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authorMarkus Pargmann <mpa@pengutronix.de>2013-06-20 17:20:28 +0400
committerMark Brown <broonie@linaro.org>2013-07-15 14:10:36 +0400
commit624dcbdea24b599484895ed5b6a18e869e08d2a5 (patch)
tree665f99bd7b05c223333929d9c1d4b71fead18b4a /Documentation/devicetree/bindings/sound/fsl,ssi.txt
parent9051cba110000985c1a50374fea16f1493955b6e (diff)
downloadlinux-624dcbdea24b599484895ed5b6a18e869e08d2a5.tar.xz
ASoC: fsl: Move fsl-ssi binding doc to sound/
fsl-ssi was located in powerpc/fsl/ssi.txt. This is no powerpc specific device, so it should be moved to sound/ as it connects to differen audio codecs. Signed-off-by: Markus Pargmann <mpa@pengutronix.de> Tested-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Mark Brown <broonie@linaro.org>
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+Freescale Synchronous Serial Interface
+
+The SSI is a serial device that communicates with audio codecs. It can
+be programmed in AC97, I2S, left-justified, or right-justified modes.
+
+Required properties:
+- compatible: Compatible list, contains "fsl,ssi".
+- cell-index: The SSI, <0> = SSI1, <1> = SSI2, and so on.
+- reg: Offset and length of the register set for the device.
+- interrupts: <a b> where a is the interrupt number and b is a
+ field that represents an encoding of the sense and
+ level information for the interrupt. This should be
+ encoded based on the information in section 2)
+ depending on the type of interrupt controller you
+ have.
+- interrupt-parent: The phandle for the interrupt controller that
+ services interrupts for this device.
+- fsl,mode: The operating mode for the SSI interface.
+ "i2s-slave" - I2S mode, SSI is clock slave
+ "i2s-master" - I2S mode, SSI is clock master
+ "lj-slave" - left-justified mode, SSI is clock slave
+ "lj-master" - l.j. mode, SSI is clock master
+ "rj-slave" - right-justified mode, SSI is clock slave
+ "rj-master" - r.j., SSI is clock master
+ "ac97-slave" - AC97 mode, SSI is clock slave
+ "ac97-master" - AC97 mode, SSI is clock master
+- fsl,playback-dma: Phandle to a node for the DMA channel to use for
+ playback of audio. This is typically dictated by SOC
+ design. See the notes below.
+- fsl,capture-dma: Phandle to a node for the DMA channel to use for
+ capture (recording) of audio. This is typically dictated
+ by SOC design. See the notes below.
+- fsl,fifo-depth: The number of elements in the transmit and receive FIFOs.
+ This number is the maximum allowed value for SFCSR[TFWM0].
+- fsl,ssi-asynchronous:
+ If specified, the SSI is to be programmed in asynchronous
+ mode. In this mode, pins SRCK, STCK, SRFS, and STFS must
+ all be connected to valid signals. In synchronous mode,
+ SRCK and SRFS are ignored. Asynchronous mode allows
+ playback and capture to use different sample sizes and
+ sample rates. Some drivers may require that SRCK and STCK
+ be connected together, and SRFS and STFS be connected
+ together. This would still allow different sample sizes,
+ but not different sample rates.
+
+Optional properties:
+- codec-handle: Phandle to a 'codec' node that defines an audio
+ codec connected to this SSI. This node is typically
+ a child of an I2C or other control node.
+
+Child 'codec' node required properties:
+- compatible: Compatible list, contains the name of the codec
+
+Child 'codec' node optional properties:
+- clock-frequency: The frequency of the input clock, which typically comes
+ from an on-board dedicated oscillator.
+
+Notes on fsl,playback-dma and fsl,capture-dma:
+
+On SOCs that have an SSI, specific DMA channels are hard-wired for playback
+and capture. On the MPC8610, for example, SSI1 must use DMA channel 0 for
+playback and DMA channel 1 for capture. SSI2 must use DMA channel 2 for
+playback and DMA channel 3 for capture. The developer can choose which
+DMA controller to use, but the channels themselves are hard-wired. The
+purpose of these two properties is to represent this hardware design.
+
+The device tree nodes for the DMA channels that are referenced by
+"fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with
+"fsl,ssi-dma-channel". The SOC-specific compatible string (e.g.
+"fsl,mpc8610-dma-channel") can remain. If these nodes are left as
+"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA
+drivers (fsldma) will attempt to use them, and it will conflict with the
+sound drivers.