Add new module for SDCA (SoundWire Device Class for Audio) support.
For now just add a parser to identify the SDCA revision and the
function mask.

Note that the SDCA definitions and related MIPI DisCo properties are
defined only for ACPI platforms and extracted with _DSD helpers. There
is currently no support for Device Tree in the specification, the
'depends on ACPI' reflects this design limitation. This might change
in a future revision of the specification but for SDCA 1.0 ACPI is the
only supported type of platform firmware.

The SDCA library is defined with static inline fallbacks, which will
allow for unconditional addition of SDCA support in common parts of
the code.

The design follows a four-step process:

1) Basic information related to Functions is extracted from MIPI DisCo
tables and stored in the 'struct sdw_slave'. Devm_ based memory
allocation is not allowed at this point prior to a driver probe, so we only
store the function node, address and type.

2) When a codec driver probes, it will register subdevices for each
Function identified in phase 1)

3) a driver will probe for each subdevice and addition parsing/memory
allocation takes place at this level. devm_ based allocation is highly
encouraged to make error handling manageable.

4) Before the peripheral device becomes physically attached, register
access is not permitted and the regmaps are cache-only. When
peripheral device is enumerated, the bus level uses the
'update_status' notification; after optional device-level
initialization, the codec driver will notify each of the subdevices so
that they can start interacting with the hardware.

Note that the context extracted in 1) should be arguably be handled
completely in the codec driver probe. That would however make it
difficult to use the ACPI information for machine quirks, and
e.g. select different machine driver and topologies as done for the
RT712_VB handling later in the series. To make the implementation of
quirks simpler, this patchset extracts a minimal amount of context
(interface revision and number/type of Functions) before the codec
driver probe, and stores this context in the scope of the 'struct
sdw_slave'.

The SDCA library can also be used in a vendor-specific driver without
creating subdevices, e.g. to retrieve the 'initialization-table'
values to write platform-specific values as needed.

For more technical details, the SDCA specification is available for
public downloads at https://www.mipi.org/mipi-sdca-v1-0-download



Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://patch.msgid.link/20241016102333.294448-4-yung-chuan.liao@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>