Message-Id: <200806292019.53376.david-b@pacbell.net>
Date:	Sun, 29 Jun 2008 20:19:53 -0700
From:	David Brownell <david-b@...bell.net>
To:	Bryan Wu <cooloney@...nel.org>,
	Michael Hennerich <michael.hennerich@...log.com>
Cc:	lkml <linux-kernel@...r.kernel.org>, linux-mtd@...ts.infradead.org
Subject: [patch 2.6.26-rc8+] mtd:  dataflash OTP support

Now that we can tell when we have one of the newer DataFlash chips,
optionally expose the 128 bytes of OTP memory they provide.  Tested
on at45db642 revision B and D chips and latest mtd-utils.

Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
This goes on top of the patch I sent earlier, "v3" based on "v2"
from Michael, teaching this driver to use the JEDEC query command
to detect new chip revisions which may be using binary page sizes.

 drivers/mtd/devices/Kconfig         |   10 +
 drivers/mtd/devices/mtd_dataflash.c |  206 ++++++++++++++++++++++++++++++++--
 drivers/mtd/mtdchar.c               |   16 ++
 3 files changed, 223 insertions(+), 9 deletions(-)

--- a/drivers/mtd/devices/Kconfig	2008-04-28 10:48:25.000000000 -0700
+++ b/drivers/mtd/devices/Kconfig	2008-06-29 13:54:08.000000000 -0700
@@ -60,6 +60,16 @@ config MTD_DATAFLASH
 	  Sometimes DataFlash chips are packaged inside MMC-format
 	  cards; at this writing, the MMC stack won't handle those.
 
+config MTD_DATAFLASH_OTP
+	bool "DataFlash OTP support (Security Register)"
+	depends on MTD_DATAFLASH
+	help
+	  Newer DataFlash chips (revisions C and D) support 128 bytes of
+	  one-time-programmable (OTP) data.  The first half may be written
+	  (once) with up to 64 bytes of data, such as a serial number or
+	  other key product data.  The second half is programmed with a
+	  unique-to-each-chip bit pattern at the factory.
+
 config MTD_M25P80
 	tristate "Support most SPI Flash chips (AT26DF, M25P, W25X, ...)"
 	depends on SPI_MASTER && EXPERIMENTAL
--- a/drivers/mtd/devices/mtd_dataflash.c	2008-06-28 22:55:36.000000000 -0700
+++ b/drivers/mtd/devices/mtd_dataflash.c	2008-06-29 15:05:12.000000000 -0700
@@ -80,7 +80,8 @@
  */
 #define OP_READ_ID		0x9F
 #define OP_READ_SECURITY	0x77
-#define OP_WRITE_SECURITY	0x9A	/* OTP bits */
+#define OP_WRITE_SECURITY_REVC	0x9A
+#define OP_WRITE_SECURITY	0x9B	/* revision D */
 
 
 struct dataflash {
@@ -451,16 +452,192 @@ static int dataflash_write(struct mtd_in
 
 /* ......................................................................... */
 
+#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,
+		u8 *buf, loff_t off, size_t len)
+{
+	struct spi_message	m;
+	size_t			l;
+	u8			*scratch;
+	struct spi_transfer	t;
+	int			status;
+
+	if (off > 64)
+		return -EINVAL;
+
+	if ((off + len) > 64)
+		len = 64 - off;
+	if (len == 0)
+		return len;
+
+	spi_message_init(&m);
+
+	l = 4 + base + off + len;
+	scratch = kzalloc(l, GFP_KERNEL);
+	if (!scratch)
+		return -ENOMEM;
+
+	/* OUT: OP_READ_SECURITY, 3 don't-care bytes, zeroes
+	 * IN:  ignore 4 bytes, data bytes 0..N (max 127)
+	 */
+	scratch[0] = OP_READ_SECURITY;
+
+	memset(&t, 0, sizeof t);
+	t.tx_buf = scratch;
+	t.rx_buf = scratch;
+	t.len = l;
+	spi_message_add_tail(&t, &m);
+
+	dataflash_waitready(spi);
+
+	status = spi_sync(spi, &m);
+	if (status >= 0) {
+		memcpy(buf, scratch + 4 + base + off, len);
+		status = len;
+	}
+
+	kfree(scratch);
+	return status;
+}
+
+static int dataflash_read_fact_otp(struct mtd_info *mtd,
+		loff_t from, size_t len, size_t *retlen, u_char *buf)
+{
+	struct dataflash	*priv = (struct dataflash *)mtd->priv;
+	int			status;
+
+	/* 64 bytes, from 0..63 ... start at 64 on-chip */
+	mutex_lock(&priv->lock);
+	status = otp_read(priv->spi, 64, buf, from, len);
+	mutex_unlock(&priv->lock);
+
+	if (status < 0)
+		return status;
+	*retlen = status;
+	return 0;
+}
+
+static int dataflash_read_user_otp(struct mtd_info *mtd,
+		loff_t from, size_t len, size_t *retlen, u_char *buf)
+{
+	struct dataflash	*priv = (struct dataflash *)mtd->priv;
+	int			status;
+
+	/* 64 bytes, from 0..63 ... start at 0 on-chip */
+	mutex_lock(&priv->lock);
+	status = otp_read(priv->spi, 0, buf, from, len);
+	mutex_unlock(&priv->lock);
+
+	if (status < 0)
+		return status;
+	*retlen = status;
+	return 0;
+}
+
+static int dataflash_write_user_otp(struct mtd_info *mtd,
+		loff_t from, size_t len, size_t *retlen, u_char *buf)
+{
+	struct spi_message	m;
+	const size_t		l = 4 + 64;
+	u8			*scratch;
+	struct spi_transfer	t;
+	struct dataflash	*priv = (struct dataflash *)mtd->priv;
+	int			status;
+
+	if (len > 64)
+		return -EINVAL;
+
+	/* Strictly speaking, we *could* truncate the write ... but
+	 * let's not do that for the only write that's ever possible.
+	 */
+	if ((from + len) > 64)
+		return -EINVAL;
+
+	/* OUT: OP_WRITE_SECURITY, 3 zeroes, 64 data-or-zero bytes
+	 * IN:  ignore all
+	 */
+	scratch = kzalloc(l, GFP_KERNEL);
+	if (!scratch)
+		return -ENOMEM;
+	scratch[0] = OP_WRITE_SECURITY;
+	memcpy(scratch + 4 + from, buf, len);
+
+	spi_message_init(&m);
+
+	memset(&t, 0, sizeof t);
+	t.tx_buf = scratch;
+	t.len = l;
+	spi_message_add_tail(&t, &m);
+
+	/* Write the OTP bits, if they've not yet been written.
+	 * This modifies SRAM buffer1.
+	 */
+	mutex_lock(&priv->lock);
+	dataflash_waitready(priv->spi);
+	status = spi_sync(priv->spi, &m);
+	mutex_unlock(&priv->lock);
+
+	kfree(scratch);
+
+	if (status >= 0) {
+		status = 0;
+		*retlen = len;
+	}
+	return status;
+}
+
+static char *otp_setup(struct mtd_info *device, char revision)
+{
+	device->get_fact_prot_info = dataflash_get_otp_info;
+	device->read_fact_prot_reg = dataflash_read_fact_otp;
+	device->get_user_prot_info = dataflash_get_otp_info;
+	device->read_user_prot_reg = dataflash_read_user_otp;
+
+	/* rev c parts (at45db321c and at45db1281 only!) use a
+	 * different write procedure; not (yet?) implemented.
+	 */
+	if (revision > 'c')
+		device->write_user_prot_reg = dataflash_write_user_otp;
+
+	return ", OTP";
+}
+
+#else
+
+static char *otp_setup(struct mtd_info *device)
+{
+	return " (OTP)";
+}
+
+#endif
+
+/* ......................................................................... */
+
 /*
  * Register DataFlash device with MTD subsystem.
  */
 static int __devinit
-add_dataflash(struct spi_device *spi, char *name,
-		int nr_pages, int pagesize, int pageoffset)
+add_dataflash_otp(struct spi_device *spi, char *name,
+		int nr_pages, int pagesize, int pageoffset, char revision)
 {
 	struct dataflash		*priv;
 	struct mtd_info			*device;
 	struct flash_platform_data	*pdata = spi->dev.platform_data;
+	char				*otp_tag = "";
 
 	priv = kzalloc(sizeof *priv, GFP_KERNEL);
 	if (!priv)
@@ -489,8 +666,12 @@ add_dataflash(struct spi_device *spi, ch
 	device->write = dataflash_write;
 	device->priv = priv;
 
-	dev_info(&spi->dev, "%s (%d KBytes) pagesize %d bytes\n",
-			name, DIV_ROUND_UP(device->size, 1024), pagesize);
+	if (revision >= 'c')
+		otp_tag = otp_setup(device, revision);
+
+	dev_info(&spi->dev, "%s (%d KBytes) pagesize %d bytes%s\n",
+			name, DIV_ROUND_UP(device->size, 1024),
+			pagesize, otp_tag);
 	dev_set_drvdata(&spi->dev, priv);
 
 	if (mtd_has_partitions()) {
@@ -519,6 +700,14 @@ add_dataflash(struct spi_device *spi, ch
 	return add_mtd_device(device) == 1 ? -ENODEV : 0;
 }
 
+static inline int __devinit
+add_dataflash(struct spi_device *spi, char *name,
+		int nr_pages, int pagesize, int pageoffset)
+{
+	return add_dataflash_otp(spi, name, nr_pages, pagesize,
+			pageoffset, 0);
+}
+
 struct flash_info {
 	char		*name;
 
@@ -665,13 +854,16 @@ static int __devinit dataflash_probe(str
 	/*
 	 * Try to detect dataflash by JEDEC ID.  If it succeeds, we
 	 * have either a C or D part.  D supports pagesize options.
+	 * Both support the security register, though with different
+	 * write procedures.
 	 */
 	info = jedec_probe(spi);
 	if (IS_ERR(info))
 		return PTR_ERR(info);
 	if (info != NULL)
-		return add_dataflash(spi, info->name, info->nr_pages,
-				 info->pagesize, info->pageoffset);
+		return add_dataflash_otp(spi, info->name, info->nr_pages,
+				info->pagesize, info->pageoffset,
+				(info->flags & SUP_POW2PS) ? 'd' : 'c');
 
 	/*
 	 * Older chips support only legacy commands, identifing
--- a/drivers/mtd/mtdchar.c	2008-02-10 15:48:25.000000000 -0800
+++ b/drivers/mtd/mtdchar.c	2008-06-29 09:23:39.000000000 -0700
@@ -20,6 +20,18 @@
 
 #include <asm/uaccess.h>
 
+#ifdef CONFIG_MTD_OTP
+#define HAVE_OTP
+#endif
+
+#ifdef CONFIG_MTD_ONENAND_OTP
+#define HAVE_OTP
+#endif
+
+#ifdef CONFIG_MTD_DATAFLASH_OTP
+#define HAVE_OTP
+#endif
+
 static struct class *mtd_class;
 
 static void mtd_notify_add(struct mtd_info* mtd)
@@ -339,7 +351,7 @@ static void mtdchar_erase_callback (stru
 	wake_up((wait_queue_head_t *)instr->priv);
 }
 
-#if defined(CONFIG_MTD_OTP) || defined(CONFIG_MTD_ONENAND_OTP)
+#ifdef HAVE_OTP
 static int otp_select_filemode(struct mtd_file_info *mfi, int mode)
 {
 	struct mtd_info *mtd = mfi->mtd;
@@ -652,7 +664,7 @@ static int mtd_ioctl(struct inode *inode
 		break;
 	}
 
-#if defined(CONFIG_MTD_OTP) || defined(CONFIG_MTD_ONENAND_OTP)
+#ifdef HAVE_OTP
 	case OTPSELECT:
 	{
 		int mode;
--
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