Renesas R-Car sound
+=============================================
+* Modules
+=============================================
+
+Renesas R-Car sound is constructed from below modules
+(for Gen2 or later)
+
+ SCU : Sampling Rate Converter Unit
+ - SRC : Sampling Rate Converter
+ - CMD
+ - CTU : Channel Transfer Unit
+ - MIX : Mixer
+ - DVC : Digital Volume and Mute Function
+ SSIU : Serial Sound Interface Unit
+ SSI : Serial Sound Interface
+
+See detail of each module's channels, connection, limitation on datasheet
+
+=============================================
+* Multi channel
+=============================================
+
+Multi channel is supported by Multi-SSI, or TDM-SSI.
+
+ Multi-SSI : 6ch case, you can use stereo x 3 SSI
+ TDM-SSI : 6ch case, you can use TDM
+
+=============================================
+* Enable/Disable each modules
+=============================================
+
+See datasheet to check SRC/CTU/MIX/DVC connect-limitation.
+DT controls enabling/disabling module.
+${LINUX}/arch/arm/boot/dts/r8a7790-lager.dts can be good example.
+This is example of
+
+Playback: [MEM] -> [SRC2] -> [DVC0] -> [SSIU0/SSI0] -> [codec]
+Capture: [MEM] <- [DVC1] <- [SRC3] <- [SSIU1/SSI1] <- [codec]
+
+ &rcar_sound {
+ ...
+ rcar_sound,dai {
+ dai0 {
+ playback = <&ssi0 &src2 &dvc0>;
+ capture = <&ssi1 &src3 &dvc1>;
+ };
+ };
+ };
+
+You can use below.
+${LINUX}/arch/arm/boot/dts/r8a7790.dts can be good example.
+
+ &src0 &ctu00 &mix0 &dvc0 &ssi0
+ &src1 &ctu01 &mix1 &dvc1 &ssi1
+ &src2 &ctu02 &ssi2
+ &src3 &ctu03 &ssi3
+ &src4 &ssi4
+ &src5 &ctu10 &ssi5
+ &src6 &ctu11 &ssi6
+ &src7 &ctu12 &ssi7
+ &src8 &ctu13 &ssi8
+ &src9 &ssi9
+
+=============================================
+* SRC (Sampling Rate Converter)
+=============================================
+
+ [xx]Hz [yy]Hz
+ ------> [SRC] ------>
+
+SRC can convert [xx]Hz to [yy]Hz. Then, it has below 2 modes
+
+ Asynchronous mode: input data / output data are based on different clocks.
+ you can use this mode on Playback / Capture
+ Synchronous mode: input data / output data are based on same clocks.
+ This mode will be used if system doesn't have its input clock,
+ for example digital TV case.
+ you can use this mode on Playback
+
+------------------
+** Asynchronous mode
+------------------
+
+You need to use "renesas,rsrc-card" sound card for it.
+example)
+
+ sound {
+ compatible = "renesas,rsrc-card";
+ ...
+ /*
+ * SRC Asynchronous mode setting
+ * Playback:
+ * All input data will be converted to 48kHz
+ * Capture:
+ * Inputed 48kHz data will be converted to
+ * system specified Hz
+ */
+ convert-rate = <48000>;
+ ...
+ cpu {
+ sound-dai = <&rcar_sound>;
+ };
+ codec {
+ ...
+ };
+ };
+
+------------------
+** Synchronous mode
+------------------
+
+ > amixer set "SRC Out Rate" on
+ > aplay xxxx.wav
+ > amixer set "SRC Out Rate" 48000
+ > amixer set "SRC Out Rate" 44100
+
+=============================================
+* CTU (Channel Transfer Unit)
+=============================================
+
+ [xx]ch [yy]ch
+ ------> [CTU] -------->
+
+CTU can convert [xx]ch to [yy]ch, or exchange outputed channel.
+CTU conversion needs matrix settings.
+For more detail information, see below
+
+ Renesas R-Car datasheet
+ - Sampling Rate Converter Unit (SCU)
+ - SCU Operation
+ - CMD Block
+ - Functional Blocks in CMD
+
+ Renesas R-Car datasheet
+ - Sampling Rate Converter Unit (SCU)
+ - Register Description
+ - CTUn Scale Value exx Register (CTUn_SVxxR)
+
+ ${LINUX}/sound/soc/sh/rcar/ctu.c
+ - comment of header
+
+You need to use "renesas,rsrc-card" sound card for it.
+example)
+
+ sound {
+ compatible = "renesas,rsrc-card";
+ ...
+ /*
+ * CTU setting
+ * All input data will be converted to 2ch
+ * as output data
+ */
+ convert-channels = <2>;
+ ...
+ cpu {
+ sound-dai = <&rcar_sound>;
+ };
+ codec {
+ ...
+ };
+ };
+
+Ex) Exchange output channel
+ Input -> Output
+ 1ch -> 0ch
+ 0ch -> 1ch
+
+ example of using matrix
+ output 0ch = (input 0ch x 0) + (input 1ch x 1)
+ output 1ch = (input 0ch x 1) + (input 1ch x 0)
+
+ amixer set "CTU Reset" on
+ amixer set "CTU Pass" 9,10
+ amixer set "CTU SV0" 0,4194304
+ amixer set "CTU SV1" 4194304,0
+
+ example of changing connection
+ amixer set "CTU Reset" on
+ amixer set "CTU Pass" 2,1
+
+=============================================
+* MIX (Mixer)
+=============================================
+
+MIX merges 2 sounds path. You can see 2 sound interface on system,
+and these sounds will be merged by MIX.
+
+ aplay -D plughw:0,0 xxxx.wav &
+ aplay -D plughw:0,1 yyyy.wav
+
+You need to use "renesas,rsrc-card" sound card for it.
+Ex)
+ [MEM] -> [SRC1] -> [CTU02] -+-> [MIX0] -> [DVC0] -> [SSI0]
+ |
+ [MEM] -> [SRC2] -> [CTU03] -+
+
+ sound {
+ compatible = "renesas,rsrc-card";
+ ...
+ cpu@0 {
+ sound-dai = <&rcar_sound 0>;
+ };
+ cpu@1 {
+ sound-dai = <&rcar_sound 1>;
+ };
+ codec {
+ ...
+ };
+ };
+
+ &rcar_sound {
+ ...
+ rcar_sound,dai {
+ dai0 {
+ playback = <&src1 &ctu02 &mix0 &dvc0 &ssi0>;
+ };
+ dai1 {
+ playback = <&src2 &ctu03 &mix0 &dvc0 &ssi0>;
+ };
+ };
+ };
+
+=============================================
+* DVC (Digital Volume and Mute Function)
+=============================================
+
+DVC controls Playback/Capture volume.
+
+Playback Volume
+ amixer set "DVC Out" 100%
+
+Capture Volume
+ amixer set "DVC In" 100%
+
+Playback Mute
+ amixer set "DVC Out Mute" on
+
+Capture Mute
+ amixer set "DVC In Mute" on
+
+Volume Ramp
+ amixer set "DVC Out Ramp Up Rate" "0.125 dB/64 steps"
+ amixer set "DVC Out Ramp Down Rate" "0.125 dB/512 steps"
+ amixer set "DVC Out Ramp" on
+ aplay xxx.wav &
+ amixer set "DVC Out" 80% // Volume Down
+ amixer set "DVC Out" 100% // Volume Up
+
+=============================================
+* SSIU (Serial Sound Interface Unit)
+=============================================
+
+There is no DT settings for SSIU, because SSIU will be automatically
+selected via SSI.
+SSIU can avoid some under/over run error, because it has some buffer.
+But you can't use it if SSI was PIO mode.
+In DMA mode, you can select not to use SSIU by using "no-busif" on DT.
+
+ &ssi0 {
+ no-busif;
+ };
+
+=============================================
+* SSI (Serial Sound Interface)
+=============================================
+
+** PIO mode
+
+You can use PIO mode which is for connection check by using.
+Note: The system will drop non-SSI modules in PIO mode
+even though if DT is selecting other modules.
+
+ &ssi0 {
+ pio-transfer
+ };
+
+** DMA mode without SSIU
+
+You can use DMA without SSIU.
+Note: under/over run, or noise are likely to occur
+
+ &ssi0 {
+ no-busif;
+ };
+
+** PIN sharing
+
+Each SSI can share WS pin. It is based on platform.
+This is example if SSI1 want to share WS pin with SSI0
+
+ &ssi1 {
+ shared-pin;
+ };
+
+** Multi-SSI
+
+You can use Multi-SSI.
+This is example of SSI0/SSI1/SSI2 (= for 6ch)
+
+ &rcar_sound {
+ ...
+ rcar_sound,dai {
+ dai0 {
+ playback = <&ssi0 &ssi1 &ssi2 &src0 &dvc0>;
+ };
+ };
+ };
+
+** TDM-SSI
+
+You can use TDM with SSI.
+This is example of TDM 6ch.
+Driver can automatically switches TDM <-> stereo mode in this case.
+
+ rsnd_tdm: sound {
+ compatible = "simple-audio-card";
+ ...
+ simple-audio-card,cpu {
+ /* system can use TDM 6ch */
+ dai-tdm-slot-num = <6>;
+ sound-dai = <&rcar_sound>;
+ };
+ simple-audio-card,codec {
+ ...
+ };
+ };
+
+
+=============================================
Required properties:
+=============================================
+
- compatible : "renesas,rcar_sound-<soctype>", fallbacks
"renesas,rcar_sound-gen1" if generation1, and
"renesas,rcar_sound-gen2" if generation2
- playback : list of playback modules
- capture : list of capture modules
+
+=============================================
Example:
+=============================================
rcar_sound: sound@ec500000 {
#sound-dai-cells = <1>;
};
};
+=============================================
Example: simple sound card
+=============================================
rsnd_ak4643: sound {
compatible = "simple-audio-card";
shared-pin;
};
+=============================================
Example: simple sound card for TDM
+=============================================
rsnd_tdm: sound {
compatible = "simple-audio-card";
};
};
+=============================================
Example: simple sound card for Multi channel
+=============================================
&rcar_sound {
pinctrl-0 = <&sound_pins &sound_clk_pins>;
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