USB: gadget: add USB Audio Gadget driver

Funtions added:
 - setup all the USB audio class device descriptors
 - handle class specific setup request
 - receive data from USB host by ISO transfer
 - play audio data by ALSA sound card
 - open and setup playback PCM interface
 - set default playback PCM parameters
 - provide playback functions for USB audio driver
 - provide PCM parameters set/get functions

Test on:
 - Host: Ubuntu 8.10, kernel 2.6.27
 - Gadget: EZKIT-BF548 with ASoC AD1980 codec

Todo:
 - add real Mute control code
 - add real Volume control code
 - maybe find another way to replace dynamic buffer handling
   with static buffer allocation
 - test on Windows system
 - provide control interface to handle mute/volume control
 - provide capture interface in the future
 - test on BF527, other USB device controler and other audio codec

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -580,6 +580,20 @@ config USB_ZERO_HNPTEST
 	  the "B-Peripheral" role, that device will use HNP to let this
 	  one serve as the USB host instead (in the "B-Host" role).
 
+config USB_AUDIO
+	tristate "Audio Gadget (EXPERIMENTAL)"
+	depends on SND
+	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.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_audio".
+
 config USB_ETH
 	tristate "Ethernet Gadget (with CDC Ethernet support)"
 	depends on NET

drivers/usb/gadget/Makefile

@@ -31,6 +31,7 @@ obj-$(CONFIG_USB_S3C_HSOTG)	+= s3c-hsotg.o
 # USB gadget drivers
 #
 g_zero-objs			:= zero.o
+g_audio-objs			:= audio.o
 g_ether-objs			:= ether.o
 g_serial-objs			:= serial.o
 g_midi-objs			:= gmidi.o
@@ -40,6 +41,7 @@ g_printer-objs			:= printer.o
 g_cdc-objs			:= cdc2.o
 
 obj-$(CONFIG_USB_ZERO)		+= g_zero.o
+obj-$(CONFIG_USB_AUDIO)		+= g_audio.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
 obj-$(CONFIG_USB_FILE_STORAGE)	+= g_file_storage.o

drivers/usb/gadget/audio.c

@@ -0,0 +1,302 @@
+/*
+ * audio.c -- Audio gadget driver
+ *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+
+#include "u_audio.h"
+
+#define DRIVER_DESC		"Linux USB Audio Gadget"
+#define DRIVER_VERSION		"Dec 18, 2008"
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Kbuild is not very cooperative with respect to linking separately
+ * compiled library objects into one module.  So for now we won't use
+ * separate compilation ... ensuring init/exit sections work to shrink
+ * the runtime footprint, and giving us at least some parts of what
+ * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
+ */
+#include "composite.c"
+#include "usbstring.c"
+#include "config.c"
+#include "epautoconf.c"
+
+#include "u_audio.c"
+#include "f_audio.c"
+
+/*-------------------------------------------------------------------------*/
+
+/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+
+/* Thanks to NetChip Technologies for donating this product ID. */
+#define AUDIO_VENDOR_NUM		0x0525	/* NetChip */
+#define AUDIO_PRODUCT_NUM		0xa4a1	/* Linux-USB Audio Gadget */
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_device_descriptor device_desc = {
+	.bLength =		sizeof device_desc,
+	.bDescriptorType =	USB_DT_DEVICE,
+
+	.bcdUSB =		__constant_cpu_to_le16(0x200),
+
+	.bDeviceClass =		USB_CLASS_PER_INTERFACE,
+	.bDeviceSubClass =	0,
+	.bDeviceProtocol =	0,
+	/* .bMaxPacketSize0 = f(hardware) */
+
+	/* Vendor and product id defaults change according to what configs
+	 * we support.  (As does bNumConfigurations.)  These values can
+	 * also be overridden by module parameters.
+	 */
+	.idVendor =		__constant_cpu_to_le16(AUDIO_VENDOR_NUM),
+	.idProduct =		__constant_cpu_to_le16(AUDIO_PRODUCT_NUM),
+	/* .bcdDevice = f(hardware) */
+	/* .iManufacturer = DYNAMIC */
+	/* .iProduct = DYNAMIC */
+	/* NO SERIAL NUMBER */
+	.bNumConfigurations =	1,
+};
+
+static struct usb_otg_descriptor otg_descriptor = {
+	.bLength =		sizeof otg_descriptor,
+	.bDescriptorType =	USB_DT_OTG,
+
+	/* REVISIT SRP-only hardware is possible, although
+	 * it would not be called "OTG" ...
+	 */
+	.bmAttributes =		USB_OTG_SRP | USB_OTG_HNP,
+};
+
+static const struct usb_descriptor_header *otg_desc[] = {
+	(struct usb_descriptor_header *) &otg_descriptor,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Handle USB audio endpoint set/get command in setup class request
+ */
+
+static int audio_set_endpoint_req(struct usb_configuration *c,
+		const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	int			value = -EOPNOTSUPP;
+	u16			ep = le16_to_cpu(ctrl->wIndex);
+	u16			len = le16_to_cpu(ctrl->wLength);
+	u16			w_value = le16_to_cpu(ctrl->wValue);
+
+	DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
+			ctrl->bRequest, w_value, len, ep);
+
+	switch (ctrl->bRequest) {
+	case SET_CUR:
+		value = 0;
+		break;
+
+	case SET_MIN:
+		break;
+
+	case SET_MAX:
+		break;
+
+	case SET_RES:
+		break;
+
+	case SET_MEM:
+		break;
+
+	default:
+		break;
+	}
+
+	return value;
+}
+
+static int audio_get_endpoint_req(struct usb_configuration *c,
+		const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	int value = -EOPNOTSUPP;
+	u8 ep = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+	u16 len = le16_to_cpu(ctrl->wLength);
+	u16 w_value = le16_to_cpu(ctrl->wValue);
+
+	DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
+			ctrl->bRequest, w_value, len, ep);
+
+	switch (ctrl->bRequest) {
+	case GET_CUR:
+	case GET_MIN:
+	case GET_MAX:
+	case GET_RES:
+		value = 3;
+		break;
+	case GET_MEM:
+		break;
+	default:
+		break;
+	}
+
+	return value;
+}
+
+static int
+audio_setup(struct usb_configuration *c, const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct usb_request *req = cdev->req;
+	int value = -EOPNOTSUPP;
+	u16 w_index = le16_to_cpu(ctrl->wIndex);
+	u16 w_value = le16_to_cpu(ctrl->wValue);
+	u16 w_length = le16_to_cpu(ctrl->wLength);
+
+	/* composite driver infrastructure handles everything except
+	 * Audio class messages; interface activation uses set_alt().
+	 */
+	switch (ctrl->bRequestType) {
+	case USB_AUDIO_SET_ENDPOINT:
+		value = audio_set_endpoint_req(c, ctrl);
+		break;
+
+	case USB_AUDIO_GET_ENDPOINT:
+		value = audio_get_endpoint_req(c, ctrl);
+		break;
+
+	default:
+		ERROR(cdev, "Invalid control req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+	}
+
+	/* respond with data transfer or status phase? */
+	if (value >= 0) {
+		DBG(cdev, "Audio req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+		req->zero = 0;
+		req->length = value;
+		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0)
+			ERROR(cdev, "Audio response on err %d\n", value);
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init audio_do_config(struct usb_configuration *c)
+{
+	/* FIXME alloc iConfiguration string, set it in c->strings */
+
+	if (gadget_is_otg(c->cdev->gadget)) {
+		c->descriptors = otg_desc;
+		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	audio_bind_config(c);
+
+	return 0;
+}
+
+static struct usb_configuration audio_config_driver = {
+	.label			= DRIVER_DESC,
+	.bind			= audio_do_config,
+	.setup			= audio_setup,
+	.bConfigurationValue	= 1,
+	/* .iConfiguration = DYNAMIC */
+	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int __init audio_bind(struct usb_composite_dev *cdev)
+{
+	int			gcnum;
+	int			status;
+
+	gcnum = usb_gadget_controller_number(cdev->gadget);
+	if (gcnum >= 0)
+		device_desc.bcdDevice = cpu_to_le16(0x0300 | gcnum);
+	else {
+		ERROR(cdev, "controller '%s' not recognized; trying %s\n",
+			cdev->gadget->name,
+			audio_config_driver.label);
+		device_desc.bcdDevice =
+			__constant_cpu_to_le16(0x0300 | 0x0099);
+	}
+
+	/* device descriptor strings: manufacturer, product */
+	snprintf(manufacturer, sizeof manufacturer, "%s %s with %s",
+		init_utsname()->sysname, init_utsname()->release,
+		cdev->gadget->name);
+	status = usb_string_id(cdev);
+	if (status < 0)
+		goto fail;
+	strings_dev[STRING_MANUFACTURER_IDX].id = status;
+	device_desc.iManufacturer = status;
+
+	status = usb_string_id(cdev);
+	if (status < 0)
+		goto fail;
+	strings_dev[STRING_PRODUCT_IDX].id = status;
+	device_desc.iProduct = status;
+
+	status = usb_add_config(cdev, &audio_config_driver);
+	if (status < 0)
+		goto fail;
+
+	INFO(cdev, "%s, version: %s\n", DRIVER_DESC, DRIVER_VERSION);
+	return 0;
+
+fail:
+	return status;
+}
+
+static int __exit audio_unbind(struct usb_composite_dev *cdev)
+{
+	return 0;
+}
+
+static struct usb_composite_driver audio_driver = {
+	.name		= "g_audio",
+	.dev		= &device_desc,
+	.strings	= audio_strings,
+	.bind		= audio_bind,
+	.unbind		= __exit_p(audio_unbind),
+};
+
+static int __init init(void)
+{
+	return usb_composite_register(&audio_driver);
+}
+module_init(init);
+
+static void __exit cleanup(void)
+{
+	usb_composite_unregister(&audio_driver);
+}
+module_exit(cleanup);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Bryan Wu <cooloney@kernel.org>");
+MODULE_LICENSE("GPL");
+