ALSA: usb-audio: Manage number of rawmidis globally

We're going to create rawmidi objects for MIDI 2.0 in a different code
from the current code for USB-MIDI 1.0.  As a preliminary work, this
patch adds the number of rawmidi objects to keep globally in a
USB-audio card instance, so that it can be referred from both MIDI 1.0
and 2.0 code.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-8-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/card.c

@@ -179,8 +179,9 @@ static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int int
 	     altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
 	    altsd->bInterfaceSubClass == USB_SUBCLASS_MIDISTREAMING) {
 		int err = __snd_usbmidi_create(chip->card, iface,
-					     &chip->midi_list, NULL,
-					     chip->usb_id);
+					       &chip->midi_list, NULL,
+					       chip->usb_id,
+					       &chip->num_rawmidis);
 		if (err < 0) {
 			dev_err(&dev->dev,
 				"%u:%d: cannot create sequencer device\n",

sound/usb/midi.c

@@ -2461,7 +2461,8 @@ int __snd_usbmidi_create(struct snd_card *card,
 			 struct usb_interface *iface,
 			 struct list_head *midi_list,
 			 const struct snd_usb_audio_quirk *quirk,
-			 unsigned int usb_id)
+			 unsigned int usb_id,
+			 unsigned int *num_rawmidis)
 {
 	struct snd_usb_midi *umidi;
 	struct snd_usb_midi_endpoint_info endpoints[MIDI_MAX_ENDPOINTS];
@@ -2476,6 +2477,8 @@ int __snd_usbmidi_create(struct snd_card *card,
 	umidi->iface = iface;
 	umidi->quirk = quirk;
 	umidi->usb_protocol_ops = &snd_usbmidi_standard_ops;
+	if (num_rawmidis)
+		umidi->next_midi_device = *num_rawmidis;
 	spin_lock_init(&umidi->disc_lock);
 	init_rwsem(&umidi->disc_rwsem);
 	mutex_init(&umidi->mutex);
@@ -2595,6 +2598,8 @@ int __snd_usbmidi_create(struct snd_card *card,
 	usb_autopm_get_interface_no_resume(umidi->iface);
 
 	list_add_tail(&umidi->list, midi_list);
+	if (num_rawmidis)
+		*num_rawmidis = umidi->next_midi_device;
 	return 0;
 
 free_midi:

sound/usb/midi.h

@@ -46,14 +46,15 @@ int __snd_usbmidi_create(struct snd_card *card,
 			 struct usb_interface *iface,
 			 struct list_head *midi_list,
 			 const struct snd_usb_audio_quirk *quirk,
-			 unsigned int usb_id);
+			 unsigned int usb_id,
+			 unsigned int *num_rawmidis);
 
 static inline int snd_usbmidi_create(struct snd_card *card,
 		       struct usb_interface *iface,
 		       struct list_head *midi_list,
 		       const struct snd_usb_audio_quirk *quirk)
 {
-	return __snd_usbmidi_create(card, iface, midi_list, quirk, 0);
+	return __snd_usbmidi_create(card, iface, midi_list, quirk, 0, NULL);
 }
 
 void snd_usbmidi_input_stop(struct list_head *p);

sound/usb/quirks.c

@@ -436,8 +436,9 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip,
 			chip->usb_id == USB_ID(0x0582, 0x002b)
 			? &ua700_quirk : &uaxx_quirk;
 		return __snd_usbmidi_create(chip->card, iface,
-					  &chip->midi_list, quirk,
-					  chip->usb_id);
+					    &chip->midi_list, quirk,
+					    chip->usb_id,
+					    &chip->num_rawmidis);
 	}
 
 	if (altsd->bNumEndpoints != 1)

sound/usb/usbaudio.h

@@ -49,6 +49,7 @@ struct snd_usb_audio {
 	struct list_head clock_ref_list; /* list of clock refcounts */
 	int pcm_devs;
 
+	unsigned int num_rawmidis;	/* number of created rawmidi devices */
 	struct list_head midi_list;	/* list of midi interfaces */
 
 	struct list_head mixer_list;	/* list of mixer interfaces */