MLK-13904-1: ASoC: fsl: add audio cpu dai driver base on rpmsg (part 1)

Add the cpu dai driver, as the rpmsg_send api can't be used in
atomic context, so using the workqueue instead of calling
rpmsg_send() directly.
The detail communication stack is defined in header file.

Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>
Acked-by: Robin Gong <yibin.gong@nxp.com>
[ Aisheng: split out imx-pcm.h changes ]
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/sound/fsl,rpmsg-i2s.txt b/Documentation/devicetree/bindings/sound/fsl,rpmsg-i2s.txt
new file mode 100644
index 000000000000..f38cf9d90500
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg-i2s.txt
@@ -0,0 +1,20 @@
+Freescale rpmsg i2s interface.
+
+The rpmsg i2s is based on RPMSG that used communicating with M4 core,
+which provides a synchronous audio interface that supports fullduplex
+serial interfaces with frame synchronization such as I2S.
+
+Required properties:
+
+  - compatible		: Compatible list, contains "fsl,imx7ulp-rpmsg-i2s".
+
+  - fsl,audioindex      : This is an index indicating the audio device index in
+			  the M4 side.
+
+Example:
+rpmsg_i2s: rpmsg-i2s {
+	compatible = "fsl,imx7ulp-rpmsg-i2s";
+	/* the audio device index in m4 domain */
+	fsl,audioindex = <0> ;
+	status = "okay";
+};