[PATCH] audio: add help option (?) for -audiodev

[Claudio Fontana]

add a simple help option for -audiodev, so users can do

qemu -audiodev ?

to get the list of drivers available.

Signed-off-by: Claudio Fontana <cfont...@suse.de>
---
 audio/audio.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/audio/audio.c b/audio/audio.c
index 4f4bb10cce..bd8c18c3cd 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -32,6 +32,7 @@
 #include "qapi/qapi-visit-audio.h"
 #include "qemu/cutils.h"
 #include "qemu/module.h"
+#include "qemu/help_option.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/replay.h"
 #include "sysemu/runstate.h"
@@ -2105,10 +2106,29 @@ static void audio_validate_opts(Audiodev *dev, Error 
**errp)
     }
 }
 
+static void audio_help(void)
+{
+    int i;
+
+    printf("Available audiodev types:\n");
+    printf("none\n");
+
+    for (i = 0; audio_prio_list[i]; i++) {
+        audio_driver *driver = audio_driver_lookup(audio_prio_list[i]);
+        if (driver) {
+            printf("%s\n", driver->name);
+        }
+    }
+}
+
 void audio_parse_option(const char *opt)
 {
     Audiodev *dev = NULL;
 
+    if (is_help_option(opt)) {
+        audio_help();
+        exit(0);
+    }
     Visitor *v = qobject_input_visitor_new_str(opt, "driver", &error_fatal);
     visit_type_Audiodev(v, NULL, &dev, &error_fatal);
     visit_free(v);
-- 
2.26.2