[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.

Switch mtdchar over to a generic HAVE_MTD_OTP flag instead of adding
another #ifdef for each type of chip whose driver has OTP support.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Bryan Wu <cooloney@kernel.org>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 11 insertions, 0 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