hwdep: device-common: add interface for common feature of ALSA HwDep device
The protocol in ALSA HwDep character device has common feature. It's
suitable for userspace implementation to have GObject interface for such
features.
This commit adds the interface. The implementation of interface should
have four methods; open, get_protocol_version, get_device_info, and
create_source. Additionally, it should emit handle-disconnection signal
when detecting ENODEV error in the interation of source. It requires to
notify userspace application since the application should release
character device immediately.
git://git.alsa-project.org / alsa-gobject.git / commit