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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /Documentation/devicetree/bindings/dma/shdma.txt
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+* SHDMA Device Tree bindings
+
+Sh-/r-mobile and r-car systems often have multiple identical DMA controller
+instances, capable of serving any of a common set of DMA slave devices, using
+the same configuration. To describe this topology we require all compatible
+SHDMA DT nodes to be placed under a DMA multiplexer node. All such compatible
+DMAC instances have the same number of channels and use the same DMA
+descriptors. Therefore respective DMA DT bindings can also all be placed in the
+multiplexer node. Even if there is only one such DMAC instance on a system, it
+still has to be placed under such a multiplexer node.
+
+* DMA multiplexer
+
+Required properties:
+- compatible: should be "renesas,shdma-mux"
+- #dma-cells: should be <1>, see "dmas" property below
+
+Optional properties (currently unused):
+- dma-channels: number of DMA channels
+- dma-requests: number of DMA request signals
+
+* DMA controller
+
+Required properties:
+- compatible: should be of the form "renesas,shdma-<soc>", where <soc> should
+ be replaced with the desired SoC model, e.g.
+ "renesas,shdma-r8a73a4" for the system DMAC on r8a73a4 SoC
+
+Example:
+ dmac: dma-multiplexer@0 {
+ compatible = "renesas,shdma-mux";
+ #dma-cells = <1>;
+ dma-channels = <20>;
+ dma-requests = <256>;
+ #address-cells = <2>;
+ #size-cells = <2>;
+ ranges;
+
+ dma0: dma-controller@e6700020 {
+ compatible = "renesas,shdma-r8a73a4";
+ reg = <0 0xe6700020 0 0x89e0>;
+ interrupt-parent = <&gic>;
+ interrupts = <0 220 4
+ 0 200 4
+ 0 201 4
+ 0 202 4
+ 0 203 4
+ 0 204 4
+ 0 205 4
+ 0 206 4
+ 0 207 4
+ 0 208 4
+ 0 209 4
+ 0 210 4
+ 0 211 4
+ 0 212 4
+ 0 213 4
+ 0 214 4
+ 0 215 4
+ 0 216 4
+ 0 217 4
+ 0 218 4
+ 0 219 4>;
+ interrupt-names = "error",
+ "ch0", "ch1", "ch2", "ch3",
+ "ch4", "ch5", "ch6", "ch7",
+ "ch8", "ch9", "ch10", "ch11",
+ "ch12", "ch13", "ch14", "ch15",
+ "ch16", "ch17", "ch18", "ch19";
+ };
+ };
+
+* DMA client
+
+Required properties:
+- dmas: a list of <[DMA multiplexer phandle] [MID/RID value]> pairs,
+ where MID/RID values are fixed handles, specified in the SoC
+ manual
+- dma-names: a list of DMA channel names, one per "dmas" entry
+
+Example:
+ dmas = <&dmac 0xd1
+ &dmac 0xd2>;
+ dma-names = "tx", "rx";