Add the DT binding documentation for NXP Audio Mixer
CPU DAI driver.
Signed-off-by: Viorel Suman <viorel.suman@xxxxxxx>
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.../devicetree/bindings/sound/fsl,audmix.txt | 50 ++++++++++++++++++++++
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create mode 100644 Documentation/devicetree/bindings/sound/fsl,audmix.txt
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+NXP Audio Mixer (AUDMIX).
+
+The Audio Mixer is a on-chip functional module that allows mixing of two
+audio streams into a single audio stream. Audio Mixer has two input serial
+audio interfaces. These are driven by two Synchronous Audio interface
+modules (SAI). Each input serial interface carries 8 audio channels in its
+frame in TDM manner. Mixer mixes audio samples of corresponding channels
+from two interfaces into a single sample. Before mixing, audio samples of
+two inputs can be attenuated based on configuration. The output of the
+Audio Mixer is also a serial audio interface. Like input interfaces it has
+the same TDM frame format. This output is used to drive the serial DAC TDM
+interface of audio codec and also sent to the external pins along with the
+receive path of normal audio SAI module for readback by the CPU.
+
+The output of Audio Mixer can be selected from any of the three streams
+ - serial audio input 1
+ - serial audio input 2
+ - mixed audio
+
+Mixing operation is independent of audio sample rate but the two audio
+input streams must have same audio sample rate with same number of channels
+in TDM frame to be eligible for mixing.
+
+Device driver required properties:
+=================================
+ - compatible : Compatible list, contains "fsl,imx8qm-audmix"
+
+ - reg : Offset and length of the register set for the device.
+
+ - clocks : Must contain an entry for each entry in clock-names.
+
+ - clock-names : Must include the "ipg" for register access.
+
+ - power-domains : Must contain the phandle to AUDMIX power domain node
+
+ - dais : Must contain a list of phandles to AUDMIX connected
+ DAIs. The current implementation requires two phandles
+ to SAI interfaces to be provided, the first SAI in the
+ list being used to route the AUDMIX output.
+
+Device driver configuration example:
+======================================
+ audmix: audmix@59840000 {
+ compatible = "fsl,imx8qm-audmix";
+ reg = <0x0 0x59840000 0x0 0x10000>;
+ clocks = <&clk IMX8QXP_AUD_AUDMIX_IPG>;
+ clock-names = "ipg";
+ power-domains = <&pd_audmix>;
+ dais = <&sai4>, <&sai5>;
+ };
--
2.7.4
