1Freescale Synchronous Serial Interface
2
3The SSI is a serial device that communicates with audio codecs.  It can
4be programmed in AC97, I2S, left-justified, or right-justified modes.
5
6Required 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- fsl,fifo-depth:   The number of elements in the transmit and receive FIFOs.
22                    This number is the maximum allowed value for SFCSR[TFWM0].
23 - clocks:          "ipg" - Required clock for the SSI unit
24                    "baud" - Required clock for SSI master mode. Otherwise this
25		      clock is not used
26
27Required are also ac97 link bindings if ac97 is used. See
28Documentation/devicetree/bindings/sound/soc-ac97link.txt for the necessary
29bindings.
30
31Optional properties:
32- codec-handle:     Phandle to a 'codec' node that defines an audio
33                    codec connected to this SSI.  This node is typically
34                    a child of an I2C or other control node.
35- fsl,fiq-stream-filter: Bool property. Disabled DMA and use FIQ instead to
36		    filter the codec stream. This is necessary for some boards
37		    where an incompatible codec is connected to this SSI, e.g.
38		    on pca100 and pcm043.
39- dmas:		    Generic dma devicetree binding as described in
40		    Documentation/devicetree/bindings/dma/dma.txt.
41- dma-names:	    Two dmas have to be defined, "tx" and "rx", if fsl,imx-fiq
42		    is not defined.
43- fsl,mode:         The operating mode for the AC97 interface only.
44                    "ac97-slave" - AC97 mode, SSI is clock slave
45                    "ac97-master" - AC97 mode, SSI is clock master
46- fsl,ssi-asynchronous:
47                    If specified, the SSI is to be programmed in asynchronous
48                    mode.  In this mode, pins SRCK, STCK, SRFS, and STFS must
49                    all be connected to valid signals.  In synchronous mode,
50                    SRCK and SRFS are ignored.  Asynchronous mode allows
51                    playback and capture to use different sample sizes and
52                    sample rates.  Some drivers may require that SRCK and STCK
53                    be connected together, and SRFS and STFS be connected
54                    together.  This would still allow different sample sizes,
55                    but not different sample rates.
56- fsl,playback-dma: Phandle to a node for the DMA channel to use for
57                    playback of audio.  This is typically dictated by SOC
58                    design.  See the notes below.
59                    Only used on Power Architecture.
60- fsl,capture-dma:  Phandle to a node for the DMA channel to use for
61                    capture (recording) of audio.  This is typically dictated
62                    by SOC design.  See the notes below.
63                    Only used on Power Architecture.
64
65Child 'codec' node required properties:
66- compatible:       Compatible list, contains the name of the codec
67
68Child 'codec' node optional properties:
69- clock-frequency:  The frequency of the input clock, which typically comes
70                    from an on-board dedicated oscillator.
71
72Notes on fsl,playback-dma and fsl,capture-dma:
73
74On SOCs that have an SSI, specific DMA channels are hard-wired for playback
75and capture.  On the MPC8610, for example, SSI1 must use DMA channel 0 for
76playback and DMA channel 1 for capture.  SSI2 must use DMA channel 2 for
77playback and DMA channel 3 for capture.  The developer can choose which
78DMA controller to use, but the channels themselves are hard-wired.  The
79purpose of these two properties is to represent this hardware design.
80
81The 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
86drivers (fsldma) will attempt to use them, and it will conflict with the
87sound drivers.
88