[RFC PATCH V1 1/6] dt-bindings: mt8183: Add binding for DIP shared memory

[Frederic Chen <frederic.chen@mediatek.com>]

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

Signed-off-by: Frederic Chen <frederic.chen@mediatek.com>
---
 .../mediatek,reserve-memory-dip_smem.txt      | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt

diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt
new file mode 100644
index 000000000000..64c001b476b9
--- /dev/null
+++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt
@@ -0,0 +1,45 @@
+Mediatek DIP Shared Memory binding
+
+This binding describes the shared memory, which serves the purpose of
+describing the shared memory region used to exchange data between Digital
+Image Processing (DIP) and 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 Digital Image Processing (DIP) can access memory through mt8183 IOMMU so
+it can use 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-dip_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.
+  If you want to enable the full feature of Digital Processing Unit,
+  you need 20 MB at least.
+
+
+Example:
+
+The following example shows the DIP shared memory setup for MT8183.
+
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+		reserve-memory-dip_smem {
+			compatible = "mediatek,reserve-memory-dip_smem";
+			size = <0 0x1400000>;
+			alignment = <0 0x1000>;
+			alloc-ranges = <0 0x40000000 0 0x50000000>;
+		};
+	};
-- 
2.18.0