ASoC: cs35l56: Use SoundWire address as firmware name suffix for new silicon

Use the SoundWire link number and device unique ID as the firmware file
qualifier suffix on CS35L57, CS35L63 and revisions of CS35L56 after B0. The
change in wm_adsp needed to support this has been included in this patch
because it is fairly trivial.

Originally, the firmware file names indicated which amplifier instance they
were for by appending the ALSA prefix string. This is the standard ASoC way
of distinguishing different instances of the same device. However, on
SoundWire systems the SoundWire physical unique address is available as a
unique identifier for each amp, and this address is hardwired by a pin on
the amp.

The firmware files are specific for each physical amp so they must be
applied to that amp. Using the ALSA prefix for the filename qualifier means
that to name a firmware file it must be determined what prefix string the
machine driver will assign to each device and then use that to name the
firmware file correctly. This is straightforward in traditional ASoC
systems where the machine driver is specific to a particular piece of
hardware. But on SoundWire the machine driver is generic and can handle a
very wide range of hardware. It is more difficult to determine exactly what
the prefix will be on any particular production device, and more prone to
mistakes. Also, when the machine driver switches to generating this
automatically from SDCA properties in ACPI, there is an additional layer of
complexity in determining the mapping. This uncertainty is unnecessary
because the firmware is built for a specific amp. with known address, so we
can use that directly instead of introducing the redundant intermediate
alias. This ensures the firmware is applied to the amp it was intended for.

There have not been any firmwares published for CS35L57 or CS35L63, so
these can safely be switched to using the SoundWire unique address as the
suffix string. Also note that the machine driver in older kernel version
only has match entries for the CS35L56 Soundwire identity so any future
product with a cs35L57 or CS35L63 would require a new kernel anyway.

There are already many published firmware for CS35L56 B0 silicon so this
keeps the original naming scheme on those, to preserve backward
compatibility.

Note that although sdw_slave.id contains a unique_id field, this cannot
be trusted because the SoundWire core code also puts magic values into it
that it uses as a flag. So the unique ID is read from the chip register.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20250612121428.1667-2-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

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