/*
 * 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/err.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/device.h>

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

#include <linux/spi/spi.h>
#include <linux/spi/flash.h>
#include <linux/mtd/spi-nor.h>

#define MAX_CMD_SIZE            6
struct m25p {
        struct spi_device       *spi;
        struct spi_nor          spi_nor;
        struct mtd_info         mtd;
        u8                      command[MAX_CMD_SIZE];
};

static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
{
        struct m25p *flash = nor->priv;
        struct spi_device *spi = flash->spi;
        int ret;

        ret = spi_write_then_read(spi, &code, 1, val, len);
        if (ret < 0)
                dev_err(&spi->dev, "error %d reading %x\n", ret, code);

        return ret;
}

static void m25p_addr2cmd(struct spi_nor *nor, unsigned int addr, u8 *cmd)
{
        /* opcode is in cmd[0] */
        cmd[1] = addr >> (nor->addr_width * 8 -  8);
        cmd[2] = addr >> (nor->addr_width * 8 - 16);
        cmd[3] = addr >> (nor->addr_width * 8 - 24);
        cmd[4] = addr >> (nor->addr_width * 8 - 32);
}

static int m25p_cmdsz(struct spi_nor *nor)
{
        return 1 + nor->addr_width;
}

static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len,
                        int wr_en)
{
        struct m25p *flash = nor->priv;
        struct spi_device *spi = flash->spi;

        flash->command[0] = opcode;
        if (buf)
                memcpy(&flash->command[1], buf, len);

        return spi_write(spi, flash->command, len + 1);
}

static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
                        size_t *retlen, const u_char *buf)
{
        struct m25p *flash = nor->priv;
        struct spi_device *spi = flash->spi;
        struct spi_transfer t[2] = {};
        struct spi_message m;
        int cmd_sz = m25p_cmdsz(nor);

        spi_message_init(&m);

        if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
                cmd_sz = 1;

        flash->command[0] = nor->program_opcode;
        m25p_addr2cmd(nor, to, flash->command);

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

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

        spi_sync(spi, &m);

        *retlen += m.actual_length - cmd_sz;
}

static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)
{
        switch (nor->flash_read) {
        case SPI_NOR_DUAL:
                return 2;
        case SPI_NOR_QUAD:
                return 4;
        default:
                return 0;
        }
}

/*
 * Read an address range from the nor chip.  The address range
 * may be any size provided it is within the physical boundaries.
 */
static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
                        size_t *retlen, u_char *buf)
{
        struct m25p *flash = nor->priv;
        struct spi_device *spi = flash->spi;
        struct spi_transfer t[2];
        struct spi_message m;
        unsigned int dummy = nor->read_dummy;

        /* convert the dummy cycles to the number of bytes */
        dummy /= 8;

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

        flash->command[0] = nor->read_opcode;
        m25p_addr2cmd(nor, from, flash->command);

        t[0].tx_buf = flash->command;
        t[0].len = m25p_cmdsz(nor) + dummy;
        spi_message_add_tail(&t[0], &m);

        t[1].rx_buf = buf;
        t[1].rx_nbits = m25p80_rx_nbits(nor);
        t[1].len = len;
        spi_message_add_tail(&t[1], &m);

        spi_sync(spi, &m);

        *retlen = m.actual_length - m25p_cmdsz(nor) - dummy;
        return 0;
}

static int m25p80_erase(struct spi_nor *nor, loff_t offset)
{
        struct m25p *flash = nor->priv;

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

        /* Set up command buffer. */
        flash->command[0] = nor->erase_opcode;
        m25p_addr2cmd(nor, offset, flash->command);

        spi_write(flash->spi, flash->command, m25p_cmdsz(nor));

        return 0;
}

/*
 * 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)
{
        struct mtd_part_parser_data     ppdata;
        struct flash_platform_data      *data;
        struct m25p *flash;
        struct spi_nor *nor;
        enum read_mode mode = SPI_NOR_NORMAL;
        char *flash_name = NULL;
        int ret;

        data = dev_get_platdata(&spi->dev);

        flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
        if (!flash)
                return -ENOMEM;

        nor = &flash->spi_nor;

        /* install the hooks */
        nor->read = m25p80_read;
        nor->write = m25p80_write;
        nor->erase = m25p80_erase;
        nor->write_reg = m25p80_write_reg;
        nor->read_reg = m25p80_read_reg;

        nor->dev = &spi->dev;
        nor->mtd = &flash->mtd;
        nor->priv = flash;

        spi_set_drvdata(spi, flash);
        flash->mtd.priv = nor;
        flash->spi = spi;

        if (spi->mode & SPI_RX_QUAD)
                mode = SPI_NOR_QUAD;
        else if (spi->mode & SPI_RX_DUAL)
                mode = SPI_NOR_DUAL;

        if (data && data->name)
                flash->mtd.name = data->name;

        /* For some (historical?) reason many platforms provide two different
         * names in flash_platform_data: "name" and "type". Quite often name is
         * set to "m25p80" and then "type" provides a real chip name.
         * If that's the case, respect "type" and ignore a "name".
         */
        if (data && data->type)
                flash_name = data->type;
        else if (!strcmp(spi->modalias, "spi-nor"))
                flash_name = NULL; /* auto-detect */
        else
                flash_name = spi->modalias;

        ret = spi_nor_scan(nor, flash_name, mode);
        if (ret)
                return ret;

        ppdata.of_node = spi->dev.of_node;

        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 = spi_get_drvdata(spi);

        /* Clean up MTD stuff. */
        return mtd_device_unregister(&flash->mtd);
}

/*
 * Do NOT add to this array without reading the following:
 *
 * Historically, many flash devices are bound to this driver by their name. But
 * since most of these flash are compatible to some extent, and their
 * differences can often be differentiated by the JEDEC read-ID command, we
 * encourage new users to add support to the spi-nor library, and simply bind
 * against a generic string here (e.g., "jedec,spi-nor").
 *
 * Many flash names are kept here in this list (as well as in spi-nor.c) to
 * keep them available as module aliases for existing platforms.
 */
static const struct spi_device_id m25p_ids[] = {
        {"at25fs010"},  {"at25fs040"},  {"at25df041a"}, {"at25df321a"},
        {"at25df641"},  {"at26f004"},   {"at26df081a"}, {"at26df161a"},
        {"at26df321"},  {"at45db081d"},
        {"en25f32"},    {"en25p32"},    {"en25q32b"},   {"en25p64"},
        {"en25q64"},    {"en25qh128"},  {"en25qh256"},
        {"f25l32pa"},
        {"mr25h256"},   {"mr25h10"},
        {"gd25q32"},    {"gd25q64"},
        {"160s33b"},    {"320s33b"},    {"640s33b"},
        {"mx25l2005a"}, {"mx25l4005a"}, {"mx25l8005"},  {"mx25l1606e"},
        {"mx25l3205d"}, {"mx25l3255e"}, {"mx25l6405d"}, {"mx25l12805d"},
        {"mx25l12855e"},{"mx25l25635e"},{"mx25l25655e"},{"mx66l51235l"},
        {"mx66l1g55g"},
        {"n25q064"},    {"n25q128a11"}, {"n25q128a13"}, {"n25q256a"},
        {"n25q512a"},   {"n25q512ax3"}, {"n25q00"},
        {"pm25lv512"},  {"pm25lv010"},  {"pm25lq032"},
        {"s25sl032p"},  {"s25sl064p"},  {"s25fl256s0"}, {"s25fl256s1"},
        {"s25fl512s"},  {"s70fl01gs"},  {"s25sl12800"}, {"s25sl12801"},
        {"s25fl129p0"}, {"s25fl129p1"}, {"s25sl004a"},  {"s25sl008a"},
        {"s25sl016a"},  {"s25sl032a"},  {"s25sl064a"},  {"s25fl008k"},
        {"s25fl016k"},  {"s25fl064k"},  {"s25fl132k"},
        {"sst25vf040b"},{"sst25vf080b"},{"sst25vf016b"},{"sst25vf032b"},
        {"sst25vf064c"},{"sst25wf512"}, {"sst25wf010"}, {"sst25wf020"},
        {"sst25wf040"},
        {"m25p05"},     {"m25p10"},     {"m25p20"},     {"m25p40"},
        {"m25p80"},     {"m25p16"},     {"m25p32"},     {"m25p64"},
        {"m25p128"},    {"n25q032"},
        {"m25p05-nonjedec"},    {"m25p10-nonjedec"},    {"m25p20-nonjedec"},
        {"m25p40-nonjedec"},    {"m25p80-nonjedec"},    {"m25p16-nonjedec"},
        {"m25p32-nonjedec"},    {"m25p64-nonjedec"},    {"m25p128-nonjedec"},
        {"m45pe10"},    {"m45pe80"},    {"m45pe16"},
        {"m25pe20"},    {"m25pe80"},    {"m25pe16"},
        {"m25px16"},    {"m25px32"},    {"m25px32-s0"}, {"m25px32-s1"},
        {"m25px64"},    {"m25px80"},
        {"w25x10"},     {"w25x20"},     {"w25x40"},     {"w25x80"},
        {"w25x16"},     {"w25x32"},     {"w25q32"},     {"w25q32dw"},
        {"w25x64"},     {"w25q64"},     {"w25q80"},     {"w25q80bl"},
        {"w25q128"},    {"w25q256"},    {"cat25c11"},
        {"cat25c03"},   {"cat25c09"},   {"cat25c17"},   {"cat25128"},

        /*
         * Generic support for SPI NOR that can be identified by the JEDEC READ
         * ID opcode (0x9F). Use this, if possible.
         */
        {"spi-nor"},
        { },
};
MODULE_DEVICE_TABLE(spi, m25p_ids);

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");