[PATCH] dt-bindings: firmware: coreboot: Document optional device specific properties

[Chen-Yu Tsai <wenst@chromium.org>]

Coreboot, or the ChromeOS second stage bootloader, depthcharge, will
insert device specific properties into the coreboot firmware node when
there are valid values.

Document these properties in the binding.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
 Documentation/devicetree/bindings/firmware/coreboot.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/firmware/coreboot.txt b/Documentation/devicetree/bindings/firmware/coreboot.txt
index 4c955703cea8..0d04ea482aa9 100644
--- a/Documentation/devicetree/bindings/firmware/coreboot.txt
+++ b/Documentation/devicetree/bindings/firmware/coreboot.txt
@@ -21,6 +21,15 @@ Required properties:
 	0xc0389481 that resides in the topmost 8 bytes of the area.
 	See coreboot's src/include/imd.h for details.
 
+Optional properties:
+- board-id: Contains the board revision number.
+- ram-code: Contains the board's DRAM configuration type.
+- sku-id: Contains the device variant SKU ID.
+- fw-config: Contains the device variant FW config value.
+
+The optional properties are only populated if the values parsed by coreboot
+are valid.
+
 Example:
 	firmware {
 		ranges;
-- 
2.52.0.rc1.455.g30608eb744-goog