/*
 * Xilinx Zynq UltraScale+ MPSoC Quad-SPI (QSPI) controller driver
 * (master mode only)
 *
 * Copyright (C) 2009 - 2015 Xilinx, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.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/spinlock.h>
#include <linux/workqueue.h>

/* Generic QSPI register offsets */
#define GQSPI_CONFIG_OFST               0x00000100
#define GQSPI_ISR_OFST                  0x00000104
#define GQSPI_IDR_OFST                  0x0000010C
#define GQSPI_IER_OFST                  0x00000108
#define GQSPI_IMASK_OFST                0x00000110
#define GQSPI_EN_OFST                   0x00000114
#define GQSPI_TXD_OFST                  0x0000011C
#define GQSPI_RXD_OFST                  0x00000120
#define GQSPI_TX_THRESHOLD_OFST         0x00000128
#define GQSPI_RX_THRESHOLD_OFST         0x0000012C
#define GQSPI_LPBK_DLY_ADJ_OFST         0x00000138
#define GQSPI_GEN_FIFO_OFST             0x00000140
#define GQSPI_SEL_OFST                  0x00000144
#define GQSPI_GF_THRESHOLD_OFST         0x00000150
#define GQSPI_FIFO_CTRL_OFST            0x0000014C
#define GQSPI_QSPIDMA_DST_CTRL_OFST     0x0000080C
#define GQSPI_QSPIDMA_DST_SIZE_OFST     0x00000804
#define GQSPI_QSPIDMA_DST_STS_OFST      0x00000808
#define GQSPI_QSPIDMA_DST_I_STS_OFST    0x00000814
#define GQSPI_QSPIDMA_DST_I_EN_OFST     0x00000818
#define GQSPI_QSPIDMA_DST_I_DIS_OFST    0x0000081C
#define GQSPI_QSPIDMA_DST_I_MASK_OFST   0x00000820
#define GQSPI_QSPIDMA_DST_ADDR_OFST     0x00000800
#define GQSPI_QSPIDMA_DST_ADDR_MSB_OFST 0x00000828

/* GQSPI register bit masks */
#define GQSPI_SEL_MASK                          0x00000001
#define GQSPI_EN_MASK                           0x00000001
#define GQSPI_LPBK_DLY_ADJ_USE_LPBK_MASK        0x00000020
#define GQSPI_ISR_WR_TO_CLR_MASK                0x00000002
#define GQSPI_IDR_ALL_MASK                      0x00000FBE
#define GQSPI_CFG_MODE_EN_MASK                  0xC0000000
#define GQSPI_CFG_GEN_FIFO_START_MODE_MASK      0x20000000
#define GQSPI_CFG_ENDIAN_MASK                   0x04000000
#define GQSPI_CFG_EN_POLL_TO_MASK               0x00100000
#define GQSPI_CFG_WP_HOLD_MASK                  0x00080000
#define GQSPI_CFG_BAUD_RATE_DIV_MASK            0x00000038
#define GQSPI_CFG_CLK_PHA_MASK                  0x00000004
#define GQSPI_CFG_CLK_POL_MASK                  0x00000002
#define GQSPI_CFG_START_GEN_FIFO_MASK           0x10000000
#define GQSPI_GENFIFO_IMM_DATA_MASK             0x000000FF
#define GQSPI_GENFIFO_DATA_XFER                 0x00000100
#define GQSPI_GENFIFO_EXP                       0x00000200
#define GQSPI_GENFIFO_MODE_SPI                  0x00000400
#define GQSPI_GENFIFO_MODE_DUALSPI              0x00000800
#define GQSPI_GENFIFO_MODE_QUADSPI              0x00000C00
#define GQSPI_GENFIFO_MODE_MASK                 0x00000C00
#define GQSPI_GENFIFO_CS_LOWER                  0x00001000
#define GQSPI_GENFIFO_CS_UPPER                  0x00002000
#define GQSPI_GENFIFO_BUS_LOWER                 0x00004000
#define GQSPI_GENFIFO_BUS_UPPER                 0x00008000
#define GQSPI_GENFIFO_BUS_BOTH                  0x0000C000
#define GQSPI_GENFIFO_BUS_MASK                  0x0000C000
#define GQSPI_GENFIFO_TX                        0x00010000
#define GQSPI_GENFIFO_RX                        0x00020000
#define GQSPI_GENFIFO_STRIPE                    0x00040000
#define GQSPI_GENFIFO_POLL                      0x00080000
#define GQSPI_GENFIFO_EXP_START                 0x00000100
#define GQSPI_FIFO_CTRL_RST_RX_FIFO_MASK        0x00000004
#define GQSPI_FIFO_CTRL_RST_TX_FIFO_MASK        0x00000002
#define GQSPI_FIFO_CTRL_RST_GEN_FIFO_MASK       0x00000001
#define GQSPI_ISR_RXEMPTY_MASK                  0x00000800
#define GQSPI_ISR_GENFIFOFULL_MASK              0x00000400
#define GQSPI_ISR_GENFIFONOT_FULL_MASK          0x00000200
#define GQSPI_ISR_TXEMPTY_MASK                  0x00000100
#define GQSPI_ISR_GENFIFOEMPTY_MASK             0x00000080
#define GQSPI_ISR_RXFULL_MASK                   0x00000020
#define GQSPI_ISR_RXNEMPTY_MASK                 0x00000010
#define GQSPI_ISR_TXFULL_MASK                   0x00000008
#define GQSPI_ISR_TXNOT_FULL_MASK               0x00000004
#define GQSPI_ISR_POLL_TIME_EXPIRE_MASK         0x00000002
#define GQSPI_IER_TXNOT_FULL_MASK               0x00000004
#define GQSPI_IER_RXEMPTY_MASK                  0x00000800
#define GQSPI_IER_POLL_TIME_EXPIRE_MASK         0x00000002
#define GQSPI_IER_RXNEMPTY_MASK                 0x00000010
#define GQSPI_IER_GENFIFOEMPTY_MASK             0x00000080
#define GQSPI_IER_TXEMPTY_MASK                  0x00000100
#define GQSPI_QSPIDMA_DST_INTR_ALL_MASK         0x000000FE
#define GQSPI_QSPIDMA_DST_STS_WTC               0x0000E000
#define GQSPI_CFG_MODE_EN_DMA_MASK              0x80000000
#define GQSPI_ISR_IDR_MASK                      0x00000994
#define GQSPI_QSPIDMA_DST_I_EN_DONE_MASK        0x00000002
#define GQSPI_QSPIDMA_DST_I_STS_DONE_MASK       0x00000002
#define GQSPI_IRQ_MASK                          0x00000980

#define GQSPI_CFG_BAUD_RATE_DIV_SHIFT           3
#define GQSPI_GENFIFO_CS_SETUP                  0x4
#define GQSPI_GENFIFO_CS_HOLD                   0x3
#define GQSPI_TXD_DEPTH                         64
#define GQSPI_RX_FIFO_THRESHOLD                 32
#define GQSPI_RX_FIFO_FILL      (GQSPI_RX_FIFO_THRESHOLD * 4)
#define GQSPI_TX_FIFO_THRESHOLD_RESET_VAL       32
#define GQSPI_TX_FIFO_FILL      (GQSPI_TXD_DEPTH -\
                                GQSPI_TX_FIFO_THRESHOLD_RESET_VAL)
#define GQSPI_GEN_FIFO_THRESHOLD_RESET_VAL      0X10
#define GQSPI_QSPIDMA_DST_CTRL_RESET_VAL        0x803FFA00
#define GQSPI_SELECT_FLASH_CS_LOWER             0x1
#define GQSPI_SELECT_FLASH_CS_UPPER             0x2
#define GQSPI_SELECT_FLASH_CS_BOTH              0x3
#define GQSPI_SELECT_FLASH_BUS_LOWER            0x1
#define GQSPI_SELECT_FLASH_BUS_UPPER            0x2
#define GQSPI_SELECT_FLASH_BUS_BOTH             0x3
#define GQSPI_BAUD_DIV_MAX      7       /* Baud rate divisor maximum */
#define GQSPI_BAUD_DIV_SHIFT    2       /* Baud rate divisor shift */
#define GQSPI_SELECT_MODE_SPI           0x1
#define GQSPI_SELECT_MODE_DUALSPI       0x2
#define GQSPI_SELECT_MODE_QUADSPI       0x4
#define GQSPI_DMA_UNALIGN               0x3
#define GQSPI_DEFAULT_NUM_CS    1       /* Default number of chip selects */

enum mode_type {GQSPI_MODE_IO, GQSPI_MODE_DMA};

/**
 * struct zynqmp_qspi - Defines qspi driver instance
 * @regs:               Virtual address of the QSPI controller registers
 * @refclk:             Pointer to the peripheral clock
 * @pclk:               Pointer to the APB clock
 * @irq:                IRQ number
 * @dev:                Pointer to struct device
 * @txbuf:              Pointer to the TX buffer
 * @rxbuf:              Pointer to the RX buffer
 * @bytes_to_transfer:  Number of bytes left to transfer
 * @bytes_to_receive:   Number of bytes left to receive
 * @genfifocs:          Used for chip select
 * @genfifobus:         Used to select the upper or lower bus
 * @dma_rx_bytes:       Remaining bytes to receive by DMA mode
 * @dma_addr:           DMA address after mapping the kernel buffer
 * @genfifoentry:       Used for storing the genfifoentry instruction.
 * @mode:               Defines the mode in which QSPI is operating
 */
struct zynqmp_qspi {
        void __iomem *regs;
        struct clk *refclk;
        struct clk *pclk;
        int irq;
        struct device *dev;
        const void *txbuf;
        void *rxbuf;
        int bytes_to_transfer;
        int bytes_to_receive;
        u32 genfifocs;
        u32 genfifobus;
        u32 dma_rx_bytes;
        dma_addr_t dma_addr;
        u32 genfifoentry;
        enum mode_type mode;
};

/**
 * zynqmp_gqspi_read:   For GQSPI controller read operation
 * @xqspi:      Pointer to the zynqmp_qspi structure
 * @offset:     Offset from where to read
 */
static u32 zynqmp_gqspi_read(struct zynqmp_qspi *xqspi, u32 offset)
{
        return readl_relaxed(xqspi->regs + offset);
}

/**
 * zynqmp_gqspi_write:  For GQSPI controller write operation
 * @xqspi:      Pointer to the zynqmp_qspi structure
 * @offset:     Offset where to write
 * @val:        Value to be written
 */
static inline void zynqmp_gqspi_write(struct zynqmp_qspi *xqspi, u32 offset,
                                      u32 val)
{
        writel_relaxed(val, (xqspi->regs + offset));
}

/**
 * zynqmp_gqspi_selectslave:    For selection of slave device
 * @instanceptr:        Pointer to the zynqmp_qspi structure
 * @flashcs:    For chip select
 * @flashbus:   To check which bus is selected- upper or lower
 */
static void zynqmp_gqspi_selectslave(struct zynqmp_qspi *instanceptr,
                                     u8 slavecs, u8 slavebus)
{
        /*
         * Bus and CS lines selected here will be updated in the instance and
         * used for subsequent GENFIFO entries during transfer.
         */

        /* Choose slave select line */
        switch (slavecs) {
        case GQSPI_SELECT_FLASH_CS_BOTH:
                instanceptr->genfifocs = GQSPI_GENFIFO_CS_LOWER |
                        GQSPI_GENFIFO_CS_UPPER;
                break;
        case GQSPI_SELECT_FLASH_CS_UPPER:
                instanceptr->genfifocs = GQSPI_GENFIFO_CS_UPPER;
                break;
        case GQSPI_SELECT_FLASH_CS_LOWER:
                instanceptr->genfifocs = GQSPI_GENFIFO_CS_LOWER;
                break;
        default:
                dev_warn(instanceptr->dev, "Invalid slave select\n");
        }

        /* Choose the bus */
        switch (slavebus) {
        case GQSPI_SELECT_FLASH_BUS_BOTH:
                instanceptr->genfifobus = GQSPI_GENFIFO_BUS_LOWER |
                        GQSPI_GENFIFO_BUS_UPPER;
                break;
        case GQSPI_SELECT_FLASH_BUS_UPPER:
                instanceptr->genfifobus = GQSPI_GENFIFO_BUS_UPPER;
                break;
        case GQSPI_SELECT_FLASH_BUS_LOWER:
                instanceptr->genfifobus = GQSPI_GENFIFO_BUS_LOWER;
                break;
        default:
                dev_warn(instanceptr->dev, "Invalid slave bus\n");
        }
}

/**
 * zynqmp_qspi_init_hw: Initialize the hardware
 * @xqspi:      Pointer to the zynqmp_qspi structure
 *
 * The default settings of the QSPI controller's configurable parameters on
 * reset are
 *      - Master mode
 *      - TX threshold set to 1
 *      - RX threshold set to 1
 *      - Flash memory interface mode enabled
 * 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 little endian mode of TX FIFO and
 *      - Enable the QSPI controller
 */
static void zynqmp_qspi_init_hw(struct zynqmp_qspi *xqspi)
{
        u32 config_reg;

        /* Select the GQSPI mode */
        zynqmp_gqspi_write(xqspi, GQSPI_SEL_OFST, GQSPI_SEL_MASK);
        /* Clear and disable interrupts */
        zynqmp_gqspi_write(xqspi, GQSPI_ISR_OFST,
                           zynqmp_gqspi_read(xqspi, GQSPI_ISR_OFST) |
                           GQSPI_ISR_WR_TO_CLR_MASK);
        /* Clear the DMA STS */
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_I_STS_OFST,
                           zynqmp_gqspi_read(xqspi,
                                             GQSPI_QSPIDMA_DST_I_STS_OFST));
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_STS_OFST,
                           zynqmp_gqspi_read(xqspi,
                                             GQSPI_QSPIDMA_DST_STS_OFST) |
                                             GQSPI_QSPIDMA_DST_STS_WTC);
        zynqmp_gqspi_write(xqspi, GQSPI_IDR_OFST, GQSPI_IDR_ALL_MASK);
        zynqmp_gqspi_write(xqspi,
                           GQSPI_QSPIDMA_DST_I_DIS_OFST,
                           GQSPI_QSPIDMA_DST_INTR_ALL_MASK);
        /* Disable the GQSPI */
        zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, 0x0);
        config_reg = zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST);
        config_reg &= ~GQSPI_CFG_MODE_EN_MASK;
        /* Manual start */
        config_reg |= GQSPI_CFG_GEN_FIFO_START_MODE_MASK;
        /* Little endian by default */
        config_reg &= ~GQSPI_CFG_ENDIAN_MASK;
        /* Disable poll time out */
        config_reg &= ~GQSPI_CFG_EN_POLL_TO_MASK;
        /* Set hold bit */
        config_reg |= GQSPI_CFG_WP_HOLD_MASK;
        /* Clear pre-scalar by default */
        config_reg &= ~GQSPI_CFG_BAUD_RATE_DIV_MASK;
        /* CPHA 0 */
        config_reg &= ~GQSPI_CFG_CLK_PHA_MASK;
        /* CPOL 0 */
        config_reg &= ~GQSPI_CFG_CLK_POL_MASK;
        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, config_reg);

        /* Clear the TX and RX FIFO */
        zynqmp_gqspi_write(xqspi, GQSPI_FIFO_CTRL_OFST,
                           GQSPI_FIFO_CTRL_RST_RX_FIFO_MASK |
                           GQSPI_FIFO_CTRL_RST_TX_FIFO_MASK |
                           GQSPI_FIFO_CTRL_RST_GEN_FIFO_MASK);
        /* Set by default to allow for high frequencies */
        zynqmp_gqspi_write(xqspi, GQSPI_LPBK_DLY_ADJ_OFST,
                           zynqmp_gqspi_read(xqspi, GQSPI_LPBK_DLY_ADJ_OFST) |
                           GQSPI_LPBK_DLY_ADJ_USE_LPBK_MASK);
        /* Reset thresholds */
        zynqmp_gqspi_write(xqspi, GQSPI_TX_THRESHOLD_OFST,
                           GQSPI_TX_FIFO_THRESHOLD_RESET_VAL);
        zynqmp_gqspi_write(xqspi, GQSPI_RX_THRESHOLD_OFST,
                           GQSPI_RX_FIFO_THRESHOLD);
        zynqmp_gqspi_write(xqspi, GQSPI_GF_THRESHOLD_OFST,
                           GQSPI_GEN_FIFO_THRESHOLD_RESET_VAL);
        zynqmp_gqspi_selectslave(xqspi,
                                 GQSPI_SELECT_FLASH_CS_LOWER,
                                 GQSPI_SELECT_FLASH_BUS_LOWER);
        /* Initialize DMA */
        zynqmp_gqspi_write(xqspi,
                        GQSPI_QSPIDMA_DST_CTRL_OFST,
                        GQSPI_QSPIDMA_DST_CTRL_RESET_VAL);

        /* Enable the GQSPI */
        zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, GQSPI_EN_MASK);
}

/**
 * zynqmp_qspi_copy_read_data:  Copy data to RX buffer
 * @xqspi:      Pointer to the zynqmp_qspi structure
 * @data:       The variable where data is stored
 * @size:       Number of bytes to be copied from data to RX buffer
 */
static void zynqmp_qspi_copy_read_data(struct zynqmp_qspi *xqspi,
                                       ulong data, u8 size)
{
        memcpy(xqspi->rxbuf, &data, size);
        xqspi->rxbuf += size;
        xqspi->bytes_to_receive -= size;
}

/**
 * zynqmp_prepare_transfer_hardware:    Prepares hardware for transfer.
 * @master:     Pointer to the spi_master structure which provides
 *              information about the controller.
 *
 * This function enables SPI master controller.
 *
 * Return:      0 on success; error value otherwise
 */
static int zynqmp_prepare_transfer_hardware(struct spi_master *master)
{
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);
        int ret;

        ret = clk_enable(xqspi->refclk);
        if (ret)
                return ret;

        ret = clk_enable(xqspi->pclk);
        if (ret)
                goto clk_err;

        zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, GQSPI_EN_MASK);
        return 0;
clk_err:
        clk_disable(xqspi->refclk);
        return ret;
}

/**
 * zynqmp_unprepare_transfer_hardware:  Relaxes hardware after transfer
 * @master:     Pointer to the spi_master structure which provides
 *              information about the controller.
 *
 * This function disables the SPI master controller.
 *
 * Return:      Always 0
 */
static int zynqmp_unprepare_transfer_hardware(struct spi_master *master)
{
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);

        zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, 0x0);
        clk_disable(xqspi->refclk);
        clk_disable(xqspi->pclk);
        return 0;
}

/**
 * zynqmp_qspi_chipselect:      Select or deselect the chip select line
 * @qspi:       Pointer to the spi_device structure
 * @is_high:    Select(0) or deselect (1) the chip select line
 */
static void zynqmp_qspi_chipselect(struct spi_device *qspi, bool is_high)
{
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(qspi->master);
        ulong timeout;
        u32 genfifoentry = 0x0, statusreg;

        genfifoentry |= GQSPI_GENFIFO_MODE_SPI;
        genfifoentry |= xqspi->genfifobus;

        if (!is_high) {
                genfifoentry |= xqspi->genfifocs;
                genfifoentry |= GQSPI_GENFIFO_CS_SETUP;
        } else {
                genfifoentry |= GQSPI_GENFIFO_CS_HOLD;
        }

        zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);

        /* Dummy generic FIFO entry */
        zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);

        /* Manually start the generic FIFO command */
        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
                        zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) |
                        GQSPI_CFG_START_GEN_FIFO_MASK);

        timeout = jiffies + msecs_to_jiffies(1000);

        /* Wait until the generic FIFO command is empty */
        do {
                statusreg = zynqmp_gqspi_read(xqspi, GQSPI_ISR_OFST);

                if ((statusreg & GQSPI_ISR_GENFIFOEMPTY_MASK) &&
                        (statusreg & GQSPI_ISR_TXEMPTY_MASK))
                        break;
                else
                        cpu_relax();
        } while (!time_after_eq(jiffies, timeout));

        if (time_after_eq(jiffies, timeout))
                dev_err(xqspi->dev, "Chip select timed out\n");
}

/**
 * zynqmp_qspi_setup_transfer:  Configure QSPI controller for specified
 *                              transfer
 * @qspi:       Pointer to the spi_device structure
 * @transfer:   Pointer to the spi_transfer structure which provides
 *              information about next transfer setup parameters
 *
 * Sets the operational mode of QSPI controller for the next QSPI transfer and
 * sets the requested clock frequency.
 *
 * Return:      Always 0
 *
 * Note:
 *      If the requested frequency is not an exact match with what can be
 *      obtained using the pre-scalar 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 zynqmp_qspi_setup_transfer(struct spi_device *qspi,
                                      struct spi_transfer *transfer)
{
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(qspi->master);
        ulong clk_rate;
        u32 config_reg, req_hz, baud_rate_val = 0;

        if (transfer)
                req_hz = transfer->speed_hz;
        else
                req_hz = qspi->max_speed_hz;

        /* Set the clock frequency */
        /* If req_hz == 0, default to lowest speed */
        clk_rate = clk_get_rate(xqspi->refclk);

        while ((baud_rate_val < GQSPI_BAUD_DIV_MAX) &&
               (clk_rate /
                (GQSPI_BAUD_DIV_SHIFT << baud_rate_val)) > req_hz)
                baud_rate_val++;

        config_reg = zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST);

        /* Set the QSPI clock phase and clock polarity */
        config_reg &= (~GQSPI_CFG_CLK_PHA_MASK) & (~GQSPI_CFG_CLK_POL_MASK);

        if (qspi->mode & SPI_CPHA)
                config_reg |= GQSPI_CFG_CLK_PHA_MASK;
        if (qspi->mode & SPI_CPOL)
                config_reg |= GQSPI_CFG_CLK_POL_MASK;

        config_reg &= ~GQSPI_CFG_BAUD_RATE_DIV_MASK;
        config_reg |= (baud_rate_val << GQSPI_CFG_BAUD_RATE_DIV_SHIFT);
        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, config_reg);
        return 0;
}

/**
 * zynqmp_qspi_setup:   Configure the QSPI controller
 * @qspi:       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; error value otherwise.
 */
static int zynqmp_qspi_setup(struct spi_device *qspi)
{
        if (qspi->master->busy)
                return -EBUSY;
        return 0;
}

/**
 * zynqmp_qspi_filltxfifo:      Fills the TX FIFO as long as there is room in
 *                              the FIFO or the bytes required to be
 *                              transmitted.
 * @xqspi:      Pointer to the zynqmp_qspi structure
 * @size:       Number of bytes to be copied from TX buffer to TX FIFO
 */
static void zynqmp_qspi_filltxfifo(struct zynqmp_qspi *xqspi, int size)
{
        u32 count = 0, intermediate;

        while ((xqspi->bytes_to_transfer > 0) && (count < size)) {
                memcpy(&intermediate, xqspi->txbuf, 4);
                zynqmp_gqspi_write(xqspi, GQSPI_TXD_OFST, intermediate);

                if (xqspi->bytes_to_transfer >= 4) {
                        xqspi->txbuf += 4;
                        xqspi->bytes_to_transfer -= 4;
                } else {
                        xqspi->txbuf += xqspi->bytes_to_transfer;
                        xqspi->bytes_to_transfer = 0;
                }
                count++;
        }
}

/**
 * zynqmp_qspi_readrxfifo:      Fills the RX FIFO as long as there is room in
 *                              the FIFO.
 * @xqspi:      Pointer to the zynqmp_qspi structure
 * @size:       Number of bytes to be copied from RX buffer to RX FIFO
 */
static void zynqmp_qspi_readrxfifo(struct zynqmp_qspi *xqspi, u32 size)
{
        ulong data;
        int count = 0;

        while ((count < size) && (xqspi->bytes_to_receive > 0)) {
                if (xqspi->bytes_to_receive >= 4) {
                        (*(u32 *) xqspi->rxbuf) =
                        zynqmp_gqspi_read(xqspi, GQSPI_RXD_OFST);
                        xqspi->rxbuf += 4;
                        xqspi->bytes_to_receive -= 4;
                        count += 4;
                } else {
                        data = zynqmp_gqspi_read(xqspi, GQSPI_RXD_OFST);
                        count += xqspi->bytes_to_receive;
                        zynqmp_qspi_copy_read_data(xqspi, data,
                                                   xqspi->bytes_to_receive);
                        xqspi->bytes_to_receive = 0;
                }
        }
}

/**
 * zynqmp_process_dma_irq:      Handler for DMA done interrupt of QSPI
 *                              controller
 * @xqspi:      zynqmp_qspi instance pointer
 *
 * This function handles DMA interrupt only.
 */
static void zynqmp_process_dma_irq(struct zynqmp_qspi *xqspi)
{
        u32 config_reg, genfifoentry;

        dma_unmap_single(xqspi->dev, xqspi->dma_addr,
                                xqspi->dma_rx_bytes, DMA_FROM_DEVICE);
        xqspi->rxbuf += xqspi->dma_rx_bytes;
        xqspi->bytes_to_receive -= xqspi->dma_rx_bytes;
        xqspi->dma_rx_bytes = 0;

        /* Disabling the DMA interrupts */
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_I_DIS_OFST,
                                        GQSPI_QSPIDMA_DST_I_EN_DONE_MASK);

        if (xqspi->bytes_to_receive > 0) {
                /* Switch to IO mode,for remaining bytes to receive */
                config_reg = zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST);
                config_reg &= ~GQSPI_CFG_MODE_EN_MASK;
                zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, config_reg);

                /* Initiate the transfer of remaining bytes */
                genfifoentry = xqspi->genfifoentry;
                genfifoentry |= xqspi->bytes_to_receive;
                zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);

                /* Dummy generic FIFO entry */
                zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);

                /* Manual start */
                zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
                        (zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) |
                        GQSPI_CFG_START_GEN_FIFO_MASK));

                /* Enable the RX interrupts for IO mode */
                zynqmp_gqspi_write(xqspi, GQSPI_IER_OFST,
                                GQSPI_IER_GENFIFOEMPTY_MASK |
                                GQSPI_IER_RXNEMPTY_MASK |
                                GQSPI_IER_RXEMPTY_MASK);
        }
}

/**
 * zynqmp_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 zynqmp_qspi_irq(int irq, void *dev_id)
{
        struct spi_master *master = dev_id;
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);
        int ret = IRQ_NONE;
        u32 status, mask, dma_status = 0;

        status = zynqmp_gqspi_read(xqspi, GQSPI_ISR_OFST);
        zynqmp_gqspi_write(xqspi, GQSPI_ISR_OFST, status);
        mask = (status & ~(zynqmp_gqspi_read(xqspi, GQSPI_IMASK_OFST)));

        /* Read and clear DMA status */
        if (xqspi->mode == GQSPI_MODE_DMA) {
                dma_status =
                        zynqmp_gqspi_read(xqspi, GQSPI_QSPIDMA_DST_I_STS_OFST);
                zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_I_STS_OFST,
                                                                dma_status);
        }

        if (mask & GQSPI_ISR_TXNOT_FULL_MASK) {
                zynqmp_qspi_filltxfifo(xqspi, GQSPI_TX_FIFO_FILL);
                ret = IRQ_HANDLED;
        }

        if (dma_status & GQSPI_QSPIDMA_DST_I_STS_DONE_MASK) {
                zynqmp_process_dma_irq(xqspi);
                ret = IRQ_HANDLED;
        } else if (!(mask & GQSPI_IER_RXEMPTY_MASK) &&
                        (mask & GQSPI_IER_GENFIFOEMPTY_MASK)) {
                zynqmp_qspi_readrxfifo(xqspi, GQSPI_RX_FIFO_FILL);
                ret = IRQ_HANDLED;
        }

        if ((xqspi->bytes_to_receive == 0) && (xqspi->bytes_to_transfer == 0)
                        && ((status & GQSPI_IRQ_MASK) == GQSPI_IRQ_MASK)) {
                zynqmp_gqspi_write(xqspi, GQSPI_IDR_OFST, GQSPI_ISR_IDR_MASK);
                spi_finalize_current_transfer(master);
                ret = IRQ_HANDLED;
        }
        return ret;
}

/**
 * zynqmp_qspi_selectspimode:   Selects SPI mode - x1 or x2 or x4.
 * @xqspi:      xqspi is a pointer to the GQSPI instance
 * @spimode:    spimode - SPI or DUAL or QUAD.
 * Return:      Mask to set desired SPI mode in GENFIFO entry.
 */
static inline u32 zynqmp_qspi_selectspimode(struct zynqmp_qspi *xqspi,
                                                u8 spimode)
{
        u32 mask = 0;

        switch (spimode) {
        case GQSPI_SELECT_MODE_DUALSPI:
                mask = GQSPI_GENFIFO_MODE_DUALSPI;
                break;
        case GQSPI_SELECT_MODE_QUADSPI:
                mask = GQSPI_GENFIFO_MODE_QUADSPI;
                break;
        case GQSPI_SELECT_MODE_SPI:
                mask = GQSPI_GENFIFO_MODE_SPI;
                break;
        default:
                dev_warn(xqspi->dev, "Invalid SPI mode\n");
        }

        return mask;
}

/**
 * zynq_qspi_setuprxdma:        This function sets up the RX DMA operation
 * @xqspi:      xqspi is a pointer to the GQSPI instance.
 */
static void zynq_qspi_setuprxdma(struct zynqmp_qspi *xqspi)
{
        u32 rx_bytes, rx_rem, config_reg;
        dma_addr_t addr;
        u64 dma_align =  (u64)(uintptr_t)xqspi->rxbuf;

        if ((xqspi->bytes_to_receive < 8) ||
                ((dma_align & GQSPI_DMA_UNALIGN) != 0x0)) {
                /* Setting to IO mode */
                config_reg = zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST);
                config_reg &= ~GQSPI_CFG_MODE_EN_MASK;
                zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, config_reg);
                xqspi->mode = GQSPI_MODE_IO;
                xqspi->dma_rx_bytes = 0;
                return;
        }

        rx_rem = xqspi->bytes_to_receive % 4;
        rx_bytes = (xqspi->bytes_to_receive - rx_rem);

        addr = dma_map_single(xqspi->dev, (void *)xqspi->rxbuf,
                                                rx_bytes, DMA_FROM_DEVICE);
        if (dma_mapping_error(xqspi->dev, addr))
                dev_err(xqspi->dev, "ERR:rxdma:memory not mapped\n");

        xqspi->dma_rx_bytes = rx_bytes;
        xqspi->dma_addr = addr;
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_ADDR_OFST,
                                (u32)(addr & 0xffffffff));
        addr = ((addr >> 16) >> 16);
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_ADDR_MSB_OFST,
                                ((u32)addr) & 0xfff);

        /* Enabling the DMA mode */
        config_reg = zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST);
        config_reg &= ~GQSPI_CFG_MODE_EN_MASK;
        config_reg |= GQSPI_CFG_MODE_EN_DMA_MASK;
        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, config_reg);

        /* Switch to DMA mode */
        xqspi->mode = GQSPI_MODE_DMA;

        /* Write the number of bytes to transfer */
        zynqmp_gqspi_write(xqspi, GQSPI_QSPIDMA_DST_SIZE_OFST, rx_bytes);
}

/**
 * zynqmp_qspi_txrxsetup:       This function checks the TX/RX buffers in
 *                              the transfer and sets up the GENFIFO entries,
 *                              TX FIFO as required.
 * @xqspi:      xqspi is a pointer to the GQSPI instance.
 * @transfer:   It is a pointer to the structure containing transfer data.
 * @genfifoentry:       genfifoentry is pointer to the variable in which
 *                      GENFIFO mask is returned to calling function
 */
static void zynqmp_qspi_txrxsetup(struct zynqmp_qspi *xqspi,
                                  struct spi_transfer *transfer,
                                  u32 *genfifoentry)
{
        u32 config_reg;

        /* Transmit */
        if ((xqspi->txbuf != NULL) && (xqspi->rxbuf == NULL)) {
                /* Setup data to be TXed */
                *genfifoentry &= ~GQSPI_GENFIFO_RX;
                *genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
                *genfifoentry |= GQSPI_GENFIFO_TX;
                *genfifoentry |=
                        zynqmp_qspi_selectspimode(xqspi, transfer->tx_nbits);
                xqspi->bytes_to_transfer = transfer->len;
                if (xqspi->mode == GQSPI_MODE_DMA) {
                        config_reg = zynqmp_gqspi_read(xqspi,
                                                        GQSPI_CONFIG_OFST);
                        config_reg &= ~GQSPI_CFG_MODE_EN_MASK;
                        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
                                                                config_reg);
                        xqspi->mode = GQSPI_MODE_IO;
                }
                zynqmp_qspi_filltxfifo(xqspi, GQSPI_TXD_DEPTH);
                /* Discard RX data */
                xqspi->bytes_to_receive = 0;
        } else if ((xqspi->txbuf == NULL) && (xqspi->rxbuf != NULL)) {
                /* Receive */

                /* TX auto fill */
                *genfifoentry &= ~GQSPI_GENFIFO_TX;
                /* Setup RX */
                *genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
                *genfifoentry |= GQSPI_GENFIFO_RX;
                *genfifoentry |=
                        zynqmp_qspi_selectspimode(xqspi, transfer->rx_nbits);
                xqspi->bytes_to_transfer = 0;
                xqspi->bytes_to_receive = transfer->len;
                zynq_qspi_setuprxdma(xqspi);
        }
}

/**
 * zynqmp_qspi_start_transfer:  Initiates the QSPI transfer
 * @master:     Pointer to the spi_master structure which provides
 *              information about the controller.
 * @qspi:       Pointer to the spi_device structure
 * @transfer:   Pointer to the spi_transfer structure which provide information
 *              about next transfer parameters
 *
 * This function fills the TX FIFO, starts the QSPI transfer, and waits for the
 * transfer to be completed.
 *
 * Return:      Number of bytes transferred in the last transfer
 */
static int zynqmp_qspi_start_transfer(struct spi_master *master,
                                      struct spi_device *qspi,
                                      struct spi_transfer *transfer)
{
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);
        u32 genfifoentry = 0x0, transfer_len;

        xqspi->txbuf = transfer->tx_buf;
        xqspi->rxbuf = transfer->rx_buf;

        zynqmp_qspi_setup_transfer(qspi, transfer);

        genfifoentry |= xqspi->genfifocs;
        genfifoentry |= xqspi->genfifobus;

        zynqmp_qspi_txrxsetup(xqspi, transfer, &genfifoentry);

        if (xqspi->mode == GQSPI_MODE_DMA)
                transfer_len = xqspi->dma_rx_bytes;
        else
                transfer_len = transfer->len;

        xqspi->genfifoentry = genfifoentry;
        if ((transfer_len) < GQSPI_GENFIFO_IMM_DATA_MASK) {
                genfifoentry &= ~GQSPI_GENFIFO_IMM_DATA_MASK;
                genfifoentry |= transfer_len;
                zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);
        } else {
                int tempcount = transfer_len;
                u32 exponent = 8;       /* 2^8 = 256 */
                u8 imm_data = tempcount & 0xFF;

                tempcount &= ~(tempcount & 0xFF);
                /* Immediate entry */
                if (tempcount != 0) {
                        /* Exponent entries */
                        genfifoentry |= GQSPI_GENFIFO_EXP;
                        while (tempcount != 0) {
                                if (tempcount & GQSPI_GENFIFO_EXP_START) {
                                        genfifoentry &=
                                            ~GQSPI_GENFIFO_IMM_DATA_MASK;
                                        genfifoentry |= exponent;
                                        zynqmp_gqspi_write(xqspi,
                                                           GQSPI_GEN_FIFO_OFST,
                                                           genfifoentry);
                                }
                                tempcount = tempcount >> 1;
                                exponent++;
                        }
                }
                if (imm_data != 0) {
                        genfifoentry &= ~GQSPI_GENFIFO_EXP;
                        genfifoentry &= ~GQSPI_GENFIFO_IMM_DATA_MASK;
                        genfifoentry |= (u8) (imm_data & 0xFF);
                        zynqmp_gqspi_write(xqspi,
                                           GQSPI_GEN_FIFO_OFST, genfifoentry);
                }
        }

        if ((xqspi->mode == GQSPI_MODE_IO) &&
                        (xqspi->rxbuf != NULL)) {
                /* Dummy generic FIFO entry */
                zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);
        }

        /* Since we are using manual mode */
        zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
                           zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) |
                           GQSPI_CFG_START_GEN_FIFO_MASK);

        if (xqspi->txbuf != NULL)
                /* Enable interrupts for TX */
                zynqmp_gqspi_write(xqspi, GQSPI_IER_OFST,
                                   GQSPI_IER_TXEMPTY_MASK |
                                        GQSPI_IER_GENFIFOEMPTY_MASK |
                                        GQSPI_IER_TXNOT_FULL_MASK);

        if (xqspi->rxbuf != NULL) {
                /* Enable interrupts for RX */
                if (xqspi->mode == GQSPI_MODE_DMA) {
                        /* Enable DMA interrupts */
                        zynqmp_gqspi_write(xqspi,
                                        GQSPI_QSPIDMA_DST_I_EN_OFST,
                                        GQSPI_QSPIDMA_DST_I_EN_DONE_MASK);
                } else {
                        zynqmp_gqspi_write(xqspi, GQSPI_IER_OFST,
                                        GQSPI_IER_GENFIFOEMPTY_MASK |
                                        GQSPI_IER_RXNEMPTY_MASK |
                                        GQSPI_IER_RXEMPTY_MASK);
                }
        }

        return transfer->len;
}

/**
 * zynqmp_qspi_suspend: Suspend method for the QSPI driver
 * @_dev:       Address of the platform_device structure
 *
 * This function stops the QSPI driver queue and disables the QSPI controller
 *
 * Return:      Always 0
 */
static int __maybe_unused zynqmp_qspi_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct spi_master *master = platform_get_drvdata(pdev);

        spi_master_suspend(master);

        zynqmp_unprepare_transfer_hardware(master);

        return 0;
}

/**
 * zynqmp_qspi_resume:  Resume method for the QSPI driver
 * @dev:        Address of the platform_device structure
 *
 * The function starts the QSPI driver queue and initializes the QSPI
 * controller
 *
 * Return:      0 on success; error value otherwise
 */
static int __maybe_unused zynqmp_qspi_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct spi_master *master = platform_get_drvdata(pdev);
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);
        int ret = 0;

        ret = clk_enable(xqspi->pclk);
        if (ret) {
                dev_err(dev, "Cannot enable APB clock.\n");
                return ret;
        }

        ret = clk_enable(xqspi->refclk);
        if (ret) {
                dev_err(dev, "Cannot enable device clock.\n");
                clk_disable(xqspi->pclk);
                return ret;
        }

        spi_master_resume(master);

        return 0;
}

static SIMPLE_DEV_PM_OPS(zynqmp_qspi_dev_pm_ops, zynqmp_qspi_suspend,
                         zynqmp_qspi_resume);

/**
 * zynqmp_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; error value otherwise
 */
static int zynqmp_qspi_probe(struct platform_device *pdev)
{
        int ret = 0;
        struct spi_master *master;
        struct zynqmp_qspi *xqspi;
        struct resource *res;
        struct device *dev = &pdev->dev;

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

        xqspi = spi_master_get_devdata(master);
        master->dev.of_node = pdev->dev.of_node;
        platform_set_drvdata(pdev, master);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        xqspi->regs = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(xqspi->regs)) {
                ret = PTR_ERR(xqspi->regs);
                goto remove_master;
        }

        xqspi->dev = dev;
        xqspi->pclk = devm_clk_get(&pdev->dev, "pclk");

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

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

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

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

        /* QSPI controller initializations */
        zynqmp_qspi_init_hw(xqspi);

        xqspi->irq = platform_get_irq(pdev, 0);
        if (xqspi->irq <= 0) {
                ret = -ENXIO;
                dev_err(dev, "irq resource not found\n");
                goto clk_dis_all;
        }
        ret = devm_request_irq(&pdev->dev, xqspi->irq, zynqmp_qspi_irq,
                               0, pdev->name, master);
        if (ret != 0) {
                ret = -ENXIO;
                dev_err(dev, "request_irq failed\n");
                goto clk_dis_all;
        }

        master->num_chipselect = GQSPI_DEFAULT_NUM_CS;

        master->setup = zynqmp_qspi_setup;
        master->set_cs = zynqmp_qspi_chipselect;
        master->transfer_one = zynqmp_qspi_start_transfer;
        master->prepare_transfer_hardware = zynqmp_prepare_transfer_hardware;
        master->unprepare_transfer_hardware =
                                        zynqmp_unprepare_transfer_hardware;
        master->max_speed_hz = clk_get_rate(xqspi->refclk) / 2;
        master->bits_per_word_mask = SPI_BPW_MASK(8);
        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_RX_DUAL | SPI_RX_QUAD |
                            SPI_TX_DUAL | SPI_TX_QUAD;

        if (master->dev.parent == NULL)
                master->dev.parent = &master->dev;

        ret = spi_register_master(master);
        if (ret)
                goto clk_dis_all;

        return 0;

clk_dis_all:
        clk_disable_unprepare(xqspi->refclk);
clk_dis_pclk:
        clk_disable_unprepare(xqspi->pclk);
remove_master:
        spi_master_put(master);

        return ret;
}

/**
 * zynqmp_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 Always
 */
static int zynqmp_qspi_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);

        zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, 0x0);
        clk_disable_unprepare(xqspi->refclk);
        clk_disable_unprepare(xqspi->pclk);

        spi_unregister_master(master);

        return 0;
}

static const struct of_device_id zynqmp_qspi_of_match[] = {
        { .compatible = "xlnx,zynqmp-qspi-1.0", },
        { /* End of table */ }
};

MODULE_DEVICE_TABLE(of, zynqmp_qspi_of_match);

static struct platform_driver zynqmp_qspi_driver = {
        .probe = zynqmp_qspi_probe,
        .remove = zynqmp_qspi_remove,
        .driver = {
                .name = "zynqmp-qspi",
                .of_match_table = zynqmp_qspi_of_match,
                .pm = &zynqmp_qspi_dev_pm_ops,
        },
};

module_platform_driver(zynqmp_qspi_driver);

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