/*
 * 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, "nor-jedec"))
		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., "nor-jedec").
 *
 * 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.
	 */
	{"nor-jedec"},
	{ },
};
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");