About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

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




Custom Search

Based on kernel version 3.15.4. Page generated on 2014-07-07 09:01 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 SSI interface.
62	                    "i2s-slave" - I2S mode, SSI is clock slave
63	                    "i2s-master" - I2S mode, SSI is clock master
64	                    "lj-slave" - left-justified mode, SSI is clock slave
65	                    "lj-master" - l.j. mode, SSI is clock master
66	                    "rj-slave" - right-justified mode, SSI is clock slave
67	                    "rj-master" - r.j., SSI is clock master
68	                    "ac97-slave" - AC97 mode, SSI is clock slave
69	                    "ac97-master" - AC97 mode, SSI is clock master
70	
71	Child 'codec' node required properties:
72	- compatible:       Compatible list, contains the name of the codec
73	
74	Child 'codec' node optional properties:
75	- clock-frequency:  The frequency of the input clock, which typically comes
76	                    from an on-board dedicated oscillator.
77	
78	Notes on fsl,playback-dma and fsl,capture-dma:
79	
80	On SOCs that have an SSI, specific DMA channels are hard-wired for playback
81	and capture.  On the MPC8610, for example, SSI1 must use DMA channel 0 for
82	playback and DMA channel 1 for capture.  SSI2 must use DMA channel 2 for
83	playback and DMA channel 3 for capture.  The developer can choose which
84	DMA controller to use, but the channels themselves are hard-wired.  The
85	purpose of these two properties is to represent this hardware design.
86	
87	The device tree nodes for the DMA channels that are referenced by
88	"fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with
89	"fsl,ssi-dma-channel".  The SOC-specific compatible string (e.g.
90	"fsl,mpc8610-dma-channel") can remain.  If these nodes are left as
91	"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA
92	drivers (fsldma) will attempt to use them, and it will conflict with the
93	sound drivers.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.