documentation: Add secure monitor bindings documentation

Add the binding documentation for the Amlogic secure monitor driver.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

diff --git a/Documentation/devicetree/bindings/firmware/meson/meson_sm.txt b/Documentation/devicetree/bindings/firmware/meson/meson_sm.txt
new file mode 100644 (file)
index 0000000..c248cd4
--- /dev/null
+++ b/Documentation/devicetree/bindings/firmware/meson/meson_sm.txt
@@ -0,0 +1,15 @@
+* Amlogic Secure Monitor
+
+In the Amlogic SoCs the Secure Monitor code is used to provide access to the
+NVMEM, enable JTAG, set USB boot, etc...
+
+Required properties for the secure monitor node:
+- compatible: Should be "amlogic,meson-gxbb-sm"
+
+Example:
+
+       firmware {
+               sm: secure-monitor {
+                       compatible = "amlogic,meson-gxbb-sm";
+               };
+       };