1* Generic DMA Controller and DMA request bindings 2 3Generic binding to provide a way for a driver using DMA Engine to retrieve the 4DMA request or channel information that goes from a hardware device to a DMA 5controller. 6 7 8* DMA controller 9 10Required property: 11- #dma-cells: Must be at least 1. Used to provide DMA controller 12 specific information. See DMA client binding below for 13 more details. 14 15Optional properties: 16- dma-channels: Number of DMA channels supported by the controller. 17- dma-requests: Number of DMA request signals supported by the 18 controller. 19 20Example: 21 22 dma: dma@48000000 { 23 compatible = "ti,omap-sdma"; 24 reg = <0x48000000 0x1000>; 25 interrupts = <0 12 0x4 26 0 13 0x4 27 0 14 0x4 28 0 15 0x4>; 29 #dma-cells = <1>; 30 dma-channels = <32>; 31 dma-requests = <127>; 32 }; 33 34* DMA router 35 36DMA routers are transparent IP blocks used to route DMA request lines from 37devices to the DMA controller. Some SoCs (like TI DRA7x) have more peripherals 38integrated with DMA requests than what the DMA controller can handle directly. 39 40Required property: 41- dma-masters: phandle of the DMA controller or list of phandles for 42 the DMA controllers the router can direct the signal to. 43- #dma-cells: Must be at least 1. Used to provide DMA router specific 44 information. See DMA client binding below for more 45 details. 46 47Optional properties: 48- dma-requests: Number of incoming request lines the router can handle. 49- In the node pointed by the dma-masters: 50 - dma-requests: The router driver might need to look for this in order 51 to configure the routing. 52 53Example: 54 sdma_xbar: dma-router@4a002b78 { 55 compatible = "ti,dra7-dma-crossbar"; 56 reg = <0x4a002b78 0xfc>; 57 #dma-cells = <1>; 58 dma-requests = <205>; 59 ti,dma-safe-map = <0>; 60 dma-masters = <&sdma>; 61 }; 62 63* DMA client 64 65Client drivers should specify the DMA property using a phandle to the controller 66followed by DMA controller specific data. 67 68Required property: 69- dmas: List of one or more DMA specifiers, each consisting of 70 - A phandle pointing to DMA controller node 71 - A number of integer cells, as determined by the 72 #dma-cells property in the node referenced by phandle 73 containing DMA controller specific information. This 74 typically contains a DMA request line number or a 75 channel number, but can contain any data that is 76 required for configuring a channel. 77- dma-names: Contains one identifier string for each DMA specifier in 78 the dmas property. The specific strings that can be used 79 are defined in the binding of the DMA client device. 80 Multiple DMA specifiers can be used to represent 81 alternatives and in this case the dma-names for those 82 DMA specifiers must be identical (see examples). 83 84Examples: 85 861. A device with one DMA read channel, one DMA write channel: 87 88 i2c1: i2c@1 { 89 ... 90 dmas = <&dma 2 /* read channel */ 91 &dma 3>; /* write channel */ 92 dma-names = "rx", "tx"; 93 ... 94 }; 95 962. A single read-write channel with three alternative DMA controllers: 97 98 dmas = <&dma1 5 99 &dma2 7 100 &dma3 2>; 101 dma-names = "rx-tx", "rx-tx", "rx-tx"; 102 1033. A device with three channels, one of which has two alternatives: 104 105 dmas = <&dma1 2 /* read channel */ 106 &dma1 3 /* write channel */ 107 &dma2 0 /* error read */ 108 &dma3 0>; /* alternative error read */ 109 dma-names = "rx", "tx", "error", "error"; 110