ALSA: usb-audio: Playback and MIDI support for Novation Twitch DJ controller

The hardware also has a PCM capture device which is not implemented in
this patch.

It may be possible to generalise this to Saffire 6 USB support and some
of the other Focusrite interfaces, but as I don't have access to these
devices we should wait until capture support is working first.

Capture support is not implemented because the code assumes the endpoint
to have its own interface (instead, it shares the interface with playback)
and some thought will be needed to lift this limitation.

Signed-off-by: Mark Hills <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/usb/quirks-table.h

···
 	}
 },
 {
+	USB_DEVICE(0x1235, 0x0018),
+	.driver_info = (unsigned long) & (const struct snd_usb_audio_quirk) {
+		.vendor_name = "Novation",
+		.product_name = "Twitch",
+		.ifnum = QUIRK_ANY_INTERFACE,
+		.type = QUIRK_COMPOSITE,
+		.data = (const struct snd_usb_audio_quirk[]) {
+			{
+				.ifnum = 0,
+				.type = QUIRK_AUDIO_FIXED_ENDPOINT,
+				.data = & (const struct audioformat) {
+					.formats = SNDRV_PCM_FMTBIT_S24_3LE,
+					.channels = 4,
+					.iface = 0,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.attributes = UAC_EP_CS_ATTR_SAMPLE_RATE,
+					.endpoint = 0x01,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC,
+					.rates = SNDRV_PCM_RATE_44100 |
+						 SNDRV_PCM_RATE_48000,
+					.rate_min = 44100,
+					.rate_max = 48000,
+					.nr_rates = 2,
+					.rate_table = (unsigned int[]) {
+						44100, 48000
+					}
+				}
+			},
+			{
+				.ifnum = 1,
+				.type = QUIRK_MIDI_RAW_BYTES
+			},
+			{
+				.ifnum = -1
+			}
+		}
+	}
+},
+{
 	USB_DEVICE_VENDOR_SPEC(0x1235, 0x4661),
 	.driver_info = (unsigned long) & (const struct snd_usb_audio_quirk) {
 		.vendor_name = "Novation",

sound/usb/quirks.c

···
 }
 
 /*
+ * Novation Twitch DJ controller
+ */
+static int snd_usb_twitch_boot_quirk(struct usb_device *dev)
+{
+	/* preemptively set up the device because otherwise the
+	 * raw MIDI endpoints are not active */
+	usb_set_interface(dev, 0, 1);
+	return 0;
+}
+
+/*
  * This call will put the synth in "USB send" mode, i.e it will send MIDI
  * messages through USB (this is disabled at startup). The synth will
  * acknowledge by sending a sysex on endpoint 0x85 and by displaying a USB
···
 	case USB_ID(0x0dba, 0x3000):
 		/* Digidesign Mbox 2 */
 		return snd_usb_mbox2_boot_quirk(dev);
+
+	case USB_ID(0x1235, 0x0018):
+		/* Focusrite Novation Twitch */
+		return snd_usb_twitch_boot_quirk(dev);
 
 	case USB_ID(0x133e, 0x0815):
 		/* Access Music VirusTI Desktop */