/*
 * 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_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 */

/* 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)

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

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;
}

/*
 * 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 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 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) },
        { "en25qh256", INFO(0x1c7019, 0, 64 * 1024, 512, 0) },

        /* 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) },

        /* 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 */
        { "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);

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;

#ifdef CONFIG_MTD_OF_PARTS
        if (!of_device_is_available(np))
                return -ENODEV;
#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;
                }
        }

        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
                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 (info->flags & SECT_4K) {
                flash->erase_opcode = OPCODE_BE_4K;
                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

#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");