[PATCH V5 RESEND 1/3] docs: iommu: Documentation for iommu in hi6220 SoC

[Chen Feng <puck.chen@hisilicon.com>]

Documentation for hi6220 iommu driver.

Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
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 .../bindings/iommu/hisi,hi6220-iommu.txt           | 32 ++++++++++++++++++++++
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+Hi6220 SoC SMMU Device Driver devicetree document
+The media system shared the same smmu IP to access DDR memory. And all
+media IP used the same page table.
+
+Below binding describes the system mmu for media system in hi6220 platform
+
+Required properties:
+- compatible: should contain "hisilicon,hi6220-smmu".
+- reg: A tuple of base address and size of System MMU registers.
+- clocks: a list of phandle + clock-specifier pairs, one for each entry
+  in clock-names.
+- clock-names: should contain:
+  * "smmu"
+  * "media-sc"
+  * "smmu-peri"
+- interrupts: An interrupt specifier for interrupt signal of System MMU.
+- #iommu-cells: The iommu-cells should be 0. Because no additional information
+  needs to be encoded in the specifier.
+
+Examples:
+	iommu@f4210000 {
+		compatible = "hisilicon,hi6220-smmu";
+		reg = <0x0 0xf4210000 0x0 0x1000>;
+		interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&sys_ctrl HI6220_MMU_CLK>,
+		         <&media_ctrl HI6220_MED_MMU>,
+		         <&sys_ctrl HI6220_MEDIA_PLL_SRC>;
+		clock-names = "smmu",
+			      "media-sc",
+			      "smmu-peri";
+		#iommu-cells = <0>;
+	};
-- 
1.9.1