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diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt new file mode 100644 index 000000000..ac949f7fe --- /dev/null +++ b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt @@ -0,0 +1,105 @@ +* Mediatek IOMMU Architecture Implementation + + Some Mediatek SOCs contain a Multimedia Memory Management Unit (M4U), and +this M4U have two generations of HW architecture. Generation one uses flat +pagetable, and only supports 4K size page mapping. Generation two 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) + | + +--------+ + | | + gals0-rx gals1-rx (Global Async Local Sync rx) + | | + | | + gals0-tx gals1-tx (Global Async Local Sync tx) + | | Some SoCs may have GALS. + +--------+ + | + SMI Common(Smart Multimedia Interface Common) + | + +----------------+------- + | | + | gals-rx There may be GALS in some larbs. + | | + | | + | gals-tx + | | + 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 bridge 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. + In some SoCs, there may be a GALS(Global Async Local Sync) module between +smi-common and m4u, and additional GALS module between smi-larb and +smi-common. GALS can been seen as a "asynchronous fifo" which could help +synchronize for the modules in different clock frequency. + +Required properties: +- compatible : must be one of the following string: + "mediatek,mt2701-m4u" for mt2701 which uses generation one m4u HW. + "mediatek,mt2712-m4u" for mt2712 which uses generation two m4u HW. + "mediatek,mt6779-m4u" for mt6779 which uses generation two m4u HW. + "mediatek,mt7623-m4u", "mediatek,mt2701-m4u" for mt7623 which uses + generation one m4u HW. + "mediatek,mt8167-m4u" for mt8167 which uses generation two m4u HW. + "mediatek,mt8173-m4u" for mt8173 which uses generation two m4u HW. + "mediatek,mt8183-m4u" for mt8183 which uses generation two m4u HW. +- reg : m4u register base and size. +- interrupts : the interrupt of m4u. +- clocks : must contain one entry for each clock-names. +- clock-names : Only 1 optional clock: + - "bclk": the block clock of m4u. + Here is the list which require this "bclk": + - mt2701, mt2712, mt7623 and mt8173. + Note that m4u use the EMI clock which always has been enabled before kernel + if there is no this "bclk". +- 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/mt2701-larb-port.h for mt2701, mt7623 + dt-binding/memory/mt2712-larb-port.h for mt2712, + dt-binding/memory/mt6779-larb-port.h for mt6779, + dt-binding/memory/mt8167-larb-port.h for mt8167, + dt-binding/memory/mt8173-larb-port.h for mt8173, and + dt-binding/memory/mt8183-larb-port.h for mt8183. + +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>; + ... + }; |