diff options
Diffstat (limited to '')
| -rw-r--r-- | Documentation/devicetree/bindings/sound/fsl,ssi.txt | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/sound/fsl,ssi.txt b/Documentation/devicetree/bindings/sound/fsl,ssi.txt new file mode 100644 index 000000000..7e15a85ce --- /dev/null +++ b/Documentation/devicetree/bindings/sound/fsl,ssi.txt @@ -0,0 +1,87 @@ +Freescale Synchronous Serial Interface + +The SSI is a serial device that communicates with audio codecs. It can +be programmed in AC97, I2S, left-justified, or right-justified modes. + +Required properties: +- compatible: Compatible list, should contain one of the following + compatibles: + fsl,mpc8610-ssi + fsl,imx51-ssi + fsl,imx35-ssi + fsl,imx21-ssi +- cell-index: The SSI, <0> = SSI1, <1> = SSI2, and so on. +- reg: Offset and length of the register set for the device. +- interrupts: <a b> where a is the interrupt number and b is a + field that represents an encoding of the sense and + level information for the interrupt. This should be + encoded based on the information in section 2) + depending on the type of interrupt controller you + have. +- fsl,fifo-depth: The number of elements in the transmit and receive FIFOs. + This number is the maximum allowed value for SFCSR[TFWM0]. + - clocks: "ipg" - Required clock for the SSI unit + "baud" - Required clock for SSI master mode. Otherwise this + clock is not used + +Required are also ac97 link bindings if ac97 is used. See +Documentation/devicetree/bindings/sound/soc-ac97link.txt for the necessary +bindings. + +Optional properties: +- codec-handle: Phandle to a 'codec' node that defines an audio + codec connected to this SSI. This node is typically + a child of an I2C or other control node. +- fsl,fiq-stream-filter: Bool property. Disabled DMA and use FIQ instead to + filter the codec stream. This is necessary for some boards + where an incompatible codec is connected to this SSI, e.g. + on pca100 and pcm043. +- dmas: Generic dma devicetree binding as described in + Documentation/devicetree/bindings/dma/dma.txt. +- dma-names: Two dmas have to be defined, "tx" and "rx", if fsl,imx-fiq + is not defined. +- fsl,mode: The operating mode for the AC97 interface only. + "ac97-slave" - AC97 mode, SSI is clock slave + "ac97-master" - AC97 mode, SSI is clock master +- fsl,ssi-asynchronous: + If specified, the SSI is to be programmed in asynchronous + mode. In this mode, pins SRCK, STCK, SRFS, and STFS must + all be connected to valid signals. In synchronous mode, + SRCK and SRFS are ignored. Asynchronous mode allows + playback and capture to use different sample sizes and + sample rates. Some drivers may require that SRCK and STCK + be connected together, and SRFS and STFS be connected + together. This would still allow different sample sizes, + but not different sample rates. +- fsl,playback-dma: Phandle to a node for the DMA channel to use for + playback of audio. This is typically dictated by SOC + design. See the notes below. + Only used on Power Architecture. +- fsl,capture-dma: Phandle to a node for the DMA channel to use for + capture (recording) of audio. This is typically dictated + by SOC design. See the notes below. + Only used on Power Architecture. + +Child 'codec' node required properties: +- compatible: Compatible list, contains the name of the codec + +Child 'codec' node optional properties: +- clock-frequency: The frequency of the input clock, which typically comes + from an on-board dedicated oscillator. + +Notes on fsl,playback-dma and fsl,capture-dma: + +On SOCs that have an SSI, specific DMA channels are hard-wired for playback +and capture. On the MPC8610, for example, SSI1 must use DMA channel 0 for +playback and DMA channel 1 for capture. SSI2 must use DMA channel 2 for +playback and DMA channel 3 for capture. The developer can choose which +DMA controller to use, but the channels themselves are hard-wired. The +purpose of these two properties is to represent this hardware design. + +The device tree nodes for the DMA channels that are referenced by +"fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with +"fsl,ssi-dma-channel". The SOC-specific compatible string (e.g. +"fsl,mpc8610-dma-channel") can remain. If these nodes are left as +"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA +drivers (fsldma) will attempt to use them, and it will conflict with the +sound drivers. |