[PATCH v2 00/17] ASoC: Add support for GPIOs driven amplifiers

Herve Codina
2026-04-29T07:44:10Z

On some embedded system boards, audio amplifiers are designed using
discrete components such as op-amp, several resistors and switches to
either adjust the gain (switching resistors) or fully switch the
audio signal path (mute and/or bypass features).

Those switches are usually driven by simple GPIOs.

This kind of amplifiers are not handled in ASoC and the fallback is to
let the user-space handle those GPIOs out of the ALSA world.

In order to have those kind of amplifiers fully integrated in the audio
stack, this series introduces the audio-gpio-amp to handle them.

This new ASoC component allows to have the amplifiers seen as ASoC
auxiliarty devices and so it allows to control them through audio mixer
controls.

Compared to previous iteration, this v2 series adds the gpio-ranges
device-tree property and removes no more needed properties. Also it
merges the previously proposed driver in the existing simple-amplifier
driver.

In order to ease the review, I choose to split modifications related
to the merge of the gpio-audio-amp part into the simple-amplfier driver
in several commits.

Best regards,
Hervé

Changes v1 -> v2
v1: https://lore.kernel.org/all/20260330101610.57942-1-herve.codina@bootlin.com/

Rebase on top of v7.1-rc1.

Patch 1:
- Add 'Acked-by: Rob Herring'

Patch 2:
- Use gpio-audio-amp-* instead of audio-gpio-amp
- Introduce mono/stereo channel distinction with gpio-audio-amp-mono
and gpio-audio-amp-stereo compatible strings (needed if the
"simple-amplifier" compatible string is deprecated in the near
future).
- Reduce the maximum numbers of gpios used for gain setting to 16.
- Use amplifier-N instead of amplifierN in examples
- Introduce gpio-ranges property and remove the no more needed
gpio-points and gpio-range properties

Other patches (full rework):
- Merge the new audio-gpio-amp driver provided in v1 into the
existing simple-amplifier driver.
- Slit modification in several commits.
- Reduce the maximum number of gpios used for gain setting to 16.
- Fix a memory leak in case of error in simple_amp_multi_add_kcontrol()
(Reported by Shahiko).
- Handle the new gpio-ranges property and drop the support for the no
more needed properties (gpio-points and gpio-range).
- Update author and copyright.

Herve Codina (17):
of: Introduce of_property_read_s32_index()
ASoC: dt-bindings: Add support for the GPIOs driven amplifier
ASoC: simple-amplifier: Remove DRV_NAME defined value
ASoC: simple-amplifier: Add missing headers
ASoC: simple-amplifier: Remove CONFIG_OF flag and of_match_ptr()
ASoC: simple-amplifier: Rename drv_event() function
ASoC: simple-amplifier: Use 'simple_amp' variable name instead of
'priv'
ASoC: simple-amplifier: Remove DAPM widgets and routes from the ASoC
component driver
ASoC: simple-amplifier: Introduce support for gpio-audio-amp
ASoC: simple-amplifier: gpio-audio-amp: Add support for extra power
supplies
ASoC: simple-amplifier: gpio-audio-amp: Add support for mute gpio
ASoC: simple-amplifier: gpio-audio-amp: Add support for bypass gpio
ASoC: simple-amplifier: gpio-audio-amp: Add support for basic gain
ASoC: simple-amplifier: gpio-audio-amp: Add support for gain-ranges
ASoC: simple-amplifier: gpio-audio-amp: Add support for gain-labels
ASoC: simple-amplifier: Update author and copyright
MAINTAINERS: Add the ASoC gpio audio amplifier entry

.../bindings/sound/gpio-audio-amp.yaml | 270 ++++++
MAINTAINERS | 7 +
include/linux/of.h | 7 +
sound/soc/codecs/simple-amplifier.c | 907 +++++++++++++++++-
4 files changed, 1165 insertions(+), 26 deletions(-)
create mode 100644 Documentation/devicetree/bindings/sound/gpio-audio-amp.yaml

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2.53.0