[RFC,V2,01/11] dt-bindings: mt8183: Add binding for ISP Pass 1 reserved memory

Jungo Lin
2019-05-10T02:01:56Z

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

Signed-off-by: Jungo Lin <jungo.lin@mediatek.com>
---
.../mediatek,reserve-memory-cam-smem.txt | 42 +++++++++++++++++++
1 file changed, 42 insertions(+)
create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam-smem.txt

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 000000000000..65a967cff91e
--- /dev/null
+++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-cam-smem.txt
@@ -0,0 +1,42 @@
+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)
+
+For additional details about reserved memory regions see reserved-memory.txt
+
+Required properties:
+
+- compatible: must be "mediatek,reserve-memory-cam-smem"
+
+- size: required for dynamic allocation. The unit is bytes.
+
+- alloc-range: required for dynamic allocation. The range must
+ between 0x40000000 and 0x100000000 due to the co-processer's
+ addressing limitation.
+
+Example:
+
+The following example shows the ISP Pass 1 shared memory setup for MT8183.
+
+ reserved-memory {
+ #address-cells = <2>;
+ #size-cells = <2>;
+ ranges;
+ cam_mem_reserved: cam_mem_region {
+ compatible = "mediatek,reserve-memory-cam-smem";
+ size = <0 0x1400000>;
+ no-map;
+ alignment = <0 0x1000>;
+ alloc-ranges = <0 0x40000000 0 0x10000000>;
+ };
+ };
--
2.18.0