Apple Macs machine-level ASoC driver

From:		Martin Povišer <povik+lin-AT-cutebit.org>
To:		Liam Girdwood <lgirdwood-AT-gmail.com>, Mark Brown <broonie-AT-kernel.org>, Rob Herring <robh+dt-AT-kernel.org>, Krzysztof Kozlowski <krzk+dt-AT-kernel.org>, Jaroslav Kysela <perex-AT-perex.cz>, Takashi Iwai <tiwai-AT-suse.com>
Subject:		[RFC PATCH 0/5] Apple Macs machine-level ASoC driver
Date:		Thu, 31 Mar 2022 02:04:44 +0200
Message-ID:		<20220331000449.41062-1-povik+lin@cutebit.org>
Cc:		Martin Povišer <povik+lin-AT-cutebit.org>, alsa-devel-AT-alsa-project.org, devicetree-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org, Mark Kettenis <kettenis-AT-openbsd.org>, Hector Martin <marcan-AT-marcan.st>, Sven Peter <sven-AT-svenpeter.dev>
Archive-link:		Article

Hi,

I put together a machine-level ASoC driver for recent Apple Macs (the
ones with ARM64 SoCs) and want to gauge opinions.

Commit 1 is the binding. It is some subset of simple-audio-card with
the extra distinction of allowing multiple CPU/CODEC DAIs per a DAI
link. I want to draw special attention to the issue of describing
speaker topologies. The way it now works is that the driver expects
the speakers to be declared in a fixed order in the sound-dai= list.
This populates a topology the driver expects on a particular machine
model. Mark (in CC) has made the suggestion of keeping the topology
descriptions with the codec nodes themselves in some generic manner,
akin to how sound-name-prefix= already helps identify codecs to the
user.

Commit 2 adds a new ASoC card method (filter_controls) to let the card
prevent some codec kcontrols from being visible to userspace. For example
the TAS2770 speaker amp driver would be happy to expose TDM slot selection
and ISENSE/VSENSE enables which is ridiculous. I am all ears on how to
make the patch acceptable to upstream.

Commit 3 makes ASoC tolerate N-to-M DAI links, not sure what the right
(simple) approach should be there. Commit 4 adds some utility function
and commit 5 is the driver itself.

Let me know what you think.

Martin

Martin Povišer (5):
  dt-bindings: sound: Add Apple Macs sound system
  HACK: ASoC: Add card->filter_controls hook
  HACK: ASoC: Tolerate N-cpus-to-M-codecs links
  ASoC: Introduce snd_soc_of_get_dai_link_cpus
  ASoC: Add macaudio machine driver

 .../bindings/sound/apple,macaudio.yaml        | 103 +++
 include/sound/soc.h                           |   7 +
 sound/soc/apple/Kconfig                       |  10 +
 sound/soc/apple/Makefile                      |   3 +
 sound/soc/apple/macaudio.c                    | 597 ++++++++++++++++++
 sound/soc/soc-core.c                          | 125 +++-
 sound/soc/soc-dapm.c                          |  34 +-
 sound/soc/soc-pcm.c                           |   3 +
 8 files changed, 860 insertions(+), 22 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/sound/apple,macaudio.yaml
 create mode 100644 sound/soc/apple/Kconfig
 create mode 100644 sound/soc/apple/Makefile
 create mode 100644 sound/soc/apple/macaudio.c

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2.33.0