[RFC,V0,1/7,media] dt-bindings: mt8183: Add binding for ISP Pass 1 shared memory

Commit Message

Frederic Chen Feb. 5, 2019, 6:42 a.m. UTC

This patch adds the binding for describing the shared memory
used to exchange configuration and tuning data between the
co-processor and Pass 1 (P1) unit of the camera ISP system on
Mediatek SoCs.

Signed-off-by: Frederic Chen <[e-mail]>
---
 .../mediatek,reserve-memory-cam_smem.txt           | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam_smem.txt

Patch

diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam_smem.txt
new file mode 100644
index 0000000..05c1bf1
--- /dev/null
+++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam_smem.txt
@@ -0,0 +1,44 @@ 
+Mediatek ISP Pass 1 Shared Memory binding
+
+This binding describes the shared memory, which serves the purpose of
+describing the shared memory region used to exchange data between Pass 1
+unit of Image Signal Processor (ISP) and the co-processor in Mediatek
+SoCs.
+
+The co-processor doesn't have the iommu so we need to use the physical
+address to access the shared buffer in the firmware.
+
+The Pass 1 unit of ISP can access memory through the iommu so it
+uses the dma address to access the memory region.
+(See iommu/mediatek,iommu.txt for the detailed description of Mediatek IOMMU)
+
+
+Required properties:
+
+- compatible: must be "mediatek,reserve-memory-cam_smem"
+
+- reg: required for static allocation (see reserved-memory.txt for
+  the detailed usage)
+
+- alloc-range: required for dynamic allocation. The range must
+  between 0x00000400 and 0x100000000 due to the co-processer's
+  addressing limitation
+
+- size: required for dynamic allocation. The unit is bytes.
+
+
+Example:
+
+The following example shows the ISP Pass1 shared memory setup for MT8183.
+
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+		reserve-memory-cam_smem {
+			compatible = "mediatek,reserve-memory-cam_smem";
+			size = <0 0x1400000>;
+			alignment = <0 0x1000>;
+			alloc-ranges = <0 0x40000000 0 0x50000000>;
+		};
+	};