mtd_dataflash.c

基于linux-2.6.28的mtd驱动

/*
 * Atmel AT45xxx DataFlash MTD driver for lightweight SPI framework
 *
 * Largely derived from at91_dataflash.c:
 *  Copyright (C) 2003-2005 SAN People (Pty) Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/err.h>

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

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


/*
 * DataFlash is a kind of SPI flash.  Most AT45 chips have two buffers in
 * each chip, which may be used for double buffered I/O; but this driver
 * doesn't (yet) use these for any kind of i/o overlap or prefetching.
 *
 * Sometimes DataFlash is packaged in MMC-format cards, although the
 * MMC stack can't (yet?) distinguish between MMC and DataFlash
 * protocols during enumeration.
 */

/* reads can bypass the buffers */
#define OP_READ_CONTINUOUS	0xE8
#define OP_READ_PAGE		0xD2

/* group B requests can run even while status reports "busy" */
#define OP_READ_STATUS		0xD7	/* group B */

/* move data between host and buffer */
#define OP_READ_BUFFER1		0xD4	/* group B */
#define OP_READ_BUFFER2		0xD6	/* group B */
#define OP_WRITE_BUFFER1	0x84	/* group B */
#define OP_WRITE_BUFFER2	0x87	/* group B */

/* erasing flash */
#define OP_ERASE_PAGE		0x81
#define OP_ERASE_BLOCK		0x50

/* move data between buffer and flash */
#define OP_TRANSFER_BUF1	0x53
#define OP_TRANSFER_BUF2	0x55
#define OP_MREAD_BUFFER1	0xD4
#define OP_MREAD_BUFFER2	0xD6
#define OP_MWERASE_BUFFER1	0x83
#define OP_MWERASE_BUFFER2	0x86
#define OP_MWRITE_BUFFER1	0x88	/* sector must be pre-erased */
#define OP_MWRITE_BUFFER2	0x89	/* sector must be pre-erased */

/* write to buffer, then write-erase to flash */
#define OP_PROGRAM_VIA_BUF1	0x82
#define OP_PROGRAM_VIA_BUF2	0x85

/* compare buffer to flash */
#define OP_COMPARE_BUF1		0x60
#define OP_COMPARE_BUF2		0x61

/* read flash to buffer, then write-erase to flash */
#define OP_REWRITE_VIA_BUF1	0x58
#define OP_REWRITE_VIA_BUF2	0x59

/* newer chips report JEDEC manufacturer and device IDs; chip
 * serial number and OTP bits; and per-sector writeprotect.
 */
#define OP_READ_ID		0x9F
#define OP_READ_SECURITY	0x77
#define OP_WRITE_SECURITY_REVC	0x9A
#define OP_WRITE_SECURITY	0x9B	/* revision D */


struct dataflash {
	uint8_t			command[4];
	char			name[24];

	unsigned		partitioned:1;

	unsigned short		page_offset;	/* offset in flash address */
	unsigned int		page_size;	/* of bytes per page */

	struct mutex		lock;
	struct spi_device	*spi;

	struct mtd_info		mtd;
};

#ifdef CONFIG_MTD_PARTITIONS
#define	mtd_has_partitions()	(1)
#else
#define	mtd_has_partitions()	(0)
#endif

/* ......................................................................... */

/*
 * Return the status of the DataFlash device.
 */
static inline int dataflash_status(struct spi_device *spi)
{
	/* NOTE:  at45db321c over 25 MHz wants to write
	 * a dummy byte after the opcode...
	 */
	return spi_w8r8(spi, OP_READ_STATUS);
}

/*
 * Poll the DataFlash device until it is READY.
 * This usually takes 5-20 msec or so; more for sector erase.
 */
static int dataflash_waitready(struct spi_device *spi)
{
	int	status;

	for (;;) {
		status = dataflash_status(spi);
		if (status < 0) {
			DEBUG(MTD_DEBUG_LEVEL1, "%s: status %d?\n",
					spi->dev.bus_id, status);
			status = 0;
		}

		if (status & (1 << 7))	/* RDY/nBSY */
			return status;

		msleep(3);
	}
}

/* ......................................................................... */

/*
 * Erase pages of flash.
 */
static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_device	*spi = priv->spi;
	struct spi_transfer	x = { .tx_dma = 0, };
	struct spi_message	msg;
	unsigned		blocksize = priv->page_size << 3;
	uint8_t			*command;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: erase addr=0x%x len 0x%x\n",
			spi->dev.bus_id,
			instr->addr, instr->len);

	/* Sanity checks */
	if ((instr->addr + instr->len) > mtd->size
			|| (instr->len % priv->page_size) != 0
			|| (instr->addr % priv->page_size) != 0)
		return -EINVAL;

	spi_message_init(&msg);

	x.tx_buf = command = priv->command;
	x.len = 4;
	spi_message_add_tail(&x, &msg);

	mutex_lock(&priv->lock);
	while (instr->len > 0) {
		unsigned int	pageaddr;
		int		status;
		int		do_block;

		/* Calculate flash page address; use block erase (for speed) if
		 * we're at a block boundary and need to erase the whole block.
		 */
		pageaddr = instr->addr / priv->page_size;
		do_block = (pageaddr & 0x7) == 0 && instr->len >= blocksize;
		pageaddr = pageaddr << priv->page_offset;

		command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;
		command[1] = (uint8_t)(pageaddr >> 16);
		command[2] = (uint8_t)(pageaddr >> 8);
		command[3] = 0;

		DEBUG(MTD_DEBUG_LEVEL3, "ERASE %s: (%x) %x %x %x [%i]\n",
			do_block ? "block" : "page",
			command[0], command[1], command[2], command[3],
			pageaddr);

		status = spi_sync(spi, &msg);
		(void) dataflash_waitready(spi);

		if (status < 0) {
			printk(KERN_ERR "%s: erase %x, err %d\n",
				spi->dev.bus_id, pageaddr, status);
			/* REVISIT:  can retry instr->retries times; or
			 * giveup and instr->fail_addr = instr->addr;
			 */
			continue;
		}

		if (do_block) {
			instr->addr += blocksize;
			instr->len -= blocksize;
		} else {
			instr->addr += priv->page_size;
			instr->len -= priv->page_size;
		}
	}
	mutex_unlock(&priv->lock);

	/* Inform MTD subsystem that erase is complete */
	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}

/*
 * Read from the DataFlash device.
 *   from   : Start offset in flash device
 *   len    : Amount to read
 *   retlen : About of data actually read
 *   buf    : Buffer containing the data
 */
static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
			       size_t *retlen, u_char *buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_transfer	x[2] = { { .tx_dma = 0, }, };
	struct spi_message	msg;
	unsigned int		addr;
	uint8_t			*command;
	int			status;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: read 0x%x..0x%x\n",
		priv->spi->dev.bus_id, (unsigned)from, (unsigned)(from + len));

	*retlen = 0;

	/* Sanity checks */
	if (!len)
		return 0;
	if (from + len > mtd->size)
		return -EINVAL;

	/* Calculate flash page/byte address */
	addr = (((unsigned)from / priv->page_size) << priv->page_offset)
		+ ((unsigned)from % priv->page_size);

	command = priv->command;

	DEBUG(MTD_DEBUG_LEVEL3, "READ: (%x) %x %x %x\n",
		command[0], command[1], command[2], command[3]);

	spi_message_init(&msg);

	x[0].tx_buf = command;
	x[0].len = 8;
	spi_message_add_tail(&x[0], &msg);

	x[1].rx_buf = buf;
	x[1].len = len;
	spi_message_add_tail(&x[1], &msg);

	mutex_lock(&priv->lock);

	/* Continuous read, max clock = f(car) which may be less than
	 * the peak rate available.  Some chips support commands with
	 * fewer "don't care" bytes.  Both buffers stay unchanged.
	 */
	command[0] = OP_READ_CONTINUOUS;
	command[1] = (uint8_t)(addr >> 16);
	command[2] = (uint8_t)(addr >> 8);
	command[3] = (uint8_t)(addr >> 0);
	/* plus 4 "don't care" bytes */

	status = spi_sync(priv->spi, &msg);
	mutex_unlock(&priv->lock);

	if (status >= 0) {
		*retlen = msg.actual_length - 8;
		status = 0;
	} else
		DEBUG(MTD_DEBUG_LEVEL1, "%s: read %x..%x --> %d\n",
			priv->spi->dev.bus_id,
			(unsigned)from, (unsigned)(from + len),
			status);
	return status;
}

/*
 * Write to the DataFlash device.
 *   to     : Start offset in flash device
 *   len    : Amount to write
 *   retlen : Amount of data actually written
 *   buf    : Buffer containing the data
 */
static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
				size_t * retlen, const u_char * buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_device	*spi = priv->spi;
	struct spi_transfer	x[2] = { { .tx_dma = 0, }, };
	struct spi_message	msg;
	unsigned int		pageaddr, addr, offset, writelen;
	size_t			remaining = len;
	u_char			*writebuf = (u_char *) buf;
	int			status = -EINVAL;
	uint8_t			*command;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: write 0x%x..0x%x\n",
		spi->dev.bus_id, (unsigned)to, (unsigned)(to + len));

	*retlen = 0;

	/* Sanity checks */
	if (!len)
		return 0;
	if ((to + len) > mtd->size)
		return -EINVAL;

	spi_message_init(&msg);

	x[0].tx_buf = command = priv->command;
	x[0].len = 4;
	spi_message_add_tail(&x[0], &msg);

	pageaddr = ((unsigned)to / priv->page_size);
	offset = ((unsigned)to % priv->page_size);
	if (offset + len > priv->page_size)
		writelen = priv->page_size - offset;
	else
		writelen = len;

	mutex_lock(&priv->lock);
	while (remaining > 0) {
		DEBUG(MTD_DEBUG_LEVEL3, "write @ %i:%i len=%i\n",
			pageaddr, offset, writelen);

		/* REVISIT:
		 * (a) each page in a sector must be rewritten at least
		 *     once every 10K sibling erase/program operations.
		 * (b) for pages that are already erased, we could
		 *     use WRITE+MWRITE not PROGRAM for ~30% speedup.
		 * (c) WRITE to buffer could be done while waiting for
		 *     a previous MWRITE/MWERASE to complete ...
		 * (d) error handling here seems to be mostly missing.
		 *
		 * Two persistent bits per page, plus a per-sector counter,
		 * could support (a) and (b) ... we might consider using
		 * the second half of sector zero, which is just one block,
		 * to track that state.  (On AT91, that sector should also
		 * support boot-from-DataFlash.)
		 */

		addr = pageaddr << priv->page_offset;

		/* (1) Maybe transfer partial page to Buffer1 */
		if (writelen != priv->page_size) {
			command[0] = OP_TRANSFER_BUF1;
			command[1] = (addr & 0x00FF0000) >> 16;
			command[2] = (addr & 0x0000FF00) >> 8;
			command[3] = 0;

			DEBUG(MTD_DEBUG_LEVEL3, "TRANSFER: (%x) %x %x %x\n",
				command[0], command[1], command[2], command[3]);

			status = spi_sync(spi, &msg);
			if (status < 0)
				DEBUG(MTD_DEBUG_LEVEL1, "%s: xfer %u -> %d \n",
					spi->dev.bus_id, addr, status);

			(void) dataflash_waitready(priv->spi);
		}

		/* (2) Program full page via Buffer1 */
		addr += offset;
		command[0] = OP_PROGRAM_VIA_BUF1;
		command[1] = (addr & 0x00FF0000) >> 16;
		command[2] = (addr & 0x0000FF00) >> 8;
		command[3] = (addr & 0x000000FF);

		DEBUG(MTD_DEBUG_LEVEL3, "PROGRAM: (%x) %x %x %x\n",
			command[0], command[1], command[2], command[3]);

		x[1].tx_buf = writebuf;
		x[1].len = writelen;
		spi_message_add_tail(x + 1, &msg);
		status = spi_sync(spi, &msg);
		spi_transfer_del(x + 1);
		if (status < 0)
			DEBUG(MTD_DEBUG_LEVEL1, "%s: pgm %u/%u -> %d \n",
				spi->dev.bus_id, addr, writelen, status);

		(void) dataflash_waitready(priv->spi);


#ifdef CONFIG_MTD_DATAFLASH_VERIFY_WRITE

		/* (3) Compare to Buffer1 */
		addr = pageaddr << priv->page_offset;
		command[0] = OP_COMPARE_BUF1;
		command[1] = (addr & 0x00FF0000) >> 16;
		command[2] = (addr & 0x0000FF00) >> 8;
		command[3] = 0;

		DEBUG(MTD_DEBUG_LEVEL3, "COMPARE: (%x) %x %x %x\n",
			command[0], command[1], command[2], command[3]);

		status = spi_sync(spi, &msg);
		if (status < 0)
			DEBUG(MTD_DEBUG_LEVEL1, "%s: compare %u -> %d \n",
				spi->dev.bus_id, addr, status);

		status = dataflash_waitready(priv->spi);

		/* Check result of the compare operation */
		if (status & (1 << 6)) {
			printk(KERN_ERR "%s: compare page %u, err %d\n",
				spi->dev.bus_id, pageaddr, status);
			remaining = 0;
			status = -EIO;
			break;
		} else
			status = 0;

#endif	/* CONFIG_MTD_DATAFLASH_VERIFY_WRITE */

		remaining = remaining - writelen;
		pageaddr++;
		offset = 0;
		writebuf += writelen;
		*retlen += writelen;

		if (remaining > priv->page_size)
			writelen = priv->page_size;
		else
			writelen = remaining;
	}
	mutex_unlock(&priv->lock);

	return status;
}

/* ......................................................................... */

#ifdef CONFIG_MTD_DATAFLASH_OTP

static int dataflash_get_otp_info(struct mtd_info *mtd,
		struct otp_info *info, size_t len)
{
	/* Report both blocks as identical:  bytes 0..64, locked.
	 * Unless the user block changed from all-ones, we can't
	 * tell whether it's still writable; so we assume it isn't.
	 */
	info->start = 0;
	info->length = 64;
	info->locked = 1;
	return sizeof(*info);
}

static ssize_t otp_read(struct spi_device *spi, unsigned base,
		uint8_t *buf, loff_t off, size_t len)
{
	struct spi_message	m;
	size_t			l;
	uint8_t			*scratch;
	struct spi_transfer	t;
	int			status;

	if (off > 64)
		return -EINVAL;

	if ((off + len) > 64)
		len = 64 - off;
	if (len == 0)