usb: gadget: add f_uac1 variant based on a new u_audio api

This patch adds a new function 'f_uac1'
(f_uac1 with virtual "ALSA card") that
uses recently created u_audio API. Comparing
to legacy f_uac1 function implementation it
doesn't require any real Audio codec to be
present on the device. In f_uac1 audio
streams are simply sinked to and sourced
from a virtual ALSA sound card created
using u_audio API.

Legacy f_uac1 approach is to write audio
samples directly to existing ALSA sound
card

f_uac1 approach is more generic/flexible
one - create an ALSA sound card that
represents USB Audio function and allows to
be used by userspace application that
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.

f_uac1 also has capture support (gadget->host)
thanks to easy implementation via u_audio.
By default, capture interface has 48000kHz/2ch
configuration, same as playback channel has.

f_uac1 descriptors naming convention
uses f_uac2 driver naming convention that
makes it more common and meaningful.

Comparing to f_uac1_legacy, the f_uac1 doesn't
have volume/mute functionality. This is because
the f_uac1 volume/mute feature unit was dummy
implementation since that driver creation (2009)
and never had any real volume control or mute
functionality, so there is no any difference
here.

Since f_uac1 functionality, exposed
interface to userspace (virtual ALSA card),
input parameters are so different comparing
to f_uac1_legacy, that there is no any
reason to keep them in the same file/module,
and separate function was created.

g_audio can be built using one of existing
UAC functions (f_uac1, f_uac1_legacy or f_uac2)

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

1 files changed, 802 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_uac1.c b/drivers/usb/gadget/function/f_uac1.c
new file mode 100644
index 000000000000..8656f84e17d9
--- /dev/null
+++ b/drivers/usb/gadget/function/f_uac1.c
@@ -0,0 +1,802 @@
+/*
+ * f_uac1.c -- USB Audio Class 1.0 Function (using u_audio API)
+ *
+ * Copyright (C) 2016 Ruslan Bilovol <ruslan.bilovol@gmail.com>
+ *
+ * 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.
+ *
+ * This file is based on f_uac1.c which is
+ *   Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ *   Copyright (C) 2008 Analog Devices, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/usb/audio.h>
+#include <linux/module.h>
+
+#include "u_audio.h"
+#include "u_uac1.h"
+
+struct f_uac1 {
+	struct g_audio g_audio;
+	u8 ac_intf, as_in_intf, as_out_intf;
+	u8 ac_alt, as_in_alt, as_out_alt;	/* needed for get_alt() */
+};
+
+static inline struct f_uac1 *func_to_uac1(struct usb_function *f)
+{
+	return container_of(f, struct f_uac1, g_audio.func);
+}
+
+/*
+ * DESCRIPTORS ... most are static, but strings and full
+ * configuration descriptors are built on demand.
+ */
+
+/*
+ * We have three interfaces - one AudioControl and two AudioStreaming
+ *
+ * The driver implements a simple UAC_1 topology.
+ * USB-OUT -> IT_1 -> OT_2 -> ALSA_Capture
+ * ALSA_Playback -> IT_3 -> OT_4 -> USB-IN
+ */
+#define F_AUDIO_AC_INTERFACE		0
+#define F_AUDIO_AS_OUT_INTERFACE	1
+#define F_AUDIO_AS_IN_INTERFACE		2
+/* Number of streaming interfaces */
+#define F_AUDIO_NUM_INTERFACES		2
+
+/* 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(2);
+
+#define UAC_DT_AC_HEADER_LENGTH	UAC_DT_AC_HEADER_SIZE(F_AUDIO_NUM_INTERFACES)
+/* 2 input terminals and 2 output terminals */
+#define UAC_DT_TOTAL_LENGTH (UAC_DT_AC_HEADER_LENGTH \
+	+ 2*UAC_DT_INPUT_TERMINAL_SIZE + 2*UAC_DT_OUTPUT_TERMINAL_SIZE)
+/* B.3.2  Class-Specific AC Interface Descriptor */
+static struct uac1_ac_header_descriptor_2 ac_header_desc = {
+	.bLength =		UAC_DT_AC_HEADER_LENGTH,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_HEADER,
+	.bcdADC =		cpu_to_le16(0x0100),
+	.wTotalLength =		cpu_to_le16(UAC_DT_TOTAL_LENGTH),
+	.bInCollection =	F_AUDIO_NUM_INTERFACES,
+	.baInterfaceNr = {
+	/* Interface number of the AudioStream interfaces */
+		[0] =		1,
+		[1] =		2,
+	}
+};
+
+#define USB_OUT_IT_ID	1
+static struct uac_input_terminal_descriptor usb_out_it_desc = {
+	.bLength =		UAC_DT_INPUT_TERMINAL_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_INPUT_TERMINAL,
+	.bTerminalID =		USB_OUT_IT_ID,
+	.wTerminalType =	UAC_TERMINAL_STREAMING,
+	.bAssocTerminal =	0,
+	.wChannelConfig =	0x3,
+};
+
+#define IO_OUT_OT_ID	2
+static struct uac1_output_terminal_descriptor io_out_ot_desc = {
+	.bLength		= UAC_DT_OUTPUT_TERMINAL_SIZE,
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype	= UAC_OUTPUT_TERMINAL,
+	.bTerminalID		= IO_OUT_OT_ID,
+	.wTerminalType		= UAC_OUTPUT_TERMINAL_SPEAKER,
+	.bAssocTerminal		= 0,
+	.bSourceID		= USB_OUT_IT_ID,
+};
+
+#define IO_IN_IT_ID	3
+static struct uac_input_terminal_descriptor io_in_it_desc = {
+	.bLength		= UAC_DT_INPUT_TERMINAL_SIZE,
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype	= UAC_INPUT_TERMINAL,
+	.bTerminalID		= IO_IN_IT_ID,
+	.wTerminalType		= UAC_INPUT_TERMINAL_MICROPHONE,
+	.bAssocTerminal		= 0,
+	.wChannelConfig		= 0x3,
+};
+
+#define USB_IN_OT_ID	4
+static struct uac1_output_terminal_descriptor usb_in_ot_desc = {
+	.bLength =		UAC_DT_OUTPUT_TERMINAL_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_OUTPUT_TERMINAL,
+	.bTerminalID =		USB_IN_OT_ID,
+	.wTerminalType =	UAC_TERMINAL_STREAMING,
+	.bAssocTerminal =	0,
+	.bSourceID =		IO_IN_IT_ID,
+};
+
+/* B.4.1  Standard AS Interface Descriptor */
+static struct usb_interface_descriptor as_out_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_out_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,
+};
+
+static struct usb_interface_descriptor as_in_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_in_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_out_header_desc = {
+	.bLength =		UAC_DT_AS_HEADER_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_AS_GENERAL,
+	.bTerminalLink =	USB_OUT_IT_ID,
+	.bDelay =		1,
+	.wFormatTag =		UAC_FORMAT_TYPE_I_PCM,
+};
+
+static struct uac1_as_header_descriptor as_in_header_desc = {
+	.bLength =		UAC_DT_AS_HEADER_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	UAC_AS_GENERAL,
+	.bTerminalLink =	USB_IN_OT_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_out_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 =		cpu_to_le16(1),
+};
+
+static struct uac_format_type_i_discrete_descriptor_1 as_in_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_in_ep_desc  = {
+	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_SYNC_ASYNC
+				| 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_in_desc = {
+	.bLength =		UAC_ISO_ENDPOINT_DESC_SIZE,
+	.bDescriptorType =	USB_DT_CS_ENDPOINT,
+	.bDescriptorSubtype =	UAC_EP_GENERAL,
+	.bmAttributes =		1,
+	.bLockDelayUnits =	0,
+	.wLockDelay =		0,
+};
+
+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 *)&usb_out_it_desc,
+	(struct usb_descriptor_header *)&io_out_ot_desc,
+	(struct usb_descriptor_header *)&io_in_it_desc,
+	(struct usb_descriptor_header *)&usb_in_ot_desc,
+
+	(struct usb_descriptor_header *)&as_out_interface_alt_0_desc,
+	(struct usb_descriptor_header *)&as_out_interface_alt_1_desc,
+	(struct usb_descriptor_header *)&as_out_header_desc,
+
+	(struct usb_descriptor_header *)&as_out_type_i_desc,
+
+	(struct usb_descriptor_header *)&as_out_ep_desc,
+	(struct usb_descriptor_header *)&as_iso_out_desc,
+
+	(struct usb_descriptor_header *)&as_in_interface_alt_0_desc,
+	(struct usb_descriptor_header *)&as_in_interface_alt_1_desc,
+	(struct usb_descriptor_header *)&as_in_header_desc,
+
+	(struct usb_descriptor_header *)&as_in_type_i_desc,
+
+	(struct usb_descriptor_header *)&as_in_ep_desc,
+	(struct usb_descriptor_header *)&as_iso_in_desc,
+	NULL,
+};
+
+enum {
+	STR_AC_IF,
+	STR_USB_OUT_IT,
+	STR_USB_OUT_IT_CH_NAMES,
+	STR_IO_OUT_OT,
+	STR_IO_IN_IT,
+	STR_IO_IN_IT_CH_NAMES,
+	STR_USB_IN_OT,
+	STR_AS_OUT_IF_ALT0,
+	STR_AS_OUT_IF_ALT1,
+	STR_AS_IN_IF_ALT0,
+	STR_AS_IN_IF_ALT1,
+};
+
+static struct usb_string strings_uac1[] = {
+	[STR_AC_IF].s = "AC Interface",
+	[STR_USB_OUT_IT].s = "Playback Input terminal",
+	[STR_USB_OUT_IT_CH_NAMES].s = "Playback Channels",
+	[STR_IO_OUT_OT].s = "Playback Output terminal",
+	[STR_IO_IN_IT].s = "Capture Input terminal",
+	[STR_IO_IN_IT_CH_NAMES].s = "Capture Channels",
+	[STR_USB_IN_OT].s = "Capture Output terminal",
+	[STR_AS_OUT_IF_ALT0].s = "Playback Inactive",
+	[STR_AS_OUT_IF_ALT1].s = "Playback Active",
+	[STR_AS_IN_IF_ALT0].s = "Capture Inactive",
+	[STR_AS_IN_IF_ALT1].s = "Capture Active",
+	{ },
+};
+
+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.
+ */
+
+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_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 usb_composite_dev *cdev = f->config->cdev;
+	struct usb_gadget *gadget = cdev->gadget;
+	struct device *dev = &gadget->dev;
+	struct f_uac1 *uac1 = func_to_uac1(f);
+	int ret = 0;
+
+	/* No i/f has more than 2 alt settings */
+	if (alt > 1) {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	if (intf == uac1->ac_intf) {
+		/* Control I/f has only 1 AltSetting - 0 */
+		if (alt) {
+			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+			return -EINVAL;
+		}
+		return 0;
+	}
+
+	if (intf == uac1->as_out_intf) {
+		uac1->as_out_alt = alt;
+
+		if (alt)
+			ret = u_audio_start_capture(&uac1->g_audio);
+		else
+			u_audio_stop_capture(&uac1->g_audio);
+	} else if (intf == uac1->as_in_intf) {
+		uac1->as_in_alt = alt;
+
+			if (alt)
+				ret = u_audio_start_playback(&uac1->g_audio);
+			else
+				u_audio_stop_playback(&uac1->g_audio);
+	} else {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int f_audio_get_alt(struct usb_function *f, unsigned intf)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct usb_gadget *gadget = cdev->gadget;
+	struct device *dev = &gadget->dev;
+	struct f_uac1 *uac1 = func_to_uac1(f);
+
+	if (intf == uac1->ac_intf)
+		return uac1->ac_alt;
+	else if (intf == uac1->as_out_intf)
+		return uac1->as_out_alt;
+	else if (intf == uac1->as_in_intf)
+		return uac1->as_in_alt;
+	else
+		dev_err(dev, "%s:%d Invalid Interface %d!\n",
+			__func__, __LINE__, intf);
+
+	return -EINVAL;
+}
+
+
+static void f_audio_disable(struct usb_function *f)
+{
+	struct f_uac1 *uac1 = func_to_uac1(f);
+
+	uac1->as_out_alt = 0;
+	uac1->as_in_alt = 0;
+
+	u_audio_stop_capture(&uac1->g_audio);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* 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 usb_gadget		*gadget = cdev->gadget;
+	struct f_uac1			*uac1 = func_to_uac1(f);
+	struct g_audio			*audio = func_to_g_audio(f);
+	struct f_uac1_opts		*audio_opts;
+	struct usb_ep			*ep = NULL;
+	struct usb_string		*us;
+	u8				*sam_freq;
+	int				rate;
+	int				status;
+
+	audio_opts = container_of(f->fi, struct f_uac1_opts, func_inst);
+
+	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;
+	usb_out_it_desc.iTerminal = us[STR_USB_OUT_IT].id;
+	usb_out_it_desc.iChannelNames = us[STR_USB_OUT_IT_CH_NAMES].id;
+	io_out_ot_desc.iTerminal = us[STR_IO_OUT_OT].id;
+	as_out_interface_alt_0_desc.iInterface = us[STR_AS_OUT_IF_ALT0].id;
+	as_out_interface_alt_1_desc.iInterface = us[STR_AS_OUT_IF_ALT1].id;
+	io_in_it_desc.iTerminal = us[STR_IO_IN_IT].id;
+	io_in_it_desc.iChannelNames = us[STR_IO_IN_IT_CH_NAMES].id;
+	usb_in_ot_desc.iTerminal = us[STR_USB_IN_OT].id;
+	as_in_interface_alt_0_desc.iInterface = us[STR_AS_IN_IF_ALT0].id;
+	as_in_interface_alt_1_desc.iInterface = us[STR_AS_IN_IF_ALT1].id;
+
+	/* Set channel numbers */
+	usb_out_it_desc.bNrChannels = num_channels(audio_opts->c_chmask);
+	usb_out_it_desc.wChannelConfig = cpu_to_le16(audio_opts->c_chmask);
+	as_out_type_i_desc.bNrChannels = num_channels(audio_opts->c_chmask);
+	as_out_type_i_desc.bSubframeSize = audio_opts->c_ssize;
+	as_out_type_i_desc.bBitResolution = audio_opts->c_ssize * 8;
+	io_in_it_desc.bNrChannels = num_channels(audio_opts->p_chmask);
+	io_in_it_desc.wChannelConfig = cpu_to_le16(audio_opts->p_chmask);
+	as_in_type_i_desc.bNrChannels = num_channels(audio_opts->p_chmask);
+	as_in_type_i_desc.bSubframeSize = audio_opts->p_ssize;
+	as_in_type_i_desc.bBitResolution = audio_opts->p_ssize * 8;
+
+	/* Set sample rates */
+	rate = audio_opts->c_srate;
+	sam_freq = as_out_type_i_desc.tSamFreq[0];
+	memcpy(sam_freq, &rate, 3);
+	rate = audio_opts->p_srate;
+	sam_freq = as_in_type_i_desc.tSamFreq[0];
+	memcpy(sam_freq, &rate, 3);
+
+	/* allocate instance-specific interface IDs, and patch descriptors */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	ac_interface_desc.bInterfaceNumber = status;
+	uac1->ac_intf = status;
+	uac1->ac_alt = 0;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	as_out_interface_alt_0_desc.bInterfaceNumber = status;
+	as_out_interface_alt_1_desc.bInterfaceNumber = status;
+	uac1->as_out_intf = status;
+	uac1->as_out_alt = 0;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	as_in_interface_alt_0_desc.bInterfaceNumber = status;
+	as_in_interface_alt_1_desc.bInterfaceNumber = status;
+	uac1->as_in_intf = status;
+	uac1->as_in_alt = 0;
+
+	audio->gadget = gadget;
+
+	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;
+
+	ep = usb_ep_autoconfig(cdev->gadget, &as_in_ep_desc);
+	if (!ep)
+		goto fail;
+	audio->in_ep = ep;
+	audio->in_ep->desc = &as_in_ep_desc;
+
+	/* copy descriptors, and track endpoint copies */
+	status = usb_assign_descriptors(f, f_audio_desc, f_audio_desc, NULL,
+					NULL);
+	if (status)
+		goto fail;
+
+	audio->out_ep_maxpsize = as_out_ep_desc.wMaxPacketSize;
+	audio->in_ep_maxpsize = as_in_ep_desc.wMaxPacketSize;
+	audio->params.c_chmask = audio_opts->c_chmask;
+	audio->params.c_srate = audio_opts->c_srate;
+	audio->params.c_ssize = audio_opts->c_ssize;
+	audio->params.p_chmask = audio_opts->p_chmask;
+	audio->params.p_srate = audio_opts->p_srate;
+	audio->params.p_ssize = audio_opts->p_ssize;
+	audio->params.req_number = audio_opts->req_number;
+
+	status = g_audio_setup(audio, "UAC1_PCM", "UAC1_Gadget");
+	if (status)
+		goto err_card_register;
+
+	return 0;
+
+err_card_register:
+	usb_free_all_descriptors(f);
+fail:
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static inline struct f_uac1_opts *to_f_uac1_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_uac1_opts,
+			    func_inst.group);
+}
+
+static void f_uac1_attr_release(struct config_item *item)
+{
+	struct f_uac1_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_ATTRIBUTE(name)						\
+static ssize_t f_uac1_opts_##name##_show(				\
+					  struct config_item *item,	\
+					  char *page)			\
+{									\
+	struct f_uac1_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_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_ATTRIBUTE(c_chmask);
+UAC1_ATTRIBUTE(c_srate);
+UAC1_ATTRIBUTE(c_ssize);
+UAC1_ATTRIBUTE(p_chmask);
+UAC1_ATTRIBUTE(p_srate);
+UAC1_ATTRIBUTE(p_ssize);
+UAC1_ATTRIBUTE(req_number);
+
+static struct configfs_attribute *f_uac1_attrs[] = {
+	&f_uac1_opts_attr_c_chmask,
+	&f_uac1_opts_attr_c_srate,
+	&f_uac1_opts_attr_c_ssize,
+	&f_uac1_opts_attr_p_chmask,
+	&f_uac1_opts_attr_p_srate,
+	&f_uac1_opts_attr_p_ssize,
+	&f_uac1_opts_attr_req_number,
+	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_opts *opts;
+
+	opts = container_of(f, struct f_uac1_opts, func_inst);
+	kfree(opts);
+}
+
+static struct usb_function_instance *f_audio_alloc_inst(void)
+{
+	struct f_uac1_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->c_chmask = UAC1_DEF_CCHMASK;
+	opts->c_srate = UAC1_DEF_CSRATE;
+	opts->c_ssize = UAC1_DEF_CSSIZE;
+	opts->p_chmask = UAC1_DEF_PCHMASK;
+	opts->p_srate = UAC1_DEF_PSRATE;
+	opts->p_ssize = UAC1_DEF_PSSIZE;
+	opts->req_number = UAC1_DEF_REQ_NUM;
+	return &opts->func_inst;
+}
+
+static void f_audio_free(struct usb_function *f)
+{
+	struct g_audio *audio;
+	struct f_uac1_opts *opts;
+
+	audio = func_to_g_audio(f);
+	opts = container_of(f->fi, struct f_uac1_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)
+{
+	struct g_audio *audio = func_to_g_audio(f);
+
+	g_audio_cleanup(audio);
+	usb_free_all_descriptors(f);
+
+	audio->gadget = NULL;
+}
+
+static struct usb_function *f_audio_alloc(struct usb_function_instance *fi)
+{
+	struct f_uac1 *uac1;
+	struct f_uac1_opts *opts;
+
+	/* allocate and initialize one new instance */
+	uac1 = kzalloc(sizeof(*uac1), GFP_KERNEL);
+	if (!uac1)
+		return ERR_PTR(-ENOMEM);
+
+	opts = container_of(fi, struct f_uac1_opts, func_inst);
+	mutex_lock(&opts->lock);
+	++opts->refcnt;
+	mutex_unlock(&opts->lock);
+
+	uac1->g_audio.func.name = "uac1_func";
+	uac1->g_audio.func.bind = f_audio_bind;
+	uac1->g_audio.func.unbind = f_audio_unbind;
+	uac1->g_audio.func.set_alt = f_audio_set_alt;
+	uac1->g_audio.func.get_alt = f_audio_get_alt;
+	uac1->g_audio.func.setup = f_audio_setup;
+	uac1->g_audio.func.disable = f_audio_disable;
+	uac1->g_audio.func.free_func = f_audio_free;
+
+	return &uac1->g_audio.func;
+}
+
+DECLARE_USB_FUNCTION_INIT(uac1, f_audio_alloc_inst, f_audio_alloc);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ruslan Bilovol");