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Subject[PATCH v12 11/31] documentation: iommu: add binding document of Exynos System MMU
Date
From: Cho KyongHo <pullip.cho@samsung.com>

This patch adds a description of the device tree binding for the
Samsung Exynos System MMU.

Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
---
.../devicetree/bindings/iommu/samsung,sysmmu.txt | 79 ++++++++++++++++++++
1 file changed, 79 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 0000000..16e13a2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iommu/samsung,sysmmu.txt
@@ -0,0 +1,79 @@
+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 one of:
+ "samsung,sysmmu-v1"
+ "samsung,sysmmu-v2"
+ "samsung,sysmmu-v3.1"
+ "samsung,sysmmu-v3.2"
+ "samsung,sysmmu-v3.3"
+
+- 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
+- mmu-masters: A phandle to device nodes representing the master for which
+ the System MMU can provide a translation. Any additional values
+ after the phandle will be ignored because a System MMU never
+ have two or more masters. "#stream-id-cells" specified in the
+ master's node will be also ignored.
+ If more than one phandle is specified, only the first phandle
+ will be treated.
+
+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,sysmmu-v3.2";
+ 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>;
+ mmu-masters = <&gsc_0>;
+ };
--
1.7.9.5


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