ASoC: Docs: Update codec documentation
Update the codec class driver documentation and bring it up to date with the current code base. This includes API changes, regmap and multi component. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com> Signed-off-by: Mark Brown <broonie@linaro.org>
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ASoC Codec Driver
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ASoC Codec Class Driver
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=================
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=======================
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The codec driver is generic and hardware independent code that configures the
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The codec class driver is generic and hardware independent code that configures
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codec to provide audio capture and playback. It should contain no code that is
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the codec, FM, MODEM, BT or external DSP to provide audio capture and playback.
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specific to the target platform or machine. All platform and machine specific
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It should contain no code that is specific to the target platform or machine.
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code should be added to the platform and machine drivers respectively.
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All platform and machine specific code should be added to the platform and
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machine drivers respectively.
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Each codec driver *must* provide the following features:-
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Each codec class driver *must* provide the following features:-
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1) Codec DAI and PCM configuration
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1) Codec DAI and PCM configuration
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2) Codec control IO - using I2C, 3 Wire(SPI) or both APIs
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2) Codec control IO - using RegMap API
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3) Mixers and audio controls
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3) Mixers and audio controls
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4) Codec audio operations
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4) Codec audio operations
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5) DAPM description.
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6) DAPM event handler.
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Optionally, codec drivers can also provide:-
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Optionally, codec drivers can also provide:-
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5) DAPM description.
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6) DAPM event handler.
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7) DAC Digital mute control.
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7) DAC Digital mute control.
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Its probably best to use this guide in conjunction with the existing codec
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Its probably best to use this guide in conjunction with the existing codec
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@ -64,26 +65,9 @@ struct snd_soc_dai_driver wm8731_dai = {
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2 - Codec control IO
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2 - Codec control IO
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--------------------
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--------------------
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The codec can usually be controlled via an I2C or SPI style interface
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The codec can usually be controlled via an I2C or SPI style interface
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(AC97 combines control with data in the DAI). The codec drivers provide
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(AC97 combines control with data in the DAI). The codec driver should use the
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functions to read and write the codec registers along with supplying a
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Regmap API for all codec IO. Please see include/linux/regmap.h and existing
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register cache:-
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codec drivers for example regmap usage.
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/* IO control data and register cache */
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void *control_data; /* codec control (i2c/3wire) data */
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void *reg_cache;
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Codec read/write should do any data formatting and call the hardware
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read write below to perform the IO. These functions are called by the
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core and ALSA when performing DAPM or changing the mixer:-
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unsigned int (*read)(struct snd_soc_codec *, unsigned int);
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int (*write)(struct snd_soc_codec *, unsigned int, unsigned int);
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Codec hardware IO functions - usually points to either the I2C, SPI or AC97
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read/write:-
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hw_write_t hw_write;
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hw_read_t hw_read;
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3 - Mixers and audio controls
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3 - Mixers and audio controls
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@ -127,7 +111,7 @@ Defines a stereo enumerated control
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4 - Codec Audio Operations
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4 - Codec Audio Operations
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--------------------------
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--------------------------
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The codec driver also supports the following ALSA operations:-
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The codec driver also supports the following ALSA PCM operations:-
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/* SoC audio ops */
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/* SoC audio ops */
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struct snd_soc_ops {
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struct snd_soc_ops {
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