audio: add driver registry

Add registry for audio drivers, using the existing audio_driver struct.
Make all drivers register themself.  The old list of audio_driver struct
pointers is now a list of audio driver names, specifying the priority
(aka probe order) in case no driver is explicitly asked for.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20180306074053.22856-2-kraxel@redhat.com

1 files changed, 7 insertions, 1 deletions

diff --git a/audio/noaudio.c b/audio/noaudio.c
index 9ca9eaf01f..1bfebeca7d 100644
--- a/audio/noaudio.c
+++ b/audio/noaudio.c
@@ -160,7 +160,7 @@ static struct audio_pcm_ops no_pcm_ops = {
     .ctl_in   = no_ctl_in
 };
 
-struct audio_driver no_audio_driver = {
+static struct audio_driver no_audio_driver = {
     .name           = "none",
     .descr          = "Timer based audio emulation",
     .options        = NULL,
@@ -173,3 +173,9 @@ struct audio_driver no_audio_driver = {
     .voice_size_out = sizeof (NoVoiceOut),
     .voice_size_in  = sizeof (NoVoiceIn)
 };
+
+static void register_audio_none(void)
+{
+    audio_driver_register(&no_audio_driver);
+}
+type_init(register_audio_none);