[PATCH] dt-bindings: chosen: document rng-seed property

[Jason A. Donenfeld]

Document the /chosen/rng-seed property, which has existed for quite some
time but without an entry in this file.

Fixes: 428826f5358c ("fdt: add support for rng-seed")
Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
 Documentation/devicetree/bindings/chosen.txt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 1cc3aa10dcb1..49b175e133b2 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -7,6 +7,21 @@ arguments. Data in the chosen node does not represent the hardware.
 
 The following properties are recognized:
 
+rng-seed
+--------
+
+This property is used to initialize the kernel's random number generator at
+the earliest possible opportunity, and will be credited if CONFIG_RANDOM_
+TRUST_BOOTLOADER is set. All hardware that has an opportunity to set this
+with high quality randomness is encouraged to do so. It is parsed as a byte
+array, which should be at least 32 bytes long:
+
+/ {
+	chosen {
+		rng-seed = <... random bytes ...>;
+	};
+};
+
 
 kaslr-seed
 -----------
-- 
2.35.1