[PATCH] spi: M25 series SPI flash

This was originally a driver for the ST M25P80 SPI flash. It's been
updated slightly to handle other M25P series chips.

For many of these chips, the specific type could be probed, but for now
this just requires static setup with flash_platform_data that lists the
chip type (size, format) and any default partitioning to use.

Signed-off-by: David Brownell <[e-mail]>
Cc: Mike Lavender <[e-mail]>
Cc: David Brownell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/mtd/devices/Kconfig

···
 	  Sometimes DataFlash chips are packaged inside MMC-format
 	  cards; at this writing, the MMC stack won't handle those.
 
+config MTD_M25P80
+	tristate "Support for M25 SPI Flash"
+	depends on MTD && SPI_MASTER && EXPERIMENTAL
+	help
+	  This enables access to ST M25P80 and similar SPI flash chips,
+	  used for program and data storage.  Set up your spi devices
+	  with the right board-specific platform data.
+
 config MTD_SLRAM
 	tristate "Uncached system RAM"
 	depends on MTD

drivers/mtd/devices/Makefile

···
 obj-$(CONFIG_MTD_BLKMTD)	+= blkmtd.o
 obj-$(CONFIG_MTD_BLOCK2MTD)	+= block2mtd.o
 obj-$(CONFIG_MTD_DATAFLASH)	+= mtd_dataflash.o
+obj-$(CONFIG_MTD_M25P80)	+= m25p80.o

drivers/mtd/devices/m25p80.c

···
+/*
+ * MTD SPI driver for ST M25Pxx flash chips
+ *
+ * Author: Mike Lavender, [e-mail]
+ *
+ * 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/module.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/interrupt.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/flash.h>
+
+#include <asm/semaphore.h>
+
+
+/* NOTE: AT 25F and SST 25LF series are very similar,
+ * but commands for sector erase and chip id differ...
+ */
+
+#define FLASH_PAGESIZE		256
+
+/* Flash opcodes. */
+#define	OPCODE_WREN		6	/* Write enable */
+#define	OPCODE_RDSR		5	/* Read status register */
+#define	OPCODE_READ		3	/* Read data bytes */
+#define	OPCODE_PP		2	/* Page program */
+#define	OPCODE_SE		0xd8	/* Sector erase */
+#define	OPCODE_RES		0xab	/* Read Electronic Signature */
+#define	OPCODE_RDID		0x9f	/* Read JEDEC ID */
+
+/* Status Register bits. */
+#define	SR_WIP			1	/* Write in progress */
+#define	SR_WEL			2	/* Write enable latch */
+#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_COUNT	100000
+
+
+#ifdef CONFIG_MTD_PARTITIONS
+#define	mtd_has_partitions()	(1)
+#else
+#define	mtd_has_partitions()	(0)
+#endif
+
+/****************************************************************************/
+
+struct m25p {
+	struct spi_device	*spi;
+	struct semaphore	lock;
+	struct mtd_info		mtd;
+	unsigned		partitioned;
+	u8			command[4];
+};
+
+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;
+}
+
+
+/*
+ * 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);
+}
+
+
+/*
+ * Service routine to read status register until ready, or timeout occurs.
+ * Returns non-zero if error.
+ */
+static int wait_till_ready(struct m25p *flash)
+{
+	int count;
+	int sr;
+
+	/* one chip guarantees max 5 msec wait here after page writes,
+	 * but potentially three seconds (!) after page erase.
+	 */
+	for (count = 0; count < MAX_READY_WAIT_COUNT; count++) {
+		if ((sr = read_sr(flash)) < 0)
+			break;
+		else if (!(sr & SR_WIP))
+			return 0;
+
+		/* REVISIT sometimes sleeping would be best */
+	}
+
+	return 1;
+}
+
+
+/*
+ * 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)
+{
+	DEBUG(MTD_DEBUG_LEVEL3, "%s: %s at 0x%08x\n", flash->spi->dev.bus_id,
+			__FUNCTION__, 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] = OPCODE_SE;
+	flash->command[1] = offset >> 16;
+	flash->command[2] = offset >> 8;
+	flash->command[3] = offset;
+
+	spi_write(flash->spi, flash->command, sizeof(flash->command));
+
+	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;
+
+	DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd\n",
+			flash->spi->dev.bus_id, __FUNCTION__, "at",
+			(u32)instr->addr, instr->len);
+
+	/* sanity checks */
+	if (instr->addr + instr->len > flash->mtd.size)
+		return -EINVAL;
+	if ((instr->addr % mtd->erasesize) != 0
+			|| (instr->len % mtd->erasesize) != 0) {
+		return -EINVAL;
+	}
+
+	addr = instr->addr;
+	len = instr->len;
+
+  	down(&flash->lock);
+
+	/* now erase those sectors */
+	while (len) {
+		if (erase_sector(flash, addr)) {
+			instr->state = MTD_ERASE_FAILED;
+			up(&flash->lock);
+			return -EIO;
+		}
+
+		addr += mtd->erasesize;
+		len -= mtd->erasesize;
+	}
+
+  	up(&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;
+
+	DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd\n",
+			flash->spi->dev.bus_id, __FUNCTION__, "from",
+			(u32)from, len);
+
+	/* sanity checks */
+	if (!len)
+		return 0;
+
+	if (from + len > flash->mtd.size)
+		return -EINVAL;
+
+	down(&flash->lock);
+
+	/* Wait till previous write/erase is done. */
+	if (wait_till_ready(flash)) {
+		/* REVISIT status return?? */
+		up(&flash->lock);
+		return 1;
+	}
+
+	memset(t, 0, (sizeof t));
+
+	/* NOTE:  OPCODE_FAST_READ (if available) is faster... */
+
+	/* Set up the write data buffer. */
+	flash->command[0] = OPCODE_READ;
+	flash->command[1] = from >> 16;
+	flash->command[2] = from >> 8;
+	flash->command[3] = from;
+
+	/* Byte count starts at zero. */
+	if (retlen)
+		*retlen = 0;
+
+	t[0].tx_buf = flash->command;
+	t[0].len = sizeof(flash->command);
+
+	t[1].rx_buf = buf;
+	t[1].len = len;
+
+	m.transfers = t;
+	m.n_transfer = 2;
+
+	spi_sync(flash->spi, &m);
+
+	*retlen = m.actual_length - sizeof(flash->command);
+
+  	up(&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;
+
+	DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd\n",
+			flash->spi->dev.bus_id, __FUNCTION__, "to",
+			(u32)to, len);
+
+	if (retlen)
+		*retlen = 0;
+
+	/* sanity checks */
+	if (!len)
+		return(0);
+
+	if (to + len > flash->mtd.size)
+		return -EINVAL;
+
+  	down(&flash->lock);
+
+	/* Wait until finished previous write command. */
+	if (wait_till_ready(flash))
+		return 1;
+
+	write_enable(flash);
+
+	memset(t, 0, (sizeof t));
+
+	/* Set up the opcode in the write buffer. */
+	flash->command[0] = OPCODE_PP;
+	flash->command[1] = to >> 16;
+	flash->command[2] = to >> 8;
+	flash->command[3] = to;
+
+	t[0].tx_buf = flash->command;
+	t[0].len = sizeof(flash->command);
+
+	m.transfers = t;
+	m.n_transfer = 2;
+
+	/* what page do we start with? */
+	page_offset = to % FLASH_PAGESIZE;
+
+	/* do all the bytes fit onto one page? */
+	if (page_offset + len <= FLASH_PAGESIZE) {
+		t[1].tx_buf = buf;
+		t[1].len = len;
+
+		spi_sync(flash->spi, &m);
+
+		*retlen = m.actual_length - sizeof(flash->command);
+	} else {
+		u32 i;
+
+		/* the size of data remaining on the first page */
+		page_size = FLASH_PAGESIZE - page_offset;
+
+		t[1].tx_buf = buf;
+		t[1].len = page_size;
+		spi_sync(flash->spi, &m);
+
+		*retlen = m.actual_length - sizeof(flash->command);
+
+		/* write everything in PAGESIZE chunks */
+		for (i = page_size; i < len; i += page_size) {
+			page_size = len - i;
+			if (page_size > FLASH_PAGESIZE)
+				page_size = FLASH_PAGESIZE;
+
+			/* write the next page to flash */
+			flash->command[1] = (to + i) >> 16;
+			flash->command[2] = (to + i) >> 8;
+			flash->command[3] = (to + i);
+
+			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 - sizeof(flash->command);
+	        }
+ 	}
+
+	up(&flash->lock);
+
+	return 0;
+}
+
+
+/****************************************************************************/
+
+/*
+ * SPI device driver setup and teardown
+ */
+
+struct flash_info {
+	char		*name;
+	u8		id;
+	u16		jedec_id;
+	unsigned	sector_size;
+	unsigned	n_sectors;
+};
+
+static struct flash_info __devinitdata m25p_data [] = {
+	/* REVISIT: fill in JEDEC ids, for parts that have them */
+	{ "m25p05", 0x05, 0x0000, 32 * 1024, 2 },
+	{ "m25p10", 0x10, 0x0000, 32 * 1024, 4 },
+	{ "m25p20", 0x11, 0x0000, 64 * 1024, 4 },
+	{ "m25p40", 0x12, 0x0000, 64 * 1024, 8 },
+	{ "m25p80", 0x13, 0x0000, 64 * 1024, 16 },
+	{ "m25p16", 0x14, 0x0000, 64 * 1024, 32 },
+	{ "m25p32", 0x15, 0x0000, 64 * 1024, 64 },
+	{ "m25p64", 0x16, 0x2017, 64 * 1024, 128 },
+};
+
+/*
+ * 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 __devinit m25p_probe(struct spi_device *spi)
+{
+	struct flash_platform_data	*data;
+	struct m25p			*flash;
+	struct flash_info		*info;
+	unsigned			i;
+
+	/* Platform data helps sort out which chip type we have, as
+	 * well as how this board partitions it.
+	 */
+	data = spi->dev.platform_data;
+	if (!data || !data->type) {
+		/* FIXME some chips can identify themselves with RES
+		 * or JEDEC get-id commands.  Try them ...
+		 */
+		DEBUG(MTD_DEBUG_LEVEL1, "%s: no chip id\n",
+				flash->spi->dev.bus_id);
+		return -ENODEV;
+	}
+
+	for (i = 0, info = m25p_data; i < ARRAY_SIZE(m25p_data); i++, info++) {
+		if (strcmp(data->type, info->name) == 0)
+			break;
+	}
+	if (i == ARRAY_SIZE(m25p_data)) {
+		DEBUG(MTD_DEBUG_LEVEL1, "%s: unrecognized id %s\n",
+				flash->spi->dev.bus_id, data->type);
+		return -ENODEV;
+	}
+
+	flash = kzalloc(sizeof *flash, SLAB_KERNEL);
+	if (!flash)
+		return -ENOMEM;
+
+	flash->spi = spi;
+	init_MUTEX(&flash->lock);
+	dev_set_drvdata(&spi->dev, flash);
+
+	if (data->name)
+		flash->mtd.name = data->name;
+	else
+		flash->mtd.name = spi->dev.bus_id;
+
+	flash->mtd.type = MTD_NORFLASH;
+	flash->mtd.flags = MTD_CAP_NORFLASH;
+	flash->mtd.size = info->sector_size * info->n_sectors;
+	flash->mtd.erasesize = info->sector_size;
+	flash->mtd.erase = m25p80_erase;
+	flash->mtd.read = m25p80_read;
+	flash->mtd.write = m25p80_write;
+
+	dev_info(&spi->dev, "%s (%d Kbytes)\n", info->name,
+			flash->mtd.size / 1024);
+
+	DEBUG(MTD_DEBUG_LEVEL2,
+		"mtd .name = %s, .size = 0x%.8x (%uM) "
+			".erasesize = 0x%.8x (%uK) .numeraseregions = %d\n",
+		flash->mtd.name,
+		flash->mtd.size, flash->mtd.size / (1024*1024),
+		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%.8x, "
+				".erasesize = 0x%.8x (%uK), "
+				".numblocks = %d }\n",
+				i, 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).
+	 */
+	if (mtd_has_partitions()) {
+		struct mtd_partition	*parts = NULL;
+		int			nr_parts = 0;
+
+#ifdef CONFIG_MTD_CMDLINE_PARTS
+		static const char *part_probes[] = { "cmdlinepart", NULL, };
+
+		nr_parts = parse_mtd_partitions(&flash->mtd,
+				part_probes, &parts, 0);
+#endif
+
+		if (nr_parts <= 0 && data && data->parts) {
+			parts = data->parts;
+			nr_parts = data->nr_parts;
+		}
+
+		if (nr_parts > 0) {
+			for (i = 0; i < data->nr_parts; i++) {
+				DEBUG(MTD_DEBUG_LEVEL2, "partitions[%d] = "
+					"{.name = %s, .offset = 0x%.8x, "
+						".size = 0x%.8x (%uK) }\n",
+					i, data->parts[i].name,
+					data->parts[i].offset,
+					data->parts[i].size,
+					data->parts[i].size / 1024);
+			}
+			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);
+
+	return add_mtd_device(&flash->mtd) == 1 ? -ENODEV : 0;
+}
+
+
+static int __devexit m25p_remove(struct spi_device *spi)
+{
+	struct m25p	*flash = dev_get_drvdata(&spi->dev);
+	int		status;
+
+	/* Clean up MTD stuff. */
+	if (mtd_has_partitions() && flash->partitioned)
+		status = del_mtd_partitions(&flash->mtd);
+	else
+		status = del_mtd_device(&flash->mtd);
+	if (status == 0)
+		kfree(flash);
+	return 0;
+}
+
+
+static struct spi_driver m25p80_driver = {
+	.driver = {
+		.name	= "m25p80",
+		.bus	= &spi_bus_type,
+		.owner	= THIS_MODULE,
+	},
+	.probe	= m25p_probe,
+	.remove	= __devexit_p(m25p_remove),
+};
+
+
+static int m25p80_init(void)
+{
+	return spi_register_driver(&m25p80_driver);
+}
+
+
+static void m25p80_exit(void)
+{
+	spi_unregister_driver(&m25p80_driver);
+}
+
+
+module_init(m25p80_init);
+module_exit(m25p80_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mike Lavender");
+MODULE_DESCRIPTION("MTD SPI driver for ST M25Pxx flash chips");

include/linux/spi/flash.h

···
  * @name: optional flash device name (eg, as used with mtdparts=)
  * @parts: optional array of mtd_partitions for static partitioning
  * @nr_parts: number of mtd_partitions for static partitoning
+ * @type: optional flash device type (e.g. m25p80 vs m25p64), for use
+ *	with chips that can't be queried for JEDEC or other IDs
  *
  * Board init code (in arch/.../mach-xxx/board-yyy.c files) can
  * provide information about SPI flash parts (such as DataFlash) to
···
 	char		*name;
 	struct mtd_partition *parts;
 	unsigned int	nr_parts;
+
+	char		*type;
 
 	/* we'll likely add more ... use JEDEC IDs, etc */
 };