Documentation: ABI: nvmem: add documentation for JZ4780 efuse ABI

This patch brings support for the JZ4780 efuse. Currently it only exposes
a read only access to the entire 8K bits efuse memory.

Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200310132257.23358-14-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/sysfs-driver-jz4780-efuse b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
new file mode 100644 (file)
index 0000000..bb6f5d6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
@@ -0,0 +1,16 @@
+What:          /sys/devices/*/<our-device>/nvmem
+Date:          December 2017
+Contact:       PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+Description:   read-only access to the efuse on the Ingenic JZ4780 SoC
+               The SoC has a one time programmable 8K efuse that is
+               split into segments. The driver supports read only.
+               The segments are
+               0x000   64 bit Random Number
+               0x008  128 bit Ingenic Chip ID
+               0x018  128 bit Customer ID
+               0x028 3520 bit Reserved
+               0x1E0    8 bit Protect Segment
+               0x1E1 2296 bit HDMI Key
+               0x300 2048 bit Security boot key
+Users:         any user space application which wants to read the Chip
+               and Customer ID