drivers/mtd/devices/sst25l.c - arm/linux-arm64-legacy - Git at Google

 /*
  * sst25l.c
  *
  * Driver for SST25L SPI Flash chips
  *
  * Copyright © 2009 Bluewater Systems Ltd
  * Author: Andre Renaud <andre@bluewatersys.com>
  * Author: Ryan Mallon <ryan@bluewatersys.com>
  *
  * Based on m25p80.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/module.h>
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/sched.h>

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

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

 /* Erases can take up to 3 seconds! */
 #define MAX_READY_WAIT_JIFFIES	msecs_to_jiffies(3000)

 #define SST25L_CMD_WRSR		0x01	/* Write status register */
 #define SST25L_CMD_WRDI		0x04	/* Write disable */
 #define SST25L_CMD_RDSR		0x05	/* Read status register */
 #define SST25L_CMD_WREN		0x06	/* Write enable */
 #define SST25L_CMD_READ		0x03	/* High speed read */

 #define SST25L_CMD_EWSR		0x50	/* Enable write status register */
 #define SST25L_CMD_SECTOR_ERASE	0x20	/* Erase sector */
 #define SST25L_CMD_READ_ID	0x90	/* Read device ID */
 #define SST25L_CMD_AAI_PROGRAM	0xaf	/* Auto address increment */

 #define SST25L_STATUS_BUSY	(1 << 0)	/* Chip is busy */
 #define SST25L_STATUS_WREN	(1 << 1)	/* Write enabled */
 #define SST25L_STATUS_BP0	(1 << 2)	/* Block protection 0 */
 #define SST25L_STATUS_BP1	(1 << 3)	/* Block protection 1 */

 struct sst25l_flash {
 	struct spi_device	*spi;
 	struct mutex		lock;
 	struct mtd_info		mtd;

 	int 			partitioned;
 };

 struct flash_info {
 	const char		*name;
 	uint16_t		device_id;
 	unsigned		page_size;
 	unsigned		nr_pages;
 	unsigned		erase_size;
 };

 #define to_sst25l_flash(x) container_of(x, struct sst25l_flash, mtd)

 static struct flash_info __initdata sst25l_flash_info[] = {
 	{"sst25lf020a", 0xbf43, 256, 1024, 4096},
 	{"sst25lf040a",	0xbf44,	256, 2048, 4096},
 };

 static int sst25l_status(struct sst25l_flash *flash, int *status)
 {
 	unsigned char command, response;
 	int err;

 	command = SST25L_CMD_RDSR;
 	err = spi_write_then_read(flash->spi, &command, 1, &response, 1);
 	if (err < 0)
 		return err;

 	*status = response;
 	return 0;
 }

 static int sst25l_write_enable(struct sst25l_flash *flash, int enable)
 {
 	unsigned char command[2];
 	int status, err;

 	command[0] = enable ? SST25L_CMD_WREN : SST25L_CMD_WRDI;
 	err = spi_write(flash->spi, command, 1);
 	if (err)
 		return err;

 	command[0] = SST25L_CMD_EWSR;
 	err = spi_write(flash->spi, command, 1);
 	if (err)
 		return err;

 	command[0] = SST25L_CMD_WRSR;
 	command[1] = enable ? 0 : SST25L_STATUS_BP0 | SST25L_STATUS_BP1;
 	err = spi_write(flash->spi, command, 2);
 	if (err)
 		return err;

 	if (enable) {
 		err = sst25l_status(flash, &status);
 		if (err)
 			return err;
 		if (!(status & SST25L_STATUS_WREN))
 			return -EROFS;
 	}

 	return 0;
 }

 static int sst25l_wait_till_ready(struct sst25l_flash *flash)
 {
 	unsigned long deadline;
 	int status, err;

 	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
 	do {
 		err = sst25l_status(flash, &status);
 		if (err)
 			return err;
 		if (!(status & SST25L_STATUS_BUSY))
 			return 0;

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

 	return -ETIMEDOUT;
 }

 static int sst25l_erase_sector(struct sst25l_flash *flash, uint32_t offset)
 {
 	unsigned char command[4];
 	int err;

 	err = sst25l_write_enable(flash, 1);
 	if (err)
 		return err;

 	command[0] = SST25L_CMD_SECTOR_ERASE;
 	command[1] = offset >> 16;
 	command[2] = offset >> 8;
 	command[3] = offset;
 	err = spi_write(flash->spi, command, 4);
 	if (err)
 		return err;

 	err = sst25l_wait_till_ready(flash);
 	if (err)
 		return err;

 	return sst25l_write_enable(flash, 0);
 }

 static int sst25l_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
 	struct sst25l_flash *flash = to_sst25l_flash(mtd);
 	uint32_t addr, end;
 	int err;

 	/* Sanity checks */
 	if (instr->addr + instr->len > flash->mtd.size)
 		return -EINVAL;

 	if ((uint32_t)instr->len % mtd->erasesize)
 		return -EINVAL;

 	if ((uint32_t)instr->addr % mtd->erasesize)
 		return -EINVAL;

 	addr = instr->addr;
 	end = addr + instr->len;

 	mutex_lock(&flash->lock);

 	err = sst25l_wait_till_ready(flash);
 	if (err) {
 		mutex_unlock(&flash->lock);
 		return err;
 	}

 	while (addr < end) {
 		err = sst25l_erase_sector(flash, addr);
 		if (err) {
 			mutex_unlock(&flash->lock);
 			instr->state = MTD_ERASE_FAILED;
 			dev_err(&flash->spi->dev, "Erase failed\n");
 			return err;
 		}

 		addr += mtd->erasesize;
 	}

 	mutex_unlock(&flash->lock);

 	instr->state = MTD_ERASE_DONE;
 	mtd_erase_callback(instr);
 	return 0;
 }

 static int sst25l_read(struct mtd_info *mtd, loff_t from, size_t len,
 		       size_t *retlen, unsigned char *buf)
 {
 	struct sst25l_flash *flash = to_sst25l_flash(mtd);
 	struct spi_transfer transfer[2];
 	struct spi_message message;
 	unsigned char command[4];
 	int ret;

 	/* Sanity checking */
 	if (len == 0)
 		return 0;

 	if (from + len > flash->mtd.size)
 		return -EINVAL;

 	if (retlen)
 		*retlen = 0;

 	spi_message_init(&message);
 	memset(&transfer, 0, sizeof(transfer));

 	command[0] = SST25L_CMD_READ;
 	command[1] = from >> 16;
 	command[2] = from >> 8;
 	command[3] = from;

 	transfer[0].tx_buf = command;
 	transfer[0].len = sizeof(command);
 	spi_message_add_tail(&transfer[0], &message);

 	transfer[1].rx_buf = buf;
 	transfer[1].len = len;
 	spi_message_add_tail(&transfer[1], &message);

 	mutex_lock(&flash->lock);

 	/* Wait for previous write/erase to complete */
 	ret = sst25l_wait_till_ready(flash);
 	if (ret) {
 		mutex_unlock(&flash->lock);
 		return ret;
 	}

 	spi_sync(flash->spi, &message);

 	if (retlen && message.actual_length > sizeof(command))
 		*retlen += message.actual_length - sizeof(command);

 	mutex_unlock(&flash->lock);
 	return 0;
 }

 static int sst25l_write(struct mtd_info *mtd, loff_t to, size_t len,
 			size_t *retlen, const unsigned char *buf)
 {
 	struct sst25l_flash *flash = to_sst25l_flash(mtd);
 	int i, j, ret, bytes, copied = 0;
 	unsigned char command[5];

 	/* Sanity checks */
 	if (!len)
 		return 0;

 	if (to + len > flash->mtd.size)
 		return -EINVAL;

 	if ((uint32_t)to % mtd->writesize)
 		return -EINVAL;

 	mutex_lock(&flash->lock);

 	ret = sst25l_write_enable(flash, 1);
 	if (ret)
 		goto out;

 	for (i = 0; i < len; i += mtd->writesize) {
 		ret = sst25l_wait_till_ready(flash);
 		if (ret)
 			goto out;

 		/* Write the first byte of the page */
 		command[0] = SST25L_CMD_AAI_PROGRAM;
 		command[1] = (to + i) >> 16;
 		command[2] = (to + i) >> 8;
 		command[3] = (to + i);
 		command[4] = buf[i];
 		ret = spi_write(flash->spi, command, 5);
 		if (ret < 0)
 			goto out;
 		copied++;

 		/*
 		 * Write the remaining bytes using auto address
 		 * increment mode
 		 */
 		bytes = min_t(uint32_t, mtd->writesize, len - i);
 		for (j = 1; j < bytes; j++, copied++) {
 			ret = sst25l_wait_till_ready(flash);
 			if (ret)
 				goto out;

 			command[1] = buf[i + j];
 			ret = spi_write(flash->spi, command, 2);
 			if (ret)
 				goto out;
 		}
 	}

 out:
 	ret = sst25l_write_enable(flash, 0);

 	if (retlen)
 		*retlen = copied;

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

 static struct flash_info *__init sst25l_match_device(struct spi_device *spi)
 {
 	struct flash_info *flash_info = NULL;
 	unsigned char command[4], response;
 	int i, err;
 	uint16_t id;

 	command[0] = SST25L_CMD_READ_ID;
 	command[1] = 0;
 	command[2] = 0;
 	command[3] = 0;
 	err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
 	if (err < 0) {
 		dev_err(&spi->dev, "error reading device id msb\n");
 		return NULL;
 	}

 	id = response << 8;

 	command[0] = SST25L_CMD_READ_ID;
 	command[1] = 0;
 	command[2] = 0;
 	command[3] = 1;
 	err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
 	if (err < 0) {
 		dev_err(&spi->dev, "error reading device id lsb\n");
 		return NULL;
 	}

 	id |= response;

 	for (i = 0; i < ARRAY_SIZE(sst25l_flash_info); i++)
 		if (sst25l_flash_info[i].device_id == id)
 			flash_info = &sst25l_flash_info[i];

 	if (!flash_info)
 		dev_err(&spi->dev, "unknown id %.4x\n", id);

 	return flash_info;
 }

 static int __init sst25l_probe(struct spi_device *spi)
 {
 	struct flash_info *flash_info;
 	struct sst25l_flash *flash;
 	struct flash_platform_data *data;
 	int ret, i;

 	flash_info = sst25l_match_device(spi);
 	if (!flash_info)
 		return -ENODEV;

 	flash = kzalloc(sizeof(struct sst25l_flash), GFP_KERNEL);
 	if (!flash)
 		return -ENOMEM;

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

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

 	flash->mtd.type		= MTD_NORFLASH;
 	flash->mtd.flags	= MTD_CAP_NORFLASH;
 	flash->mtd.erasesize	= flash_info->erase_size;
 	flash->mtd.writesize	= flash_info->page_size;
 	flash->mtd.size		= flash_info->page_size * flash_info->nr_pages;
 	flash->mtd.erase	= sst25l_erase;
 	flash->mtd.read		= sst25l_read;
 	flash->mtd.write 	= sst25l_write;

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

 	DEBUG(MTD_DEBUG_LEVEL2,
 	      "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++)
 			DEBUG(MTD_DEBUG_LEVEL2,
 			      "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);

 	if (mtd_has_partitions()) {
 		struct mtd_partition *parts = NULL;
 		int nr_parts = 0;

 		if (mtd_has_cmdlinepart()) {
 			static const char *part_probes[] =
 				{"cmdlinepart", NULL};

 			nr_parts = parse_mtd_partitions(&flash->mtd,
 							part_probes,
 							&parts, 0);
 		}

 		if (nr_parts <= 0 && data && data->parts) {
 			parts = data->parts;
 			nr_parts = data->nr_parts;
 		}

 		if (nr_parts > 0) {
 			for (i = 0; i < nr_parts; i++) {
 				DEBUG(MTD_DEBUG_LEVEL2, "partitions[%d] = "
 				      "{.name = %s, .offset = 0x%llx, "
 				      ".size = 0x%llx (%lldKiB) }\n",
 				      i, parts[i].name,
 				      (long long)parts[i].offset,
 				      (long long)parts[i].size,
 				      (long long)(parts[i].size >> 10));
 			}

 			flash->partitioned = 1;
 			return add_mtd_partitions(&flash->mtd,
 						  parts, nr_parts);
 		}

 	} else if (data->nr_parts) {
 		dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",
 			 data->nr_parts, data->name);
 	}

 	ret = add_mtd_device(&flash->mtd);
 	if (ret == 1) {
 		kfree(flash);
 		dev_set_drvdata(&spi->dev, NULL);
 		return -ENODEV;
 	}

 	return 0;
 }

 static int __exit sst25l_remove(struct spi_device *spi)
 {
 	struct sst25l_flash *flash = dev_get_drvdata(&spi->dev);
 	int ret;

 	if (mtd_has_partitions() && flash->partitioned)
 		ret = del_mtd_partitions(&flash->mtd);
 	else
 		ret = del_mtd_device(&flash->mtd);
 	if (ret == 0)
 		kfree(flash);
 	return ret;
 }

 static struct spi_driver sst25l_driver = {
 	.driver = {
 		.name	= "sst25l",
 		.bus	= &spi_bus_type,
 		.owner	= THIS_MODULE,
 	},
 	.probe		= sst25l_probe,
 	.remove		= __exit_p(sst25l_remove),
 };

 static int __init sst25l_init(void)
 {
 	return spi_register_driver(&sst25l_driver);
 }

 static void __exit sst25l_exit(void)
 {
 	spi_unregister_driver(&sst25l_driver);
 }

 module_init(sst25l_init);
 module_exit(sst25l_exit);

 MODULE_DESCRIPTION("MTD SPI driver for SST25L Flash chips");
 MODULE_AUTHOR("Andre Renaud <andre@bluewatersys.com>, "
 	      "Ryan Mallon <ryan@bluewatersys.com>");
 MODULE_LICENSE("GPL");
	/*
	* sst25l.c
	*
	* Driver for SST25L SPI Flash chips
	*
	* Copyright © 2009 Bluewater Systems Ltd
	* Author: Andre Renaud <andre@bluewatersys.com>
	* Author: Ryan Mallon <ryan@bluewatersys.com>
	*
	* Based on m25p80.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/module.h>
	#include <linux/device.h>
	#include <linux/mutex.h>
	#include <linux/interrupt.h>
	#include <linux/slab.h>
	#include <linux/sched.h>

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

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

	/* Erases can take up to 3 seconds! */
	#define MAX_READY_WAIT_JIFFIES msecs_to_jiffies(3000)

	#define SST25L_CMD_WRSR 0x01 /* Write status register */
	#define SST25L_CMD_WRDI 0x04 /* Write disable */
	#define SST25L_CMD_RDSR 0x05 /* Read status register */
	#define SST25L_CMD_WREN 0x06 /* Write enable */
	#define SST25L_CMD_READ 0x03 /* High speed read */

	#define SST25L_CMD_EWSR 0x50 /* Enable write status register */
	#define SST25L_CMD_SECTOR_ERASE 0x20 /* Erase sector */
	#define SST25L_CMD_READ_ID 0x90 /* Read device ID */
	#define SST25L_CMD_AAI_PROGRAM 0xaf /* Auto address increment */

	#define SST25L_STATUS_BUSY (1 << 0) /* Chip is busy */
	#define SST25L_STATUS_WREN (1 << 1) /* Write enabled */
	#define SST25L_STATUS_BP0 (1 << 2) /* Block protection 0 */
	#define SST25L_STATUS_BP1 (1 << 3) /* Block protection 1 */

	struct sst25l_flash {
	struct spi_device *spi;
	struct mutex lock;
	struct mtd_info mtd;

	int partitioned;
	};

	struct flash_info {
	const char *name;
	uint16_t device_id;
	unsigned page_size;
	unsigned nr_pages;
	unsigned erase_size;
	};

	#define to_sst25l_flash(x) container_of(x, struct sst25l_flash, mtd)

	static struct flash_info __initdata sst25l_flash_info[] = {
	{"sst25lf020a", 0xbf43, 256, 1024, 4096},
	{"sst25lf040a", 0xbf44, 256, 2048, 4096},
	};

	static int sst25l_status(struct sst25l_flash flash, int status)
	{
	unsigned char command, response;
	int err;

	command = SST25L_CMD_RDSR;
	err = spi_write_then_read(flash->spi, &command, 1, &response, 1);
	if (err < 0)
	return err;

	*status = response;
	return 0;
	}

	static int sst25l_write_enable(struct sst25l_flash *flash, int enable)
	{
	unsigned char command[2];
	int status, err;

	command[0] = enable ? SST25L_CMD_WREN : SST25L_CMD_WRDI;
	err = spi_write(flash->spi, command, 1);
	if (err)
	return err;

	command[0] = SST25L_CMD_EWSR;
	err = spi_write(flash->spi, command, 1);
	if (err)
	return err;

	command[0] = SST25L_CMD_WRSR;
	command[1] = enable ? 0 : SST25L_STATUS_BP0 \| SST25L_STATUS_BP1;
	err = spi_write(flash->spi, command, 2);
	if (err)
	return err;

	if (enable) {
	err = sst25l_status(flash, &status);
	if (err)
	return err;
	if (!(status & SST25L_STATUS_WREN))
	return -EROFS;
	}

	return 0;
	}

	static int sst25l_wait_till_ready(struct sst25l_flash *flash)
	{
	unsigned long deadline;
	int status, err;

	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
	do {
	err = sst25l_status(flash, &status);
	if (err)
	return err;
	if (!(status & SST25L_STATUS_BUSY))
	return 0;

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

	return -ETIMEDOUT;
	}

	static int sst25l_erase_sector(struct sst25l_flash *flash, uint32_t offset)
	{
	unsigned char command[4];
	int err;

	err = sst25l_write_enable(flash, 1);
	if (err)
	return err;

	command[0] = SST25L_CMD_SECTOR_ERASE;
	command[1] = offset >> 16;
	command[2] = offset >> 8;
	command[3] = offset;
	err = spi_write(flash->spi, command, 4);
	if (err)
	return err;

	err = sst25l_wait_till_ready(flash);
	if (err)
	return err;

	return sst25l_write_enable(flash, 0);
	}

	static int sst25l_erase(struct mtd_info mtd, struct erase_info instr)
	{
	struct sst25l_flash *flash = to_sst25l_flash(mtd);
	uint32_t addr, end;
	int err;

	/* Sanity checks */
	if (instr->addr + instr->len > flash->mtd.size)
	return -EINVAL;

	if ((uint32_t)instr->len % mtd->erasesize)
	return -EINVAL;

	if ((uint32_t)instr->addr % mtd->erasesize)
	return -EINVAL;

	addr = instr->addr;
	end = addr + instr->len;

	mutex_lock(&flash->lock);

	err = sst25l_wait_till_ready(flash);
	if (err) {
	mutex_unlock(&flash->lock);
	return err;
	}

	while (addr < end) {
	err = sst25l_erase_sector(flash, addr);
	if (err) {
	mutex_unlock(&flash->lock);
	instr->state = MTD_ERASE_FAILED;
	dev_err(&flash->spi->dev, "Erase failed\n");
	return err;
	}

	addr += mtd->erasesize;
	}

	mutex_unlock(&flash->lock);

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);
	return 0;
	}

	static int sst25l_read(struct mtd_info *mtd, loff_t from, size_t len,
	size_t retlen, unsigned char buf)
	{
	struct sst25l_flash *flash = to_sst25l_flash(mtd);
	struct spi_transfer transfer[2];
	struct spi_message message;
	unsigned char command[4];
	int ret;

	/* Sanity checking */
	if (len == 0)
	return 0;

	if (from + len > flash->mtd.size)
	return -EINVAL;

	if (retlen)
	*retlen = 0;

	spi_message_init(&message);
	memset(&transfer, 0, sizeof(transfer));

	command[0] = SST25L_CMD_READ;
	command[1] = from >> 16;
	command[2] = from >> 8;
	command[3] = from;

	transfer[0].tx_buf = command;
	transfer[0].len = sizeof(command);
	spi_message_add_tail(&transfer[0], &message);

	transfer[1].rx_buf = buf;
	transfer[1].len = len;
	spi_message_add_tail(&transfer[1], &message);

	mutex_lock(&flash->lock);

	/* Wait for previous write/erase to complete */
	ret = sst25l_wait_till_ready(flash);
	if (ret) {
	mutex_unlock(&flash->lock);
	return ret;
	}

	spi_sync(flash->spi, &message);

	if (retlen && message.actual_length > sizeof(command))
	*retlen += message.actual_length - sizeof(command);

	mutex_unlock(&flash->lock);
	return 0;
	}

	static int sst25l_write(struct mtd_info *mtd, loff_t to, size_t len,
	size_t retlen, const unsigned char buf)
	{
	struct sst25l_flash *flash = to_sst25l_flash(mtd);
	int i, j, ret, bytes, copied = 0;
	unsigned char command[5];

	/* Sanity checks */
	if (!len)
	return 0;

	if (to + len > flash->mtd.size)
	return -EINVAL;

	if ((uint32_t)to % mtd->writesize)
	return -EINVAL;

	mutex_lock(&flash->lock);

	ret = sst25l_write_enable(flash, 1);
	if (ret)
	goto out;

	for (i = 0; i < len; i += mtd->writesize) {
	ret = sst25l_wait_till_ready(flash);
	if (ret)
	goto out;

	/* Write the first byte of the page */
	command[0] = SST25L_CMD_AAI_PROGRAM;
	command[1] = (to + i) >> 16;
	command[2] = (to + i) >> 8;
	command[3] = (to + i);
	command[4] = buf[i];
	ret = spi_write(flash->spi, command, 5);
	if (ret < 0)
	goto out;
	copied++;

	/*
	* Write the remaining bytes using auto address
	* increment mode
	*/
	bytes = min_t(uint32_t, mtd->writesize, len - i);
	for (j = 1; j < bytes; j++, copied++) {
	ret = sst25l_wait_till_ready(flash);
	if (ret)
	goto out;

	command[1] = buf[i + j];
	ret = spi_write(flash->spi, command, 2);
	if (ret)
	goto out;
	}
	}

	out:
	ret = sst25l_write_enable(flash, 0);

	if (retlen)
	*retlen = copied;

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

	static struct flash_info __init sst25l_match_device(struct spi_device spi)
	{
	struct flash_info *flash_info = NULL;
	unsigned char command[4], response;
	int i, err;
	uint16_t id;

	command[0] = SST25L_CMD_READ_ID;
	command[1] = 0;
	command[2] = 0;
	command[3] = 0;
	err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
	if (err < 0) {
	dev_err(&spi->dev, "error reading device id msb\n");
	return NULL;
	}

	id = response << 8;

	command[0] = SST25L_CMD_READ_ID;
	command[1] = 0;
	command[2] = 0;
	command[3] = 1;
	err = spi_write_then_read(spi, command, sizeof(command), &response, 1);
	if (err < 0) {
	dev_err(&spi->dev, "error reading device id lsb\n");
	return NULL;
	}

	id \|= response;

	for (i = 0; i < ARRAY_SIZE(sst25l_flash_info); i++)
	if (sst25l_flash_info[i].device_id == id)
	flash_info = &sst25l_flash_info[i];

	if (!flash_info)
	dev_err(&spi->dev, "unknown id %.4x\n", id);

	return flash_info;
	}

	static int __init sst25l_probe(struct spi_device *spi)
	{
	struct flash_info *flash_info;
	struct sst25l_flash *flash;
	struct flash_platform_data *data;
	int ret, i;

	flash_info = sst25l_match_device(spi);
	if (!flash_info)
	return -ENODEV;

	flash = kzalloc(sizeof(struct sst25l_flash), GFP_KERNEL);
	if (!flash)
	return -ENOMEM;

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

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

	flash->mtd.type = MTD_NORFLASH;
	flash->mtd.flags = MTD_CAP_NORFLASH;
	flash->mtd.erasesize = flash_info->erase_size;
	flash->mtd.writesize = flash_info->page_size;
	flash->mtd.size = flash_info->page_size * flash_info->nr_pages;
	flash->mtd.erase = sst25l_erase;
	flash->mtd.read = sst25l_read;
	flash->mtd.write = sst25l_write;

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

	DEBUG(MTD_DEBUG_LEVEL2,
	"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++)
	DEBUG(MTD_DEBUG_LEVEL2,
	"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);

	if (mtd_has_partitions()) {
	struct mtd_partition *parts = NULL;
	int nr_parts = 0;

	if (mtd_has_cmdlinepart()) {
	static const char *part_probes[] =
	{"cmdlinepart", NULL};

	nr_parts = parse_mtd_partitions(&flash->mtd,
	part_probes,
	&parts, 0);
	}

	if (nr_parts <= 0 && data && data->parts) {
	parts = data->parts;
	nr_parts = data->nr_parts;
	}

	if (nr_parts > 0) {
	for (i = 0; i < nr_parts; i++) {
	DEBUG(MTD_DEBUG_LEVEL2, "partitions[%d] = "
	"{.name = %s, .offset = 0x%llx, "
	".size = 0x%llx (%lldKiB) }\n",
	i, parts[i].name,
	(long long)parts[i].offset,
	(long long)parts[i].size,
	(long long)(parts[i].size >> 10));
	}

	flash->partitioned = 1;
	return add_mtd_partitions(&flash->mtd,
	parts, nr_parts);
	}

	} else if (data->nr_parts) {
	dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",
	data->nr_parts, data->name);
	}

	ret = add_mtd_device(&flash->mtd);
	if (ret == 1) {
	kfree(flash);
	dev_set_drvdata(&spi->dev, NULL);
	return -ENODEV;
	}

	return 0;
	}

	static int __exit sst25l_remove(struct spi_device *spi)
	{
	struct sst25l_flash *flash = dev_get_drvdata(&spi->dev);
	int ret;

	if (mtd_has_partitions() && flash->partitioned)
	ret = del_mtd_partitions(&flash->mtd);
	else
	ret = del_mtd_device(&flash->mtd);
	if (ret == 0)
	kfree(flash);
	return ret;
	}

	static struct spi_driver sst25l_driver = {
	.driver = {
	.name = "sst25l",
	.bus = &spi_bus_type,
	.owner = THIS_MODULE,
	},
	.probe = sst25l_probe,
	.remove = __exit_p(sst25l_remove),
	};

	static int __init sst25l_init(void)
	{
	return spi_register_driver(&sst25l_driver);
	}

	static void __exit sst25l_exit(void)
	{
	spi_unregister_driver(&sst25l_driver);
	}

	module_init(sst25l_init);
	module_exit(sst25l_exit);

	MODULE_DESCRIPTION("MTD SPI driver for SST25L Flash chips");
	MODULE_AUTHOR("Andre Renaud <andre@bluewatersys.com>, "
	"Ryan Mallon <ryan@bluewatersys.com>");
	MODULE_LICENSE("GPL");