Based on kernel version 4.13.3. Page generated on 2017-09-23 13:55 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,fifo-depth: The number of elements in the transmit and receive FIFOs. 24 This number is the maximum allowed value for SFCSR[TFWM0]. 25 - clocks: "ipg" - Required clock for the SSI unit 26 "baud" - Required clock for SSI master mode. Otherwise this 27 clock is not used 28 29 Required are also ac97 link bindings if ac97 is used. See 30 Documentation/devicetree/bindings/sound/soc-ac97link.txt for the necessary 31 bindings. 32 33 Optional properties: 34 - codec-handle: Phandle to a 'codec' node that defines an audio 35 codec connected to this SSI. This node is typically 36 a child of an I2C or other control node. 37 - fsl,fiq-stream-filter: Bool property. Disabled DMA and use FIQ instead to 38 filter the codec stream. This is necessary for some boards 39 where an incompatible codec is connected to this SSI, e.g. 40 on pca100 and pcm043. 41 - dmas: Generic dma devicetree binding as described in 42 Documentation/devicetree/bindings/dma/dma.txt. 43 - dma-names: Two dmas have to be defined, "tx" and "rx", if fsl,imx-fiq 44 is not defined. 45 - fsl,mode: The operating mode for the AC97 interface only. 46 "ac97-slave" - AC97 mode, SSI is clock slave 47 "ac97-master" - AC97 mode, SSI is clock master 48 - fsl,ssi-asynchronous: 49 If specified, the SSI is to be programmed in asynchronous 50 mode. In this mode, pins SRCK, STCK, SRFS, and STFS must 51 all be connected to valid signals. In synchronous mode, 52 SRCK and SRFS are ignored. Asynchronous mode allows 53 playback and capture to use different sample sizes and 54 sample rates. Some drivers may require that SRCK and STCK 55 be connected together, and SRFS and STFS be connected 56 together. This would still allow different sample sizes, 57 but not different sample rates. 58 - fsl,playback-dma: Phandle to a node for the DMA channel to use for 59 playback of audio. This is typically dictated by SOC 60 design. See the notes below. 61 Only used on Power Architecture. 62 - fsl,capture-dma: Phandle to a node for the DMA channel to use for 63 capture (recording) of audio. This is typically dictated 64 by SOC design. See the notes below. 65 Only used on Power Architecture. 66 67 Child 'codec' node required properties: 68 - compatible: Compatible list, contains the name of the codec 69 70 Child 'codec' node optional properties: 71 - clock-frequency: The frequency of the input clock, which typically comes 72 from an on-board dedicated oscillator. 73 74 Notes on fsl,playback-dma and fsl,capture-dma: 75 76 On SOCs that have an SSI, specific DMA channels are hard-wired for playback 77 and capture. On the MPC8610, for example, SSI1 must use DMA channel 0 for 78 playback and DMA channel 1 for capture. SSI2 must use DMA channel 2 for 79 playback and DMA channel 3 for capture. The developer can choose which 80 DMA controller to use, but the channels themselves are hard-wired. The 81 purpose of these two properties is to represent this hardware design. 82 83 The device tree nodes for the DMA channels that are referenced by 84 "fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with 85 "fsl,ssi-dma-channel". The SOC-specific compatible string (e.g. 86 "fsl,mpc8610-dma-channel") can remain. If these nodes are left as 87 "fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA 88 drivers (fsldma) will attempt to use them, and it will conflict with the 89 sound drivers.