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| -rw-r--r-- | Documentation/devicetree/bindings/dma/shdma.txt | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/dma/shdma.txt b/Documentation/devicetree/bindings/dma/shdma.txt new file mode 100644 index 000000000..a91920a49 --- /dev/null +++ b/Documentation/devicetree/bindings/dma/shdma.txt @@ -0,0 +1,84 @@ +* 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"; |