usb: gadget: Add Audio Class 2.0 Driver

This is a flexible USB Audio Class 2.0 compliant gadget driver that
implements a simple topology with a virtual sound card exposed at
the function side.

The driver doesn't expect any real audio codec to be present on the
function - the audio streams are simply sinked to and sourced from a
virtual ALSA sound card created. The user-space application may choose
to do whatever it wants with the data received from the USB Host and
choose to provide whatever it wants as audio data to the USB Host.

Capture(USB-Out) and Playback(USB-In) can be run at independent
configurations specified via module parameters while loading the driver.

Make this new version as the default selection by a new Kconfig choice.

Signed-off-by: Yadi Brar <yadi.brar01@gmail.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -599,16 +599,29 @@ config USB_AUDIO
 	depends on SND
 	select SND_PCM
 	help
-	  Gadget Audio is compatible with USB Audio Class specification 1.0.
-	  It will include at least one AudioControl interface, zero or more
-	  AudioStream interface and zero or more MIDIStream interface.
-
-	  Gadget Audio will use on-board ALSA (CONFIG_SND) audio card to
-	  playback or capture audio stream.
+	  This Gadget Audio driver is compatible with USB Audio Class
+	  specification 2.0. It implements 1 AudioControl interface,
+	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
+	  Number of channels, sample rate and sample size can be
+	  specified as module parameters.
+	  This driver doesn't expect any real Audio codec to be present
+	  on the device - the audio streams are simply sinked to and
+	  sourced from a virtual ALSA sound card created. The user-space
+	  application may choose to do whatever it wants with the data
+	  received from the USB Host and choose to provide whatever it
+	  wants as audio data to the USB Host.
 
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_audio".
 
+config GADGET_UAC1
+	bool "UAC 1.0 (Legacy)"
+	depends on USB_AUDIO
+	help
+	  If you instead want older UAC Spec-1.0 driver that also has audio
+	  paths hardwired to the Audio codec chip on-board and doesn't work
+	  without one.
+
 config USB_ETH
 	tristate "Ethernet Gadget (with CDC Ethernet support)"
 	depends on NET

drivers/usb/gadget/audio.c

@@ -14,10 +14,8 @@
 #include <linux/kernel.h>
 #include <linux/utsname.h>
 
-#include "u_uac1.h"
-
 #define DRIVER_DESC		"Linux USB Audio Gadget"
-#define DRIVER_VERSION		"Dec 18, 2008"
+#define DRIVER_VERSION		"Feb 2, 2012"
 
 /*-------------------------------------------------------------------------*/
 
@@ -56,8 +54,13 @@ static struct usb_gadget_strings *audio_strings[] = {
 	NULL,
 };
 
+#ifdef CONFIG_GADGET_UAC1
+#include "u_uac1.h"
 #include "u_uac1.c"
 #include "f_uac1.c"
+#else
+#include "f_uac2.c"
+#endif
 
 /*-------------------------------------------------------------------------*/
 
@@ -77,9 +80,15 @@ static struct usb_device_descriptor device_desc = {
 
 	.bcdUSB =		__constant_cpu_to_le16(0x200),
 
+#ifdef CONFIG_GADGET_UAC1
 	.bDeviceClass =		USB_CLASS_PER_INTERFACE,
 	.bDeviceSubClass =	0,
 	.bDeviceProtocol =	0,
+#else
+	.bDeviceClass =		USB_CLASS_MISC,
+	.bDeviceSubClass =	0x02,
+	.bDeviceProtocol =	0x01,
+#endif
 	/* .bMaxPacketSize0 = f(hardware) */
 
 	/* Vendor and product id defaults change according to what configs
@@ -131,6 +140,9 @@ static struct usb_configuration audio_config_driver = {
 	.bConfigurationValue	= 1,
 	/* .iConfiguration = DYNAMIC */
 	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
+#ifndef CONFIG_GADGET_UAC1
+	.unbind			= uac2_unbind_config,
+#endif
 };
 
 /*-------------------------------------------------------------------------*/
@@ -180,7 +192,9 @@ fail:
 
 static int __exit audio_unbind(struct usb_composite_dev *cdev)
 {
+#ifdef CONFIG_GADGET_UAC1
 	gaudio_cleanup();
+#endif
 	return 0;
 }