2 files changed, 210 insertions, 7 deletions

diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 9c613f06623c..88f4df047464 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -59,6 +59,17 @@ 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
+        select HAVE_MTD_OTP
+        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
diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index 8bd0dea6885f..17c9b20dca87 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -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_info *mtd, loff_t to, size_t len,
 
 /* ......................................................................... */
 
+#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)
+                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;
+        uint8_t                 *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, char *name,
         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, char *name,
         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;
 
@@ -664,13 +853,16 @@ static int __devinit dataflash_probe(struct spi_device *spi)
          * Try to detect dataflash by JEDEC ID.
          * If it succeeds we know we have either a C or D part.
          * D will support power of 2 pagesize option.
+         * 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