media: dt-bindings: media: Document bindings for venus firmware device

Add devicetree binding documentation for firmware loader for video
hardware running on qualcomm chip.

Signed-off-by: Vikash Garodia <vgarodia@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Tested-by: Alexandre Courbot <acourbot@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/devicetree/bindings/media/qcom,venus.txt

@@ -53,7 +53,8 @@
 
 * Subnodes
 The Venus video-codec node must contain two subnodes representing
-video-decoder and video-encoder.
+video-decoder and video-encoder, and one optional firmware subnode.
+Firmware subnode is needed when the platform does not have TrustZone.
 
 Every of video-encoder or video-decoder subnode should have:
 
@@ -79,6 +80,13 @@ Every of video-encoder or video-decoder subnode should have:
 		    power domain which is responsible for collapsing
 		    and restoring power to the subcore.
 
+The firmware subnode must have:
+
+- iommus:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: A list of phandle and IOMMU specifier pairs.
+
 * An Example
 	video-codec@1d00000 {
 		compatible = "qcom,msm8916-venus";
@@ -105,4 +113,8 @@ Every of video-encoder or video-decoder subnode should have:
 			clock-names = "core";
 			power-domains = <&mmcc VENUS_CORE1_GDSC>;
 		};
+
+		video-firmware {
+			iommus = <&apps_iommu 0x10b2 0x0>;
+		};
 	};