[PATCH] ASoC: wm_adsp: Expand firmware loading search options

[Charles Keepax]

On Thu, Mar 03, 2022 at 03:50:16PM +0000, Simon Trimmer wrote:
> The parts supported by this driver can have product-specific
> firmware and tunings files. Typically these have been used on
> embedded systems where the manufacturer is responsible for
> installing the correct product-specific firmware files into
> /lib/firmware. However, the linux-firmware repository places all
> available firmwares into /lib/firmware and it is up to the driver to
> select the correct product-specific firmware from that directory.
> 
> For example a product containing four smart amplifiers may provide
> firmware specific for that product and each of the amplifiers may
> have coefficient files containing tunings for their placement in the
> mechanical design.
> 
> This change extends firmware (wmfw) and coefficient (bin) filenames
> to be of the general form:
> 
> <cirrus/>part-dspN-fwtype<-system_name<-asoc_component_prefix>>.type
> 
> Where the cirrus subdirectory, system_name and asoc_component_prefix
> are optional.
> 
> New files will be placed in the cirrus subdirectory to avoid
> polluting the main /lib/firmware/ location. The generic name must be
> searched in /lib/firmware before /lib/firmware/cirrus so that a
> generic file in the new location does not override existing
> product-specific files in the legacy location.
> 
> The search order for firmware files is:
>   - cirrus/part-dspN-fwtype-system_name-asoc_component_prefix.wmfw
>   - cirrus/part-dspN-fwtype-system_name.wmfw
>   - part-dspN-fwtype.wmfw
>   - cirrus/part-dspN-fwtype.wmfw
> 
> - Qualifications are added to the filename so that rightwards is more
>   specific.
> - The system_name is provided by the codec driver.
> - The asoc_component_prefix is used to identify tunings for individual
>   parts because it would already exist to disambiguate the controls
>   and it makes it obvious which firmware file applies to which device.
> 
> The optional coefficient file must have the same filename
> construction as the discovered wmfw except:
>   - where the wmfw has only system_name then the bin file can
>     optionally include the asoc_component_prefix. This is to allow a
>     common wmfw for all amps but separate tunings per amp.
> 
> Signed-off-by: Simon Trimmer <simont at opensource.cirrus.com>
> ---

Acked-by: Charles Keepax <ckeepax at opensource.cirrus.com>

Thanks,
Charles