diff mbox series

[RFC,v2,5/5] ASoC: apple: Add macaudio machine driver

Message ID 20220606191910.16580-6-povik+lin@cutebit.org
State New
Headers show
Series Apple Macs machine/platform ASoC driver | expand

Commit Message

Martin Povišer June 6, 2022, 7:19 p.m. UTC 
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
---
 sound/soc/apple/Kconfig    |   16 +
 sound/soc/apple/Makefile   |    2 +
 sound/soc/apple/macaudio.c | 1004 ++++++++++++++++++++++++++++++++++++
 3 files changed, 1022 insertions(+)
 create mode 100644 sound/soc/apple/macaudio.c

Comments

Mark Brown June 9, 2022, 1:16 p.m. UTC | #1 
On Mon, Jun 06, 2022 at 09:19:10PM +0200, Martin Povišer wrote:

> + *  ┌──────────┐       ┌───────────────► ┌─────┐     ┌──────────┐
> + *  │ Primary  ├───────┤                 │ Mux │ ──► │ Speakers │
> + *  └──────────┘       │    ┌──────────► └─────┘     └──────────┘
> + *                ┌─── │ ───┘             ▲
> + *  ┌──────────┐  │    │                  │
> + *  │Secondary ├──┘    │     ┌────────────┴┐
> + *  └──────────┘       ├────►│Plug-in Demux│
> + *                     │     └────────────┬┘
> + *                     │                  │
> + *                     │                  ▼
> + *                     │                 ┌─────┐     ┌──────────┐
> + *                     └───────────────► │ Mux │ ──► │Headphones│
> + *                                       └─────┘     └──────────┘

As far as I can tell this demux is entirely software based - why not
just expose the routing control to userspace and let it handle
switching (which I suspect may be more featureful than what's
implemented here)?

> +static int macaudio_jack_event(struct notifier_block *nb, unsigned long event,
> +                               void *data)
> +{
> +       struct snd_soc_jack *jack = data;
> +       struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(jack->card);
> +
> +       ma->jack_plugin_state = !!event;
> +
> +       if (!ma->plugin_demux_kcontrol)
> +               return 0;
> +
> +       snd_soc_dapm_mux_update_power(&ma->card.dapm, ma->plugin_demux_kcontrol,
> +                                     ma->jack_plugin_state,
> +                                     (struct soc_enum *) &macaudio_plugin_demux_enum, NULL);
> +
> +       return 0;
> +}

This should be integrated with the core jack detection stuff in
soc-jack.c and/or the core stuff that's wrapping - that way you'll
ensure that events are generated and status readable via all the
interfaces userspace might be looking for.  The ASoC stuff also has some
DAPM integration for turning on/off outputs which might DTRT for you if
you do need it in kernel.
Mark Brown June 9, 2022, 1:33 p.m. UTC | #2 
On Mon, Jun 06, 2022 at 09:19:10PM +0200, Martin Povišer wrote:

> +		/*
> +		 * Primary FE
> +		 *
> +		 * The mclk/fs ratio at 64 for the primary frontend is important
> +		 * to ensure that the headphones codec's idea of left and right
> +		 * in a stereo stream over I2S fits in nicely with everyone else's.
> +		 * (This is until the headphones codec's driver supports
> +		 * set_tdm_slot.)
> +		 *
> +		 * The low mclk/fs ratio precludes transmitting more than two
> +		 * channels over I2S, but that's okay since there is the secondary
> +		 * FE for speaker arrays anyway.
> +		 */
> +		.mclk_fs = 64,
> +	},

This seems weird - it looks like it's confusing MCLK and the bit clock
for the audio bus.  These are two different clocks.  Note that it's very
common for devices to require a higher MCLK/fs ratio to deliver the best
audio performance, 256fs is standard.

> +	{
> +		/*
> +		 * Secondary FE
> +		 *
> +		 * Here we want frames plenty long to be able to drive all
> +		 * those fancy speaker arrays.
> +		 */
> +		.mclk_fs = 256,
> +	}

Same thing here - this is at least confusing MCLK and the bit clock.

> +static bool macaudio_match_kctl_name(const char *pattern, const char *name)
> +{
> +	if (pattern[0] == '*') {
> +		int namelen, patternlen;
> +
> +		pattern++;
> +		if (pattern[0] == ' ')
> +			pattern++;
> +
> +		namelen = strlen(name);
> +		patternlen = strlen(pattern);
> +
> +		if (namelen > patternlen)
> +			name += (namelen - patternlen);
> +	}
> +
> +	return !strcmp(name, pattern);
> +}
> +
> +static int macaudio_limit_volume(struct snd_soc_card *card,
> +				 const char *pattern, int max)
> +{
> +	struct snd_kcontrol *kctl;
> +	struct soc_mixer_control *mc;
> +	int found = 0;
> +
> +	list_for_each_entry(kctl, &card->snd_card->controls, list) {
> +		if (!macaudio_match_kctl_name(pattern, kctl->id.name))
> +			continue;
> +
> +		found++;
> +		dev_dbg(card->dev, "limiting volume on '%s'\n", kctl->id.name);
> +
> +		/*
> +		 * TODO: This doesn't decrease the volume if it's already
> +		 * above the limit!
> +		 */
> +		mc = (struct soc_mixer_control *)kctl->private_value;
> +		if (max <= mc->max)
> +			mc->platform_max = max;
> +
> +	}
> +
> +	return found;
> +}

This shouldn't be open coded in a driver, please factor it out into the
core so we've got an API for "set limit X on control Y" then call that.
Martin Povišer June 9, 2022, 1:42 p.m. UTC | #3 
> On 9. 6. 2022, at 15:16, Mark Brown <broonie@kernel.org> wrote:
> 
> On Mon, Jun 06, 2022 at 09:19:10PM +0200, Martin Povišer wrote:
> 
>> + *  ┌──────────┐       ┌───────────────► ┌─────┐     ┌──────────┐
>> + *  │ Primary  ├───────┤                 │ Mux │ ──► │ Speakers │
>> + *  └──────────┘       │    ┌──────────► └─────┘     └──────────┘
>> + *                ┌─── │ ───┘             ▲
>> + *  ┌──────────┐  │    │                  │
>> + *  │Secondary ├──┘    │     ┌────────────┴┐
>> + *  └──────────┘       ├────►│Plug-in Demux│
>> + *                     │     └────────────┬┘
>> + *                     │                  │
>> + *                     │                  ▼
>> + *                     │                 ┌─────┐     ┌──────────┐
>> + *                     └───────────────► │ Mux │ ──► │Headphones│
>> + *                                       └─────┘     └──────────┘
> 
> As far as I can tell this demux is entirely software based - why not
> just expose the routing control to userspace and let it handle
> switching (which I suspect may be more featureful than what's
> implemented here)?

Well, userspace should have the other two muxes at its disposal to
implement any routing/switching it wishes -- but in addition we are
also offering letting kernel take care of the switching, by pointing
the muxes to the demux.

I assume (but I don’t know the extent of what’s possible with UCM files),
that this will be of some value to users running plain ALSA with no
sound server.

>> +static int macaudio_jack_event(struct notifier_block *nb, unsigned long event,
>> +                               void *data)
>> +{
>> +       struct snd_soc_jack *jack = data;
>> +       struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(jack->card);
>> +
>> +       ma->jack_plugin_state = !!event;
>> +
>> +       if (!ma->plugin_demux_kcontrol)
>> +               return 0;
>> +
>> +       snd_soc_dapm_mux_update_power(&ma->card.dapm, ma->plugin_demux_kcontrol,
>> +                                     ma->jack_plugin_state,
>> +                                     (struct soc_enum *) &macaudio_plugin_demux_enum, NULL);
>> +
>> +       return 0;
>> +}
> 
> This should be integrated with the core jack detection stuff in
> soc-jack.c and/or the core stuff that's wrapping - that way you'll
> ensure that events are generated and status readable via all the
> interfaces userspace might be looking for.  The ASoC stuff also has some
> DAPM integration for turning on/off outputs which might DTRT for you if
> you do need it in kernel.

Aren’t all the right events to userspace generated already by the
codec calling snd_soc_jack_report?

I looked at the existing DAPM integration but I couldn’t figure out
how to switch the demux with it.
Martin Povišer June 9, 2022, 2:09 p.m. UTC | #4 
> On 9. 6. 2022, at 15:33, Mark Brown <broonie@kernel.org> wrote:
> 
> On Mon, Jun 06, 2022 at 09:19:10PM +0200, Martin Povišer wrote:
> 
>> +		/*
>> +		 * Primary FE
>> +		 *
>> +		 * The mclk/fs ratio at 64 for the primary frontend is important
>> +		 * to ensure that the headphones codec's idea of left and right
>> +		 * in a stereo stream over I2S fits in nicely with everyone else's.
>> +		 * (This is until the headphones codec's driver supports
>> +		 * set_tdm_slot.)
>> +		 *
>> +		 * The low mclk/fs ratio precludes transmitting more than two
>> +		 * channels over I2S, but that's okay since there is the secondary
>> +		 * FE for speaker arrays anyway.
>> +		 */
>> +		.mclk_fs = 64,
>> +	},
> 
> This seems weird - it looks like it's confusing MCLK and the bit clock
> for the audio bus.  These are two different clocks.  Note that it's very
> common for devices to require a higher MCLK/fs ratio to deliver the best
> audio performance, 256fs is standard.

On these machines we are not producing any other clock for the codecs
besides the bit clock, so I am using MCLK interchangeably for it. (It is
what the sample rate is derived from after all.)

One of the codec drivers this is to be used with (cs42l42) expects to be
given the I2S bit clock with

  snd_soc_dai_set_sysclk(dai, 0, mclk, SND_SOC_CLOCK_IN);

I can rename mclk to bclk in all of the code to make it clearer maybe.
Also the platform driver can take the bit clock value from set_bclk_ratio,
instead of set_sysclk from where it takes it now. The cs42l42 driver I can
patch too to accept set_bclk_ratio.

>> +	{
>> +		/*
>> +		 * Secondary FE
>> +		 *
>> +		 * Here we want frames plenty long to be able to drive all
>> +		 * those fancy speaker arrays.
>> +		 */
>> +		.mclk_fs = 256,
>> +	}
> 
> Same thing here - this is at least confusing MCLK and the bit clock.
> 
>> +static bool macaudio_match_kctl_name(const char *pattern, const char *name)
>> +{
>> +	if (pattern[0] == '*') {
>> +		int namelen, patternlen;
>> +
>> +		pattern++;
>> +		if (pattern[0] == ' ')
>> +			pattern++;
>> +
>> +		namelen = strlen(name);
>> +		patternlen = strlen(pattern);
>> +
>> +		if (namelen > patternlen)
>> +			name += (namelen - patternlen);
>> +	}
>> +
>> +	return !strcmp(name, pattern);
>> +}
>> +
>> +static int macaudio_limit_volume(struct snd_soc_card *card,
>> +				 const char *pattern, int max)
>> +{
>> +	struct snd_kcontrol *kctl;
>> +	struct soc_mixer_control *mc;
>> +	int found = 0;
>> +
>> +	list_for_each_entry(kctl, &card->snd_card->controls, list) {
>> +		if (!macaudio_match_kctl_name(pattern, kctl->id.name))
>> +			continue;
>> +
>> +		found++;
>> +		dev_dbg(card->dev, "limiting volume on '%s'\n", kctl->id.name);
>> +
>> +		/*
>> +		 * TODO: This doesn't decrease the volume if it's already
>> +		 * above the limit!
>> +		 */
>> +		mc = (struct soc_mixer_control *)kctl->private_value;
>> +		if (max <= mc->max)
>> +			mc->platform_max = max;
>> +
>> +	}
>> +
>> +	return found;
>> +}
> 
> This shouldn't be open coded in a driver, please factor it out into the
> core so we've got an API for "set limit X on control Y" then call that.

There’s already snd_soc_limit_volume, but it takes a fixed control name.
Can I extend it to understand patterns beginning with a wildcard, like
'* Amp Gain Volume’?
Mark Brown June 9, 2022, 3:03 p.m. UTC | #5 
On Thu, Jun 09, 2022 at 03:42:09PM +0200, Martin Povišer wrote:
> > On 9. 6. 2022, at 15:16, Mark Brown <broonie@kernel.org> wrote:

> > As far as I can tell this demux is entirely software based - why not
> > just expose the routing control to userspace and let it handle
> > switching (which I suspect may be more featureful than what's
> > implemented here)?

> Well, userspace should have the other two muxes at its disposal to
> implement any routing/switching it wishes -- but in addition we are
> also offering letting kernel take care of the switching, by pointing
> the muxes to the demux.

> I assume (but I don’t know the extent of what’s possible with UCM files),
> that this will be of some value to users running plain ALSA with no
> sound server.

That's basically no userspaces at this point TBH.  I'm not convinced
it's a good idea to be adding custom code for that use case.

> > This should be integrated with the core jack detection stuff in
> > soc-jack.c and/or the core stuff that's wrapping - that way you'll
> > ensure that events are generated and status readable via all the
> > interfaces userspace might be looking for.  The ASoC stuff also has some
> > DAPM integration for turning on/off outputs which might DTRT for you if
> > you do need it in kernel.

> Aren’t all the right events to userspace generated already by the
> codec calling snd_soc_jack_report?

I wasn't able to find any references to snd_soc_jack_report() in your
series?

> I looked at the existing DAPM integration but I couldn’t figure out
> how to switch the demux with it.

Yes, it won't do that.  If you can't stream the same audio to both then
you'd need something else.
Mark Brown June 9, 2022, 3:16 p.m. UTC | #6 
On Thu, Jun 09, 2022 at 04:09:57PM +0200, Martin Povišer wrote:
> > On 9. 6. 2022, at 15:33, Mark Brown <broonie@kernel.org> wrote:

> >> +		/*
> >> +		 * Primary FE
> >> +		 *
> >> +		 * The mclk/fs ratio at 64 for the primary frontend is important
> >> +		 * to ensure that the headphones codec's idea of left and right
> >> +		 * in a stereo stream over I2S fits in nicely with everyone else's.
> >> +		 * (This is until the headphones codec's driver supports
> >> +		 * set_tdm_slot.)
> >> +		 *
> >> +		 * The low mclk/fs ratio precludes transmitting more than two
> >> +		 * channels over I2S, but that's okay since there is the secondary
> >> +		 * FE for speaker arrays anyway.
> >> +		 */
> >> +		.mclk_fs = 64,
> >> +	},

> > This seems weird - it looks like it's confusing MCLK and the bit clock
> > for the audio bus.  These are two different clocks.  Note that it's very
> > common for devices to require a higher MCLK/fs ratio to deliver the best
> > audio performance, 256fs is standard.

> On these machines we are not producing any other clock for the codecs
> besides the bit clock, so I am using MCLK interchangeably for it. (It is
> what the sample rate is derived from after all.)

Please don't do this, you're just making everything needlessly hard to
understand by using standard terminology inappropriately and there's a
risk of breakage further down the line with drivers implementing the
standard ops.

> One of the codec drivers this is to be used with (cs42l42) expects to be
> given the I2S bit clock with

>   snd_soc_dai_set_sysclk(dai, 0, mclk, SND_SOC_CLOCK_IN);

That's very, very non-standard...

> I can rename mclk to bclk in all of the code to make it clearer maybe.
> Also the platform driver can take the bit clock value from set_bclk_ratio,
> instead of set_sysclk from where it takes it now. The cs42l42 driver I can
> patch too to accept set_bclk_ratio.

...indeed, set_bclk_ratio() is a better interface for setting the bclk
ratio - the CODEC driver should really be doing that as well.

> > This shouldn't be open coded in a driver, please factor it out into the
> > core so we've got an API for "set limit X on control Y" then call that.

> There’s already snd_soc_limit_volume, but it takes a fixed control name.
> Can I extend it to understand patterns beginning with a wildcard, like
> '* Amp Gain Volume’?

Or add a new call that does that.
Martin Povišer June 9, 2022, 3:27 p.m. UTC | #7 
> On 9. 6. 2022, at 17:16, Mark Brown <broonie@kernel.org> wrote:
> 
> On Thu, Jun 09, 2022 at 04:09:57PM +0200, Martin Povišer wrote:
>>> On 9. 6. 2022, at 15:33, Mark Brown <broonie@kernel.org> wrote:
> 
>>>> +		/*
>>>> +		 * Primary FE
>>>> +		 *
>>>> +		 * The mclk/fs ratio at 64 for the primary frontend is important
>>>> +		 * to ensure that the headphones codec's idea of left and right
>>>> +		 * in a stereo stream over I2S fits in nicely with everyone else's.
>>>> +		 * (This is until the headphones codec's driver supports
>>>> +		 * set_tdm_slot.)
>>>> +		 *
>>>> +		 * The low mclk/fs ratio precludes transmitting more than two
>>>> +		 * channels over I2S, but that's okay since there is the secondary
>>>> +		 * FE for speaker arrays anyway.
>>>> +		 */
>>>> +		.mclk_fs = 64,
>>>> +	},
> 
>>> This seems weird - it looks like it's confusing MCLK and the bit clock
>>> for the audio bus.  These are two different clocks.  Note that it's very
>>> common for devices to require a higher MCLK/fs ratio to deliver the best
>>> audio performance, 256fs is standard.
> 
>> On these machines we are not producing any other clock for the codecs
>> besides the bit clock, so I am using MCLK interchangeably for it. (It is
>> what the sample rate is derived from after all.)
> 
> Please don't do this, you're just making everything needlessly hard to
> understand by using standard terminology inappropriately and there's a
> risk of breakage further down the line with drivers implementing the
> standard ops.

OK

>> One of the codec drivers this is to be used with (cs42l42) expects to be
>> given the I2S bit clock with
> 
>>  snd_soc_dai_set_sysclk(dai, 0, mclk, SND_SOC_CLOCK_IN);
> 
> That's very, very non-standard...
> 
>> I can rename mclk to bclk in all of the code to make it clearer maybe.
>> Also the platform driver can take the bit clock value from set_bclk_ratio,
>> instead of set_sysclk from where it takes it now. The cs42l42 driver I can
>> patch too to accept set_bclk_ratio.
> 
> ...indeed, set_bclk_ratio() is a better interface for setting the bclk
> ratio - the CODEC driver should really be doing that as well.

OK, adding that to my TODOs.

>>> This shouldn't be open coded in a driver, please factor it out into the
>>> core so we've got an API for "set limit X on control Y" then call that.
> 
>> There’s already snd_soc_limit_volume, but it takes a fixed control name.
>> Can I extend it to understand patterns beginning with a wildcard, like
>> '* Amp Gain Volume’?
> 
> Or add a new call that does that.

OK
Martin Povišer June 9, 2022, 4:19 p.m. UTC | #8 
> On 9. 6. 2022, at 17:50, Mark Brown <broonie@kernel.org> wrote:
> 
> On Thu, Jun 09, 2022 at 05:24:49PM +0200, Martin Povišer wrote:
>>> On 9. 6. 2022, at 17:03, Mark Brown <broonie@kernel.org> wrote:
> 
> Why is this off list?

By accident, added the CC list back with this reply (hopefully it
still attaches to the thread when people receive it).

>>> That's basically no userspaces at this point TBH.  I'm not convinced
>>> it's a good idea to be adding custom code for that use case.
>> 
>> FWIW I know of at least one user of the WIP audio support on Macs who
>> would welcome this feature. My preference is to keep it in, but in
>> the end I guess it’s your call.
> 
> I'd rather not have this open coded in individual drivers, we already
> have an unfortunate abundance of jack detection interfaces.  If we're
> going to add anything I'd rather it were in core code and TBH I'm
> struggling to be enthusiastic.

Noted.

> Can you say anything more about the use case?

I can restate: The alleged use case is running userspace without sound
server, but having playback switch transparently between speakers and
headphones even mid-stream based on jack detection.

>>>> I looked at the existing DAPM integration but I couldn’t figure out
>>>> how to switch the demux with it.
> 
>>> Yes, it won't do that.  If you can't stream the same audio to both then
>>> you'd need something else.
> 
>> I don’t understand what’s meant by streaming the same audio here.
> 
> Playing one audio stream from the host which appears on both speakers
> and headphones - I don't know what the mixing and muxing capabilities of
> the hardware are.
> 
>> Taking a guess: The existing DAPM integration can enable the headphones
>> path based on jack being plugged in, but it can’t disable the speakers
>> path like the demux does?
> 
> No, that works perfectly fine - you can enable or disable pins depending
> on the jack state.

Ah, I peeked into soc-jack.c. What about this then: If I understand what
pins represent, they would be at the remote end of the DAPM paths. So if
for the speakers I add something like

   Headphones Codec Out —> Jack pin

                       +--> Always-on pin
                       |
   Speaker Amp Out -> Mux
                       |
                       +--> Jack inverted pin

and let userspace control the mux, it would in effect support the same
use cases as what I attempted in the code so far. Sounds somewhat right?
Mark Brown June 9, 2022, 4:35 p.m. UTC | #9 
On Thu, Jun 09, 2022 at 06:19:37PM +0200, Martin Povišer wrote:
> > On 9. 6. 2022, at 17:50, Mark Brown <broonie@kernel.org> wrote:

> > Can you say anything more about the use case?

> I can restate: The alleged use case is running userspace without sound
> server, but having playback switch transparently between speakers and
> headphones even mid-stream based on jack detection.

Sure, but why?

> > No, that works perfectly fine - you can enable or disable pins depending
> > on the jack state.

> Ah, I peeked into soc-jack.c. What about this then: If I understand what
> pins represent, they would be at the remote end of the DAPM paths. So if
> for the speakers I add something like

>    Headphones Codec Out —> Jack pin
> 
>                        +--> Always-on pin
>                        |
>    Speaker Amp Out -> Mux
>                        |
>                        +--> Jack inverted pin

> and let userspace control the mux, it would in effect support the same
> use cases as what I attempted in the code so far. Sounds somewhat right?

Yes, that should DTRT.  If the mux is working properly with DAPM (not
sure it does with DPCM but ICBW) then you shouldn't even need the jack
integration since the mux would disconnect the unused output when it
gets switched.
diff mbox series

Patch

diff --git a/sound/soc/apple/Kconfig b/sound/soc/apple/Kconfig
index 0ba955657e98..8db30569af9c 100644
--- a/sound/soc/apple/Kconfig
+++ b/sound/soc/apple/Kconfig
@@ -1,3 +1,19 @@ 
+config SND_SOC_APPLE_MACAUDIO
+	tristate "Audio support for Apple Silicon Macs"
+	depends on ARCH_APPLE || COMPILE_TEST
+	select SND_SOC_APPLE_MCA
+	select SND_SIMPLE_CARD_UTILS
+	select APPLE_ADMAC
+	select COMMON_CLK_APPLE_NCO
+	select SND_SOC_TAS2764
+	select SND_SOC_TAS2770
+	select SND_SOC_CS42L42
+	default ARCH_APPLE
+	help
+	  This option enables an ASoC machine-level driver for Apple Silicon Macs
+	  and it also enables the required SoC and codec drivers for overall
+	  sound support on these machines.
+
 config SND_SOC_APPLE_MCA
 	tristate "Apple Silicon MCA driver"
 	depends on ARCH_APPLE || COMPILE_TEST
diff --git a/sound/soc/apple/Makefile b/sound/soc/apple/Makefile
index 7a30bf452817..3ffb19ed1d0a 100644
--- a/sound/soc/apple/Makefile
+++ b/sound/soc/apple/Makefile
@@ -1,3 +1,5 @@ 
 snd-soc-apple-mca-objs	:= mca.o
+snd-soc-macaudio-objs	:= macaudio.o
 
+obj-$(CONFIG_SND_SOC_APPLE_MACAUDIO)	+= snd-soc-macaudio.o
 obj-$(CONFIG_SND_SOC_APPLE_MCA)	+= snd-soc-apple-mca.o
diff --git a/sound/soc/apple/macaudio.c b/sound/soc/apple/macaudio.c
new file mode 100644
index 000000000000..24a7200e06f6
--- /dev/null
+++ b/sound/soc/apple/macaudio.c
@@ -0,0 +1,1004 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ASoC machine driver for Apple Silicon Macs
+ *
+ * Copyright (C) The Asahi Linux Contributors
+ *
+ * Based on sound/soc/qcom/{sc7180.c|common.c}
+ *
+ * Copyright (c) 2018, Linaro Limited.
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ *
+ *
+ * Virtual FE/BE Playback Topology
+ * -------------------------------
+ *
+ * The platform driver has independent frontend and backend DAIs with the
+ * option of routing backends to any of the frontends. The platform
+ * driver configures the routing based on DPCM couplings in ASoC runtime
+ * structures, which in turn is determined from DAPM paths by ASoC. But the
+ * platform driver doesn't supply relevant DAPM paths and leaves that up for
+ * the machine driver to fill in. The filled-in virtual topology can be
+ * anything as long as a particular backend isn't connected to more than one
+ * frontend at any given time. (The limitation is due to the unsupported case
+ * of reparenting of live BEs.)
+ *
+ * The DAPM routing that this machine-level driver makes up has two use-cases
+ * in mind:
+ *
+ * - Using a single PCM for playback such that it conditionally sinks to either
+ *   speakers or headphones based on the plug-in state of the headphones jack.
+ *   All the while making the switch transparent to userspace. This has the
+ *   drawback of requiring a sample stream suited for both speakers and
+ *   headphones, which is hard to come by on machines where tailored DSP for
+ *   speakers in userspace is desirable or required.
+ *
+ * - Driving the headphones and speakers from distinct PCMs, having userspace
+ *   bridge the difference and apply different signal processing to the two.
+ *
+ * In the end the topology supplied by this driver looks like this:
+ *
+ *  PCMs (frontends)                   I2S Port Groups (backends)
+ *  ────────────────                   ──────────────────────────
+ *
+ *  ┌──────────┐       ┌───────────────► ┌─────┐     ┌──────────┐
+ *  │ Primary  ├───────┤                 │ Mux │ ──► │ Speakers │
+ *  └──────────┘       │    ┌──────────► └─────┘     └──────────┘
+ *                ┌─── │ ───┘             ▲
+ *  ┌──────────┐  │    │                  │
+ *  │Secondary ├──┘    │     ┌────────────┴┐
+ *  └──────────┘       ├────►│Plug-in Demux│
+ *                     │     └────────────┬┘
+ *                     │                  │
+ *                     │                  ▼
+ *                     │                 ┌─────┐     ┌──────────┐
+ *                     └───────────────► │ Mux │ ──► │Headphones│
+ *                                       └─────┘     └──────────┘
+ */
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <sound/core.h>
+#include <sound/jack.h>
+#include <sound/pcm.h>
+#include <sound/simple_card_utils.h>
+#include <sound/soc.h>
+#include <uapi/linux/input-event-codes.h>
+
+#define DRIVER_NAME "snd-soc-macaudio"
+
+/*
+ * CPU side is bit and frame clock provider
+ * I2S has both clocks inverted
+ */
+#define MACAUDIO_DAI_FMT	(SND_SOC_DAIFMT_I2S | \
+				 SND_SOC_DAIFMT_CBC_CFC | \
+				 SND_SOC_DAIFMT_GATED | \
+				 SND_SOC_DAIFMT_IB_IF)
+#define MACAUDIO_JACK_MASK	(SND_JACK_HEADSET | SND_JACK_HEADPHONE)
+#define MACAUDIO_SLOTWIDTH	32
+
+struct macaudio_model_data {
+	bool deactive_asi1_sel;
+	int spk_amp_gain_max;
+};
+
+struct macaudio_snd_data {
+	struct snd_soc_card card;
+	struct snd_soc_jack_pin pin;
+	struct snd_soc_jack jack;
+	int jack_plugin_state;
+	struct snd_kcontrol *plugin_demux_kcontrol;
+
+	struct macaudio_link_props {
+		/* frontend props */
+		unsigned int mclk_fs;
+
+		/* backend props */
+		bool is_speakers;
+		bool is_headphones;
+		unsigned int tdm_mask;
+	} *link_props;
+
+	unsigned int speaker_nchans_array[2];
+	struct snd_pcm_hw_constraint_list speaker_nchans_list;
+
+	struct macaudio_model_data *mdata;
+};
+
+static bool void_warranty;
+module_param(void_warranty, bool, 0644);
+MODULE_PARM_DESC(void_warranty, "Keep going even without speaker volume safety caps");
+
+SND_SOC_DAILINK_DEFS(primary,
+	DAILINK_COMP_ARRAY(COMP_CPU("mca-pcm-0")), // CPU
+	DAILINK_COMP_ARRAY(COMP_DUMMY()), // CODEC
+	DAILINK_COMP_ARRAY(COMP_EMPTY())); // platform (filled at runtime)
+
+SND_SOC_DAILINK_DEFS(secondary,
+	DAILINK_COMP_ARRAY(COMP_CPU("mca-pcm-1")), // CPU
+	DAILINK_COMP_ARRAY(COMP_DUMMY()), // CODEC
+	DAILINK_COMP_ARRAY(COMP_EMPTY()));
+
+static struct snd_soc_dai_link macaudio_fe_links[] = {
+	{
+		.name = "Primary",
+		.stream_name = "Primary",
+		.dynamic = 1,
+		.dpcm_playback = 1,
+		.dpcm_capture = 1,
+		.dpcm_merged_rate = 1,
+		.dpcm_merged_chan = 1,
+		.dpcm_merged_format = 1,
+		.dai_fmt = MACAUDIO_DAI_FMT,
+		SND_SOC_DAILINK_REG(primary),
+	},
+	{
+		.name = "Secondary",
+		.stream_name = "Secondary",
+		.dynamic = 1,
+		.dpcm_playback = 1,
+		.dpcm_merged_rate = 1,
+		.dpcm_merged_chan = 1,
+		.dpcm_merged_format = 1,
+		.dai_fmt = MACAUDIO_DAI_FMT,
+		SND_SOC_DAILINK_REG(secondary),
+	},
+};
+
+static struct macaudio_link_props macaudio_fe_link_props[] = {
+	{
+		/*
+		 * Primary FE
+		 *
+		 * The mclk/fs ratio at 64 for the primary frontend is important
+		 * to ensure that the headphones codec's idea of left and right
+		 * in a stereo stream over I2S fits in nicely with everyone else's.
+		 * (This is until the headphones codec's driver supports
+		 * set_tdm_slot.)
+		 *
+		 * The low mclk/fs ratio precludes transmitting more than two
+		 * channels over I2S, but that's okay since there is the secondary
+		 * FE for speaker arrays anyway.
+		 */
+		.mclk_fs = 64,
+	},
+	{
+		/*
+		 * Secondary FE
+		 *
+		 * Here we want frames plenty long to be able to drive all
+		 * those fancy speaker arrays.
+		 */
+		.mclk_fs = 256,
+	}
+};
+
+static int macaudio_copy_link(struct device *dev, struct snd_soc_dai_link *target,
+			       struct snd_soc_dai_link *source)
+{
+	memcpy(target, source, sizeof(struct snd_soc_dai_link));
+
+	target->cpus = devm_kcalloc(dev, target->num_cpus,
+				sizeof(*target->cpus), GFP_KERNEL);
+	target->codecs = devm_kcalloc(dev, target->num_codecs,
+				sizeof(*target->codecs), GFP_KERNEL);
+	target->platforms = devm_kcalloc(dev, target->num_platforms,
+				sizeof(*target->platforms), GFP_KERNEL);
+
+	if (!target->cpus || !target->codecs || !target->platforms)
+		return -ENOMEM;
+
+	memcpy(target->cpus, source->cpus, sizeof(*target->cpus) * target->num_cpus);
+	memcpy(target->codecs, source->codecs, sizeof(*target->codecs) * target->num_codecs);
+	memcpy(target->platforms, source->platforms, sizeof(*target->platforms) * target->num_platforms);
+
+	return 0;
+}
+
+static int macaudio_parse_of_component(struct device_node *node, int index,
+				struct snd_soc_dai_link_component *comp)
+{
+	struct of_phandle_args args;
+	int ret;
+
+	ret = of_parse_phandle_with_args(node, "sound-dai", "#sound-dai-cells",
+						index, &args);
+	if (ret)
+		return ret;
+	comp->of_node = args.np;
+	return snd_soc_get_dai_name(&args, &comp->dai_name);
+}
+
+/*
+ * Parse one DPCM backend from the devicetree. This means taking one
+ * of the CPU DAIs and combining it with one or more CODEC DAIs.
+ */
+static int macaudio_parse_of_be_dai_link(struct macaudio_snd_data *ma,
+				struct snd_soc_dai_link *link,
+				int be_index, int ncodecs_per_be,
+				struct device_node *cpu,
+				struct device_node *codec)
+{
+	struct snd_soc_dai_link_component *comp;
+	struct device *dev = ma->card.dev;
+	int codec_base = be_index * ncodecs_per_be;
+	int ret, i;
+
+	link->no_pcm = 1;
+	link->dpcm_playback = 1;
+	link->dpcm_capture = 1;
+
+	link->dai_fmt = MACAUDIO_DAI_FMT;
+
+	link->num_codecs = ncodecs_per_be;
+	link->codecs = devm_kcalloc(dev, ncodecs_per_be,
+				    sizeof(*comp), GFP_KERNEL);
+	link->num_cpus = 1;
+	link->cpus = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+
+	if (!link->codecs || !link->cpus)
+		return -ENOMEM;
+
+	link->num_platforms = 0;
+
+	for_each_link_codecs(link, i, comp) {
+		ret = macaudio_parse_of_component(codec, codec_base + i, comp);
+		if (ret)
+			return ret;
+	}
+
+	ret = macaudio_parse_of_component(cpu, be_index, link->cpus);
+	if (ret)
+		return ret;
+
+	link->name = link->cpus[0].dai_name;
+
+	return 0;
+}
+
+static int macaudio_parse_of(struct macaudio_snd_data *ma)
+{
+	struct device_node *codec = NULL;
+	struct device_node *cpu = NULL;
+	struct device_node *np = NULL;
+	struct device_node *platform = NULL;
+	struct snd_soc_dai_link *link = NULL;
+	struct snd_soc_card *card = &ma->card;
+	struct device *dev = card->dev;
+	struct macaudio_link_props *link_props;
+	int ret, num_links, i;
+
+	ret = snd_soc_of_parse_card_name(card, "model");
+	if (ret) {
+		dev_err(dev, "Error parsing card name: %d\n", ret);
+		return ret;
+	}
+
+	/* Populate links, start with the fixed number of FE links */
+	num_links = ARRAY_SIZE(macaudio_fe_links);
+
+	/* Now add together the (dynamic) number of BE links */
+	for_each_available_child_of_node(dev->of_node, np) {
+		int num_cpus;
+
+		cpu = of_get_child_by_name(np, "cpu");
+		if (!cpu) {
+			dev_err(dev, "missing CPU DAI node at %pOF\n", np);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		num_cpus = of_count_phandle_with_args(cpu, "sound-dai",
+						"#sound-dai-cells");
+
+		if (num_cpus <= 0) {
+			dev_err(card->dev, "missing sound-dai property at %pOF\n", cpu);
+			ret = -EINVAL;
+			goto err_free;
+		}
+		of_node_put(cpu);
+		cpu = NULL;
+
+		/* Each CPU specified counts as one BE link */
+		num_links += num_cpus;
+	}
+
+	/* Allocate the DAI link array */
+	card->dai_link = devm_kcalloc(dev, num_links, sizeof(*link), GFP_KERNEL);
+	ma->link_props = devm_kcalloc(dev, num_links, sizeof(*ma->link_props), GFP_KERNEL);
+	if (!card->dai_link || !ma->link_props)
+		return -ENOMEM;
+
+	card->num_links = num_links;
+	link = card->dai_link;
+	link_props = ma->link_props;
+
+	for (i = 0; i < ARRAY_SIZE(macaudio_fe_links); i++) {
+		ret = macaudio_copy_link(dev, link, &macaudio_fe_links[i]);
+		if (ret)
+			goto err_free;
+
+		memcpy(link_props, &macaudio_fe_link_props[i], sizeof(struct macaudio_link_props));
+		link++; link_props++;
+	}
+
+	for (i = 0; i < num_links; i++)
+		card->dai_link[i].id = i;
+
+	/* Fill in the BEs */
+	for_each_available_child_of_node(dev->of_node, np) {
+		const char *link_name;
+		bool speakers;
+		int be_index, num_codecs, num_bes, ncodecs_per_cpu, nchannels;
+		unsigned int left_mask, right_mask;
+
+		ret = of_property_read_string(np, "link-name", &link_name);
+		if (ret) {
+			dev_err(card->dev, "missing link name\n");
+			goto err_free;
+		}
+
+		speakers = !strcmp(link_name, "Speaker")
+			   || !strcmp(link_name, "Speakers");
+
+		cpu = of_get_child_by_name(np, "cpu");
+		codec = of_get_child_by_name(np, "codec");
+
+		if (!codec || !cpu) {
+			dev_err(dev, "missing DAI specifications for '%s'\n", link_name);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		num_bes = of_count_phandle_with_args(cpu, "sound-dai",
+						     "#sound-dai-cells");
+		if (num_bes <= 0) {
+			dev_err(card->dev, "missing sound-dai property at %pOF\n", cpu);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		num_codecs = of_count_phandle_with_args(codec, "sound-dai",
+							"#sound-dai-cells");
+		if (num_codecs <= 0) {
+			dev_err(card->dev, "missing sound-dai property at %pOF\n", codec);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		if (num_codecs % num_bes != 0) {
+			dev_err(card->dev, "bad combination of CODEC (%d) and CPU (%d) number at %pOF\n",
+				num_codecs, num_bes, np);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		/*
+		 * Now parse the cpu/codec lists into a number of DPCM backend links.
+		 * In each link there will be one DAI from the cpu list paired with
+		 * an evenly distributed number of DAIs from the codec list. (As is
+		 * the binding semantics.)
+		 */
+		ncodecs_per_cpu = num_codecs / num_bes;
+		nchannels = num_codecs * (speakers ? 1 : 2);
+
+		/*
+		 * If there is a single speaker, assign two channels to it, because
+		 * it can do downmix.
+		 */
+		if (nchannels < 2)
+			nchannels = 2;
+
+		left_mask = 0;
+		for (i = 0; i < nchannels; i += 2)
+			left_mask = left_mask << 2 | 1;
+		right_mask = left_mask << 1;
+
+		for (be_index = 0; be_index < num_bes; be_index++) {
+			ret = macaudio_parse_of_be_dai_link(ma, link, be_index,
+							    ncodecs_per_cpu, cpu, codec);
+			if (ret)
+				goto err_free;
+
+			link_props->is_speakers = speakers;
+			link_props->is_headphones = !speakers;
+
+			if (num_bes == 2)
+				/* This sound peripheral is split between left and right BE */
+				link_props->tdm_mask = be_index ? right_mask : left_mask;
+			else
+				/* One BE covers all of the peripheral */
+				link_props->tdm_mask = left_mask | right_mask;
+
+			/* Steal platform OF reference for use in FE links later */
+			platform = link->cpus->of_node;
+
+			link++; link_props++;
+		}
+
+		of_node_put(codec);
+		of_node_put(cpu);
+		cpu = codec = NULL;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(macaudio_fe_links); i++)
+		card->dai_link[i].platforms->of_node = platform;
+
+	return 0;
+
+err_free:
+	of_node_put(codec);
+	of_node_put(cpu);
+	of_node_put(np);
+
+	if (!card->dai_link)
+		return ret;
+
+	for (i = 0; i < num_links; i++) {
+		/*
+		 * TODO: If we don't go through this path are the references
+		 * freed inside ASoC?
+		 */
+		snd_soc_of_put_dai_link_codecs(&card->dai_link[i]);
+		snd_soc_of_put_dai_link_cpus(&card->dai_link[i]);
+	}
+
+	return ret;
+}
+
+static int macaudio_get_runtime_mclk_fs(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(rtd->card);
+	struct snd_soc_dpcm *dpcm;
+
+	/*
+	 * If this is a FE, look it up in link_props directly.
+	 * If this is a BE, look it up in the respective FE.
+	 */
+	if (!rtd->dai_link->no_pcm)
+		return ma->link_props[rtd->dai_link->id].mclk_fs;
+
+	for_each_dpcm_fe(rtd, substream->stream, dpcm) {
+		int fe_id = dpcm->fe->dai_link->id;
+
+		return ma->link_props[fe_id].mclk_fs;
+	}
+
+	return 0;
+}
+
+static int macaudio_dpcm_hw_params(struct snd_pcm_substream *substream,
+				   struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+	struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0);
+	int mclk_fs = macaudio_get_runtime_mclk_fs(substream);
+	int i;
+
+	if (mclk_fs) {
+		struct snd_soc_dai *dai;
+		int mclk = params_rate(params) * mclk_fs;
+
+		for_each_rtd_codec_dais(rtd, i, dai)
+			snd_soc_dai_set_sysclk(dai, 0, mclk, SND_SOC_CLOCK_IN);
+
+		snd_soc_dai_set_sysclk(cpu_dai, 0, mclk, SND_SOC_CLOCK_OUT);
+	}
+
+	return 0;
+}
+
+static void macaudio_dpcm_shutdown(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+	struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0);
+	struct snd_soc_dai *dai;
+	int mclk_fs = macaudio_get_runtime_mclk_fs(substream);
+	int i;
+
+	if (mclk_fs) {
+		for_each_rtd_codec_dais(rtd, i, dai)
+			snd_soc_dai_set_sysclk(dai, 0, 0, SND_SOC_CLOCK_IN);
+
+		snd_soc_dai_set_sysclk(cpu_dai, 0, 0, SND_SOC_CLOCK_OUT);
+	}
+}
+
+static const struct snd_soc_ops macaudio_fe_ops = {
+	.shutdown	= macaudio_dpcm_shutdown,
+	.hw_params	= macaudio_dpcm_hw_params,
+};
+
+static const struct snd_soc_ops macaudio_be_ops = {
+	.shutdown	= macaudio_dpcm_shutdown,
+	.hw_params	= macaudio_dpcm_hw_params,
+};
+
+static int macaudio_be_assign_tdm(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_card *card = rtd->card;
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	struct macaudio_link_props *props = &ma->link_props[rtd->dai_link->id];
+	struct snd_soc_dai *dai;
+	unsigned int mask;
+	int nslots, ret, i;
+
+	if (!props->tdm_mask)
+		return 0;
+
+	mask = props->tdm_mask;
+	nslots = __fls(mask) + 1;
+
+	if (rtd->num_codecs == 1) {
+		ret = snd_soc_dai_set_tdm_slot(asoc_rtd_to_codec(rtd, 0), mask,
+					       0, nslots, MACAUDIO_SLOTWIDTH);
+
+		/*
+		 * Headphones get a pass on -EOPNOTSUPP (see the comment
+		 * around mclk_fs value for primary FE).
+		 */
+		if (ret == -EOPNOTSUPP && props->is_headphones)
+			return 0;
+
+		return ret;
+	}
+
+	for_each_rtd_codec_dais(rtd, i, dai) {
+		int slot = __ffs(mask);
+
+		mask &= ~(1 << slot);
+		ret = snd_soc_dai_set_tdm_slot(dai, 1 << slot, 0, nslots,
+					       MACAUDIO_SLOTWIDTH);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int macaudio_be_init(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_card *card = rtd->card;
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	struct macaudio_link_props *props = &ma->link_props[rtd->dai_link->id];
+	struct snd_soc_dai *dai;
+	int i, ret;
+
+	ret = macaudio_be_assign_tdm(rtd);
+	if (ret < 0)
+		return ret;
+
+	if (props->is_headphones) {
+		for_each_rtd_codec_dais(rtd, i, dai)
+			snd_soc_component_set_jack(dai->component, &ma->jack, NULL);
+	}
+
+	return 0;
+}
+
+static void macaudio_be_exit(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_card *card = rtd->card;
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	struct macaudio_link_props *props = &ma->link_props[rtd->dai_link->id];
+	struct snd_soc_dai *dai;
+	int i;
+
+	if (props->is_headphones) {
+		for_each_rtd_codec_dais(rtd, i, dai)
+			snd_soc_component_set_jack(dai->component, NULL, NULL);
+	}
+}
+
+static int macaudio_fe_init(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_card *card = rtd->card;
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	struct macaudio_link_props *props = &ma->link_props[rtd->dai_link->id];
+	int nslots = props->mclk_fs / MACAUDIO_SLOTWIDTH;
+
+	return snd_soc_dai_set_tdm_slot(asoc_rtd_to_cpu(rtd, 0), (1 << nslots) - 1,
+					(1 << nslots) - 1, nslots, MACAUDIO_SLOTWIDTH);
+}
+
+
+static int macaudio_jack_event(struct notifier_block *nb, unsigned long event,
+				void *data);
+
+static struct notifier_block macaudio_jack_nb = {
+	.notifier_call = macaudio_jack_event,
+};
+
+static int macaudio_probe(struct snd_soc_card *card)
+{
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	int ret;
+
+	ma->pin.pin = "Headphones";
+	ma->pin.mask = SND_JACK_HEADSET | SND_JACK_HEADPHONE;
+	ret = snd_soc_card_jack_new(card, ma->pin.pin,
+			SND_JACK_HEADSET |
+			SND_JACK_HEADPHONE |
+			SND_JACK_BTN_0 | SND_JACK_BTN_1 |
+			SND_JACK_BTN_2 | SND_JACK_BTN_3,
+			&ma->jack, &ma->pin, 1);
+
+	if (ret < 0) {
+		dev_err(card->dev, "jack creation failed: %d\n", ret);
+		return ret;
+	}
+
+	snd_soc_jack_notifier_register(&ma->jack, &macaudio_jack_nb);
+
+	return ret;
+}
+
+static int macaudio_add_backend_dai_route(struct snd_soc_card *card, struct snd_soc_dai *dai,
+					  bool is_speakers)
+{
+	struct snd_soc_dapm_route routes[2];
+	int nroutes;
+	int ret;
+	memset(routes, 0, sizeof(routes));
+
+	dev_dbg(card->dev, "adding routes for '%s'\n", dai->name);
+
+	if (is_speakers)
+		routes[0].source = "Speakers Playback";
+	else
+		routes[0].source = "Headphones Playback";
+	routes[0].sink = dai->playback_widget->name;
+	nroutes = 1;
+
+	if (!is_speakers) {
+		routes[1].source = dai->capture_widget->name;
+		routes[1].sink = "Headphones Capture";
+		nroutes = 2;
+	}
+
+	ret = snd_soc_dapm_add_routes(&card->dapm, routes, nroutes);
+	if (ret)
+		dev_err(card->dev, "failed adding dynamic DAPM routes for %s\n",
+			dai->name);
+	return ret;
+}
+
+static bool macaudio_match_kctl_name(const char *pattern, const char *name)
+{
+	if (pattern[0] == '*') {
+		int namelen, patternlen;
+
+		pattern++;
+		if (pattern[0] == ' ')
+			pattern++;
+
+		namelen = strlen(name);
+		patternlen = strlen(pattern);
+
+		if (namelen > patternlen)
+			name += (namelen - patternlen);
+	}
+
+	return !strcmp(name, pattern);
+}
+
+static int macaudio_limit_volume(struct snd_soc_card *card,
+				 const char *pattern, int max)
+{
+	struct snd_kcontrol *kctl;
+	struct soc_mixer_control *mc;
+	int found = 0;
+
+	list_for_each_entry(kctl, &card->snd_card->controls, list) {
+		if (!macaudio_match_kctl_name(pattern, kctl->id.name))
+			continue;
+
+		found++;
+		dev_dbg(card->dev, "limiting volume on '%s'\n", kctl->id.name);
+
+		/*
+		 * TODO: This doesn't decrease the volume if it's already
+		 * above the limit!
+		 */
+		mc = (struct soc_mixer_control *)kctl->private_value;
+		if (max <= mc->max)
+			mc->platform_max = max;
+
+	}
+
+	return found;
+}
+
+static int macaudio_late_probe(struct snd_soc_card *card)
+{
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	struct snd_soc_pcm_runtime *rtd;
+	struct snd_soc_dai *dai;
+	int ret, i;
+
+	/* Add the dynamic DAPM routes */
+	for_each_card_rtds(card, rtd) {
+		struct macaudio_link_props *props = &ma->link_props[rtd->dai_link->id];
+
+		if (!rtd->dai_link->no_pcm)
+			continue;
+
+		for_each_rtd_cpu_dais(rtd, i, dai) {
+			ret = macaudio_add_backend_dai_route(card, dai, props->is_speakers);
+
+			if (ret)
+				return ret;
+		}
+	}
+
+	if (!ma->mdata) {
+		dev_err(card->dev, "driver doesn't know speaker limits for this model\n");
+		return void_warranty ? 0 : -EINVAL;
+	}
+
+	macaudio_limit_volume(card, "* Amp Gain", ma->mdata->spk_amp_gain_max);
+	return 0;
+}
+
+static const char * const macaudio_plugin_demux_texts[] = {
+	"Speakers",
+	"Headphones"
+};
+
+SOC_ENUM_SINGLE_VIRT_DECL(macaudio_plugin_demux_enum, macaudio_plugin_demux_texts);
+
+static int macaudio_plugin_demux_get(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_dapm_context *dapm = snd_soc_dapm_kcontrol_dapm(kcontrol);
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(dapm->card);
+
+	/*
+	 * TODO: Determine what locking is in order here...
+	 */
+	ucontrol->value.enumerated.item[0] = ma->jack_plugin_state;
+
+	return 0;
+}
+
+static int macaudio_jack_event(struct notifier_block *nb, unsigned long event,
+				void *data)
+{
+	struct snd_soc_jack *jack = data;
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(jack->card);
+
+	ma->jack_plugin_state = !!event;
+
+	if (!ma->plugin_demux_kcontrol)
+		return 0;
+
+	snd_soc_dapm_mux_update_power(&ma->card.dapm, ma->plugin_demux_kcontrol,
+				      ma->jack_plugin_state,
+				      (struct soc_enum *) &macaudio_plugin_demux_enum, NULL);
+
+	return 0;
+}
+
+static const struct snd_kcontrol_new macaudio_plugin_demux = {
+	.access = (SNDRV_CTL_ELEM_ACCESS_READ |
+		   SNDRV_CTL_ELEM_ACCESS_VOLATILE),
+	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	.name = "Plug-in Playback Demux",
+	.info = snd_soc_info_enum_double,
+	.get = macaudio_plugin_demux_get,
+	.private_value = (unsigned long) &macaudio_plugin_demux_enum
+};
+
+static int macaudio_kctl_set_enum(struct snd_kcontrol *kctl,
+				   const char *strvalue)
+{
+	struct snd_ctl_elem_value value;
+	struct snd_ctl_elem_info info;
+	int sel, i, ret;
+
+	ret = kctl->info(kctl, &info);
+	if (ret < 0)
+		return ret;
+
+	if (info.type != SNDRV_CTL_ELEM_TYPE_ENUMERATED)
+		return -EINVAL;
+
+	for (sel = 0; sel < info.value.enumerated.items; sel++) {
+		info.value.enumerated.item = sel;
+		ret = kctl->info(kctl, &info);
+		if (ret < 0)
+			return ret;
+
+		if (!strcmp(strvalue, info.value.enumerated.name))
+			break;
+	}
+
+	if (sel == info.value.enumerated.items)
+		return -EINVAL;
+
+	for (i = 0; i < info.count; i++)
+		value.value.enumerated.item[i] = sel;
+
+	return kctl->put(kctl, &value);
+}
+
+static void macaudio_deactivate_asi1_sel(struct snd_soc_card *card)
+{
+	struct snd_kcontrol *kctl;
+	int ret;
+
+	list_for_each_entry(kctl, &card->snd_card->controls, list) {
+		if (!macaudio_match_kctl_name("* ASI1 Sel", kctl->id.name))
+			continue;
+
+		ret = macaudio_kctl_set_enum(kctl, "Left");
+		if (ret < 0)
+			dev_err(card->dev, "can't pin '%s': %d\n", kctl->id.name, ret);
+
+		ret = snd_ctl_activate_id(card->snd_card, &kctl->id, 0);
+		if (ret < 0)
+			dev_err(card->dev, "can't deactivate '%s': %d\n", kctl->id.name, ret);
+		else
+			dev_dbg(card->dev, "deactivated '%s'\n", kctl->id.name);
+	}
+}
+
+static void macaudio_fixup_controls(struct snd_soc_card *card)
+{
+	struct macaudio_snd_data *ma = snd_soc_card_get_drvdata(card);
+	const char *name = macaudio_plugin_demux.name;
+
+	ma->plugin_demux_kcontrol = snd_soc_card_get_kcontrol(card, name);
+
+	if (!ma->plugin_demux_kcontrol)
+		dev_err(card->dev, "can't find control '%s'\n", name);
+
+	if (ma->mdata && ma->mdata->deactive_asi1_sel)
+		macaudio_deactivate_asi1_sel(card);
+
+	macaudio_limit_volume(card, "* Amp Gain Volume", ma->mdata->spk_amp_gain_max);
+}
+
+static const char * const macaudio_spk_mux_texts[] = {
+	"Primary (Conditional)",
+	"Primary",
+	"Secondary"
+};
+
+SOC_ENUM_SINGLE_VIRT_DECL(macaudio_spk_mux_enum, macaudio_spk_mux_texts);
+
+static const struct snd_kcontrol_new macaudio_spk_mux =
+	SOC_DAPM_ENUM("Speakers Playback Mux", macaudio_spk_mux_enum);
+
+static const char * const macaudio_hp_mux_texts[] = {
+	"Primary (Conditional)",
+	"Primary",
+};
+
+SOC_ENUM_SINGLE_VIRT_DECL(macaudio_hp_mux_enum, macaudio_hp_mux_texts);
+
+static const struct snd_kcontrol_new macaudio_hp_mux =
+	SOC_DAPM_ENUM("Headphones Playback Mux", macaudio_hp_mux_enum);
+
+static const struct snd_soc_dapm_widget macaudio_snd_widgets[] = {
+	SND_SOC_DAPM_HP("Headphones", NULL),
+	SND_SOC_DAPM_SPK("Speakers", NULL),
+
+	SND_SOC_DAPM_MUX("Speakers Playback Mux", SND_SOC_NOPM, 0, 0, &macaudio_spk_mux),
+	SND_SOC_DAPM_MUX("Headphones Playback Mux", SND_SOC_NOPM, 0, 0, &macaudio_hp_mux),
+	SND_SOC_DAPM_DEMUX("Plug-in Playback Demux", SND_SOC_NOPM, 0, 0, &macaudio_plugin_demux),
+
+	SND_SOC_DAPM_AIF_OUT("Plug-in Headphones Playback", NULL, 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("Plug-in Speakers Playback", NULL, 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("Speakers Playback", NULL, 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("Headphones Playback", NULL, 0, SND_SOC_NOPM, 0, 0),
+
+	SND_SOC_DAPM_AIF_IN("Headphones Capture", NULL, 0, SND_SOC_NOPM, 0, 0),
+};
+
+static const struct snd_soc_dapm_route macaudio_dapm_routes[] = {
+	/* Playback paths */
+	{ "Plug-in Playback Demux", NULL, "PCM0 TX" },
+	{ "Plug-in Speakers Playback", "Speakers", "Plug-in Playback Demux" },
+	{ "Plug-in Headphones Playback", "Headphones", "Plug-in Playback Demux" },
+
+	{ "Speakers Playback Mux", "Primary (Conditional)", "Plug-in Speakers Playback" },
+	{ "Speakers Playback Mux", "Primary", "PCM0 TX" },
+	{ "Speakers Playback Mux", "Secondary", "PCM1 TX" },
+	{ "Speakers Playback", NULL, "Speakers Playback Mux"},
+
+	{ "Headphones Playback Mux", "Primary (Conditional)", "Plug-in Headphones Playback" },
+	{ "Headphones Playback Mux", "Primary", "PCM0 TX" },
+	{ "Headphones Playback", NULL, "Headphones Playback Mux"},
+	/*
+	 * Additional paths (to specific I2S ports) are added dynamically.
+	 */
+
+	/* Capture paths */
+	{ "PCM0 RX", NULL, "Headphones Capture" },
+};
+
+struct macaudio_model_data macaudio_j274_mdata = {
+	.spk_amp_gain_max = 20,
+};
+
+struct macaudio_model_data macaudio_j314_mdata = {
+	.deactive_asi1_sel = true,
+	.spk_amp_gain_max = 15,
+};
+
+static const struct of_device_id macaudio_snd_device_id[]  = {
+	{ .compatible = "apple,j274-macaudio", .data = &macaudio_j274_mdata },
+	{ .compatible = "apple,j314-macaudio", .data = &macaudio_j314_mdata },
+	{ .compatible = "apple,macaudio"},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, macaudio_snd_device_id);
+
+static int macaudio_snd_platform_probe(struct platform_device *pdev)
+{
+	struct snd_soc_card *card;
+	struct macaudio_snd_data *data;
+	struct device *dev = &pdev->dev;
+	struct snd_soc_dai_link *link;
+	const struct of_device_id *of_id;
+	int ret;
+	int i;
+
+	of_id = of_match_device(macaudio_snd_device_id, dev);
+	if (!of_id)
+		return -EINVAL;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	card = &data->card;
+	snd_soc_card_set_drvdata(card, data);
+
+	data->mdata = (struct macaudio_model_data *) of_id->data;
+
+	card->owner = THIS_MODULE;
+	card->driver_name = DRIVER_NAME;
+	card->dev = dev;
+	card->dapm_widgets = macaudio_snd_widgets;
+	card->num_dapm_widgets = ARRAY_SIZE(macaudio_snd_widgets);
+	card->dapm_routes = macaudio_dapm_routes;
+	card->num_dapm_routes = ARRAY_SIZE(macaudio_dapm_routes);
+	card->probe = macaudio_probe;
+	card->late_probe = macaudio_late_probe;
+	card->fixup_controls = macaudio_fixup_controls;
+
+	ret = macaudio_parse_of(data);
+	if (ret)
+		return ret;
+
+	for_each_card_prelinks(card, i, link) {
+		if (link->no_pcm) {
+			link->ops = &macaudio_be_ops;
+			link->init = macaudio_be_init;
+			link->exit = macaudio_be_exit;
+		} else {
+			link->ops = &macaudio_fe_ops;
+			link->init = macaudio_fe_init;
+		}
+	}
+
+	return devm_snd_soc_register_card(dev, card);
+}
+
+static struct platform_driver macaudio_snd_driver = {
+	.probe = macaudio_snd_platform_probe,
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = macaudio_snd_device_id,
+		.pm = &snd_soc_pm_ops,
+	},
+};
+module_platform_driver(macaudio_snd_driver);
+
+MODULE_AUTHOR("Martin Povišer <povik+lin@cutebit.org>");
+MODULE_DESCRIPTION("Apple Silicon Macs machine-level sound driver");
+MODULE_LICENSE("GPL");