/*
 * Freescale QuadSPI driver.
 *
 * Copyright (C) 2013 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/completion.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/spi-nor.h>
#include <linux/mutex.h>
#include <linux/pm_qos.h>
#include <linux/sizes.h>

/* Controller needs driver to swap endian */
#define QUADSPI_QUIRK_SWAP_ENDIAN       (1 << 0)
/* Controller needs 4x internal clock */
#define QUADSPI_QUIRK_4X_INT_CLK        (1 << 1)
/*
 * TKT253890, Controller needs driver to fill txfifo till 16 byte to
 * trigger data transfer even though extern data will not transferred.
 */
#define QUADSPI_QUIRK_TKT253890         (1 << 2)
/* Controller cannot wake up from wait mode, TKT245618 */
#define QUADSPI_QUIRK_TKT245618         (1 << 3)

/* The registers */
#define QUADSPI_MCR                     0x00
#define QUADSPI_MCR_RESERVED_SHIFT      16
#define QUADSPI_MCR_RESERVED_MASK       (0xF << QUADSPI_MCR_RESERVED_SHIFT)
#define QUADSPI_MCR_MDIS_SHIFT          14
#define QUADSPI_MCR_MDIS_MASK           (1 << QUADSPI_MCR_MDIS_SHIFT)
#define QUADSPI_MCR_CLR_TXF_SHIFT       11
#define QUADSPI_MCR_CLR_TXF_MASK        (1 << QUADSPI_MCR_CLR_TXF_SHIFT)
#define QUADSPI_MCR_CLR_RXF_SHIFT       10
#define QUADSPI_MCR_CLR_RXF_MASK        (1 << QUADSPI_MCR_CLR_RXF_SHIFT)
#define QUADSPI_MCR_DDR_EN_SHIFT        7
#define QUADSPI_MCR_DDR_EN_MASK         (1 << QUADSPI_MCR_DDR_EN_SHIFT)
#define QUADSPI_MCR_END_CFG_SHIFT       2
#define QUADSPI_MCR_END_CFG_MASK        (3 << QUADSPI_MCR_END_CFG_SHIFT)
#define QUADSPI_MCR_SWRSTHD_SHIFT       1
#define QUADSPI_MCR_SWRSTHD_MASK        (1 << QUADSPI_MCR_SWRSTHD_SHIFT)
#define QUADSPI_MCR_SWRSTSD_SHIFT       0
#define QUADSPI_MCR_SWRSTSD_MASK        (1 << QUADSPI_MCR_SWRSTSD_SHIFT)

#define QUADSPI_IPCR                    0x08
#define QUADSPI_IPCR_SEQID_SHIFT        24
#define QUADSPI_IPCR_SEQID_MASK         (0xF << QUADSPI_IPCR_SEQID_SHIFT)

#define QUADSPI_BUF0CR                  0x10
#define QUADSPI_BUF1CR                  0x14
#define QUADSPI_BUF2CR                  0x18
#define QUADSPI_BUFXCR_INVALID_MSTRID   0xe

#define QUADSPI_BUF3CR                  0x1c
#define QUADSPI_BUF3CR_ALLMST_SHIFT     31
#define QUADSPI_BUF3CR_ALLMST_MASK      (1 << QUADSPI_BUF3CR_ALLMST_SHIFT)
#define QUADSPI_BUF3CR_ADATSZ_SHIFT             8
#define QUADSPI_BUF3CR_ADATSZ_MASK      (0xFF << QUADSPI_BUF3CR_ADATSZ_SHIFT)

#define QUADSPI_BFGENCR                 0x20
#define QUADSPI_BFGENCR_PAR_EN_SHIFT    16
#define QUADSPI_BFGENCR_PAR_EN_MASK     (1 << (QUADSPI_BFGENCR_PAR_EN_SHIFT))
#define QUADSPI_BFGENCR_SEQID_SHIFT     12
#define QUADSPI_BFGENCR_SEQID_MASK      (0xF << QUADSPI_BFGENCR_SEQID_SHIFT)

#define QUADSPI_BUF0IND                 0x30
#define QUADSPI_BUF1IND                 0x34
#define QUADSPI_BUF2IND                 0x38
#define QUADSPI_SFAR                    0x100

#define QUADSPI_SMPR                    0x108
#define QUADSPI_SMPR_DDRSMP_SHIFT       16
#define QUADSPI_SMPR_DDRSMP_MASK        (7 << QUADSPI_SMPR_DDRSMP_SHIFT)
#define QUADSPI_SMPR_FSDLY_SHIFT        6
#define QUADSPI_SMPR_FSDLY_MASK         (1 << QUADSPI_SMPR_FSDLY_SHIFT)
#define QUADSPI_SMPR_FSPHS_SHIFT        5
#define QUADSPI_SMPR_FSPHS_MASK         (1 << QUADSPI_SMPR_FSPHS_SHIFT)
#define QUADSPI_SMPR_HSENA_SHIFT        0
#define QUADSPI_SMPR_HSENA_MASK         (1 << QUADSPI_SMPR_HSENA_SHIFT)

#define QUADSPI_RBSR                    0x10c
#define QUADSPI_RBSR_RDBFL_SHIFT        8
#define QUADSPI_RBSR_RDBFL_MASK         (0x3F << QUADSPI_RBSR_RDBFL_SHIFT)

#define QUADSPI_RBCT                    0x110
#define QUADSPI_RBCT_WMRK_MASK          0x1F
#define QUADSPI_RBCT_RXBRD_SHIFT        8
#define QUADSPI_RBCT_RXBRD_USEIPS       (0x1 << QUADSPI_RBCT_RXBRD_SHIFT)

#define QUADSPI_TBSR                    0x150
#define QUADSPI_TBDR                    0x154
#define QUADSPI_SR                      0x15c
#define QUADSPI_SR_IP_ACC_SHIFT         1
#define QUADSPI_SR_IP_ACC_MASK          (0x1 << QUADSPI_SR_IP_ACC_SHIFT)
#define QUADSPI_SR_AHB_ACC_SHIFT        2
#define QUADSPI_SR_AHB_ACC_MASK         (0x1 << QUADSPI_SR_AHB_ACC_SHIFT)

#define QUADSPI_FR                      0x160
#define QUADSPI_FR_TFF_MASK             0x1

#define QUADSPI_SFA1AD                  0x180
#define QUADSPI_SFA2AD                  0x184
#define QUADSPI_SFB1AD                  0x188
#define QUADSPI_SFB2AD                  0x18c
#define QUADSPI_RBDR                    0x200

#define QUADSPI_LUTKEY                  0x300
#define QUADSPI_LUTKEY_VALUE            0x5AF05AF0

#define QUADSPI_LCKCR                   0x304
#define QUADSPI_LCKER_LOCK              0x1
#define QUADSPI_LCKER_UNLOCK            0x2

#define QUADSPI_RSER                    0x164
#define QUADSPI_RSER_TFIE               (0x1 << 0)

#define QUADSPI_LUT_BASE                0x310

/*
 * The definition of the LUT register shows below:
 *
 *  ---------------------------------------------------
 *  | INSTR1 | PAD1 | OPRND1 | INSTR0 | PAD0 | OPRND0 |
 *  ---------------------------------------------------
 */
#define OPRND0_SHIFT            0
#define PAD0_SHIFT              8
#define INSTR0_SHIFT            10
#define OPRND1_SHIFT            16

/* Instruction set for the LUT register. */
#define LUT_STOP                0
#define LUT_CMD                 1
#define LUT_ADDR                2
#define LUT_DUMMY               3
#define LUT_MODE                4
#define LUT_MODE2               5
#define LUT_MODE4               6
#define LUT_FSL_READ            7
#define LUT_FSL_WRITE           8
#define LUT_JMP_ON_CS           9
#define LUT_ADDR_DDR            10
#define LUT_MODE_DDR            11
#define LUT_MODE2_DDR           12
#define LUT_MODE4_DDR           13
#define LUT_FSL_READ_DDR                14
#define LUT_FSL_WRITE_DDR               15
#define LUT_DATA_LEARN          16

/*
 * The PAD definitions for LUT register.
 *
 * The pad stands for the lines number of IO[0:3].
 * For example, the Quad read need four IO lines, so you should
 * set LUT_PAD4 which means we use four IO lines.
 */
#define LUT_PAD1                0
#define LUT_PAD2                1
#define LUT_PAD4                2

/* Oprands for the LUT register. */
#define ADDR24BIT               0x18
#define ADDR32BIT               0x20

/* Macros for constructing the LUT register. */
#define LUT0(ins, pad, opr)                                             \
                (((opr) << OPRND0_SHIFT) | ((LUT_##pad) << PAD0_SHIFT) | \
                ((LUT_##ins) << INSTR0_SHIFT))

#define LUT1(ins, pad, opr)     (LUT0(ins, pad, opr) << OPRND1_SHIFT)

/* other macros for LUT register. */
#define QUADSPI_LUT(x)          (QUADSPI_LUT_BASE + (x) * 4)
#define QUADSPI_LUT_NUM         64

/* SEQID -- we can have 16 seqids at most. */
#define SEQID_QUAD_READ         0
#define SEQID_WREN              1
#define SEQID_WRDI              2
#define SEQID_RDSR              3
#define SEQID_SE                4
#define SEQID_CHIP_ERASE        5
#define SEQID_PP                6
#define SEQID_RDID              7
#define SEQID_WRSR              8
#define SEQID_RDCR              9
#define SEQID_EN4B              10
#define SEQID_BRWR              11

#define QUADSPI_MIN_IOMAP SZ_4M

enum fsl_qspi_devtype {
        FSL_QUADSPI_VYBRID,
        FSL_QUADSPI_IMX6SX,
        FSL_QUADSPI_IMX7D,
        FSL_QUADSPI_IMX6UL,
        FSL_QUADSPI_LS1021A,
};

struct fsl_qspi_devtype_data {
        enum fsl_qspi_devtype devtype;
        int rxfifo;
        int txfifo;
        int ahb_buf_size;
        int driver_data;
};

static const struct fsl_qspi_devtype_data vybrid_data = {
        .devtype = FSL_QUADSPI_VYBRID,
        .rxfifo = 128,
        .txfifo = 64,
        .ahb_buf_size = 1024,
        .driver_data = QUADSPI_QUIRK_SWAP_ENDIAN,
};

static const struct fsl_qspi_devtype_data imx6sx_data = {
        .devtype = FSL_QUADSPI_IMX6SX,
        .rxfifo = 128,
        .txfifo = 512,
        .ahb_buf_size = 1024,
        .driver_data = QUADSPI_QUIRK_4X_INT_CLK
                       | QUADSPI_QUIRK_TKT245618,
};

static const struct fsl_qspi_devtype_data imx7d_data = {
        .devtype = FSL_QUADSPI_IMX7D,
        .rxfifo = 512,
        .txfifo = 512,
        .ahb_buf_size = 1024,
        .driver_data = QUADSPI_QUIRK_TKT253890
                       | QUADSPI_QUIRK_4X_INT_CLK,
};

static const struct fsl_qspi_devtype_data imx6ul_data = {
        .devtype = FSL_QUADSPI_IMX6UL,
        .rxfifo = 128,
        .txfifo = 512,
        .ahb_buf_size = 1024,
        .driver_data = QUADSPI_QUIRK_TKT253890
                       | QUADSPI_QUIRK_4X_INT_CLK,
};

static struct fsl_qspi_devtype_data ls1021a_data = {
        .devtype = FSL_QUADSPI_LS1021A,
        .rxfifo = 128,
        .txfifo = 64,
        .ahb_buf_size = 1024,
        .driver_data = 0,
};

#define FSL_QSPI_MAX_CHIP       4
struct fsl_qspi {
        struct spi_nor nor[FSL_QSPI_MAX_CHIP];
        void __iomem *iobase;
        void __iomem *ahb_addr;
        u32 memmap_phy;
        u32 memmap_offs;
        u32 memmap_len;
        struct clk *clk, *clk_en;
        struct device *dev;
        struct completion c;
        const struct fsl_qspi_devtype_data *devtype_data;
        u32 nor_size;
        u32 nor_num;
        u32 clk_rate;
        unsigned int chip_base_addr; /* We may support two chips. */
        bool has_second_chip;
        bool big_endian;
        struct mutex lock;
        struct pm_qos_request pm_qos_req;
};

static inline int needs_swap_endian(struct fsl_qspi *q)
{
        return q->devtype_data->driver_data & QUADSPI_QUIRK_SWAP_ENDIAN;
}

static inline int needs_4x_clock(struct fsl_qspi *q)
{
        return q->devtype_data->driver_data & QUADSPI_QUIRK_4X_INT_CLK;
}

static inline int needs_fill_txfifo(struct fsl_qspi *q)
{
        return q->devtype_data->driver_data & QUADSPI_QUIRK_TKT253890;
}

static inline int needs_wakeup_wait_mode(struct fsl_qspi *q)
{
        return q->devtype_data->driver_data & QUADSPI_QUIRK_TKT245618;
}

/*
 * R/W functions for big- or little-endian registers:
 * The qSPI controller's endian is independent of the CPU core's endian.
 * So far, although the CPU core is little-endian but the qSPI have two
 * versions for big-endian and little-endian.
 */
static void qspi_writel(struct fsl_qspi *q, u32 val, void __iomem *addr)
{
        if (q->big_endian)
                iowrite32be(val, addr);
        else
                iowrite32(val, addr);
}

static u32 qspi_readl(struct fsl_qspi *q, void __iomem *addr)
{
        if (q->big_endian)
                return ioread32be(addr);
        else
                return ioread32(addr);
}

/*
 * An IC bug makes us to re-arrange the 32-bit data.
 * The following chips, such as IMX6SLX, have fixed this bug.
 */
static inline u32 fsl_qspi_endian_xchg(struct fsl_qspi *q, u32 a)
{
        return needs_swap_endian(q) ? __swab32(a) : a;
}

static inline void fsl_qspi_unlock_lut(struct fsl_qspi *q)
{
        qspi_writel(q, QUADSPI_LUTKEY_VALUE, q->iobase + QUADSPI_LUTKEY);
        qspi_writel(q, QUADSPI_LCKER_UNLOCK, q->iobase + QUADSPI_LCKCR);
}

static inline void fsl_qspi_lock_lut(struct fsl_qspi *q)
{
        qspi_writel(q, QUADSPI_LUTKEY_VALUE, q->iobase + QUADSPI_LUTKEY);
        qspi_writel(q, QUADSPI_LCKER_LOCK, q->iobase + QUADSPI_LCKCR);
}

static irqreturn_t fsl_qspi_irq_handler(int irq, void *dev_id)
{
        struct fsl_qspi *q = dev_id;
        u32 reg;

        /* clear interrupt */
        reg = qspi_readl(q, q->iobase + QUADSPI_FR);
        qspi_writel(q, reg, q->iobase + QUADSPI_FR);

        if (reg & QUADSPI_FR_TFF_MASK)
                complete(&q->c);

        dev_dbg(q->dev, "QUADSPI_FR : 0x%.8x:0x%.8x\n", q->chip_base_addr, reg);
        return IRQ_HANDLED;
}

static void fsl_qspi_init_lut(struct fsl_qspi *q)
{
        void __iomem *base = q->iobase;
        int rxfifo = q->devtype_data->rxfifo;
        u32 lut_base;
        u8 cmd, addrlen, dummy;
        int i;

        fsl_qspi_unlock_lut(q);

        /* Clear all the LUT table */
        for (i = 0; i < QUADSPI_LUT_NUM; i++)
                qspi_writel(q, 0, base + QUADSPI_LUT_BASE + i * 4);

        /* Quad Read */
        lut_base = SEQID_QUAD_READ * 4;

        if (q->nor_size <= SZ_16M) {
                cmd = SPINOR_OP_READ_1_1_4;
                addrlen = ADDR24BIT;
                dummy = 8;
        } else {
                /* use the 4-byte address */
                cmd = SPINOR_OP_READ_1_1_4;
                addrlen = ADDR32BIT;
                dummy = 8;
        }

        qspi_writel(q, LUT0(CMD, PAD1, cmd) | LUT1(ADDR, PAD1, addrlen),
                        base + QUADSPI_LUT(lut_base));
        qspi_writel(q, LUT0(DUMMY, PAD1, dummy) | LUT1(FSL_READ, PAD4, rxfifo),
                        base + QUADSPI_LUT(lut_base + 1));

        /* Write enable */
        lut_base = SEQID_WREN * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_WREN),
                        base + QUADSPI_LUT(lut_base));

        /* Page Program */
        lut_base = SEQID_PP * 4;

        if (q->nor_size <= SZ_16M) {
                cmd = SPINOR_OP_PP;
                addrlen = ADDR24BIT;
        } else {
                /* use the 4-byte address */
                cmd = SPINOR_OP_PP;
                addrlen = ADDR32BIT;
        }

        qspi_writel(q, LUT0(CMD, PAD1, cmd) | LUT1(ADDR, PAD1, addrlen),
                        base + QUADSPI_LUT(lut_base));
        qspi_writel(q, LUT0(FSL_WRITE, PAD1, 0),
                        base + QUADSPI_LUT(lut_base + 1));

        /* Read Status */
        lut_base = SEQID_RDSR * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_RDSR) |
                        LUT1(FSL_READ, PAD1, 0x1),
                        base + QUADSPI_LUT(lut_base));

        /* Erase a sector */
        lut_base = SEQID_SE * 4;

        cmd = q->nor[0].erase_opcode;
        addrlen = q->nor_size <= SZ_16M ? ADDR24BIT : ADDR32BIT;

        qspi_writel(q, LUT0(CMD, PAD1, cmd) | LUT1(ADDR, PAD1, addrlen),
                        base + QUADSPI_LUT(lut_base));

        /* Erase the whole chip */
        lut_base = SEQID_CHIP_ERASE * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_CHIP_ERASE),
                        base + QUADSPI_LUT(lut_base));

        /* READ ID */
        lut_base = SEQID_RDID * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_RDID) |
                        LUT1(FSL_READ, PAD1, 0x8),
                        base + QUADSPI_LUT(lut_base));

        /* Write Register */
        lut_base = SEQID_WRSR * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_WRSR) |
                        LUT1(FSL_WRITE, PAD1, 0x2),
                        base + QUADSPI_LUT(lut_base));

        /* Read Configuration Register */
        lut_base = SEQID_RDCR * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_RDCR) |
                        LUT1(FSL_READ, PAD1, 0x1),
                        base + QUADSPI_LUT(lut_base));

        /* Write disable */
        lut_base = SEQID_WRDI * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_WRDI),
                        base + QUADSPI_LUT(lut_base));

        /* Enter 4 Byte Mode (Micron) */
        lut_base = SEQID_EN4B * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_EN4B),
                        base + QUADSPI_LUT(lut_base));

        /* Enter 4 Byte Mode (Spansion) */
        lut_base = SEQID_BRWR * 4;
        qspi_writel(q, LUT0(CMD, PAD1, SPINOR_OP_BRWR),
                        base + QUADSPI_LUT(lut_base));

        fsl_qspi_lock_lut(q);
}

/* Get the SEQID for the command */
static int fsl_qspi_get_seqid(struct fsl_qspi *q, u8 cmd)
{
        switch (cmd) {
        case SPINOR_OP_READ_1_1_4:
                return SEQID_QUAD_READ;
        case SPINOR_OP_WREN:
                return SEQID_WREN;
        case SPINOR_OP_WRDI:
                return SEQID_WRDI;
        case SPINOR_OP_RDSR:
                return SEQID_RDSR;
        case SPINOR_OP_SE:
                return SEQID_SE;
        case SPINOR_OP_CHIP_ERASE:
                return SEQID_CHIP_ERASE;
        case SPINOR_OP_PP:
                return SEQID_PP;
        case SPINOR_OP_RDID:
                return SEQID_RDID;
        case SPINOR_OP_WRSR:
                return SEQID_WRSR;
        case SPINOR_OP_RDCR:
                return SEQID_RDCR;
        case SPINOR_OP_EN4B:
                return SEQID_EN4B;
        case SPINOR_OP_BRWR:
                return SEQID_BRWR;
        default:
                if (cmd == q->nor[0].erase_opcode)
                        return SEQID_SE;
                dev_err(q->dev, "Unsupported cmd 0x%.2x\n", cmd);
                break;
        }
        return -EINVAL;
}

static int
fsl_qspi_runcmd(struct fsl_qspi *q, u8 cmd, unsigned int addr, int len)
{
        void __iomem *base = q->iobase;
        int seqid;
        u32 reg, reg2;
        int err;

        init_completion(&q->c);
        dev_dbg(q->dev, "to 0x%.8x:0x%.8x, len:%d, cmd:%.2x\n",
                        q->chip_base_addr, addr, len, cmd);

        /* save the reg */
        reg = qspi_readl(q, base + QUADSPI_MCR);

        qspi_writel(q, q->memmap_phy + q->chip_base_addr + addr,
                        base + QUADSPI_SFAR);
        qspi_writel(q, QUADSPI_RBCT_WMRK_MASK | QUADSPI_RBCT_RXBRD_USEIPS,
                        base + QUADSPI_RBCT);
        qspi_writel(q, reg | QUADSPI_MCR_CLR_RXF_MASK, base + QUADSPI_MCR);

        do {
                reg2 = qspi_readl(q, base + QUADSPI_SR);
                if (reg2 & (QUADSPI_SR_IP_ACC_MASK | QUADSPI_SR_AHB_ACC_MASK)) {
                        udelay(1);
                        dev_dbg(q->dev, "The controller is busy, 0x%x\n", reg2);
                        continue;
                }
                break;
        } while (1);

        /* trigger the LUT now */
        seqid = fsl_qspi_get_seqid(q, cmd);
        qspi_writel(q, (seqid << QUADSPI_IPCR_SEQID_SHIFT) | len,
                        base + QUADSPI_IPCR);

        /* Wait for the interrupt. */
        if (!wait_for_completion_timeout(&q->c, msecs_to_jiffies(1000))) {
                dev_err(q->dev,
                        "cmd 0x%.2x timeout, addr@%.8x, FR:0x%.8x, SR:0x%.8x\n",
                        cmd, addr, qspi_readl(q, base + QUADSPI_FR),
                        qspi_readl(q, base + QUADSPI_SR));
                err = -ETIMEDOUT;
        } else {
                err = 0;
        }

        /* restore the MCR */
        qspi_writel(q, reg, base + QUADSPI_MCR);

        return err;
}

/* Read out the data from the QUADSPI_RBDR buffer registers. */
static void fsl_qspi_read_data(struct fsl_qspi *q, int len, u8 *rxbuf)
{
        u32 tmp;
        int i = 0;

        while (len > 0) {
                tmp = qspi_readl(q, q->iobase + QUADSPI_RBDR + i * 4);
                tmp = fsl_qspi_endian_xchg(q, tmp);
                dev_dbg(q->dev, "chip addr:0x%.8x, rcv:0x%.8x\n",
                                q->chip_base_addr, tmp);

                if (len >= 4) {
                        *((u32 *)rxbuf) = tmp;
                        rxbuf += 4;
                } else {
                        memcpy(rxbuf, &tmp, len);
                        break;
                }

                len -= 4;
                i++;
        }
}

/*
 * If we have changed the content of the flash by writing or erasing,
 * we need to invalidate the AHB buffer. If we do not do so, we may read out
 * the wrong data. The spec tells us reset the AHB domain and Serial Flash
 * domain at the same time.
 */
static inline void fsl_qspi_invalid(struct fsl_qspi *q)
{
        u32 reg;

        reg = qspi_readl(q, q->iobase + QUADSPI_MCR);
        reg |= QUADSPI_MCR_SWRSTHD_MASK | QUADSPI_MCR_SWRSTSD_MASK;
        qspi_writel(q, reg, q->iobase + QUADSPI_MCR);

        /*
         * The minimum delay : 1 AHB + 2 SFCK clocks.
         * Delay 1 us is enough.
         */
        udelay(1);

        reg &= ~(QUADSPI_MCR_SWRSTHD_MASK | QUADSPI_MCR_SWRSTSD_MASK);
        qspi_writel(q, reg, q->iobase + QUADSPI_MCR);
}

static ssize_t fsl_qspi_nor_write(struct fsl_qspi *q, struct spi_nor *nor,
                                u8 opcode, unsigned int to, u32 *txbuf,
                                unsigned count)
{
        int ret, i, j;
        u32 tmp;

        dev_dbg(q->dev, "to 0x%.8x:0x%.8x, len : %d\n",
                q->chip_base_addr, to, count);

        /* clear the TX FIFO. */
        tmp = qspi_readl(q, q->iobase + QUADSPI_MCR);
        qspi_writel(q, tmp | QUADSPI_MCR_CLR_TXF_MASK, q->iobase + QUADSPI_MCR);

        /* fill the TX data to the FIFO */
        for (j = 0, i = ((count + 3) / 4); j < i; j++) {
                tmp = fsl_qspi_endian_xchg(q, *txbuf);
                qspi_writel(q, tmp, q->iobase + QUADSPI_TBDR);
                txbuf++;
        }

        /* fill the TXFIFO upto 16 bytes for i.MX7d */
        if (needs_fill_txfifo(q))
                for (; i < 4; i++)
                        qspi_writel(q, tmp, q->iobase + QUADSPI_TBDR);

        /* Trigger it */
        ret = fsl_qspi_runcmd(q, opcode, to, count);

        if (ret == 0)
                return count;

        return ret;
}

static void fsl_qspi_set_map_addr(struct fsl_qspi *q)
{
        int nor_size = q->nor_size;
        void __iomem *base = q->iobase;

        qspi_writel(q, nor_size + q->memmap_phy, base + QUADSPI_SFA1AD);
        qspi_writel(q, nor_size * 2 + q->memmap_phy, base + QUADSPI_SFA2AD);
        qspi_writel(q, nor_size * 3 + q->memmap_phy, base + QUADSPI_SFB1AD);
        qspi_writel(q, nor_size * 4 + q->memmap_phy, base + QUADSPI_SFB2AD);
}

/*
 * There are two different ways to read out the data from the flash:
 *  the "IP Command Read" and the "AHB Command Read".
 *
 * The IC guy suggests we use the "AHB Command Read" which is faster
 * then the "IP Command Read". (What's more is that there is a bug in
 * the "IP Command Read" in the Vybrid.)
 *
 * After we set up the registers for the "AHB Command Read", we can use
 * the memcpy to read the data directly. A "missed" access to the buffer
 * causes the controller to clear the buffer, and use the sequence pointed
 * by the QUADSPI_BFGENCR[SEQID] to initiate a read from the flash.
 */
static void fsl_qspi_init_abh_read(struct fsl_qspi *q)
{
        void __iomem *base = q->iobase;
        int seqid;

        /* AHB configuration for access buffer 0/1/2 .*/
        qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF0CR);
        qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF1CR);
        qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF2CR);
        /*
         * Set ADATSZ with the maximum AHB buffer size to improve the
         * read performance.
         */
        qspi_writel(q, QUADSPI_BUF3CR_ALLMST_MASK |
                        ((q->devtype_data->ahb_buf_size / 8)
                        << QUADSPI_BUF3CR_ADATSZ_SHIFT),
                        base + QUADSPI_BUF3CR);

        /* We only use the buffer3 */
        qspi_writel(q, 0, base + QUADSPI_BUF0IND);
        qspi_writel(q, 0, base + QUADSPI_BUF1IND);
        qspi_writel(q, 0, base + QUADSPI_BUF2IND);

        /* Set the default lut sequence for AHB Read. */
        seqid = fsl_qspi_get_seqid(q, q->nor[0].read_opcode);
        qspi_writel(q, seqid << QUADSPI_BFGENCR_SEQID_SHIFT,
                q->iobase + QUADSPI_BFGENCR);
}

/* This function was used to prepare and enable QSPI clock */
static int fsl_qspi_clk_prep_enable(struct fsl_qspi *q)
{
        int ret;

        ret = clk_prepare_enable(q->clk_en);
        if (ret)
                return ret;

        ret = clk_prepare_enable(q->clk);
        if (ret) {
                clk_disable_unprepare(q->clk_en);
                return ret;
        }

        if (needs_wakeup_wait_mode(q))
                pm_qos_add_request(&q->pm_qos_req, PM_QOS_CPU_DMA_LATENCY, 0);

        return 0;
}

/* This function was used to disable and unprepare QSPI clock */
static void fsl_qspi_clk_disable_unprep(struct fsl_qspi *q)
{
        if (needs_wakeup_wait_mode(q))
                pm_qos_remove_request(&q->pm_qos_req);

        clk_disable_unprepare(q->clk);
        clk_disable_unprepare(q->clk_en);

}

/* We use this function to do some basic init for spi_nor_scan(). */
static int fsl_qspi_nor_setup(struct fsl_qspi *q)
{
        void __iomem *base = q->iobase;
        u32 reg;
        int ret;

        /* disable and unprepare clock to avoid glitch pass to controller */
        fsl_qspi_clk_disable_unprep(q);

        /* the default frequency, we will change it in the future. */
        ret = clk_set_rate(q->clk, 66000000);
        if (ret)
                return ret;

        ret = fsl_qspi_clk_prep_enable(q);
        if (ret)
                return ret;

        /* Reset the module */
        qspi_writel(q, QUADSPI_MCR_SWRSTSD_MASK | QUADSPI_MCR_SWRSTHD_MASK,
                base + QUADSPI_MCR);
        udelay(1);

        /* Init the LUT table. */
        fsl_qspi_init_lut(q);

        /* Disable the module */
        qspi_writel(q, QUADSPI_MCR_MDIS_MASK | QUADSPI_MCR_RESERVED_MASK,
                        base + QUADSPI_MCR);

        reg = qspi_readl(q, base + QUADSPI_SMPR);
        qspi_writel(q, reg & ~(QUADSPI_SMPR_FSDLY_MASK
                        | QUADSPI_SMPR_FSPHS_MASK
                        | QUADSPI_SMPR_HSENA_MASK
                        | QUADSPI_SMPR_DDRSMP_MASK), base + QUADSPI_SMPR);

        /* Enable the module */
        qspi_writel(q, QUADSPI_MCR_RESERVED_MASK | QUADSPI_MCR_END_CFG_MASK,
                        base + QUADSPI_MCR);

        /* clear all interrupt status */
        qspi_writel(q, 0xffffffff, q->iobase + QUADSPI_FR);

        /* enable the interrupt */
        qspi_writel(q, QUADSPI_RSER_TFIE, q->iobase + QUADSPI_RSER);

        return 0;
}

static int fsl_qspi_nor_setup_last(struct fsl_qspi *q)
{
        unsigned long rate = q->clk_rate;
        int ret;

        if (needs_4x_clock(q))
                rate *= 4;

        /* disable and unprepare clock to avoid glitch pass to controller */
        fsl_qspi_clk_disable_unprep(q);

        ret = clk_set_rate(q->clk, rate);
        if (ret)
                return ret;

        ret = fsl_qspi_clk_prep_enable(q);
        if (ret)
                return ret;

        /* Init the LUT table again. */
        fsl_qspi_init_lut(q);

        /* Init for AHB read */
        fsl_qspi_init_abh_read(q);

        return 0;
}

static const struct of_device_id fsl_qspi_dt_ids[] = {
        { .compatible = "fsl,vf610-qspi", .data = (void *)&vybrid_data, },
        { .compatible = "fsl,imx6sx-qspi", .data = (void *)&imx6sx_data, },
        { .compatible = "fsl,imx7d-qspi", .data = (void *)&imx7d_data, },
        { .compatible = "fsl,imx6ul-qspi", .data = (void *)&imx6ul_data, },
        { .compatible = "fsl,ls1021a-qspi", .data = (void *)&ls1021a_data, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, fsl_qspi_dt_ids);

static void fsl_qspi_set_base_addr(struct fsl_qspi *q, struct spi_nor *nor)
{
        q->chip_base_addr = q->nor_size * (nor - q->nor);
}

static int fsl_qspi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
{
        int ret;
        struct fsl_qspi *q = nor->priv;

        ret = fsl_qspi_runcmd(q, opcode, 0, len);
        if (ret)
                return ret;

        fsl_qspi_read_data(q, len, buf);
        return 0;
}

static int fsl_qspi_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
{
        struct fsl_qspi *q = nor->priv;
        int ret;

        if (!buf) {
                ret = fsl_qspi_runcmd(q, opcode, 0, 1);
                if (ret)
                        return ret;

                if (opcode == SPINOR_OP_CHIP_ERASE)
                        fsl_qspi_invalid(q);

        } else if (len > 0) {
                ret = fsl_qspi_nor_write(q, nor, opcode, 0,
                                        (u32 *)buf, len);
                if (ret > 0)
                        return 0;
        } else {
                dev_err(q->dev, "invalid cmd %d\n", opcode);
                ret = -EINVAL;
        }

        return ret;
}

static ssize_t fsl_qspi_write(struct spi_nor *nor, loff_t to,
                              size_t len, const u_char *buf)
{
        struct fsl_qspi *q = nor->priv;
        ssize_t ret = fsl_qspi_nor_write(q, nor, nor->program_opcode, to,
                                         (u32 *)buf, len);

        /* invalid the data in the AHB buffer. */
        fsl_qspi_invalid(q);
        return ret;
}

static ssize_t fsl_qspi_read(struct spi_nor *nor, loff_t from,
                             size_t len, u_char *buf)
{
        struct fsl_qspi *q = nor->priv;
        u8 cmd = nor->read_opcode;

        /* if necessary,ioremap buffer before AHB read, */
        if (!q->ahb_addr) {
                q->memmap_offs = q->chip_base_addr + from;
                q->memmap_len = len > QUADSPI_MIN_IOMAP ? len : QUADSPI_MIN_IOMAP;

                q->ahb_addr = ioremap_nocache(
                                q->memmap_phy + q->memmap_offs,
                                q->memmap_len);
                if (!q->ahb_addr) {
                        dev_err(q->dev, "ioremap failed\n");
                        return -ENOMEM;
                }
        /* ioremap if the data requested is out of range */
        } else if (q->chip_base_addr + from < q->memmap_offs
                        || q->chip_base_addr + from + len >
                        q->memmap_offs + q->memmap_len) {
                iounmap(q->ahb_addr);

                q->memmap_offs = q->chip_base_addr + from;
                q->memmap_len = len > QUADSPI_MIN_IOMAP ? len : QUADSPI_MIN_IOMAP;
                q->ahb_addr = ioremap_nocache(
                                q->memmap_phy + q->memmap_offs,
                                q->memmap_len);
                if (!q->ahb_addr) {
                        dev_err(q->dev, "ioremap failed\n");
                        return -ENOMEM;
                }
        }

        dev_dbg(q->dev, "cmd [%x],read from %p, len:%zd\n",
                cmd, q->ahb_addr + q->chip_base_addr + from - q->memmap_offs,
                len);

        /* Read out the data directly from the AHB buffer.*/
        memcpy(buf, q->ahb_addr + q->chip_base_addr + from - q->memmap_offs,
                len);

        return len;
}

static int fsl_qspi_erase(struct spi_nor *nor, loff_t offs)
{
        struct fsl_qspi *q = nor->priv;
        int ret;

        dev_dbg(nor->dev, "%dKiB at 0x%08x:0x%08x\n",
                nor->mtd.erasesize / 1024, q->chip_base_addr, (u32)offs);

        ret = fsl_qspi_runcmd(q, nor->erase_opcode, offs, 0);
        if (ret)
                return ret;

        fsl_qspi_invalid(q);
        return 0;
}

static int fsl_qspi_prep(struct spi_nor *nor, enum spi_nor_ops ops)
{
        struct fsl_qspi *q = nor->priv;
        int ret;

        mutex_lock(&q->lock);

        ret = fsl_qspi_clk_prep_enable(q);
        if (ret)
                goto err_mutex;

        fsl_qspi_set_base_addr(q, nor);
        return 0;

err_mutex:
        mutex_unlock(&q->lock);
        return ret;
}

static void fsl_qspi_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
{
        struct fsl_qspi *q = nor->priv;

        fsl_qspi_clk_disable_unprep(q);
        mutex_unlock(&q->lock);
}

static int fsl_qspi_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct device *dev = &pdev->dev;
        struct fsl_qspi *q;
        struct resource *res;
        struct spi_nor *nor;
        struct mtd_info *mtd;
        int ret, i = 0;

        q = devm_kzalloc(dev, sizeof(*q), GFP_KERNEL);
        if (!q)
                return -ENOMEM;

        q->nor_num = of_get_child_count(dev->of_node);
        if (!q->nor_num || q->nor_num > FSL_QSPI_MAX_CHIP)
                return -ENODEV;

        q->dev = dev;
        q->devtype_data = of_device_get_match_data(dev);
        if (!q->devtype_data)
                return -ENODEV;
        platform_set_drvdata(pdev, q);

        /* find the resources */
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "QuadSPI");
        q->iobase = devm_ioremap_resource(dev, res);

        if (IS_ERR(q->iobase))
                return PTR_ERR(q->iobase);

        q->big_endian = of_property_read_bool(np, "big-endian");
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                        "QuadSPI-memory");
        if (!devm_request_mem_region(dev, res->start, resource_size(res),
                                     res->name)) {
                dev_err(dev, "can't request region for resource %pR\n", res);
                return -EBUSY;
        }

        q->memmap_phy = res->start;

        /* find the clocks */
        q->clk_en = devm_clk_get(dev, "qspi_en");
        if (IS_ERR(q->clk_en))
                return PTR_ERR(q->clk_en);

        q->clk = devm_clk_get(dev, "qspi");
        if (IS_ERR(q->clk))
                return PTR_ERR(q->clk);

        ret = fsl_qspi_clk_prep_enable(q);
        if (ret) {
                dev_err(dev, "can not enable the clock\n");
                goto clk_failed;
        }

        /* find the irq */
        ret = platform_get_irq(pdev, 0);
        if (ret < 0) {
                dev_err(dev, "failed to get the irq: %d\n", ret);
                goto irq_failed;
        }

        ret = devm_request_irq(dev, ret,
                        fsl_qspi_irq_handler, 0, pdev->name, q);
        if (ret) {
                dev_err(dev, "failed to request irq: %d\n", ret);
                goto irq_failed;
        }

        ret = fsl_qspi_nor_setup(q);
        if (ret)
                goto irq_failed;

        if (of_get_property(np, "fsl,qspi-has-second-chip", NULL))
                q->has_second_chip = true;

        mutex_init(&q->lock);

        /* iterate the subnodes. */
        for_each_available_child_of_node(dev->of_node, np) {
                /* skip the holes */
                if (!q->has_second_chip)
                        i *= 2;

                nor = &q->nor[i];
                mtd = &nor->mtd;

                nor->dev = dev;
                spi_nor_set_flash_node(nor, np);
                nor->priv = q;

                /* fill the hooks */
                nor->read_reg = fsl_qspi_read_reg;
                nor->write_reg = fsl_qspi_write_reg;
                nor->read = fsl_qspi_read;
                nor->write = fsl_qspi_write;
                nor->erase = fsl_qspi_erase;

                nor->prepare = fsl_qspi_prep;
                nor->unprepare = fsl_qspi_unprep;

                ret = of_property_read_u32(np, "spi-max-frequency",
                                &q->clk_rate);
                if (ret < 0)
                        goto mutex_failed;

                /* set the chip address for READID */
                fsl_qspi_set_base_addr(q, nor);

                ret = spi_nor_scan(nor, NULL, SPI_NOR_QUAD);
                if (ret)
                        goto mutex_failed;

                ret = mtd_device_register(mtd, NULL, 0);
                if (ret)
                        goto mutex_failed;

                /* Set the correct NOR size now. */
                if (q->nor_size == 0) {
                        q->nor_size = mtd->size;

                        /* Map the SPI NOR to accessiable address */
                        fsl_qspi_set_map_addr(q);
                }

                /*
                 * The TX FIFO is 64 bytes in the Vybrid, but the Page Program
                 * may writes 265 bytes per time. The write is working in the
                 * unit of the TX FIFO, not in the unit of the SPI NOR's page
                 * size.
                 *
                 * So shrink the spi_nor->page_size if it is larger then the
                 * TX FIFO.
                 */
                if (nor->page_size > q->devtype_data->txfifo)
                        nor->page_size = q->devtype_data->txfifo;

                i++;
        }

        /* finish the rest init. */
        ret = fsl_qspi_nor_setup_last(q);
        if (ret)
                goto last_init_failed;

        fsl_qspi_clk_disable_unprep(q);
        return 0;

last_init_failed:
        for (i = 0; i < q->nor_num; i++) {
                /* skip the holes */
                if (!q->has_second_chip)
                        i *= 2;
                mtd_device_unregister(&q->nor[i].mtd);
        }
mutex_failed:
        mutex_destroy(&q->lock);
irq_failed:
        fsl_qspi_clk_disable_unprep(q);
clk_failed:
        dev_err(dev, "Freescale QuadSPI probe failed\n");
        return ret;
}

static int fsl_qspi_remove(struct platform_device *pdev)
{
        struct fsl_qspi *q = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < q->nor_num; i++) {
                /* skip the holes */
                if (!q->has_second_chip)
                        i *= 2;
                mtd_device_unregister(&q->nor[i].mtd);
        }

        /* disable the hardware */
        qspi_writel(q, QUADSPI_MCR_MDIS_MASK, q->iobase + QUADSPI_MCR);
        qspi_writel(q, 0x0, q->iobase + QUADSPI_RSER);

        mutex_destroy(&q->lock);

        if (q->ahb_addr)
                iounmap(q->ahb_addr);

        return 0;
}

static int fsl_qspi_suspend(struct platform_device *pdev, pm_message_t state)
{
        return 0;
}

static int fsl_qspi_resume(struct platform_device *pdev)
{
        int ret;
        struct fsl_qspi *q = platform_get_drvdata(pdev);

        ret = fsl_qspi_clk_prep_enable(q);
        if (ret)
                return ret;

        fsl_qspi_nor_setup(q);
        fsl_qspi_set_map_addr(q);
        fsl_qspi_nor_setup_last(q);

        fsl_qspi_clk_disable_unprep(q);

        return 0;
}

static struct platform_driver fsl_qspi_driver = {
        .driver = {
                .name   = "fsl-quadspi",
                .bus    = &platform_bus_type,
                .of_match_table = fsl_qspi_dt_ids,
        },
        .probe          = fsl_qspi_probe,
        .remove         = fsl_qspi_remove,
        .suspend        = fsl_qspi_suspend,
        .resume         = fsl_qspi_resume,
};
module_platform_driver(fsl_qspi_driver);

MODULE_DESCRIPTION("Freescale QuadSPI Controller Driver");
MODULE_AUTHOR("Freescale Semiconductor Inc.");
MODULE_LICENSE("GPL v2");