1 This file has been moved to dma-controller.yam !! 1 * Generic DMA Controller and DMA request bindings
>> 2
>> 3 Generic binding to provide a way for a driver using DMA Engine to retrieve the
>> 4 DMA request or channel information that goes from a hardware device to a DMA
>> 5 controller.
>> 6
>> 7
>> 8 * DMA controller
>> 9
>> 10 Required 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
>> 15 Optional 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
>> 23 Example:
>> 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
>> 40 DMA routers are transparent IP blocks used to route DMA request lines from
>> 41 devices to the DMA controller. Some SoCs (like TI DRA7x) have more peripherals
>> 42 integrated with DMA requests than what the DMA controller can handle directly.
>> 43
>> 44 Required 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
>> 51 Optional 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
>> 57 Example:
>> 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
>> 69 Client drivers should specify the DMA property using a phandle to the controller
>> 70 followed by DMA controller specific data.
>> 71
>> 72 Required 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
>> 88 Examples:
>> 89
>> 90 1. 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
>> 100 2. 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
>> 107 3. 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";
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.