Commit f1511a14 authored by Kuninori Morimoto's avatar Kuninori Morimoto Committed by Mark Brown
Browse files

ASoC: rsnd: add simplified module explanation 



Renesas sound driver user needs to read its datasheet when create DT.
But it is difficult to understand, because it has many modules
(SRC/CTU/MIX/DVC/SSIU/SSI/AudioDMAC/AudioDMACperiperi),
and many features (Asynchronous/Synchronous mode on SRC, CTU matrix,
DVC volume settings feature, Multi-SSI/TDM-SSI, etc).
This patch adds simplified explanation to help setting/understanding.

Signed-off-by: default avatarKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 09e59075

Documentation/devicetree/bindings/sound/renesas,rsnd.txt

+340 −0
Original line number Diff line number Diff line 
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
@@ -64,7 +395,10 @@ DAI subnode properties: 
- playback			: list of playback modules

- capture			: list of capture  modules





=============================================

Example:

=============================================



rcar_sound: sound@ec500000 {

	#sound-dai-cells = <1>;
@@ -250,7 +584,9 @@ rcar_sound: sound@ec500000 { 
	};

};



=============================================

Example: simple sound card

=============================================



	rsnd_ak4643: sound {

		compatible = "simple-audio-card";
@@ -290,7 +626,9 @@ Example: simple sound card 
	shared-pin;

};



=============================================

Example: simple sound card for TDM

=============================================



	rsnd_tdm: sound {

		compatible = "simple-audio-card";
@@ -309,7 +647,9 @@ Example: simple sound card for TDM 
		};

	};



=============================================

Example: simple sound card for Multi channel

=============================================



&rcar_sound {

	pinctrl-0 = <&sound_pins &sound_clk_pins>;

sound/soc/sh/rcar/dvc.c

+23 −0
Original line number Diff line number Diff line
@@ -8,6 +8,29 @@ 
 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



/*

 * 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

 */



#include "rsnd.h"



#define RSND_DVC_NAME_SIZE	16

CRA Git | Maintained and supported by SUSTech CRA and CCSE