[MTD] Support for protection register support on Intel FLASH chips

This enables support for reading, writing and locking so called
"Protection Registers" present on some flash chips.
A subset of them are pre-programmed at the factory with a
unique set of values. The rest is user-programmable.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/mtd/chips/Kconfig b/drivers/mtd/chips/Kconfig
index d682dbc8157..f4eda1e40d5 100644
--- a/drivers/mtd/chips/Kconfig
+++ b/drivers/mtd/chips/Kconfig
@@ -1,5 +1,5 @@
 # drivers/mtd/chips/Kconfig
-# $Id: Kconfig,v 1.13 2004/12/01 15:49:10 nico Exp $
+# $Id: Kconfig,v 1.14 2005/02/08 17:11:15 nico Exp $
 
 menu "RAM/ROM/Flash chip drivers"
         depends on MTD!=n
@@ -155,6 +155,31 @@ config MTD_CFI_I8
           If your flash chips are interleaved in eights - i.e. you have eight
           flash chips addressed by each bus cycle, then say 'Y'.
 
+config MTD_OTP
+        bool "Protection Registers aka one-time programmable (OTP) bits"
+        depends on MTD_CFI_ADV_OPTIONS
+        default n
+        help
+          This enables support for reading, writing and locking so called
+          "Protection Registers" present on some flash chips.
+          A subset of them are pre-programmed at the factory with a
+          unique set of values. The rest is user-programmable.
+
+          The user-programmable Protection Registers contain one-time
+          programmable (OTP) bits; when programmed, register bits cannot be
+          erased. Each Protection Register can be accessed multiple times to
+          program individual bits, as long as the register remains unlocked.
+
+          Each Protection Register has an associated Lock Register bit. When a
+          Lock Register bit is programmed, the associated Protection Register
+          can only be read; it can no longer be programmed. Additionally,
+          because the Lock Register bits themselves are OTP, when programmed,
+          Lock Register bits cannot be erased. Therefore, when a Protection
+          Register is locked, it cannot be unlocked.
+
+          This feature should therefore be used with extreme care. Any mistake
+          in the programming of OTP bits will waste them.
+
 config MTD_CFI_INTELEXT
         tristate "Support for Intel/Sharp flash chips"
         depends on MTD_GEN_PROBE