Based on kernel version 4.2. Page generated on 2015-09-09 12:11 EST.
1 Freescale Synchronous Serial Interface 2 3 The SSI is a serial device that communicates with audio codecs. It can 4 be programmed in AC97, I2S, left-justified, or right-justified modes. 5 6 Required properties: 7 - compatible: Compatible list, should contain one of the following 8 compatibles: 9 fsl,mpc8610-ssi 10 fsl,imx51-ssi 11 fsl,imx35-ssi 12 fsl,imx21-ssi 13 - cell-index: The SSI, <0> = SSI1, <1> = SSI2, and so on. 14 - reg: Offset and length of the register set for the device. 15 - interrupts: <a b> where a is the interrupt number and b is a 16 field that represents an encoding of the sense and 17 level information for the interrupt. This should be 18 encoded based on the information in section 2) 19 depending on the type of interrupt controller you 20 have. 21 - interrupt-parent: The phandle for the interrupt controller that 22 services interrupts for this device. 23 - fsl,playback-dma: Phandle to a node for the DMA channel to use for 24 playback of audio. This is typically dictated by SOC 25 design. See the notes below. 26 - fsl,capture-dma: Phandle to a node for the DMA channel to use for 27 capture (recording) of audio. This is typically dictated 28 by SOC design. See the notes below. 29 - fsl,fifo-depth: The number of elements in the transmit and receive FIFOs. 30 This number is the maximum allowed value for SFCSR[TFWM0]. 31 - fsl,ssi-asynchronous: 32 If specified, the SSI is to be programmed in asynchronous 33 mode. In this mode, pins SRCK, STCK, SRFS, and STFS must 34 all be connected to valid signals. In synchronous mode, 35 SRCK and SRFS are ignored. Asynchronous mode allows 36 playback and capture to use different sample sizes and 37 sample rates. Some drivers may require that SRCK and STCK 38 be connected together, and SRFS and STFS be connected 39 together. This would still allow different sample sizes, 40 but not different sample rates. 41 - clocks: "ipg" - Required clock for the SSI unit 42 "baud" - Required clock for SSI master mode. Otherwise this 43 clock is not used 44 45 Required are also ac97 link bindings if ac97 is used. See 46 Documentation/devicetree/bindings/sound/soc-ac97link.txt for the necessary 47 bindings. 48 49 Optional properties: 50 - codec-handle: Phandle to a 'codec' node that defines an audio 51 codec connected to this SSI. This node is typically 52 a child of an I2C or other control node. 53 - fsl,fiq-stream-filter: Bool property. Disabled DMA and use FIQ instead to 54 filter the codec stream. This is necessary for some boards 55 where an incompatible codec is connected to this SSI, e.g. 56 on pca100 and pcm043. 57 - dmas: Generic dma devicetree binding as described in 58 Documentation/devicetree/bindings/dma/dma.txt. 59 - dma-names: Two dmas have to be defined, "tx" and "rx", if fsl,imx-fiq 60 is not defined. 61 - fsl,mode: The operating mode for the AC97 interface only. 62 "ac97-slave" - AC97 mode, SSI is clock slave 63 "ac97-master" - AC97 mode, SSI is clock master 64 65 Child 'codec' node required properties: 66 - compatible: Compatible list, contains the name of the codec 67 68 Child 'codec' node optional properties: 69 - clock-frequency: The frequency of the input clock, which typically comes 70 from an on-board dedicated oscillator. 71 72 Notes on fsl,playback-dma and fsl,capture-dma: 73 74 On SOCs that have an SSI, specific DMA channels are hard-wired for playback 75 and capture. On the MPC8610, for example, SSI1 must use DMA channel 0 for 76 playback and DMA channel 1 for capture. SSI2 must use DMA channel 2 for 77 playback and DMA channel 3 for capture. The developer can choose which 78 DMA controller to use, but the channels themselves are hard-wired. The 79 purpose of these two properties is to represent this hardware design. 80 81 The device tree nodes for the DMA channels that are referenced by 82 "fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with 83 "fsl,ssi-dma-channel". The SOC-specific compatible string (e.g. 84 "fsl,mpc8610-dma-channel") can remain. If these nodes are left as 85 "fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA 86 drivers (fsldma) will attempt to use them, and it will conflict with the 87 sound drivers.