From 93e268dca82eafb59157bfb7eb70e97fe3564412 Mon Sep 17 00:00:00 2001 From: Cho KyongHo Date: Mon, 12 May 2014 11:45:01 +0530 Subject: 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 --- .../devicetree/bindings/iommu/samsung,sysmmu.txt | 65 ++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt (limited to 'Documentation/devicetree') 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>; + }; -- cgit v1.2.3 From df15e1de9c7f18289f40c9cf1f6bfa5fd662b1dd Mon Sep 17 00:00:00 2001 From: Shaik Ameer Basha Date: Wed, 14 May 2014 11:23:33 +0530 Subject: documentation/iommu: Add note on existing DT binding status The current dt binding for Exynos System MMU can be changed, if found incompatible with the support for "Generic IOMMU Binding". This patch adds a note to the binding documentation stating the same. Signed-off-by: Shaik Ameer Basha Acked-by: Arnd Bergmann Signed-off-by: Joerg Roedel --- Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation/devicetree') diff --git a/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt b/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt index 15b2a2baa22a..6fa4c737af23 100644 --- a/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt +++ b/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt @@ -27,6 +27,11 @@ 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. +Note: +The current DT binding for the Exynos System MMU is incomplete. +The following properties can be removed or changed, if found incompatible with +the "Generic IOMMU Binding" support for attaching devices to the IOMMU. + Required properties: - compatible: Should be "samsung,exynos-sysmmu" - reg: A tuple of base address and size of System MMU registers. -- cgit v1.2.3