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/*
 * MTD SPI driver for ST M25Pxx (and similar) serial flash chips
 *
 * Author: Mike Lavender, mike@steroidmicros.com
 *
 * Copyright (c) 2005, Intec Automation Inc.
 *
 * Some parts are based on lart.c by Abraham Van Der Merwe
 *
 * Cleaned up and generalized based on mtd_dataflash.c
 *
 * This code 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.
 *
 */

#include <linux/init.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/math64.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mod_devicetable.h>

#include <linux/mtd/cfi.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/of_platform.h>

#include <linux/spi/spi.h>
#include <linux/spi/flash.h>

/* Flash opcodes. */
#define	OPCODE_WREN		0x06	/* Write enable */
#define	OPCODE_RDSR		0x05	/* Read status register */
#define	OPCODE_WRSR		0x01	/* Write status register 1 byte */
#define	OPCODE_NORM_READ	0x03	/* Read data bytes (low frequency) */
#define	OPCODE_FAST_READ	0x0b	/* Read data bytes (high frequency) */
#define	OPCODE_PP		0x02	/* Page program (up to 256 bytes) */
#define	OPCODE_BE_4K		0x20	/* Erase 4KiB block */
#define	OPCODE_BE_4K_PMC	0xd7	/* Erase 4KiB block on PMC chips */
#define	OPCODE_BE_32K		0x52	/* Erase 32KiB block */
#define	OPCODE_CHIP_ERASE	0xc7	/* Erase whole flash chip */
#define	OPCODE_SE		0xd8	/* Sector erase (usually 64KiB) */
#define	OPCODE_RDID		0x9f	/* Read JEDEC ID */

/* Used for SST flashes only. */
#define	OPCODE_BP		0x02	/* Byte program */
#define	OPCODE_WRDI		0x04	/* Write disable */
#define	OPCODE_AAI_WP		0xad	/* Auto address increment word program */

/* Used for Macronix flashes only. */
#define	OPCODE_EN4B		0xb7	/* Enter 4-byte mode */
#define	OPCODE_EX4B		0xe9	/* Exit 4-byte mode */

/* Used for Spansion flashes only. */
#define	OPCODE_BRWR		0x17	/* Bank register write */

/* Used for Winbond flashes only. */
#define OPCODE_WINBOND_ID    0x4b    /* Get flash unique id */

/* Status Register bits. */
#define	SR_WIP			1	/* Write in progress */
#define	SR_WEL			2	/* Write enable latch */
/* meaning of other SR_* bits may differ between vendors */
#define	SR_BP0			4	/* Block protect 0 */
#define	SR_BP1			8	/* Block protect 1 */
#define	SR_BP2			0x10	/* Block protect 2 */
#define	SR_SRWD			0x80	/* SR write protect */

/* Define max times to check status register before we give up. */
#define	MAX_READY_WAIT_JIFFIES	(40 * HZ)	/* M25P16 specs 40s max chip erase */
#define	MAX_CMD_SIZE		5

#define JEDEC_MFR(_jedec_id)	((_jedec_id) >> 16)

#ifdef CONFIG_M25PXX_PREFER_SMALL_SECTOR_ERASE
#define PREFER_SMALL_SECTOR_ERASE 1
#else
#define PREFER_SMALL_SECTOR_ERASE 0
#endif

/****************************************************************************/

struct m25p {
    struct spi_device	*spi;
    struct mutex		lock;
    struct mtd_info		mtd;
    u16			page_size;
    u16			addr_width;
    u8			erase_opcode;
    u8			*command;
    bool			fast_read;
};

static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
{
    return container_of(mtd, struct m25p, mtd);
}

/****************************************************************************/

/*
 * Internal helper functions
 */

/*
 * Read the status register, returning its value in the location
 * Return the status register value.
 * Returns negative if error occurred.
 */
static int read_sr(struct m25p *flash)
{
    ssize_t retval;
    u8 code = OPCODE_RDSR;
    u8 val;

    retval = spi_write_then_read(flash->spi, &code, 1, &val, 1);

    if (retval < 0) {
        dev_err(&flash->spi->dev, "error %d reading SR\n",
                (int) retval);
        return retval;
    }

    return val;
}

/*
 * Write status register 1 byte
 * Returns negative if error occurred.
 */
static int write_sr(struct m25p *flash, u8 val)
{
    flash->command[0] = OPCODE_WRSR;
    flash->command[1] = val;

    return spi_write(flash->spi, flash->command, 2);
}

/*
 * Set write enable latch with Write Enable command.
 * Returns negative if error occurred.
 */
static inline int write_enable(struct m25p *flash)
{
    u8	code = OPCODE_WREN;

    return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}

/*
 * Send write disble instruction to the chip.
 */
static inline int write_disable(struct m25p *flash)
{
    u8	code = OPCODE_WRDI;

    return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}

/*
 * Enable/disable 4-byte addressing mode.
 */
static inline int set_4byte(struct m25p *flash, u32 jedec_id, int enable)
{
    switch (JEDEC_MFR(jedec_id)) {
    case CFI_MFR_MACRONIX:
    case 0xEF /* winbond */:
        flash->command[0] = enable ? OPCODE_EN4B : OPCODE_EX4B;
        return spi_write(flash->spi, flash->command, 1);
    default:
        /* Spansion style */
        flash->command[0] = OPCODE_BRWR;
        flash->command[1] = enable << 7;
        return spi_write(flash->spi, flash->command, 2);
    }
}

/*
 * Service routine to read status register until ready, or timeout occurs.
 * Returns non-zero if error.
 */
static int wait_till_ready(struct m25p *flash)
{
    unsigned long deadline;
    int sr;

    deadline = jiffies + MAX_READY_WAIT_JIFFIES;

    do {
        if ((sr = read_sr(flash)) < 0)
            break;
        else if (!(sr & SR_WIP))
            return 0;

        cond_resched();

    } while (!time_after_eq(jiffies, deadline));

    return 1;
}

/*
 * Erase the whole flash memory
 *
 * Returns 0 if successful, non-zero otherwise.
 */
static int erase_chip(struct m25p *flash)
{
    pr_debug("%s: %s %lldKiB\n", dev_name(&flash->spi->dev), __func__,
            (long long)(flash->mtd.size >> 10));

    /* Wait until finished previous write command. */
    if (wait_till_ready(flash))
        return 1;

    /* Send write enable, then erase commands. */
    write_enable(flash);

    /* Set up command buffer. */
    flash->command[0] = OPCODE_CHIP_ERASE;

    spi_write(flash->spi, flash->command, 1);

    return 0;
}

static void m25p_addr2cmd(struct m25p *flash, unsigned int addr, u8 *cmd)
{
    /* opcode is in cmd[0] */
    cmd[1] = addr >> (flash->addr_width * 8 -  8);
    cmd[2] = addr >> (flash->addr_width * 8 - 16);
    cmd[3] = addr >> (flash->addr_width * 8 - 24);
    cmd[4] = addr >> (flash->addr_width * 8 - 32);
}

static int m25p_cmdsz(struct m25p *flash)
{
    return 1 + flash->addr_width;
}

/*
 * Erase one sector of flash memory at offset ``offset'' which is any
 * address within the sector which should be erased.
 *
 * Returns 0 if successful, non-zero otherwise.
 */
static int erase_sector(struct m25p *flash, u32 offset)
{
    pr_debug("%s: %s %dKiB at 0x%08x\n", dev_name(&flash->spi->dev),
            __func__, flash->mtd.erasesize / 1024, offset);

    /* Wait until finished previous write command. */
    if (wait_till_ready(flash))
        return 1;

    /* Send write enable, then erase commands. */
    write_enable(flash);

    /* Set up command buffer. */
    flash->command[0] = flash->erase_opcode;
    m25p_addr2cmd(flash, offset, flash->command);

    spi_write(flash->spi, flash->command, m25p_cmdsz(flash));

    return 0;
}

/****************************************************************************/

/*
 * MTD implementation
 */

/*
 * Erase an address range on the flash chip.  The address range may extend
 * one or more erase sectors.  Return an error is there is a problem erasing.
 */
static int m25p80_erase(struct mtd_info *mtd, struct erase_info *instr)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    u32 addr,len;
    uint32_t rem;

    pr_debug("%s: %s at 0x%llx, len %lld\n", dev_name(&flash->spi->dev),
            __func__, (long long)instr->addr,
            (long long)instr->len);

    div_u64_rem(instr->len, mtd->erasesize, &rem);
    if (rem)
        return -EINVAL;

    addr = instr->addr;
    len = instr->len;

    mutex_lock(&flash->lock);

    /* whole-chip erase? */
    if (len == flash->mtd.size) {
        if (erase_chip(flash)) {
            instr->state = MTD_ERASE_FAILED;
            mutex_unlock(&flash->lock);
            return -EIO;
        }

    /* REVISIT in some cases we could speed up erasing large regions
     * by using OPCODE_SE instead of OPCODE_BE_4K.  We may have set up
     * to use "small sector erase", but that's not always optimal.
     */

    /* "sector"-at-a-time erase */
    } else {
        while (len) {
            if (erase_sector(flash, addr)) {
                instr->state = MTD_ERASE_FAILED;
                mutex_unlock(&flash->lock);
                return -EIO;
            }

            addr += mtd->erasesize;
            len -= mtd->erasesize;
        }
    }

    mutex_unlock(&flash->lock);

    instr->state = MTD_ERASE_DONE;
    mtd_erase_callback(instr);

    return 0;
}

/*
 * Read an address range from the flash chip.  The address range
 * may be any size provided it is within the physical boundaries.
 */
static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
    size_t *retlen, u_char *buf)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    struct spi_transfer t[2];
    struct spi_message m;
    uint8_t opcode;

    pr_debug("%s: %s from 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
            __func__, (u32)from, len);

    spi_message_init(&m);
    memset(t, 0, (sizeof t));

    /* NOTE:
     * OPCODE_FAST_READ (if available) is faster.
     * Should add 1 byte DUMMY_BYTE.
     */
    t[0].tx_buf = flash->command;
    t[0].len = m25p_cmdsz(flash) + (flash->fast_read ? 1 : 0);
    spi_message_add_tail(&t[0], &m);

    t[1].rx_buf = buf;
    t[1].len = len;
    spi_message_add_tail(&t[1], &m);

    mutex_lock(&flash->lock);

    /* Wait till previous write/erase is done. */
    if (wait_till_ready(flash)) {
        /* REVISIT status return?? */
        mutex_unlock(&flash->lock);
        return 1;
    }

    /* FIXME switch to OPCODE_FAST_READ.  It's required for higher
     * clocks; and at this writing, every chip this driver handles
     * supports that opcode.
     */

    /* Set up the write data buffer. */
    opcode = flash->fast_read ? OPCODE_FAST_READ : OPCODE_NORM_READ;
    flash->command[0] = opcode;
    m25p_addr2cmd(flash, from, flash->command);

    spi_sync(flash->spi, &m);

    *retlen = m.actual_length - m25p_cmdsz(flash) -
            (flash->fast_read ? 1 : 0);

    mutex_unlock(&flash->lock);

    return 0;
}

static int m25p80_read_chunked(struct mtd_info *mtd, loff_t from, size_t len,
    size_t *retlen, u_char *buf)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    struct spi_transfer t[2];
    struct spi_message m;
    uint8_t opcode;
    int idx = 0;

    pr_debug("%s: %s from 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
            __func__, (u32)from, len);

    spi_message_init(&m);
    memset(t, 0, (sizeof t));

    t[0].tx_buf = flash->command;
    t[0].len = m25p_cmdsz(flash);
    spi_message_add_tail(&t[0], &m);
    spi_message_add_tail(&t[1], &m);

    *retlen = 0;

    while (idx < len) {
        int rlen = (len - idx > 4) ? (4) : (len - idx);

        t[1].rx_buf = &buf[idx];
        t[1].len = rlen;

        mutex_lock(&flash->lock);

        /* Wait till previous write/erase is done. */
        if (wait_till_ready(flash)) {
            /* REVISIT status return?? */
            mutex_unlock(&flash->lock);
            return 1;
        }

        /* Set up the write data buffer. */
        opcode = OPCODE_NORM_READ;
        flash->command[0] = opcode;
        m25p_addr2cmd(flash, from + idx, flash->command);

        spi_sync(flash->spi, &m);

        *retlen += m.actual_length - m25p_cmdsz(flash);

        mutex_unlock(&flash->lock);
        idx += rlen;
    }
    return 0;
}

/*
 * Write an address range to the flash chip.  Data must be written in
 * FLASH_PAGESIZE chunks.  The address range may be any size provided
 * it is within the physical boundaries.
 */
static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
    size_t *retlen, const u_char *buf)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    u32 page_offset, page_size;
    struct spi_transfer t[2];
    struct spi_message m;

    pr_debug("%s: %s to 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
            __func__, (u32)to, len);

    spi_message_init(&m);
    memset(t, 0, (sizeof t));

    t[0].tx_buf = flash->command;
    t[0].len = m25p_cmdsz(flash);
    spi_message_add_tail(&t[0], &m);

    t[1].tx_buf = buf;
    spi_message_add_tail(&t[1], &m);

    mutex_lock(&flash->lock);

    /* Wait until finished previous write command. */
    if (wait_till_ready(flash)) {
        mutex_unlock(&flash->lock);
        return 1;
    }

    write_enable(flash);

    /* Set up the opcode in the write buffer. */
    flash->command[0] = OPCODE_PP;
    m25p_addr2cmd(flash, to, flash->command);

    page_offset = to & (flash->page_size - 1);

    /* do all the bytes fit onto one page? */
    if (page_offset + len <= flash->page_size) {
        t[1].len = len;

        spi_sync(flash->spi, &m);

        *retlen = m.actual_length - m25p_cmdsz(flash);
    } else {
        u32 i;

        /* the size of data remaining on the first page */
        page_size = flash->page_size - page_offset;

        t[1].len = page_size;
        spi_sync(flash->spi, &m);

        *retlen = m.actual_length - m25p_cmdsz(flash);

        /* write everything in flash->page_size chunks */
        for (i = page_size; i < len; i += page_size) {
            page_size = len - i;
            if (page_size > flash->page_size)
                page_size = flash->page_size;

            /* write the next page to flash */
            m25p_addr2cmd(flash, to + i, flash->command);

            t[1].tx_buf = buf + i;
            t[1].len = page_size;

            wait_till_ready(flash);

            write_enable(flash);

            spi_sync(flash->spi, &m);

            *retlen += m.actual_length - m25p_cmdsz(flash);
        }
    }

    mutex_unlock(&flash->lock);

    return 0;
}

static int m25p80_write_chunked(struct mtd_info *mtd, loff_t to, size_t len,
    size_t *retlen, const u_char *buf)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    struct spi_transfer t;
    struct spi_message m;
    u32 i, page_size;
    u8 tmp[8];

    pr_debug("%s: %s to 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
            __func__, (u32)to, len);

    spi_message_init(&m);
    memset(&t, 0, (sizeof t));

    t.tx_buf = tmp;
    t.len = 8;
    spi_message_add_tail(&t, &m);

    mutex_lock(&flash->lock);

    /* Wait until finished previous write command. */
    if (wait_till_ready(flash)) {
        mutex_unlock(&flash->lock);
        return 1;
    }

    write_enable(flash);

    /* Set up the opcode in the write buffer. */
    flash->command[0] = OPCODE_PP;
    m25p_addr2cmd(flash, to, flash->command);

    t.len = 4 + (to & 0x3);
    if (t.len == 4)
        t.len = 8;
    memcpy(tmp, flash->command, 4);
    memcpy(&tmp[4], buf, t.len - 4);
    spi_sync(flash->spi, &m);
    page_size = t.len - 4;

    *retlen = m.actual_length - m25p_cmdsz(flash);

    /* write everything in flash->page_size chunks */
    for (i = page_size; i < len; i += page_size) {
        page_size = len - i;
        if (page_size > 4)
            page_size = 4;

        /* write the next page to flash */
        m25p_addr2cmd(flash, to + i, flash->command);

        memcpy(tmp, flash->command, 4);
        memcpy(&tmp[4], buf + i, page_size);
        t.len = 4 + page_size;

        wait_till_ready(flash);

        write_enable(flash);

        spi_sync(flash->spi, &m);

        *retlen += m.actual_length - m25p_cmdsz(flash);
    }

    mutex_unlock(&flash->lock);

    return 0;
}

static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
        size_t *retlen, const u_char *buf)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    struct spi_transfer t[2];
    struct spi_message m;
    size_t actual;
    int cmd_sz, ret;

    pr_debug("%s: %s to 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
            __func__, (u32)to, len);

    spi_message_init(&m);
    memset(t, 0, (sizeof t));

    t[0].tx_buf = flash->command;
    t[0].len = m25p_cmdsz(flash);
    spi_message_add_tail(&t[0], &m);

    t[1].tx_buf = buf;
    spi_message_add_tail(&t[1], &m);

    mutex_lock(&flash->lock);

    /* Wait until finished previous write command. */
    ret = wait_till_ready(flash);
    if (ret)
        goto time_out;

    write_enable(flash);

    actual = to % 2;
    /* Start write from odd address. */
    if (actual) {
        flash->command[0] = OPCODE_BP;
        m25p_addr2cmd(flash, to, flash->command);

        /* write one byte. */
        t[1].len = 1;
        spi_sync(flash->spi, &m);
        ret = wait_till_ready(flash);
        if (ret)
            goto time_out;
        *retlen += m.actual_length - m25p_cmdsz(flash);
    }
    to += actual;

    flash->command[0] = OPCODE_AAI_WP;
    m25p_addr2cmd(flash, to, flash->command);

    /* Write out most of the data here. */
    cmd_sz = m25p_cmdsz(flash);
    for (; actual < len - 1; actual += 2) {
        t[0].len = cmd_sz;
        /* write two bytes. */
        t[1].len = 2;
        t[1].tx_buf = buf + actual;

        spi_sync(flash->spi, &m);
        ret = wait_till_ready(flash);
        if (ret)
            goto time_out;
        *retlen += m.actual_length - cmd_sz;
        cmd_sz = 1;
        to += 2;
    }
    write_disable(flash);
    ret = wait_till_ready(flash);
    if (ret)
        goto time_out;

    /* Write out trailing byte if it exists. */
    if (actual != len) {
        write_enable(flash);
        flash->command[0] = OPCODE_BP;
        m25p_addr2cmd(flash, to, flash->command);
        t[0].len = m25p_cmdsz(flash);
        t[1].len = 1;
        t[1].tx_buf = buf + actual;

        spi_sync(flash->spi, &m);
        ret = wait_till_ready(flash);
        if (ret)
            goto time_out;
        *retlen += m.actual_length - m25p_cmdsz(flash);
        write_disable(flash);
    }

time_out:
    mutex_unlock(&flash->lock);
    return ret;
}

static int m25p80_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    uint32_t offset = ofs;
    uint8_t status_old, status_new;
    int res = 0;

    mutex_lock(&flash->lock);
    /* Wait until finished previous command */
    if (wait_till_ready(flash)) {
        res = 1;
        goto err;
    }

    status_old = read_sr(flash);

    if (offset < flash->mtd.size-(flash->mtd.size/2))
        status_new = status_old | SR_BP2 | SR_BP1 | SR_BP0;
    else if (offset < flash->mtd.size-(flash->mtd.size/4))
        status_new = (status_old & ~SR_BP0) | SR_BP2 | SR_BP1;
    else if (offset < flash->mtd.size-(flash->mtd.size/8))
        status_new = (status_old & ~SR_BP1) | SR_BP2 | SR_BP0;
    else if (offset < flash->mtd.size-(flash->mtd.size/16))
        status_new = (status_old & ~(SR_BP0|SR_BP1)) | SR_BP2;
    else if (offset < flash->mtd.size-(flash->mtd.size/32))
        status_new = (status_old & ~SR_BP2) | SR_BP1 | SR_BP0;
    else if (offset < flash->mtd.size-(flash->mtd.size/64))
        status_new = (status_old & ~(SR_BP2|SR_BP0)) | SR_BP1;
    else
        status_new = (status_old & ~(SR_BP2|SR_BP1)) | SR_BP0;

    /* Only modify protection if it will not unlock other areas */
    if ((status_new&(SR_BP2|SR_BP1|SR_BP0)) >
                    (status_old&(SR_BP2|SR_BP1|SR_BP0))) {
        write_enable(flash);
        if (write_sr(flash, status_new) < 0) {
            res = 1;
            goto err;
        }
    }

err:	mutex_unlock(&flash->lock);
    return res;
}

static int m25p80_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
    struct m25p *flash = mtd_to_m25p(mtd);
    uint32_t offset = ofs;
    uint8_t status_old, status_new;
    int res = 0;

    mutex_lock(&flash->lock);
    /* Wait until finished previous command */
    if (wait_till_ready(flash)) {
        res = 1;
        goto err;
    }

    status_old = read_sr(flash);

    if (offset+len > flash->mtd.size-(flash->mtd.size/64))
        status_new = status_old & ~(SR_BP2|SR_BP1|SR_BP0);
    else if (offset+len > flash->mtd.size-(flash->mtd.size/32))
        status_new = (status_old & ~(SR_BP2|SR_BP1)) | SR_BP0;
    else if (offset+len > flash->mtd.size-(flash->mtd.size/16))
        status_new = (status_old & ~(SR_BP2|SR_BP0)) | SR_BP1;
    else if (offset+len > flash->mtd.size-(flash->mtd.size/8))
        status_new = (status_old & ~SR_BP2) | SR_BP1 | SR_BP0;
    else if (offset+len > flash->mtd.size-(flash->mtd.size/4))
        status_new = (status_old & ~(SR_BP0|SR_BP1)) | SR_BP2;
    else if (offset+len > flash->mtd.size-(flash->mtd.size/2))
        status_new = (status_old & ~SR_BP1) | SR_BP2 | SR_BP0;
    else
        status_new = (status_old & ~SR_BP0) | SR_BP2 | SR_BP1;

    /* Only modify protection if it will not lock other areas */
    if ((status_new&(SR_BP2|SR_BP1|SR_BP0)) <
                    (status_old&(SR_BP2|SR_BP1|SR_BP0))) {
        write_enable(flash);
        if (write_sr(flash, status_new) < 0) {
            res = 1;
            goto err;
        }
    }

err:	mutex_unlock(&flash->lock);
    return res;
}

/****************************************************************************/

/*
 * SPI device driver setup and teardown
 */

struct flash_info {
    /* JEDEC id zero means "no ID" (most older chips); otherwise it has
     * a high byte of zero plus three data bytes: the manufacturer id,
     * then a two byte device id.
     */
    u32		jedec_id;
    u16             ext_id;

    /* The size listed here is what works with OPCODE_SE, which isn't
     * necessarily called a "sector" by the vendor.
     */
    unsigned	sector_size;
    u16		n_sectors;

    u16		page_size;
    u16		addr_width;

    u16		flags;
#define	SECT_4K		0x01		/* OPCODE_BE_4K works uniformly */
#define	M25P_NO_ERASE	0x02		/* No erase command needed */
#define	SST_WRITE	0x04		/* use SST byte programming */
#define	SECT_4K_PMC	0x10		/* OPCODE_BE_4K_PMC works uniformly */
};

#define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags)	\
    ((kernel_ulong_t)&(struct flash_info) {				\
        .jedec_id = (_jedec_id),				\
        .ext_id = (_ext_id),					\
        .sector_size = (_sector_size),				\
        .n_sectors = (_n_sectors),				\
        .page_size = 256,					\
        .flags = (_flags),					\
    })

#define CAT25_INFO(_sector_size, _n_sectors, _page_size, _addr_width)	\
    ((kernel_ulong_t)&(struct flash_info) {				\
        .sector_size = (_sector_size),				\
        .n_sectors = (_n_sectors),				\
        .page_size = (_page_size),				\
        .addr_width = (_addr_width),				\
        .flags = M25P_NO_ERASE,					\
    })

/* NOTE: double check command sets and memory organization when you add
 * more flash chips.  This current list focusses on newer chips, which
 * have been converging on command sets which including JEDEC ID.
 */
static const struct spi_device_id m25p_ids[] = {
    /* Atmel -- some are (confusingly) marketed as "DataFlash" */
    { "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K) },
    { "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K) },

    { "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K) },
    { "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K) },
    { "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },

    { "at26f004",   INFO(0x1f0400, 0, 64 * 1024,  8, SECT_4K) },
    { "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K) },
    { "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K) },
    { "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },

    { "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },

    /* EON -- en25xxx */
    { "en25f32", INFO(0x1c3116, 0, 64 * 1024,  64, SECT_4K) },
    { "en25p32", INFO(0x1c2016, 0, 64 * 1024,  64, 0) },
    { "en25q32b", INFO(0x1c3016, 0, 64 * 1024,  64, 0) },
    { "en25p64", INFO(0x1c2017, 0, 64 * 1024, 128, 0) },
    { "en25q64", INFO(0x1c3017, 0, 64 * 1024, 128, SECT_4K) },
    { "en25qh128", INFO(0x1c7018, 0, 64 * 1024, 256, 0) },
    { "en25qh256", INFO(0x1c7019, 0, 64 * 1024, 512, 0) },

    /* ESMT */
    { "f25l32pa", INFO(0x8c2016, 0, 64 * 1024, 64, SECT_4K) },

    /* Everspin */
    { "mr25h256", CAT25_INFO(  32 * 1024, 1, 256, 2) },

    /* GigaDevice */
    { "gd25q32", INFO(0xc84016, 0, 64 * 1024,  64, SECT_4K) },
    { "gd25q64", INFO(0xc84017, 0, 64 * 1024, 128, SECT_4K) },

    /* Intel/Numonyx -- xxxs33b */
    { "160s33b",  INFO(0x898911, 0, 64 * 1024,  32, 0) },
    { "320s33b",  INFO(0x898912, 0, 64 * 1024,  64, 0) },
    { "640s33b",  INFO(0x898913, 0, 64 * 1024, 128, 0) },

    /* Macronix */
    { "mx25l2005a",  INFO(0xc22012, 0, 64 * 1024,   4, SECT_4K) },
    { "mx25l4005a",  INFO(0xc22013, 0, 64 * 1024,   8, SECT_4K) },
    { "mx25l8005",   INFO(0xc22014, 0, 64 * 1024,  16, 0) },
    { "mx25l1606e",  INFO(0xc22015, 0, 64 * 1024,  32, SECT_4K) },
    { "mx25l3205d",  INFO(0xc22016, 0, 64 * 1024,  64, 0) },
    { "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128, 0) },
    { "mx25l12805d", INFO(0xc22018, 0, 64 * 1024, 256, 0) },
    { "mx25l12855e", INFO(0xc22618, 0, 64 * 1024, 256, 0) },
    { "mx25l25635e", INFO(0xc22019, 0, 64 * 1024, 512, 0) },
    { "mx25l25655e", INFO(0xc22619, 0, 64 * 1024, 512, 0) },
    { "mx66l51235l", INFO(0xc2201a, 0, 64 * 1024, 1024, 0) },

    /* Micron */
    { "n25q064",  INFO(0x20ba17, 0, 64 * 1024, 128, 0) },
    { "n25q128a11",  INFO(0x20bb18, 0, 64 * 1024, 256, 0) },
    { "n25q128a13",  INFO(0x20ba18, 0, 64 * 1024, 256, 0) },
    { "n25q256a", INFO(0x20ba19, 0, 64 * 1024, 512, SECT_4K) },

    /* PMC */
    { "pm25lv512", INFO(0, 0, 32 * 1024, 2, SECT_4K_PMC) },
    { "pm25lv010", INFO(0, 0, 32 * 1024, 4, SECT_4K_PMC) },
    { "pm25lq032", INFO(0x7f9d46, 0, 64 * 1024,  64, SECT_4K) },

    /* Spansion -- single (large) sector size only, at least
     * for the chips listed here (without boot sectors).
     */
    { "s25sl032p",  INFO(0x010215, 0x4d00,  64 * 1024,  64, 0) },
    { "s25sl064p",  INFO(0x010216, 0x4d00,  64 * 1024, 128, 0) },
    { "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, 0) },
    { "s25fl256s1", INFO(0x010219, 0x4d01,  64 * 1024, 512, 0) },
    { "s25fl512s",  INFO(0x010220, 0x4d00, 256 * 1024, 256, 0) },
    { "s70fl01gs",  INFO(0x010221, 0x4d00, 256 * 1024, 256, 0) },
    { "s25sl12800", INFO(0x012018, 0x0300, 256 * 1024,  64, 0) },
    { "s25sl12801", INFO(0x012018, 0x0301,  64 * 1024, 256, 0) },
    { "s25fl129p0", INFO(0x012018, 0x4d00, 256 * 1024,  64, 0) },
    { "s25fl129p1", INFO(0x012018, 0x4d01,  64 * 1024, 256, 0) },
    { "s25sl004a",  INFO(0x010212,      0,  64 * 1024,   8, 0) },
    { "s25sl008a",  INFO(0x010213,      0,  64 * 1024,  16, 0) },
    { "s25sl016a",  INFO(0x010214,      0,  64 * 1024,  32, 0) },
    { "s25sl032a",  INFO(0x010215,      0,  64 * 1024,  64, 0) },
    { "s25sl064a",  INFO(0x010216,      0,  64 * 1024, 128, 0) },
    { "s25fl016k",  INFO(0xef4015,      0,  64 * 1024,  32, SECT_4K) },
    { "s25fl064k",  INFO(0xef4017,      0,  64 * 1024, 128, SECT_4K) },

    /* SST -- large erase sizes are "overlays", "sectors" are 4K */
    { "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8, SECT_4K | SST_WRITE) },
    { "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16, SECT_4K | SST_WRITE) },
    { "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32, SECT_4K | SST_WRITE) },
    { "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64, SECT_4K | SST_WRITE) },
    { "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K) },
    { "sst25wf512",  INFO(0xbf2501, 0, 64 * 1024,  1, SECT_4K | SST_WRITE) },
    { "sst25wf010",  INFO(0xbf2502, 0, 64 * 1024,  2, SECT_4K | SST_WRITE) },
    { "sst25wf020",  INFO(0xbf2503, 0, 64 * 1024,  4, SECT_4K | SST_WRITE) },
    { "sst25wf040",  INFO(0xbf2504, 0, 64 * 1024,  8, SECT_4K | SST_WRITE) },

    /* ST Microelectronics -- newer production may have feature updates */
    { "m25p05",  INFO(0x202010,  0,  32 * 1024,   2, 0) },
    { "m25p10",  INFO(0x202011,  0,  32 * 1024,   4, 0) },
    { "m25p20",  INFO(0x202012,  0,  64 * 1024,   4, 0) },
    { "m25p40",  INFO(0x202013,  0,  64 * 1024,   8, 0) },
    { "m25p80",  INFO(0x202014,  0,  64 * 1024,  16, 0) },
    { "m25p16",  INFO(0x202015,  0,  64 * 1024,  32, 0) },
    { "m25p32",  INFO(0x202016,  0,  64 * 1024,  64, 0) },
    { "m25p64",  INFO(0x202017,  0,  64 * 1024, 128, 0) },
    { "m25p128", INFO(0x202018,  0, 256 * 1024,  64, 0) },
    { "n25q032", INFO(0x20ba16,  0,  64 * 1024,  64, 0) },

    { "m25p05-nonjedec",  INFO(0, 0,  32 * 1024,   2, 0) },
    { "m25p10-nonjedec",  INFO(0, 0,  32 * 1024,   4, 0) },
    { "m25p20-nonjedec",  INFO(0, 0,  64 * 1024,   4, 0) },
    { "m25p40-nonjedec",  INFO(0, 0,  64 * 1024,   8, 0) },
    { "m25p80-nonjedec",  INFO(0, 0,  64 * 1024,  16, 0) },
    { "m25p16-nonjedec",  INFO(0, 0,  64 * 1024,  32, 0) },
    { "m25p32-nonjedec",  INFO(0, 0,  64 * 1024,  64, 0) },
    { "m25p64-nonjedec",  INFO(0, 0,  64 * 1024, 128, 0) },
    { "m25p128-nonjedec", INFO(0, 0, 256 * 1024,  64, 0) },

    { "m45pe10", INFO(0x204011,  0, 64 * 1024,    2, 0) },
    { "m45pe80", INFO(0x204014,  0, 64 * 1024,   16, 0) },
    { "m45pe16", INFO(0x204015,  0, 64 * 1024,   32, 0) },

    { "m25pe20", INFO(0x208012,  0, 64 * 1024,  4,       0) },
    { "m25pe80", INFO(0x208014,  0, 64 * 1024, 16,       0) },
    { "m25pe16", INFO(0x208015,  0, 64 * 1024, 32, SECT_4K) },

    { "m25px32",    INFO(0x207116,  0, 64 * 1024, 64, SECT_4K) },
    { "m25px32-s0", INFO(0x207316,  0, 64 * 1024, 64, SECT_4K) },
    { "m25px32-s1", INFO(0x206316,  0, 64 * 1024, 64, SECT_4K) },
    { "m25px64",    INFO(0x207117,  0, 64 * 1024, 128, 0) },

    /* Winbond -- w25x "blocks" are 64K, "sectors" are 4KiB */
    { "w25x05", INFO(0xef3010, 0, 64 * 1024,  1,  SECT_4K) },
    { "w25x10", INFO(0xef3011, 0, 64 * 1024,  2,  SECT_4K) },
    { "w25x20", INFO(0xef3012, 0, 64 * 1024,  4,  SECT_4K) },
    { "w25x40", INFO(0xef3013, 0, 64 * 1024,  8,  SECT_4K) },
    { "w25x80", INFO(0xef3014, 0, 64 * 1024,  16, SECT_4K) },
    { "w25x16", INFO(0xef3015, 0, 64 * 1024,  32, SECT_4K) },
    { "w25x32", INFO(0xef3016, 0, 64 * 1024,  64, SECT_4K) },
    { "w25q32", INFO(0xef4016, 0, 64 * 1024,  64, SECT_4K) },
    { "w25q32dw", INFO(0xef6016, 0, 64 * 1024,  64, SECT_4K) },
    { "w25x64", INFO(0xef3017, 0, 64 * 1024, 128, SECT_4K) },
    { "w25q64", INFO(0xef4017, 0, 64 * 1024, 128, SECT_4K) },
    { "w25q80", INFO(0xef5014, 0, 64 * 1024,  16, SECT_4K) },
    { "w25q80bl", INFO(0xef4014, 0, 64 * 1024,  16, SECT_4K) },
    { "w25q128", INFO(0xef4018, 0, 64 * 1024, 256, SECT_4K) },
    { "w25q256", INFO(0xef4019, 0, 64 * 1024, 512, SECT_4K) },

    /* Catalyst / On Semiconductor -- non-JEDEC */
    { "cat25c11", CAT25_INFO(  16, 8, 16, 1) },
    { "cat25c03", CAT25_INFO(  32, 8, 16, 2) },
    { "cat25c09", CAT25_INFO( 128, 8, 32, 2) },
    { "cat25c17", CAT25_INFO( 256, 8, 32, 2) },
    { "cat25128", CAT25_INFO(2048, 8, 64, 2) },
    { },
};
MODULE_DEVICE_TABLE(spi, m25p_ids);

/* flash unique id probe */
static int unique_id_prob(struct spi_device *spi, u8 *id)
{
    int			tmp;
    u8			code[5];

    code[0] = OPCODE_WINBOND_ID;
    tmp = spi_write_then_read(spi, &code, 5, id, 8);
    if (tmp < 0) {
        pr_debug("%s: error %d reading UNIQUE ID\n",
                dev_name(&spi->dev), tmp);
        return tmp;
    }
    return 0;
}

static const struct spi_device_id *jedec_probe(struct spi_device *spi)
{
    int			tmp;
    u8			code = OPCODE_RDID;
    u8			id[5];
    u32			jedec;
    u16                     ext_jedec;
    struct flash_info	*info;

    /* JEDEC also defines an optional "extended device information"
     * string for after vendor-specific data, after the three bytes
     * we use here.  Supporting some chips might require using it.
     */
    tmp = spi_write_then_read(spi, &code, 1, id, 5);
    if (tmp < 0) {
        pr_debug("%s: error %d reading JEDEC ID\n",
                dev_name(&spi->dev), tmp);
        return ERR_PTR(tmp);
    }
    jedec = id[0];
    jedec = jedec << 8;
    jedec |= id[1];
    jedec = jedec << 8;
    jedec |= id[2];

    ext_jedec = id[3] << 8 | id[4];

    for (tmp = 0; tmp < ARRAY_SIZE(m25p_ids) - 1; tmp++) {
        info = (void *)m25p_ids[tmp].driver_data;
        if (info->jedec_id == jedec) {
            if (info->ext_id != 0 && info->ext_id != ext_jedec)
                continue;
            return &m25p_ids[tmp];
        }
    }
    dev_err(&spi->dev, "unrecognized JEDEC id %06x\n", jedec);
    return ERR_PTR(-ENODEV);
}


/*
 * board specific setup should have ensured the SPI clock used here
 * matches what the READ command supports, at least until this driver
 * understands FAST_READ (for clocks over 25 MHz).
 */
static int m25p_probe(struct spi_device *spi)
{
    const struct spi_device_id	*id = spi_get_device_id(spi);
    struct flash_platform_data	*data;
    struct m25p			*flash;
    struct flash_info		*info;
    unsigned			i;
    struct mtd_part_parser_data	ppdata;
    struct device_node __maybe_unused *np = spi->dev.of_node;
    const char __maybe_unused	*of_mtd_name = NULL;

#ifdef CONFIG_MTD_OF_PARTS
    if (!of_device_is_available(np))
        return -ENODEV;
    of_property_read_string(spi->dev.of_node,
                    "linux,mtd-name", &of_mtd_name);
#endif

    /* Platform data helps sort out which chip type we have, as
     * well as how this board partitions it.  If we don't have
     * a chip ID, try the JEDEC id commands; they'll work for most
     * newer chips, even if we don't recognize the particular chip.
     */
    data = spi->dev.platform_data;
    if (data && data->type) {
        const struct spi_device_id *plat_id;

        for (i = 0; i < ARRAY_SIZE(m25p_ids) - 1; i++) {
            plat_id = &m25p_ids[i];
            if (strcmp(data->type, plat_id->name))
                continue;
            break;
        }

        if (i < ARRAY_SIZE(m25p_ids) - 1)
            id = plat_id;
        else
            dev_warn(&spi->dev, "unrecognized id %s\n", data->type);
    }

    info = (void *)id->driver_data;

    if (info->jedec_id) {
        const struct spi_device_id *jid;

        jid = jedec_probe(spi);
        if (IS_ERR(jid)) {
            return PTR_ERR(jid);
        } else if (jid != id) {
            /*
             * JEDEC knows better, so overwrite platform ID. We
             * can't trust partitions any longer, but we'll let
             * mtd apply them anyway, since some partitions may be
             * marked read-only, and we don't want to lose that
             * information, even if it's not 100% accurate.
             */
            dev_warn(&spi->dev, "found %s, expected %s\n",
                 jid->name, id->name);
            id = jid;
            info = (void *)jid->driver_data;
        }
    }

    /* show unique id in kernel debug log for w25q64 or w25q128. */
    if(info->jedec_id == 0xef4017 || info->jedec_id == 0xef4018) {
        u8 unique_id[8];
        if(!unique_id_prob(spi, unique_id)) {
            dev_warn(&spi->dev, "flash id: %02x%02x%02x%02x%02x%02x%02x%02x\n",
                    unique_id[7], unique_id[6], unique_id[5], unique_id[4],
                    unique_id[3], unique_id[2], unique_id[1], unique_id[0]);
        } else {
            dev_warn(&spi->dev, "failed to get flash unique id.\n");
        }
    }

    flash = kzalloc(sizeof *flash, GFP_KERNEL);
    if (!flash)
        return -ENOMEM;
    flash->command = kmalloc(MAX_CMD_SIZE + (flash->fast_read ? 1 : 0),
                    GFP_KERNEL);
    if (!flash->command) {
        kfree(flash);
        return -ENOMEM;
    }

    flash->spi = spi;
    mutex_init(&flash->lock);
    dev_set_drvdata(&spi->dev, flash);

    /*
     * Atmel, SST and Intel/Numonyx serial flash tend to power
     * up with the software protection bits set
     */

    if (JEDEC_MFR(info->jedec_id) == CFI_MFR_ATMEL ||
        JEDEC_MFR(info->jedec_id) == CFI_MFR_INTEL ||
        JEDEC_MFR(info->jedec_id) == CFI_MFR_SST) {
        write_enable(flash);
        write_sr(flash, 0);
    }

    if (data && data->name)
        flash->mtd.name = data->name;
    else if (of_mtd_name)
        flash->mtd.name = of_mtd_name;
    else
        flash->mtd.name = dev_name(&spi->dev);

    flash->mtd.type = MTD_NORFLASH;
    flash->mtd.writesize = 1;
    flash->mtd.flags = MTD_CAP_NORFLASH;
    flash->mtd.size = info->sector_size * info->n_sectors;
    flash->mtd._erase = m25p80_erase;
    flash->mtd._read = m25p80_read;

    /* flash protection support for STmicro chips */
    if (JEDEC_MFR(info->jedec_id) == CFI_MFR_ST) {
        flash->mtd._lock = m25p80_lock;
        flash->mtd._unlock = m25p80_unlock;
    }

    /* sst flash chips use AAI word program */
    if (info->flags & SST_WRITE)
        flash->mtd._write = sst_write;
    else
        flash->mtd._write = m25p80_write;

    /* prefer "small sector" erase if possible */
    if (PREFER_SMALL_SECTOR_ERASE && (info->flags & SECT_4K)) {
        flash->erase_opcode = OPCODE_BE_4K;
        flash->mtd.erasesize = 4096;
    } else if (info->flags & SECT_4K_PMC) {
        flash->erase_opcode = OPCODE_BE_4K_PMC;
        flash->mtd.erasesize = 4096;
    } else {
        flash->erase_opcode = OPCODE_SE;
        flash->mtd.erasesize = info->sector_size;
    }

    if (info->flags & M25P_NO_ERASE)
        flash->mtd.flags |= MTD_NO_ERASE;

    ppdata.of_node = spi->dev.of_node;
    flash->mtd.dev.parent = &spi->dev;
    flash->page_size = info->page_size;
    flash->mtd.writebufsize = flash->page_size;

    flash->fast_read = false;
#ifdef CONFIG_OF
    if (np && of_property_read_bool(np, "m25p,fast-read"))
        flash->fast_read = true;
#endif

    if (np && of_property_read_bool(np, "m25p,chunked-io")) {
        dev_warn(&spi->dev, "using chunked io\n");
        flash->mtd._read = m25p80_read_chunked;
        flash->mtd._write = m25p80_write_chunked;
    }

#ifdef CONFIG_M25PXX_USE_FAST_READ
    flash->fast_read = true;
#endif

    if (info->addr_width)
        flash->addr_width = info->addr_width;
    else {
        /* enable 4-byte addressing if the device exceeds 16MiB */
        if (flash->mtd.size > 0x1000000) {
            flash->addr_width = 4;
            set_4byte(flash, info->jedec_id, 1);
        } else
            flash->addr_width = 3;
    }

    dev_info(&spi->dev, "%s (%lld Kbytes)\n", id->name,
            (long long)flash->mtd.size >> 10);

    pr_debug("mtd .name = %s, .size = 0x%llx (%lldMiB) "
            ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
        flash->mtd.name,
        (long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
        flash->mtd.erasesize, flash->mtd.erasesize / 1024,
        flash->mtd.numeraseregions);

    if (flash->mtd.numeraseregions)
        for (i = 0; i < flash->mtd.numeraseregions; i++)
            pr_debug("mtd.eraseregions[%d] = { .offset = 0x%llx, "
                ".erasesize = 0x%.8x (%uKiB), "
                ".numblocks = %d }\n",
                i, (long long)flash->mtd.eraseregions[i].offset,
                flash->mtd.eraseregions[i].erasesize,
                flash->mtd.eraseregions[i].erasesize / 1024,
                flash->mtd.eraseregions[i].numblocks);


    /* partitions should match sector boundaries; and it may be good to
     * use readonly partitions for writeprotected sectors (BP2..BP0).
     */
    return mtd_device_parse_register(&flash->mtd, NULL, &ppdata,
            data ? data->parts : NULL,
            data ? data->nr_parts : 0);
}


static int m25p_remove(struct spi_device *spi)
{
    struct m25p	*flash = dev_get_drvdata(&spi->dev);
    int		status;

    /* Clean up MTD stuff. */
    status = mtd_device_unregister(&flash->mtd);
    if (status == 0) {
        kfree(flash->command);
        kfree(flash);
    }
    return 0;
}


static struct spi_driver m25p80_driver = {
    .driver = {
        .name	= "m25p80",
        .owner	= THIS_MODULE,
    },
    .id_table	= m25p_ids,
    .probe	= m25p_probe,
    .remove	= m25p_remove,

    /* REVISIT: many of these chips have deep power-down modes, which
     * should clearly be entered on suspend() to minimize power use.
     * And also when they're otherwise idle...
     */
};

module_spi_driver(m25p80_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mike Lavender");
MODULE_DESCRIPTION("MTD SPI driver for ST M25Pxx flash chips");