| 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, containing "fsl,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. |
| - interrupt-parent : the phandle for the interrupt controller that |
| services interrupts for this device. |
| - fsl,mode : the operating mode for the SSI interface |
| "i2s-slave" - I2S mode, SSI is clock slave |
| "i2s-master" - I2S mode, SSI is clock master |
| "lj-slave" - left-justified mode, SSI is clock slave |
| "lj-master" - l.j. mode, SSI is clock master |
| "rj-slave" - right-justified mode, SSI is clock slave |
| "rj-master" - r.j., SSI is clock master |
| "ac97-slave" - AC97 mode, SSI is clock slave |
| "ac97-master" - AC97 mode, SSI is clock master |
| - 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. |
| - 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. |
| |
| 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. |
| |
| 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. |