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- dma-channel-mask:	Bitmask of available DMA channels in ascending order
20			that are not reserved by firmware and are available to
21			the kernel. i.e. first channel corresponds to LSB.
22
23Example:
24
25	dma: dma@48000000 {
26		compatible = "ti,omap-sdma";
27		reg = <0x48000000 0x1000>;
28		interrupts = <0 12 0x4
29			      0 13 0x4
30			      0 14 0x4
31			      0 15 0x4>;
32		#dma-cells = <1>;
33		dma-channels = <32>;
34		dma-requests = <127>;
35		dma-channel-mask = <0xfffe>
36	};
37
38* DMA router
39
40DMA routers are transparent IP blocks used to route DMA request lines from
41devices to the DMA controller. Some SoCs (like TI DRA7x) have more peripherals
42integrated with DMA requests than what the DMA controller can handle directly.
43
44Required property:
45- dma-masters:		phandle of the DMA controller or list of phandles for
46			the DMA controllers the router can direct the signal to.
47- #dma-cells: 		Must be at least 1. Used to provide DMA router specific
48			information. See DMA client binding below for more
49			details.
50
51Optional properties:
52- dma-requests: 	Number of incoming request lines the router can handle.
53- In the node pointed by the dma-masters:
54	- dma-requests:	The router driver might need to look for this in order
55			to configure the routing.
56
57Example:
58	sdma_xbar: dma-router@4a002b78 {
59		compatible = "ti,dra7-dma-crossbar";
60		reg = <0x4a002b78 0xfc>;
61		#dma-cells = <1>;
62		dma-requests = <205>;
63		ti,dma-safe-map = <0>;
64		dma-masters = <&sdma>;
65	};
66
67* DMA client
68
69Client drivers should specify the DMA property using a phandle to the controller
70followed by DMA controller specific data.
71
72Required property:
73- dmas:			List of one or more DMA specifiers, each consisting of
74			- A phandle pointing to DMA controller node
75			- A number of integer cells, as determined by the
76			  #dma-cells property in the node referenced by phandle
77			  containing DMA controller specific information. This
78			  typically contains a DMA request line number or a
79			  channel number, but can contain any data that is
80			  required for configuring a channel.
81- dma-names: 		Contains one identifier string for each DMA specifier in
82			the dmas property. The specific strings that can be used
83			are defined in the binding of the DMA client device.
84			Multiple DMA specifiers can be used to represent
85			alternatives and in this case the dma-names for those
86			DMA specifiers must be identical (see examples).
87
88Examples:
89
901. A device with one DMA read channel, one DMA write channel:
91
92	i2c1: i2c@1 {
93		...
94		dmas = <&dma 2		/* read channel */
95			&dma 3>;	/* write channel */
96		dma-names = "rx", "tx";
97		...
98	};
99
1002. A single read-write channel with three alternative DMA controllers:
101
102	dmas = <&dma1 5
103		&dma2 7
104		&dma3 2>;
105	dma-names = "rx-tx", "rx-tx", "rx-tx";
106
1073. A device with three channels, one of which has two alternatives:
108
109	dmas = <&dma1 2			/* read channel */
110		&dma1 3			/* write channel */
111		&dma2 0			/* error read */
112		&dma3 0>;		/* alternative error read */
113	dma-names = "rx", "tx", "error", "error";
114