This patch add mediatek iommu dts binding document.
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
---
.../devicetree/bindings/iommu/mediatek,iommu.txt | 68 ++++++++++++++++++++++
1 file changed, 68 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
new file mode 100644
index 0000000..c2fb06e
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+* Mediatek IOMMU Architecture Implementation
+
+ Some Mediatek SOCs contain a Multimedia Memory Management Unit (M4U) which
+uses the ARM Short-Descriptor translation table format for address translation.
+
+ About the M4U Hardware Block Diagram, please check below:
+
+ EMI (External Memory Interface)
+ |
+ m4u (Multimedia Memory Management Unit)
+ |
+ SMI Common(Smart Multimedia Interface Common)
+ |
+ +----------------+-------
+ | |
+ | |
+ SMI larb0 SMI larb1 ... SoCs have several SMI local arbiter(larb).
+ (display) (vdec)
+ | |
+ | |
+ +-----+-----+ +----+----+
+ | | | | | |
+ | | |... | | | ... There are different ports in each larb.
+ | | | | | |
+OVL0 RDMA0 WDMA0 MC PP VLD
+
+ As above, The Multimedia HW will go through SMI and M4U while it
+access EMI. SMI is a brige between m4u and the Multimedia HW. It contain
+smi local arbiter and smi common. It will control whether the Multimedia
+HW should go though the m4u for translation or bypass it and talk
+directly with EMI. And also SMI help control the power domain and clocks for
+each local arbiter.
+ Normally we specify a local arbiter(larb) for each multimedia HW
+like display, video decode, and camera. And there are different ports
+in each larb. Take a example, There are many ports like MC, PP, VLD in the
+video decode local arbiter, all these ports are according to the video HW.
+
+Required properties:
+- compatible : must be "mediatek,mt8173-m4u".
+- reg : m4u register base and size.
+- interrupts : the interrupt of m4u.
+- clocks : must contain one entry for each clock-names.
+- clock-names : must be "bclk", It is the block clock of m4u.
+- mediatek,larbs : List of phandle to the local arbiters in the current Socs.
+ Refer to bindings/memory-controllers/mediatek,smi-larb.txt. It must sort
+ according to the local arbiter index, like larb0, larb1, larb2...
+- iommu-cells : must be 1. This is the mtk_m4u_id according to the HW.
+ Specifies the mtk_m4u_id as defined in
+ dt-binding/memory/mt8173-larb-port.h.
+
+Example:
+ iommu: iommu@10205000 {
+ compatible = "mediatek,mt8173-m4u";
+ reg = <0 0x10205000 0 0x1000>;
+ interrupts = <GIC_SPI 139 IRQ_TYPE_LEVEL_LOW>;
+ clocks = <&infracfg CLK_INFRA_M4U>;
+ clock-names = "bclk";
+ mediatek,larbs = <&larb0 &larb1 &larb2 &larb3 &larb4 &larb5>;
+ #iommu-cells = <1>;
+ };
+
+Example for a client device:
+ display {
+ compatible = "mediatek,mt8173-disp";
+ iommus = <&iommu M4U_PORT_DISP_OVL0>,
+ <&iommu M4U_PORT_DISP_RDMA0>;
+ ...
+ };
--
1.8.1.1.dirty
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