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>
diff --git a/drivers/usb/gadget/f_audio.c b/drivers/usb/gadget/f_audio.c
new file mode 100644
index 0000000..66527ba
--- /dev/null
+++ b/drivers/usb/gadget/f_audio.c
@@ -0,0 +1,707 @@
+/*
+ * f_audio.c -- USB Audio class function 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <asm/atomic.h>
+
+#include "u_audio.h"
+
+#define OUT_EP_MAX_PACKET_SIZE 200
+static int req_buf_size = OUT_EP_MAX_PACKET_SIZE;
+module_param(req_buf_size, int, S_IRUGO);
+MODULE_PARM_DESC(req_buf_size, "ISO OUT endpoint request buffer size");
+
+static int req_count = 256;
+module_param(req_count, int, S_IRUGO);
+MODULE_PARM_DESC(req_count, "ISO OUT endpoint request count");
+
+static int audio_buf_size = 48000;
+module_param(audio_buf_size, int, S_IRUGO);
+MODULE_PARM_DESC(audio_buf_size, "Audio buffer size");
+
+/*
+ * DESCRIPTORS ... most are static, but strings and full
+ * configuration descriptors are built on demand.
+ */
+
+/*
+ * We have two interfaces- AudioControl and AudioStreaming
+ * TODO: only supcard playback currently
+ */
+#define F_AUDIO_AC_INTERFACE 0
+#define F_AUDIO_AS_INTERFACE 1
+#define F_AUDIO_NUM_INTERFACES 2
+
+/* B.3.1 Standard AC Interface Descriptor */
+static struct usb_interface_descriptor ac_interface_desc __initdata = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ .bNumEndpoints = 0,
+ .bInterfaceClass = USB_CLASS_AUDIO,
+ .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL,
+};
+
+DECLARE_USB_AC_HEADER_DESCRIPTOR(2);
+
+#define USB_DT_AC_HEADER_LENGH USB_DT_AC_HEADER_SIZE(F_AUDIO_NUM_INTERFACES)
+/* B.3.2 Class-Specific AC Interface Descriptor */
+static struct usb_ac_header_descriptor_2 ac_header_desc = {
+ .bLength = USB_DT_AC_HEADER_LENGH,
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = HEADER,
+ .bcdADC = __constant_cpu_to_le16(0x0100),
+ .wTotalLength = __constant_cpu_to_le16(USB_DT_AC_HEADER_LENGH),
+ .bInCollection = F_AUDIO_NUM_INTERFACES,
+ .baInterfaceNr = {
+ [0] = F_AUDIO_AC_INTERFACE,
+ [1] = F_AUDIO_AS_INTERFACE,
+ }
+};
+
+#define INPUT_TERMINAL_ID 1
+static struct usb_input_terminal_descriptor input_terminal_desc = {
+ .bLength = USB_DT_AC_INPUT_TERMINAL_SIZE,
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = INPUT_TERMINAL,
+ .bTerminalID = INPUT_TERMINAL_ID,
+ .wTerminalType = USB_AC_TERMINAL_STREAMING,
+ .bAssocTerminal = 0,
+ .wChannelConfig = 0x3,
+};
+
+DECLARE_USB_AC_FEATURE_UNIT_DESCRIPTOR(0);
+
+#define FEATURE_UNIT_ID 2
+static struct usb_ac_feature_unit_descriptor_0 feature_unit_desc = {
+ .bLength = USB_DT_AC_FEATURE_UNIT_SIZE(0),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = FEATURE_UNIT,
+ .bUnitID = FEATURE_UNIT_ID,
+ .bSourceID = INPUT_TERMINAL_ID,
+ .bControlSize = 2,
+ .bmaControls[0] = (FU_MUTE | FU_VOLUME),
+};
+
+static struct usb_audio_control mute_control = {
+ .list = LIST_HEAD_INIT(mute_control.list),
+ .name = "Mute Control",
+ .type = MUTE_CONTROL,
+ /* Todo: add real Mute control code */
+ .set = generic_set_cmd,
+ .get = generic_get_cmd,
+};
+
+static struct usb_audio_control volume_control = {
+ .list = LIST_HEAD_INIT(volume_control.list),
+ .name = "Volume Control",
+ .type = VOLUME_CONTROL,
+ /* Todo: add real Volume control code */
+ .set = generic_set_cmd,
+ .get = generic_get_cmd,
+};
+
+static struct usb_audio_control_selector feature_unit = {
+ .list = LIST_HEAD_INIT(feature_unit.list),
+ .id = FEATURE_UNIT_ID,
+ .name = "Mute & Volume Control",
+ .type = FEATURE_UNIT,
+ .desc = (struct usb_descriptor_header *)&feature_unit_desc,
+};
+
+#define OUTPUT_TERMINAL_ID 3
+static struct usb_output_terminal_descriptor output_terminal_desc = {
+ .bLength = USB_DT_AC_OUTPUT_TERMINAL_SIZE,
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = OUTPUT_TERMINAL,
+ .bTerminalID = OUTPUT_TERMINAL_ID,
+ .wTerminalType = USB_AC_OUTPUT_TERMINAL_SPEAKER,
+ .bAssocTerminal = FEATURE_UNIT_ID,
+ .bSourceID = FEATURE_UNIT_ID,
+};
+
+/* B.4.1 Standard AS Interface Descriptor */
+static struct usb_interface_descriptor as_interface_alt_0_desc = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ .bAlternateSetting = 0,
+ .bNumEndpoints = 0,
+ .bInterfaceClass = USB_CLASS_AUDIO,
+ .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+};
+
+static struct usb_interface_descriptor as_interface_alt_1_desc = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ .bAlternateSetting = 1,
+ .bNumEndpoints = 1,
+ .bInterfaceClass = USB_CLASS_AUDIO,
+ .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+};
+
+/* B.4.2 Class-Specific AS Interface Descriptor */
+static struct usb_as_header_descriptor as_header_desc = {
+ .bLength = USB_DT_AS_HEADER_SIZE,
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = AS_GENERAL,
+ .bTerminalLink = INPUT_TERMINAL_ID,
+ .bDelay = 1,
+ .wFormatTag = USB_AS_AUDIO_FORMAT_TYPE_I_PCM,
+};
+
+DECLARE_USB_AS_FORMAT_TYPE_I_DISCRETE_DESC(1);
+
+static struct usb_as_formate_type_i_discrete_descriptor_1 as_type_i_desc = {
+ .bLength = USB_AS_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubtype = FORMAT_TYPE,
+ .bFormatType = USB_AS_FORMAT_TYPE_I,
+ .bSubframeSize = 2,
+ .bBitResolution = 16,
+ .bSamFreqType = 1,
+};
+
+/* Standard ISO OUT Endpoint Descriptor */
+static struct usb_endpoint_descriptor as_out_ep_desc __initdata = {
+ .bLength = USB_DT_ENDPOINT_AUDIO_SIZE,
+ .bDescriptorType = USB_DT_ENDPOINT,
+ .bEndpointAddress = USB_DIR_OUT,
+ .bmAttributes = USB_AS_ENDPOINT_ADAPTIVE
+ | USB_ENDPOINT_XFER_ISOC,
+ .wMaxPacketSize = __constant_cpu_to_le16(OUT_EP_MAX_PACKET_SIZE),
+ .bInterval = 4,
+};
+
+/* Class-specific AS ISO OUT Endpoint Descriptor */
+static struct usb_as_iso_endpoint_descriptor as_iso_out_desc __initdata = {
+ .bLength = USB_AS_ISO_ENDPOINT_DESC_SIZE,
+ .bDescriptorType = USB_DT_CS_ENDPOINT,
+ .bDescriptorSubtype = EP_GENERAL,
+ .bmAttributes = 1,
+ .bLockDelayUnits = 1,
+ .wLockDelay = __constant_cpu_to_le16(1),
+};
+
+static struct usb_descriptor_header *f_audio_desc[] __initdata = {
+ (struct usb_descriptor_header *)&ac_interface_desc,
+ (struct usb_descriptor_header *)&ac_header_desc,
+
+ (struct usb_descriptor_header *)&input_terminal_desc,
+ (struct usb_descriptor_header *)&output_terminal_desc,
+ (struct usb_descriptor_header *)&feature_unit_desc,
+
+ (struct usb_descriptor_header *)&as_interface_alt_0_desc,
+ (struct usb_descriptor_header *)&as_interface_alt_1_desc,
+ (struct usb_descriptor_header *)&as_header_desc,
+
+ (struct usb_descriptor_header *)&as_type_i_desc,
+
+ (struct usb_descriptor_header *)&as_out_ep_desc,
+ (struct usb_descriptor_header *)&as_iso_out_desc,
+ NULL,
+};
+
+/* string IDs are assigned dynamically */
+
+#define STRING_MANUFACTURER_IDX 0
+#define STRING_PRODUCT_IDX 1
+
+static char manufacturer[50];
+
+static struct usb_string strings_dev[] = {
+ [STRING_MANUFACTURER_IDX].s = manufacturer,
+ [STRING_PRODUCT_IDX].s = DRIVER_DESC,
+ { } /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_dev = {
+ .language = 0x0409, /* en-us */
+ .strings = strings_dev,
+};
+
+static struct usb_gadget_strings *audio_strings[] = {
+ &stringtab_dev,
+ NULL,
+};
+
+/*
+ * This function is an ALSA sound card following USB Audio Class Spec 1.0.
+ */
+
+/*-------------------------------------------------------------------------*/
+struct f_audio_buf {
+ u8 *buf;
+ int actual;
+ struct list_head list;
+};
+
+static struct f_audio_buf *f_audio_buffer_alloc(int buf_size)
+{
+ struct f_audio_buf *copy_buf;
+
+ copy_buf = kzalloc(sizeof *copy_buf, GFP_ATOMIC);
+ if (!copy_buf)
+ return (struct f_audio_buf *)-ENOMEM;
+
+ copy_buf->buf = kzalloc(buf_size, GFP_ATOMIC);
+ if (!copy_buf->buf) {
+ kfree(copy_buf);
+ return (struct f_audio_buf *)-ENOMEM;
+ }
+
+ return copy_buf;
+}
+
+static void f_audio_buffer_free(struct f_audio_buf *audio_buf)
+{
+ kfree(audio_buf->buf);
+ kfree(audio_buf);
+}
+/*-------------------------------------------------------------------------*/
+
+struct f_audio {
+ struct gaudio card;
+
+ /* endpoints handle full and/or high speeds */
+ struct usb_ep *out_ep;
+ struct usb_endpoint_descriptor *out_desc;
+
+ spinlock_t lock;
+ struct f_audio_buf *copy_buf;
+ struct work_struct playback_work;
+ struct list_head play_queue;
+
+ /* Control Set command */
+ struct list_head cs;
+ u8 set_cmd;
+ struct usb_audio_control *set_con;
+};
+
+static inline struct f_audio *func_to_audio(struct usb_function *f)
+{
+ return container_of(f, struct f_audio, card.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void f_audio_playback_work(struct work_struct *data)
+{
+ struct f_audio *audio = container_of(data, struct f_audio,
+ playback_work);
+ struct f_audio_buf *play_buf;
+
+ spin_lock_irq(&audio->lock);
+ if (list_empty(&audio->play_queue)) {
+ spin_unlock_irq(&audio->lock);
+ return;
+ }
+ play_buf = list_first_entry(&audio->play_queue,
+ struct f_audio_buf, list);
+ list_del(&play_buf->list);
+ spin_unlock_irq(&audio->lock);
+
+ u_audio_playback(&audio->card, play_buf->buf, play_buf->actual);
+ f_audio_buffer_free(play_buf);
+
+ return;
+}
+
+static int f_audio_out_ep_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct f_audio *audio = req->context;
+ struct usb_composite_dev *cdev = audio->card.func.config->cdev;
+ struct f_audio_buf *copy_buf = audio->copy_buf;
+ int err;
+
+ if (!copy_buf)
+ return -EINVAL;
+
+ /* Copy buffer is full, add it to the play_queue */
+ if (audio_buf_size - copy_buf->actual < req->actual) {
+ list_add_tail(©_buf->list, &audio->play_queue);
+ schedule_work(&audio->playback_work);
+ copy_buf = f_audio_buffer_alloc(audio_buf_size);
+ if (copy_buf < 0)
+ return -ENOMEM;
+ }
+
+ memcpy(copy_buf->buf + copy_buf->actual, req->buf, req->actual);
+ copy_buf->actual += req->actual;
+ audio->copy_buf = copy_buf;
+
+ err = usb_ep_queue(ep, req, GFP_ATOMIC);
+ if (err)
+ ERROR(cdev, "%s queue req: %d\n", ep->name, err);
+
+ return 0;
+
+}
+
+static void f_audio_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct f_audio *audio = req->context;
+ int status = req->status;
+ u32 data = 0;
+ struct usb_ep *out_ep = audio->out_ep;
+
+ switch (status) {
+
+ case 0: /* normal completion? */
+ if (ep == out_ep)
+ f_audio_out_ep_complete(ep, req);
+ else if (audio->set_con) {
+ memcpy(&data, req->buf, req->length);
+ audio->set_con->set(audio->set_con, audio->set_cmd,
+ le16_to_cpu(data));
+ audio->set_con = NULL;
+ }
+ break;
+ default:
+ break;
+ }
+}
+
+static int audio_set_intf_req(struct usb_function *f,
+ const struct usb_ctrlrequest *ctrl)
+{
+ struct f_audio *audio = func_to_audio(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct usb_request *req = cdev->req;
+ u8 id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+ u16 len = le16_to_cpu(ctrl->wLength);
+ u16 w_value = le16_to_cpu(ctrl->wValue);
+ u8 con_sel = (w_value >> 8) & 0xFF;
+ u8 cmd = (ctrl->bRequest & 0x0F);
+ struct usb_audio_control_selector *cs;
+ struct usb_audio_control *con;
+
+ DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
+ ctrl->bRequest, w_value, len, id);
+
+ list_for_each_entry(cs, &audio->cs, list) {
+ if (cs->id == id) {
+ list_for_each_entry(con, &cs->control, list) {
+ if (con->type == con_sel) {
+ audio->set_con = con;
+ break;
+ }
+ }
+ break;
+ }
+ }
+
+ audio->set_cmd = cmd;
+ req->context = audio;
+ req->complete = f_audio_complete;
+
+ return len;
+}
+
+static int audio_get_intf_req(struct usb_function *f,
+ const struct usb_ctrlrequest *ctrl)
+{
+ struct f_audio *audio = func_to_audio(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct usb_request *req = cdev->req;
+ int value = -EOPNOTSUPP;
+ u8 id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+ u16 len = le16_to_cpu(ctrl->wLength);
+ u16 w_value = le16_to_cpu(ctrl->wValue);
+ u8 con_sel = (w_value >> 8) & 0xFF;
+ u8 cmd = (ctrl->bRequest & 0x0F);
+ struct usb_audio_control_selector *cs;
+ struct usb_audio_control *con;
+
+ DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
+ ctrl->bRequest, w_value, len, id);
+
+ list_for_each_entry(cs, &audio->cs, list) {
+ if (cs->id == id) {
+ list_for_each_entry(con, &cs->control, list) {
+ if (con->type == con_sel && con->get) {
+ value = con->get(con, cmd);
+ break;
+ }
+ }
+ break;
+ }
+ }
+
+ req->context = audio;
+ req->complete = f_audio_complete;
+ memcpy(req->buf, &value, len);
+
+ return len;
+}
+
+static int
+f_audio_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+ struct usb_composite_dev *cdev = f->config->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_INTF:
+ value = audio_set_intf_req(f, ctrl);
+ break;
+
+ case USB_AUDIO_GET_INTF:
+ value = audio_get_intf_req(f, 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 f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+ struct f_audio *audio = func_to_audio(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct usb_ep *out_ep = audio->out_ep;
+ struct usb_request *req;
+ int i = 0, err = 0;
+
+ DBG(cdev, "intf %d, alt %d\n", intf, alt);
+
+ if (intf == 1) {
+ if (alt == 1) {
+ usb_ep_enable(out_ep, audio->out_desc);
+ out_ep->driver_data = audio;
+ audio->copy_buf = f_audio_buffer_alloc(audio_buf_size);
+
+ /*
+ * allocate a bunch of read buffers
+ * and queue them all at once.
+ */
+ for (i = 0; i < req_count && err == 0; i++) {
+ req = usb_ep_alloc_request(out_ep, GFP_ATOMIC);
+ if (req) {
+ req->buf = kzalloc(req_buf_size,
+ GFP_ATOMIC);
+ if (req->buf) {
+ req->length = req_buf_size;
+ req->context = audio;
+ req->complete =
+ f_audio_complete;
+ err = usb_ep_queue(out_ep,
+ req, GFP_ATOMIC);
+ if (err)
+ ERROR(cdev,
+ "%s queue req: %d\n",
+ out_ep->name, err);
+ } else
+ err = -ENOMEM;
+ } else
+ err = -ENOMEM;
+ }
+
+ } else {
+ struct f_audio_buf *copy_buf = audio->copy_buf;
+ if (copy_buf) {
+ list_add_tail(©_buf->list,
+ &audio->play_queue);
+ schedule_work(&audio->playback_work);
+ }
+ }
+ }
+
+ return err;
+}
+
+static void f_audio_disable(struct usb_function *f)
+{
+ return;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void f_audio_build_desc(struct f_audio *audio)
+{
+ struct gaudio *card = &audio->card;
+ u8 *sam_freq;
+ int rate;
+
+ /* Set channel numbers */
+ input_terminal_desc.bNrChannels = u_audio_get_playback_channels(card);
+ as_type_i_desc.bNrChannels = u_audio_get_playback_channels(card);
+
+ /* Set sample rates */
+ rate = u_audio_get_playback_rate(card);
+ sam_freq = as_type_i_desc.tSamFreq[0];
+ memcpy(sam_freq, &rate, 3);
+
+ /* Todo: Set Sample bits and other parameters */
+
+ return;
+}
+
+/* audio function driver setup/binding */
+static int __init
+f_audio_bind(struct usb_configuration *c, struct usb_function *f)
+{
+ struct usb_composite_dev *cdev = c->cdev;
+ struct f_audio *audio = func_to_audio(f);
+ int status;
+ struct usb_ep *ep;
+
+ f_audio_build_desc(audio);
+
+ /* allocate instance-specific interface IDs, and patch descriptors */
+ status = usb_interface_id(c, f);
+ if (status < 0)
+ goto fail;
+ ac_interface_desc.bInterfaceNumber = status;
+
+ status = usb_interface_id(c, f);
+ if (status < 0)
+ goto fail;
+ as_interface_alt_0_desc.bInterfaceNumber = status;
+ as_interface_alt_1_desc.bInterfaceNumber = status;
+
+ status = -ENODEV;
+
+ /* allocate instance-specific endpoints */
+ ep = usb_ep_autoconfig(cdev->gadget, &as_out_ep_desc);
+ if (!ep)
+ goto fail;
+ audio->out_ep = ep;
+ ep->driver_data = cdev; /* claim */
+
+ status = -ENOMEM;
+
+ /* supcard all relevant hardware speeds... we expect that when
+ * hardware is dual speed, all bulk-capable endpoints work at
+ * both speeds
+ */
+
+ /* copy descriptors, and track endpoint copies */
+ if (gadget_is_dualspeed(c->cdev->gadget)) {
+ c->highspeed = true;
+ f->hs_descriptors = usb_copy_descriptors(f_audio_desc);
+ } else
+ f->descriptors = usb_copy_descriptors(f_audio_desc);
+
+ return 0;
+
+fail:
+
+ return status;
+}
+
+static void
+f_audio_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+ struct f_audio *audio = func_to_audio(f);
+
+ usb_free_descriptors(f->descriptors);
+ kfree(audio);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Todo: add more control selecotor dynamically */
+int __init control_selector_init(struct f_audio *audio)
+{
+ INIT_LIST_HEAD(&audio->cs);
+ list_add(&feature_unit.list, &audio->cs);
+
+ INIT_LIST_HEAD(&feature_unit.control);
+ list_add(&mute_control.list, &feature_unit.control);
+ list_add(&volume_control.list, &feature_unit.control);
+
+ volume_control.data[_CUR] = 0xffc0;
+ volume_control.data[_MIN] = 0xe3a0;
+ volume_control.data[_MAX] = 0xfff0;
+ volume_control.data[_RES] = 0x0030;
+
+ return 0;
+}
+
+/**
+ * audio_bind_config - add USB audio fucntion to a configuration
+ * @c: the configuration to supcard the USB audio function
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ */
+int __init audio_bind_config(struct usb_configuration *c)
+{
+ struct f_audio *audio;
+ int status;
+
+ /* allocate and initialize one new instance */
+ audio = kzalloc(sizeof *audio, GFP_KERNEL);
+ if (!audio)
+ return -ENOMEM;
+
+ audio->card.func.name = "g_audio";
+ audio->card.gadget = c->cdev->gadget;
+
+ INIT_LIST_HEAD(&audio->play_queue);
+ spin_lock_init(&audio->lock);
+
+ /* set up ASLA audio devices */
+ status = gaudio_setup(&audio->card);
+ if (status < 0)
+ goto setup_fail;
+
+ audio->card.func.strings = audio_strings;
+ audio->card.func.bind = f_audio_bind;
+ audio->card.func.unbind = f_audio_unbind;
+ audio->card.func.set_alt = f_audio_set_alt;
+ audio->card.func.setup = f_audio_setup;
+ audio->card.func.disable = f_audio_disable;
+ audio->out_desc = &as_out_ep_desc;
+
+ control_selector_init(audio);
+
+ INIT_WORK(&audio->playback_work, f_audio_playback_work);
+
+ status = usb_add_function(c, &audio->card.func);
+ if (status)
+ goto add_fail;
+
+ INFO(c->cdev, "audio_buf_size %d, req_buf_size %d, req_count %d\n",
+ audio_buf_size, req_buf_size, req_count);
+
+ return status;
+
+add_fail:
+ gaudio_cleanup(&audio->card);
+setup_fail:
+ kfree(audio);
+ return status;
+}