytes) {
                                zynq_qspi_write(xqspi,
                                                ZYNQ_QSPI_IDIS_OFFSET,
                                                ZYNQ_QSPI_IXR_RXTX_MASK);
                                complete(&xqspi->data_completion);
                        }
                }
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/**
 * zynq_qspi_exec_mem_op() - Initiates the QSPI transfer
 * @mem: the SPI memory
 * @op: the memory operation to execute
 *
 * Executes a memory operation.
 *
 * This function first selects the chip and starts the memory operation.
 *
 * Return: 0 in case of success, a negative error code otherwise.
 */
static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
                                 const struct spi_mem_op *op)
{
        struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
        int err = 0, i;
        u8 *tmpbuf;
        u8 opcode = op->cmd.opcode;

        dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
                opcode, op->cmd.buswidth, op->addr.buswidth,
                op->dummy.buswidth, op->data.buswidth);

        zynq_qspi_chipselect(mem->spi, true);
        zynq_qspi_config_op(xqspi, mem->spi);

        if (op->cmd.nbytes) {
                reinit_completion(&xqspi->data_completion);
                xqspi->txbuf = &opcode;
                xqspi->rxbuf = NULL;
                xqspi->tx_bytes = op->cmd.nbytes;
                xqspi->rx_bytes = op->cmd.nbytes;
                zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
                zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
                                ZYNQ_QSPI_IXR_RXTX_MASK);
                if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
                                                               msecs_to_jiffies(1000)))
                        err = -ETIMEDOUT;
        }

        if (op->addr.nbytes) {
                for (i = 0; i < op->addr.nbytes; i++) {
                        xqspi->txbuf[i] = op->addr.val >>
                                        (8 * (op->addr.nbytes - i - 1));
                }

                reinit_completion(&xqspi->data_completion);
                xqspi->rxbuf = NULL;
                xqspi->tx_bytes = op->addr.nbytes;
                xqspi->rx_bytes = op->addr.nbytes;
                zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
                zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
                                ZYNQ_QSPI_IXR_RXTX_MASK);
                if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
                                                               msecs_to_jiffies(1000)))
                        err = -ETIMEDOUT;
        }

        if (op->dummy.nbytes) {
                tmpbuf = kzalloc(op->dummy.nbytes, GFP_KERNEL);
                memset(tmpbuf, 0xff, op->dummy.nbytes);
                reinit_completion(&xqspi->data_completion);
                xqspi->txbuf = tmpbuf;
                xqspi->rxbuf = NULL;
                xqspi->tx_bytes = op->dummy.nbytes;
                xqspi->rx_bytes = op->dummy.nbytes;
                zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
                zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
                                ZYNQ_QSPI_IXR_RXTX_MASK);
                if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
                                                               msecs_to_jiffies(1000)))
                        err = -ETIMEDOUT;

                kfree(tmpbuf);
        }

        if (op->data.nbytes) {
                reinit_completion(&xqspi->data_completion);
                if (op->data.dir == SPI_MEM_DATA_OUT) {
                        xqspi->txbuf = (u8 *)op->data.buf.out;
                        xqspi->tx_bytes = op->data.nbytes;
                        xqspi->rxbuf = NULL;
                        xqspi->rx_bytes = op->data.nbytes;
                } else {
                        xqspi->txbuf = NULL;
                        xqspi->rxbuf = (u8 *)op->data.buf.in;
                        xqspi->rx_bytes = op->data.nbytes;
                        xqspi->tx_bytes = op->data.nbytes;
                }

                zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
                zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
                                ZYNQ_QSPI_IXR_RXTX_MASK);
                if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
                                                               msecs_to_jiffies(1000)))
                        err = -ETIMEDOUT;
        }
        zynq_qspi_chipselect(mem->spi, false);

        return err;
}

static const struct spi_controller_mem_ops zynq_qspi_mem_ops = {
        .supports_op = zynq_qspi_supports_op,
        .exec_op = zynq_qspi_exec_mem_op,
};

/**
 * zynq_qspi_probe - Probe method for the QSPI driver
 * @pdev:       Pointer to the platform_device structure
 *
 * This function initializes the driver data structures and the hardware.
 *
 * Return:      0 on success and error value on failure
 */
static int zynq_qspi_probe(struct platform_device *pdev)
{
        int ret = 0;
        struct spi_controller *ctlr;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct zynq_qspi *xqspi;
        u32 num_cs;

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

        xqspi = spi_controller_get_devdata(ctlr);
        xqspi->dev = dev;
        platform_set_drvdata(pdev, xqspi);
        xqspi->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(xqspi->regs)) {
                ret = PTR_ERR(xqspi->regs);
                goto remove_master;
        }

        xqspi->pclk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(xqspi->pclk)) {
                dev_err(&pdev->dev, "pclk clock not found.\n");
                ret = PTR_ERR(xqspi->pclk);
                goto remove_master;
        }

        init_completion(&xqspi->data_completion);

        xqspi->refclk = devm_clk_get(&pdev->dev, "ref_clk");
        if (IS_ERR(xqspi->refclk)) {
                dev_err(&pdev->dev, "ref_clk clock not found.\n");
                ret = PTR_ERR(xqspi->refclk);
                goto remove_master;
        }

        ret = clk_prepare_enable(xqspi->pclk);
        if (ret) {
                dev_err(&pdev->dev, "Unable to enable APB clock.\n");
                goto remove_master;
        }

        ret = clk_prepare_enable(xqspi->refclk);
        if (ret) {
                dev_err(&pdev->dev, "Unable to enable device clock.\n");
                goto clk_dis_pclk;
        }

        xqspi->irq = platform_get_irq(pdev, 0);
        if (xqspi->irq <= 0) {
                ret = -ENXIO;
                goto remove_master;
        }
        ret = devm_request_irq(&pdev->dev, xqspi->irq, zynq_qspi_irq,
                               0, pdev->name, xqspi);
        if (ret != 0) {
                ret = -ENXIO;
                dev_err(&pdev->dev, "request_irq failed\n");
                goto remove_master;
        }

        ret = of_property_read_u32(np, "num-cs",
                                   &num_cs);
        if (ret < 0) {
                ctlr->num_chipselect = 1;
        } else if (num_cs > ZYNQ_QSPI_MAX_NUM_CS) {
                dev_err(&pdev->dev, "only 2 chip selects are available\n");
                goto remove_master;
        } else {
                ctlr->num_chipselect = num_cs;
        }

        ctlr->mode_bits =  SPI_RX_DUAL | SPI_RX_QUAD |
                            SPI_TX_DUAL | SPI_TX_QUAD;
        ctlr->mem_ops = &zynq_qspi_mem_ops;
        ctlr->setup = zynq_qspi_setup_op;
        ctlr->max_speed_hz = clk_get_rate(xqspi->refclk) / 2;
        ctlr->dev.of_node = np;

        /* QSPI controller initializations */
        zynq_qspi_init_hw(xqspi, ctlr->num_chipselect);

        ret = devm_spi_register_controller(&pdev->dev, ctlr);
        if (ret) {
                dev_err(&pdev->dev, "spi_register_master failed\n");
                goto clk_dis_all;
        }

        return ret;

clk_dis_all:
        clk_disable_unprepare(xqspi->refclk);
clk_dis_pclk:
        clk_disable_unprepare(xqspi->pclk);
remove_master:
        spi_controller_put(ctlr);

        return ret;
}

/**
 * zynq_qspi_remove - Remove method for the QSPI driver
 * @pdev:       Pointer to the platform_device structure
 *
 * This function is called if a device is physically removed from the system or
 * if the driver module is being unloaded. It frees all resources allocated to
 * the device.
 *
 * Return:      0 on success and error value on failure
 */
static int zynq_qspi_remove(struct platform_device *pdev)
{
        struct zynq_qspi *xqspi = platform_get_drvdata(pdev);

        zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);

        clk_disable_unprepare(xqspi->refclk);
        clk_disable_unprepare(xqspi->pclk);

        return 0;
}

static const struct of_device_id zynq_qspi_of_match[] = {
        { .compatible = "xlnx,zynq-qspi-1.0", },
        { /* end of table */ }
};

MODULE_DEVICE_TABLE(of, zynq_qspi_of_match);

/*
 * zynq_qspi_driver - This structure defines the QSPI platform driver
 */
static struct platform_driver zynq_qspi_driver = {
        .probe = zynq_qspi_probe,
        .remove = zynq_qspi_remove,
        .driver = {
                .name = "zynq-qspi",
                .of_match_table = zynq_qspi_of_match,
        },
};

module_platform_driver(zynq_qspi_driver);

MODULE_AUTHOR("Xilinx, Inc.");
MODULE_DESCRIPTION("Xilinx Zynq QSPI driver");
MODULE_LICENSE("GPL");