usb: gadget: function: make current f_uac1 implementation legacy

Before introducing new f_uac1 function (with virtual
ALSA card) make current implementation legacy.

This includes renaming of existing files, some
variables, config options and documentation

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

1 files changed, 1021 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_uac1_legacy.c b/drivers/usb/gadget/function/f_uac1_legacy.c
new file mode 100644
index 000000000000..5d229e72912e
--- /dev/null
+++ b/drivers/usb/gadget/function/f_uac1_legacy.c
@@ -0,0 +1,1021 @@
+/*
+ * 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/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/atomic.h>
+
+#include "u_uac1_legacy.h"
+
+static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value);
+static int generic_get_cmd(struct usb_audio_control *con, u8 cmd);
+
+/*
+ * 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	1
+
+/* B.3.1  Standard AC Interface Descriptor */
+static struct usb_interface_descriptor ac_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bNumEndpoints =	0,
+	.bInterfaceClass =	USB_CLASS_AUDIO,
+	.bInterfaceSubClass =	USB_SUBCLASS_AUDIOCONTROL,
+};
+
+/*
+ * The number of AudioStreaming and MIDIStreaming interfaces
+ * in the Audio Interface Collection
+ */
+DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
+
+#define UAC_DT_AC_HEADER_LENGTH	UAC_DT_AC_HEADER_SIZE(F_AUDIO_NUM_INTERFACES)
+/* 1 input terminal, 1 output terminal and 1 feature unit */
+#define UAC_DT_TOTAL_LENGTH (UAC_DT_AC_HEADER_LENGTH + UAC_DT_INPUT_TERMINAL_SIZE \
+	+ UAC_DT_OUTPUT_TERMINAL_SIZE + UAC_DT_FEATURE_UNIT_SIZE(0))
+/* B.3.2  Class-Specific AC Interface Descriptor */
+static struct uac1_ac_header_descriptor_1 ac_header_desc = {
+	.bLength =		UAC_DT_AC_HEADER_LENGTH,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_HEADER,
+	.bcdADC =		__constant_cpu_to_le16(0x0100),
+	.wTotalLength =		__constant_cpu_to_le16(UAC_DT_TOTAL_LENGTH),
+	.bInCollection =	F_AUDIO_NUM_INTERFACES,
+	.baInterfaceNr = {
+	/* Interface number of the first AudioStream interface */
+		[0] =		1,
+	}
+};
+
+#define INPUT_TERMINAL_ID	1
+static struct uac_input_terminal_descriptor input_terminal_desc = {
+	.bLength =		UAC_DT_INPUT_TERMINAL_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_INPUT_TERMINAL,
+	.bTerminalID =		INPUT_TERMINAL_ID,
+	.wTerminalType =	UAC_TERMINAL_STREAMING,
+	.bAssocTerminal =	0,
+	.wChannelConfig =	0x3,
+};
+
+DECLARE_UAC_FEATURE_UNIT_DESCRIPTOR(0);
+
+#define FEATURE_UNIT_ID		2
+static struct uac_feature_unit_descriptor_0 feature_unit_desc = {
+	.bLength		= UAC_DT_FEATURE_UNIT_SIZE(0),
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype	= UAC_FEATURE_UNIT,
+	.bUnitID		= FEATURE_UNIT_ID,
+	.bSourceID		= INPUT_TERMINAL_ID,
+	.bControlSize		= 2,
+	.bmaControls[0]		= (UAC_FU_MUTE | UAC_FU_VOLUME),
+};
+
+static struct usb_audio_control mute_control = {
+	.list = LIST_HEAD_INIT(mute_control.list),
+	.name = "Mute Control",
+	.type = UAC_FU_MUTE,
+	/* 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 = UAC_FU_VOLUME,
+	/* 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 = UAC_FEATURE_UNIT,
+	.desc = (struct usb_descriptor_header *)&feature_unit_desc,
+};
+
+#define OUTPUT_TERMINAL_ID	3
+static struct uac1_output_terminal_descriptor output_terminal_desc = {
+	.bLength		= UAC_DT_OUTPUT_TERMINAL_SIZE,
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype	= UAC_OUTPUT_TERMINAL,
+	.bTerminalID		= OUTPUT_TERMINAL_ID,
+	.wTerminalType		= UAC_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 uac1_as_header_descriptor as_header_desc = {
+	.bLength =		UAC_DT_AS_HEADER_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_AS_GENERAL,
+	.bTerminalLink =	INPUT_TERMINAL_ID,
+	.bDelay =		1,
+	.wFormatTag =		UAC_FORMAT_TYPE_I_PCM,
+};
+
+DECLARE_UAC_FORMAT_TYPE_I_DISCRETE_DESC(1);
+
+static struct uac_format_type_i_discrete_descriptor_1 as_type_i_desc = {
+	.bLength =		UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_FORMAT_TYPE,
+	.bFormatType =		UAC_FORMAT_TYPE_I,
+	.bSubframeSize =	2,
+	.bBitResolution =	16,
+	.bSamFreqType =		1,
+};
+
+/* Standard ISO OUT Endpoint Descriptor */
+static struct usb_endpoint_descriptor as_out_ep_desc  = {
+	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_SYNC_ADAPTIVE
+				| USB_ENDPOINT_XFER_ISOC,
+	.wMaxPacketSize	=	cpu_to_le16(UAC1_OUT_EP_MAX_PACKET_SIZE),
+	.bInterval =		4,
+};
+
+/* Class-specific AS ISO OUT Endpoint Descriptor */
+static struct uac_iso_endpoint_descriptor as_iso_out_desc = {
+	.bLength =		UAC_ISO_ENDPOINT_DESC_SIZE,
+	.bDescriptorType =	USB_DT_CS_ENDPOINT,
+	.bDescriptorSubtype =	UAC_EP_GENERAL,
+	.bmAttributes = 	1,
+	.bLockDelayUnits =	1,
+	.wLockDelay =		__constant_cpu_to_le16(1),
+};
+
+static struct usb_descriptor_header *f_audio_desc[] = {
+	(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,
+};
+
+enum {
+	STR_AC_IF,
+	STR_INPUT_TERMINAL,
+	STR_INPUT_TERMINAL_CH_NAMES,
+	STR_FEAT_DESC_0,
+	STR_OUTPUT_TERMINAL,
+	STR_AS_IF_ALT0,
+	STR_AS_IF_ALT1,
+};
+
+static struct usb_string strings_uac1[] = {
+	[STR_AC_IF].s = "AC Interface",
+	[STR_INPUT_TERMINAL].s = "Input terminal",
+	[STR_INPUT_TERMINAL_CH_NAMES].s = "Channels",
+	[STR_FEAT_DESC_0].s = "Volume control & mute",
+	[STR_OUTPUT_TERMINAL].s = "Output terminal",
+	[STR_AS_IF_ALT0].s = "AS Interface",
+	[STR_AS_IF_ALT1].s = "AS Interface",
+	{ },
+};
+
+static struct usb_gadget_strings str_uac1 = {
+	.language = 0x0409,	/* en-us */
+	.strings = strings_uac1,
+};
+
+static struct usb_gadget_strings *uac1_strings[] = {
+	&str_uac1,
+	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 ERR_PTR(-ENOMEM);
+
+	copy_buf->buf = kzalloc(buf_size, GFP_ATOMIC);
+	if (!copy_buf->buf) {
+		kfree(copy_buf);
+		return ERR_PTR(-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;
+
+	u8 ac_intf, ac_alt;
+	u8 as_intf, as_alt;
+
+	/* endpoints handle full and/or high speeds */
+	struct usb_ep			*out_ep;
+
+	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);
+}
+
+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;
+	struct f_uac1_legacy_opts *opts;
+	int audio_buf_size;
+	int err;
+
+	opts = container_of(audio->card.func.fi, struct f_uac1_legacy_opts,
+			    func_inst);
+	audio_buf_size = opts->audio_buf_size;
+
+	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(&copy_buf->list, &audio->play_queue);
+		schedule_work(&audio->playback_work);
+		copy_buf = f_audio_buffer_alloc(audio_buf_size);
+		if (IS_ERR(copy_buf))
+			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;
+	len = min_t(size_t, sizeof(value), len);
+	memcpy(req->buf, &value, len);
+
+	return len;
+}
+
+static int audio_set_endpoint_req(struct usb_function *f,
+		const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = f->config->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 UAC_SET_CUR:
+		value = len;
+		break;
+
+	case UAC_SET_MIN:
+		break;
+
+	case UAC_SET_MAX:
+		break;
+
+	case UAC_SET_RES:
+		break;
+
+	case UAC_SET_MEM:
+		break;
+
+	default:
+		break;
+	}
+
+	return value;
+}
+
+static int audio_get_endpoint_req(struct usb_function *f,
+		const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = f->config->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 UAC_GET_CUR:
+	case UAC_GET_MIN:
+	case UAC_GET_MAX:
+	case UAC_GET_RES:
+		value = len;
+		break;
+	case UAC_GET_MEM:
+		break;
+	default:
+		break;
+	}
+
+	return value;
+}
+
+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; interface
+	 * activation uses set_alt().
+	 */
+	switch (ctrl->bRequestType) {
+	case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
+		value = audio_set_intf_req(f, ctrl);
+		break;
+
+	case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
+		value = audio_get_intf_req(f, ctrl);
+		break;
+
+	case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_ENDPOINT:
+		value = audio_set_endpoint_req(f, ctrl);
+		break;
+
+	case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT:
+		value = audio_get_endpoint_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;
+	struct f_uac1_legacy_opts *opts;
+	int req_buf_size, req_count, audio_buf_size;
+	int i = 0, err = 0;
+
+	DBG(cdev, "intf %d, alt %d\n", intf, alt);
+
+	opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
+	req_buf_size = opts->req_buf_size;
+	req_count = opts->req_count;
+	audio_buf_size = opts->audio_buf_size;
+
+	/* No i/f has more than 2 alt settings */
+	if (alt > 1) {
+		ERROR(cdev, "%s:%d Error!\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	if (intf == audio->ac_intf) {
+		/* Control I/f has only 1 AltSetting - 0 */
+		if (alt) {
+			ERROR(cdev, "%s:%d Error!\n", __func__, __LINE__);
+			return -EINVAL;
+		}
+		return 0;
+	} else if (intf == audio->as_intf) {
+		if (alt == 1) {
+			err = config_ep_by_speed(cdev->gadget, f, out_ep);
+			if (err)
+				return err;
+
+			usb_ep_enable(out_ep);
+			audio->copy_buf = f_audio_buffer_alloc(audio_buf_size);
+			if (IS_ERR(audio->copy_buf))
+				return -ENOMEM;
+
+			/*
+			 * 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(&copy_buf->list,
+						&audio->play_queue);
+				schedule_work(&audio->playback_work);
+			}
+		}
+		audio->as_alt = alt;
+	}
+
+	return err;
+}
+
+static int f_audio_get_alt(struct usb_function *f, unsigned intf)
+{
+	struct f_audio		*audio = func_to_audio(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	if (intf == audio->ac_intf)
+		return audio->ac_alt;
+	else if (intf == audio->as_intf)
+		return audio->as_alt;
+	else
+		ERROR(cdev, "%s:%d Invalid Interface %d!\n",
+		      __func__, __LINE__, intf);
+
+	return -EINVAL;
+}
+
+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
+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);
+	struct usb_string	*us;
+	int			status;
+	struct usb_ep		*ep = NULL;
+	struct f_uac1_legacy_opts	*audio_opts;
+
+	audio_opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
+	audio->card.gadget = c->cdev->gadget;
+	/* set up ASLA audio devices */
+	if (!audio_opts->bound) {
+		status = gaudio_setup(&audio->card);
+		if (status < 0)
+			return status;
+		audio_opts->bound = true;
+	}
+	us = usb_gstrings_attach(cdev, uac1_strings, ARRAY_SIZE(strings_uac1));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+	ac_interface_desc.iInterface = us[STR_AC_IF].id;
+	input_terminal_desc.iTerminal = us[STR_INPUT_TERMINAL].id;
+	input_terminal_desc.iChannelNames = us[STR_INPUT_TERMINAL_CH_NAMES].id;
+	feature_unit_desc.iFeature = us[STR_FEAT_DESC_0].id;
+	output_terminal_desc.iTerminal = us[STR_OUTPUT_TERMINAL].id;
+	as_interface_alt_0_desc.iInterface = us[STR_AS_IF_ALT0].id;
+	as_interface_alt_1_desc.iInterface = us[STR_AS_IF_ALT1].id;
+
+
+	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;
+	audio->ac_intf = status;
+	audio->ac_alt = 0;
+
+	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;
+	audio->as_intf = status;
+	audio->as_alt = 0;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &as_out_ep_desc);
+	if (!ep)
+		goto fail;
+	audio->out_ep = ep;
+	audio->out_ep->desc = &as_out_ep_desc;
+
+	status = -ENOMEM;
+
+	/* copy descriptors, and track endpoint copies */
+	status = usb_assign_descriptors(f, f_audio_desc, f_audio_desc, NULL,
+					NULL);
+	if (status)
+		goto fail;
+	return 0;
+
+fail:
+	gaudio_cleanup(&audio->card);
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value)
+{
+	con->data[cmd] = value;
+
+	return 0;
+}
+
+static int generic_get_cmd(struct usb_audio_control *con, u8 cmd)
+{
+	return con->data[cmd];
+}
+
+/* Todo: add more control selecotor dynamically */
+static int 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[UAC__CUR] = 0xffc0;
+	volume_control.data[UAC__MIN] = 0xe3a0;
+	volume_control.data[UAC__MAX] = 0xfff0;
+	volume_control.data[UAC__RES] = 0x0030;
+
+	return 0;
+}
+
+static inline
+struct f_uac1_legacy_opts *to_f_uac1_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_uac1_legacy_opts,
+			    func_inst.group);
+}
+
+static void f_uac1_attr_release(struct config_item *item)
+{
+	struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations f_uac1_item_ops = {
+	.release	= f_uac1_attr_release,
+};
+
+#define UAC1_INT_ATTRIBUTE(name)					\
+static ssize_t f_uac1_opts_##name##_show(struct config_item *item,	\
+					 char *page)			\
+{									\
+	struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);		\
+	int result;							\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", opts->name);			\
+	mutex_unlock(&opts->lock);					\
+									\
+	return result;							\
+}									\
+									\
+static ssize_t f_uac1_opts_##name##_store(struct config_item *item,		\
+					  const char *page, size_t len)	\
+{									\
+	struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);		\
+	int ret;							\
+	u32 num;							\
+									\
+	mutex_lock(&opts->lock);					\
+	if (opts->refcnt) {						\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = kstrtou32(page, 0, &num);					\
+	if (ret)							\
+		goto end;						\
+									\
+	opts->name = num;						\
+	ret = len;							\
+									\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	return ret;							\
+}									\
+									\
+CONFIGFS_ATTR(f_uac1_opts_, name)
+
+UAC1_INT_ATTRIBUTE(req_buf_size);
+UAC1_INT_ATTRIBUTE(req_count);
+UAC1_INT_ATTRIBUTE(audio_buf_size);
+
+#define UAC1_STR_ATTRIBUTE(name)					\
+static ssize_t f_uac1_opts_##name##_show(struct config_item *item,	\
+					 char *page)			\
+{									\
+	struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);		\
+	int result;							\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%s\n", opts->name);			\
+	mutex_unlock(&opts->lock);					\
+									\
+	return result;							\
+}									\
+									\
+static ssize_t f_uac1_opts_##name##_store(struct config_item *item,	\
+					  const char *page, size_t len)	\
+{									\
+	struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);		\
+	int ret = -EBUSY;						\
+	char *tmp;							\
+									\
+	mutex_lock(&opts->lock);					\
+	if (opts->refcnt)						\
+		goto end;						\
+									\
+	tmp = kstrndup(page, len, GFP_KERNEL);				\
+	if (tmp) {							\
+		ret = -ENOMEM;						\
+		goto end;						\
+	}								\
+	if (opts->name##_alloc)						\
+		kfree(opts->name);					\
+	opts->name##_alloc = true;					\
+	opts->name = tmp;						\
+	ret = len;							\
+									\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	return ret;							\
+}									\
+									\
+CONFIGFS_ATTR(f_uac1_opts_, name)
+
+UAC1_STR_ATTRIBUTE(fn_play);
+UAC1_STR_ATTRIBUTE(fn_cap);
+UAC1_STR_ATTRIBUTE(fn_cntl);
+
+static struct configfs_attribute *f_uac1_attrs[] = {
+	&f_uac1_opts_attr_req_buf_size,
+	&f_uac1_opts_attr_req_count,
+	&f_uac1_opts_attr_audio_buf_size,
+	&f_uac1_opts_attr_fn_play,
+	&f_uac1_opts_attr_fn_cap,
+	&f_uac1_opts_attr_fn_cntl,
+	NULL,
+};
+
+static struct config_item_type f_uac1_func_type = {
+	.ct_item_ops	= &f_uac1_item_ops,
+	.ct_attrs	= f_uac1_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void f_audio_free_inst(struct usb_function_instance *f)
+{
+	struct f_uac1_legacy_opts *opts;
+
+	opts = container_of(f, struct f_uac1_legacy_opts, func_inst);
+	if (opts->fn_play_alloc)
+		kfree(opts->fn_play);
+	if (opts->fn_cap_alloc)
+		kfree(opts->fn_cap);
+	if (opts->fn_cntl_alloc)
+		kfree(opts->fn_cntl);
+	kfree(opts);
+}
+
+static struct usb_function_instance *f_audio_alloc_inst(void)
+{
+	struct f_uac1_legacy_opts *opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&opts->lock);
+	opts->func_inst.free_func_inst = f_audio_free_inst;
+
+	config_group_init_type_name(&opts->func_inst.group, "",
+				    &f_uac1_func_type);
+
+	opts->req_buf_size = UAC1_OUT_EP_MAX_PACKET_SIZE;
+	opts->req_count = UAC1_REQ_COUNT;
+	opts->audio_buf_size = UAC1_AUDIO_BUF_SIZE;
+	opts->fn_play = FILE_PCM_PLAYBACK;
+	opts->fn_cap = FILE_PCM_CAPTURE;
+	opts->fn_cntl = FILE_CONTROL;
+	return &opts->func_inst;
+}
+
+static void f_audio_free(struct usb_function *f)
+{
+	struct f_audio *audio = func_to_audio(f);
+	struct f_uac1_legacy_opts *opts;
+
+	gaudio_cleanup(&audio->card);
+	opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
+	kfree(audio);
+	mutex_lock(&opts->lock);
+	--opts->refcnt;
+	mutex_unlock(&opts->lock);
+}
+
+static void f_audio_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	usb_free_all_descriptors(f);
+}
+
+static struct usb_function *f_audio_alloc(struct usb_function_instance *fi)
+{
+	struct f_audio *audio;
+	struct f_uac1_legacy_opts *opts;
+
+	/* allocate and initialize one new instance */
+	audio = kzalloc(sizeof(*audio), GFP_KERNEL);
+	if (!audio)
+		return ERR_PTR(-ENOMEM);
+
+	audio->card.func.name = "g_audio";
+
+	opts = container_of(fi, struct f_uac1_legacy_opts, func_inst);
+	mutex_lock(&opts->lock);
+	++opts->refcnt;
+	mutex_unlock(&opts->lock);
+	INIT_LIST_HEAD(&audio->play_queue);
+	spin_lock_init(&audio->lock);
+
+	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.get_alt = f_audio_get_alt;
+	audio->card.func.setup = f_audio_setup;
+	audio->card.func.disable = f_audio_disable;
+	audio->card.func.free_func = f_audio_free;
+
+	control_selector_init(audio);
+
+	INIT_WORK(&audio->playback_work, f_audio_playback_work);
+
+	return &audio->card.func;
+}
+
+DECLARE_USB_FUNCTION_INIT(uac1_legacy, f_audio_alloc_inst, f_audio_alloc);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bryan Wu");