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- 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
45Required are also ac97 link bindings if ac97 is used. See
46Documentation/devicetree/bindings/sound/soc-ac97link.txt for the necessary
47bindings.
48
49Optional 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
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