From 93e268dca82eafb59157bfb7eb70e97fe3564412 Mon Sep 17 00:00:00 2001 From: Cho KyongHo Date: Mon, 12 May 2014 11:45:01 +0530 Subject: [PATCH] documentation: iommu: Add binding document of Exynos System MMU This patch adds a description of the device tree binding for the Samsung Exynos System MMU. Signed-off-by: Cho KyongHo Signed-off-by: Shaik Ameer Basha Signed-off-by: Joerg Roedel --- .../bindings/iommu/samsung,sysmmu.txt | 65 +++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt diff --git a/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt b/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt new file mode 100644 index 000000000000..15b2a2baa22a --- /dev/null +++ b/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt @@ -0,0 +1,65 @@ +Samsung Exynos IOMMU H/W, System MMU (System Memory Management Unit) + +Samsung's Exynos architecture contains System MMUs that enables scattered +physical memory chunks visible as a contiguous region to DMA-capable peripheral +devices like MFC, FIMC, FIMD, GScaler, FIMC-IS and so forth. + +System MMU is an IOMMU and supports identical translation table format to +ARMv7 translation tables with minimum set of page properties including access +permissions, shareability and security protection. In addition, System MMU has +another capabilities like L2 TLB or block-fetch buffers to minimize translation +latency. + +System MMUs are in many to one relation with peripheral devices, i.e. single +peripheral device might have multiple System MMUs (usually one for each bus +master), but one System MMU can handle transactions from only one peripheral +device. The relation between a System MMU and the peripheral device needs to be +defined in device node of the peripheral device. + +MFC in all Exynos SoCs and FIMD, M2M Scalers and G2D in Exynos5420 has 2 System +MMUs. +* MFC has one System MMU on its left and right bus. +* FIMD in Exynos5420 has one System MMU for window 0 and 4, the other system MMU + for window 1, 2 and 3. +* M2M Scalers and G2D in Exynos5420 has one System MMU on the read channel and + the other System MMU on the write channel. +The drivers must consider how to handle those System MMUs. One of the idea is +to implement child devices or sub-devices which are the client devices of the +System MMU. + +Required properties: +- compatible: Should be "samsung,exynos-sysmmu" +- reg: A tuple of base address and size of System MMU registers. +- interrupt-parent: The phandle of the interrupt controller of System MMU +- interrupts: An interrupt specifier for interrupt signal of System MMU, + according to the format defined by a particular interrupt + controller. +- clock-names: Should be "sysmmu" if the System MMU is needed to gate its clock. + Optional "master" if the clock to the System MMU is gated by + another gate clock other than "sysmmu". + Exynos4 SoCs, there needs no "master" clock. + Exynos5 SoCs, some System MMUs must have "master" clocks. +- clocks: Required if the System MMU is needed to gate its clock. +- samsung,power-domain: Required if the System MMU is needed to gate its power. + Please refer to the following document: + Documentation/devicetree/bindings/arm/exynos/power_domain.txt + +Examples: + gsc_0: gsc@13e00000 { + compatible = "samsung,exynos5-gsc"; + reg = <0x13e00000 0x1000>; + interrupts = <0 85 0>; + samsung,power-domain = <&pd_gsc>; + clocks = <&clock CLK_GSCL0>; + clock-names = "gscl"; + }; + + sysmmu_gsc0: sysmmu@13E80000 { + compatible = "samsung,exynos-sysmmu"; + reg = <0x13E80000 0x1000>; + interrupt-parent = <&combiner>; + interrupts = <2 0>; + clock-names = "sysmmu", "master"; + clocks = <&clock CLK_SMMU_GSCL0>, <&clock CLK_GSCL0>; + samsung,power-domain = <&pd_gsc>; + }; -- 2.39.5