spi: add config option to enable the WP pin function on st micron flashes
enable the W#/Vpp signal to disable writing to the status
register on ST MICRON flashes like the N25Q128 thorugh
the new config option CONFIG_SYS_SPI_ST_ENABLE_WP_PIN
Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
diff --git a/README b/README
index a35b92c..37e4d1b 100644
--- a/README
+++ b/README
@@ -2930,6 +2930,17 @@
memories can be connected with a given cs line.
currently Xilinx Zynq qspi support these type of connections.
+ CONFIG_SYS_SPI_ST_ENABLE_WP_PIN
+ enable the W#/Vpp signal to disable writing to the status
+ register on ST MICRON flashes like the N25Q128.
+ The status register write enable/disable bit, combined with
+ the W#/VPP signal provides hardware data protection for the
+ device as follows: When the enable/disable bit is set to 1,
+ and the W#/VPP signal is driven LOW, the status register
+ nonvolatile bits become read-only and the WRITE STATUS REGISTER
+ operation will not execute. The only way to exit this
+ hardware-protected mode is to drive W#/VPP HIGH.
+
- SystemACE Support:
CONFIG_SYSTEMACE