[ALSA] usb-audio - add support for Miditech USB MIDI keyboards

USB generic driver
Add support for Miditech Midistart and MidiStudio keyboards (another
case of devices using the standard protocol but having no descriptors).
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>

sound/usb/usbaudio.c

@@ -2972,6 +2972,7 @@ static int snd_usb_create_quirk(snd_usb_audio_t *chip,
 	case QUIRK_MIDI_NOVATION:
 	case QUIRK_MIDI_RAW:
 	case QUIRK_MIDI_EMAGIC:
+	case QUIRK_MIDI_MIDITECH:
 		return snd_usb_create_midi_interface(chip, iface, quirk);
 	case QUIRK_COMPOSITE:
 		return create_composite_quirk(chip, iface, quirk);

sound/usb/usbaudio.h

@@ -167,6 +167,7 @@ struct snd_usb_audio {
 #define QUIRK_MIDI_NOVATION		10
 #define QUIRK_MIDI_RAW			11
 #define QUIRK_MIDI_EMAGIC		12
+#define QUIRK_MIDI_MIDITECH		13
 
 typedef struct snd_usb_audio_quirk snd_usb_audio_quirk_t;
 typedef struct snd_usb_midi_endpoint_info snd_usb_midi_endpoint_info_t;
@@ -210,6 +211,8 @@ struct snd_usb_midi_endpoint_info {
 /* for QUIRK_MIDI_EMAGIC, data points to a snd_usb_midi_endpoint_info
  * structure (out_cables and in_cables only) */
 
+/* for QUIRK_MIDI_MIDITECH, data is NULL */
+
 /*
  */
 

sound/usb/usbmidi.c

@@ -1515,6 +1515,9 @@ int snd_usb_create_midi_interface(snd_usb_audio_t* chip,
 			       sizeof(snd_usb_midi_endpoint_info_t));
 			err = snd_usbmidi_detect_endpoints(umidi, &endpoints[0], 1);
 			break;
+		case QUIRK_MIDI_MIDITECH:
+			err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints);
+			break;
 		default:
 			snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type);
 			err = -ENXIO;

sound/usb/usbquirks.h

@@ -1378,6 +1378,25 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 	}
 },
 
+{
+	USB_DEVICE(0x4752, 0x0011),
+	.driver_info = (unsigned long) & (const snd_usb_audio_quirk_t) {
+		.vendor_name = "Miditech",
+		.product_name = "Midistart-2",
+		.ifnum = 0,
+		.type = QUIRK_MIDI_MIDITECH
+	}
+},
+{
+	USB_DEVICE(0x7104, 0x2202),
+	.driver_info = (unsigned long) & (const snd_usb_audio_quirk_t) {
+		.vendor_name = "Miditech",
+		.product_name = "MidiStudio-2",
+		.ifnum = 0,
+		.type = QUIRK_MIDI_MIDITECH
+	}
+},
+
 {
 	/*
 	 * Some USB MIDI devices don't have an audio control interface,