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Documentation / devicetree / bindings / sound / fsl,ssi.txt




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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.
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