usb: gadget: f_uac1: add volume and mute support

This adds bi-directional (host->device, device->host)
volume/mute support to the f_uac1 driver by adding
Feature Units and interrupt endpoint.

Currently only master channel is supported.

Volume and mute are configurable through configfs,
by default volume has -100..0 dB range with 1 dB step.

Similar to existing flexible endpoints configuration,
Feature Unit won't be added to the topology if both
mute and volume are not enabled, also interrupt endpoint
isn't added to the device if no feature unit is present

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20210712125529.76070-5-pavel.hofman@ivitera.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 652 insertions, 22 deletions

diff --git a/drivers/usb/gadget/function/f_uac1.c b/drivers/usb/gadget/function/f_uac1.c
index d04707580068..3b3db1a8df75 100644
--- a/drivers/usb/gadget/function/f_uac1.c
+++ b/drivers/usb/gadget/function/f_uac1.c
@@ -22,13 +22,26 @@
 /* UAC1 spec: 3.7.2.3 Audio Channel Cluster Format */
 #define UAC1_CHANNEL_MASK 0x0FFF
 
+#define USB_OUT_FU_ID	(out_feature_unit_desc->bUnitID)
+#define USB_IN_FU_ID	(in_feature_unit_desc->bUnitID)
+
 #define EPIN_EN(_opts) ((_opts)->p_chmask != 0)
 #define EPOUT_EN(_opts) ((_opts)->c_chmask != 0)
+#define FUIN_EN(_opts) ((_opts)->p_mute_present \
+			|| (_opts)->p_volume_present)
+#define FUOUT_EN(_opts) ((_opts)->c_mute_present \
+			|| (_opts)->c_volume_present)
 
 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() */
+
+	struct usb_ctrlrequest setup_cr;	/* will be used in data stage */
+
+	/* Interrupt IN endpoint of AC interface */
+	struct usb_ep	*int_ep;
+	atomic_t	int_count;
 };
 
 static inline struct f_uac1 *func_to_uac1(struct usb_function *f)
@@ -58,7 +71,7 @@ static inline struct f_uac1_opts *g_audio_to_uac1_opts(struct g_audio *audio)
 static struct usb_interface_descriptor ac_interface_desc = {
 	.bLength =		USB_DT_INTERFACE_SIZE,
 	.bDescriptorType =	USB_DT_INTERFACE,
-	.bNumEndpoints =	0,
+	/* .bNumEndpoints =	DYNAMIC */
 	.bInterfaceClass =	USB_CLASS_AUDIO,
 	.bInterfaceSubClass =	USB_SUBCLASS_AUDIOCONTROL,
 };
@@ -106,6 +119,19 @@ static struct uac1_output_terminal_descriptor usb_in_ot_desc = {
 	/* .bSourceID =		DYNAMIC */
 };
 
+static struct uac_feature_unit_descriptor *in_feature_unit_desc;
+static struct uac_feature_unit_descriptor *out_feature_unit_desc;
+
+/* AC IN Interrupt Endpoint */
+static struct usb_endpoint_descriptor ac_int_ep_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = USB_DIR_IN,
+	.bmAttributes = USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize = cpu_to_le16(2),
+	.bInterval = 4,
+};
+
 /* B.4.1  Standard AS Interface Descriptor */
 static struct usb_interface_descriptor as_out_interface_alt_0_desc = {
 	.bLength =		USB_DT_INTERFACE_SIZE,
@@ -232,8 +258,13 @@ static struct usb_descriptor_header *f_audio_desc[] = {
 
 	(struct usb_descriptor_header *)&usb_out_it_desc,
 	(struct usb_descriptor_header *)&io_out_ot_desc,
+	(struct usb_descriptor_header *)&out_feature_unit_desc,
+
 	(struct usb_descriptor_header *)&io_in_it_desc,
 	(struct usb_descriptor_header *)&usb_in_ot_desc,
+	(struct usb_descriptor_header *)&in_feature_unit_desc,
+
+	(struct usb_descriptor_header *)&ac_int_ep_desc,
 
 	(struct usb_descriptor_header *)&as_out_interface_alt_0_desc,
 	(struct usb_descriptor_header *)&as_out_interface_alt_1_desc,
@@ -263,6 +294,8 @@ enum {
 	STR_IO_IN_IT,
 	STR_IO_IN_IT_CH_NAMES,
 	STR_USB_IN_OT,
+	STR_FU_IN,
+	STR_FU_OUT,
 	STR_AS_OUT_IF_ALT0,
 	STR_AS_OUT_IF_ALT1,
 	STR_AS_IN_IF_ALT0,
@@ -277,6 +310,8 @@ static struct usb_string strings_uac1[] = {
 	[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_FU_IN].s = "Capture Volume",
+	[STR_FU_OUT].s = "Playback Volume",
 	[STR_AS_OUT_IF_ALT0].s = "Playback Inactive",
 	[STR_AS_OUT_IF_ALT1].s = "Playback Active",
 	[STR_AS_IN_IF_ALT0].s = "Capture Inactive",
@@ -298,6 +333,376 @@ static struct usb_gadget_strings *uac1_strings[] = {
  * This function is an ALSA sound card following USB Audio Class Spec 1.0.
  */
 
+static void audio_notify_complete(struct usb_ep *_ep, struct usb_request *req)
+{
+	struct g_audio *audio = req->context;
+	struct f_uac1 *uac1 = func_to_uac1(&audio->func);
+
+	atomic_dec(&uac1->int_count);
+	kfree(req->buf);
+	usb_ep_free_request(_ep, req);
+}
+
+static int audio_notify(struct g_audio *audio, int unit_id, int cs)
+{
+	struct f_uac1 *uac1 = func_to_uac1(&audio->func);
+	struct usb_request *req;
+	struct uac1_status_word *msg;
+	int ret;
+
+	if (!uac1->int_ep->enabled)
+		return 0;
+
+	if (atomic_inc_return(&uac1->int_count) > UAC1_DEF_INT_REQ_NUM) {
+		atomic_dec(&uac1->int_count);
+		return 0;
+	}
+
+	req = usb_ep_alloc_request(uac1->int_ep, GFP_ATOMIC);
+	if (req == NULL) {
+		ret = -ENOMEM;
+		goto err_dec_int_count;
+	}
+
+	msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
+	if (msg == NULL) {
+		ret = -ENOMEM;
+		goto err_free_request;
+	}
+
+	msg->bStatusType = UAC1_STATUS_TYPE_IRQ_PENDING
+				| UAC1_STATUS_TYPE_ORIG_AUDIO_CONTROL_IF;
+	msg->bOriginator = unit_id;
+
+	req->length = sizeof(*msg);
+	req->buf = msg;
+	req->context = audio;
+	req->complete = audio_notify_complete;
+
+	ret = usb_ep_queue(uac1->int_ep, req, GFP_ATOMIC);
+
+	if (ret)
+		goto err_free_msg;
+
+	return 0;
+
+err_free_msg:
+	kfree(msg);
+err_free_request:
+	usb_ep_free_request(uac1->int_ep, req);
+err_dec_int_count:
+	atomic_dec(&uac1->int_count);
+
+	return ret;
+}
+
+static int
+in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct g_audio *audio = func_to_g_audio(fn);
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	int value = -EOPNOTSUPP;
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		unsigned int is_playback = 0;
+
+		if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
+			is_playback = 1;
+
+		if (control_selector == UAC_FU_MUTE) {
+			unsigned int mute;
+
+			u_audio_get_mute(audio, is_playback, &mute);
+
+			*(u8 *)req->buf = mute;
+			value = min_t(unsigned int, w_length, 1);
+		} else if (control_selector == UAC_FU_VOLUME) {
+			__le16 c;
+			s16 volume;
+
+			u_audio_get_volume(audio, is_playback, &volume);
+
+			c = cpu_to_le16(volume);
+
+			value = min_t(unsigned int, w_length, sizeof(c));
+			memcpy(req->buf, &c, value);
+		} else {
+			dev_err(&audio->gadget->dev,
+				"%s:%d control_selector=%d TODO!\n",
+				__func__, __LINE__, control_selector);
+		}
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+	}
+
+	return value;
+}
+
+static int
+in_rq_min(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct g_audio *audio = func_to_g_audio(fn);
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	int value = -EOPNOTSUPP;
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		unsigned int is_playback = 0;
+
+		if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
+			is_playback = 1;
+
+		if (control_selector == UAC_FU_VOLUME) {
+			__le16 r;
+			s16 min_db;
+
+			if (is_playback)
+				min_db = opts->p_volume_min;
+			else
+				min_db = opts->c_volume_min;
+
+			r = cpu_to_le16(min_db);
+
+			value = min_t(unsigned int, w_length, sizeof(r));
+			memcpy(req->buf, &r, value);
+		} else {
+			dev_err(&audio->gadget->dev,
+				"%s:%d control_selector=%d TODO!\n",
+				__func__, __LINE__, control_selector);
+		}
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+	}
+
+	return value;
+}
+
+static int
+in_rq_max(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct g_audio *audio = func_to_g_audio(fn);
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	int value = -EOPNOTSUPP;
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		unsigned int is_playback = 0;
+
+		if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
+			is_playback = 1;
+
+		if (control_selector == UAC_FU_VOLUME) {
+			__le16 r;
+			s16 max_db;
+
+			if (is_playback)
+				max_db = opts->p_volume_max;
+			else
+				max_db = opts->c_volume_max;
+
+			r = cpu_to_le16(max_db);
+
+			value = min_t(unsigned int, w_length, sizeof(r));
+			memcpy(req->buf, &r, value);
+		} else {
+			dev_err(&audio->gadget->dev,
+				"%s:%d control_selector=%d TODO!\n",
+				__func__, __LINE__, control_selector);
+		}
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+	}
+
+	return value;
+}
+
+static int
+in_rq_res(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct g_audio *audio = func_to_g_audio(fn);
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	int value = -EOPNOTSUPP;
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		unsigned int is_playback = 0;
+
+		if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
+			is_playback = 1;
+
+		if (control_selector == UAC_FU_VOLUME) {
+			__le16 r;
+			s16 res_db;
+
+			if (is_playback)
+				res_db = opts->p_volume_res;
+			else
+				res_db = opts->c_volume_res;
+
+			r = cpu_to_le16(res_db);
+
+			value = min_t(unsigned int, w_length, sizeof(r));
+			memcpy(req->buf, &r, value);
+		} else {
+			dev_err(&audio->gadget->dev,
+				"%s:%d control_selector=%d TODO!\n",
+				__func__, __LINE__, control_selector);
+		}
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+	}
+
+	return value;
+}
+
+static void
+out_rq_cur_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct g_audio *audio = req->context;
+	struct usb_composite_dev *cdev = audio->func.config->cdev;
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	struct f_uac1 *uac1 = func_to_uac1(&audio->func);
+	struct usb_ctrlrequest *cr = &uac1->setup_cr;
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+
+	if (req->status != 0) {
+		dev_dbg(&cdev->gadget->dev, "completion err %d\n", req->status);
+		return;
+	}
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		unsigned int is_playback = 0;
+
+		if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
+			is_playback = 1;
+
+		if (control_selector == UAC_FU_MUTE) {
+			u8 mute = *(u8 *)req->buf;
+
+			u_audio_set_mute(audio, is_playback, mute);
+
+			return;
+		} else if (control_selector == UAC_FU_VOLUME) {
+			__le16 *c = req->buf;
+			s16 volume;
+
+			volume = le16_to_cpu(*c);
+			u_audio_set_volume(audio, is_playback, volume);
+
+			return;
+		} else {
+			dev_err(&audio->gadget->dev,
+				"%s:%d control_selector=%d TODO!\n",
+				__func__, __LINE__, control_selector);
+			usb_ep_set_halt(ep);
+		}
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+		usb_ep_set_halt(ep);
+
+	}
+}
+
+static int
+out_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct g_audio *audio = func_to_g_audio(fn);
+	struct f_uac1_opts *opts = g_audio_to_uac1_opts(audio);
+	struct f_uac1 *uac1 = func_to_uac1(&audio->func);
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+
+	if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
+			(FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
+		memcpy(&uac1->setup_cr, cr, sizeof(*cr));
+		req->context = audio;
+		req->complete = out_rq_cur_complete;
+
+		return w_length;
+	} else {
+		dev_err(&audio->gadget->dev,
+			"%s:%d entity_id=%d control_selector=%d TODO!\n",
+			__func__, __LINE__, entity_id, control_selector);
+	}
+	return -EOPNOTSUPP;
+}
+
+static int ac_rq_in(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:
+		return in_rq_cur(f, ctrl);
+	case UAC_GET_MIN:
+		return in_rq_min(f, ctrl);
+	case UAC_GET_MAX:
+		return in_rq_max(f, ctrl);
+	case UAC_GET_RES:
+		return in_rq_res(f, ctrl);
+	case UAC_GET_MEM:
+		break;
+	case UAC_GET_STAT:
+		value = len;
+		break;
+	default:
+		break;
+	}
+
+	return value;
+}
+
 static int audio_set_endpoint_req(struct usb_function *f,
 		const struct usb_ctrlrequest *ctrl)
 {
@@ -383,7 +788,13 @@ f_audio_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
 	case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT:
 		value = audio_get_endpoint_req(f, ctrl);
 		break;
-
+	case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
+		if (ctrl->bRequest == UAC_SET_CUR)
+			value = out_rq_cur(f, ctrl);
+		break;
+	case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
+		value = ac_rq_in(f, ctrl);
+		break;
 	default:
 		ERROR(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
 			ctrl->bRequestType, ctrl->bRequest,
@@ -411,6 +822,7 @@ 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 g_audio *audio = func_to_g_audio(f);
 	struct f_uac1 *uac1 = func_to_uac1(f);
 	int ret = 0;
 
@@ -426,6 +838,14 @@ static int f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
 			return -EINVAL;
 		}
+
+		/* restart interrupt endpoint */
+		if (uac1->int_ep) {
+			usb_ep_disable(uac1->int_ep);
+			config_ep_by_speed(gadget, &audio->func, uac1->int_ep);
+			usb_ep_enable(uac1->int_ep);
+		}
+
 		return 0;
 	}
 
@@ -481,10 +901,33 @@ static void f_audio_disable(struct usb_function *f)
 
 	u_audio_stop_playback(&uac1->g_audio);
 	u_audio_stop_capture(&uac1->g_audio);
+	if (uac1->int_ep)
+		usb_ep_disable(uac1->int_ep);
 }
 
 /*-------------------------------------------------------------------------*/
+static struct uac_feature_unit_descriptor *build_fu_desc(int chmask)
+{
+	struct uac_feature_unit_descriptor *fu_desc;
+	int channels = num_channels(chmask);
+	int fu_desc_size = UAC_DT_FEATURE_UNIT_SIZE(channels);
+
+	fu_desc = kzalloc(fu_desc_size, GFP_KERNEL);
+	if (!fu_desc)
+		return NULL;
+
+	fu_desc->bLength = fu_desc_size;
+	fu_desc->bDescriptorType = USB_DT_CS_INTERFACE;
+
+	fu_desc->bDescriptorSubtype = UAC_FEATURE_UNIT;
+	fu_desc->bControlSize  = 2;
 
+	/* bUnitID, bSourceID and bmaControls will be defined later */
+
+	return fu_desc;
+}
+
+/* B.3.2  Class-Specific AC Interface Descriptor */
 static struct
 uac1_ac_header_descriptor *build_ac_header_desc(struct f_uac1_opts *opts)
 {
@@ -530,9 +973,23 @@ static void setup_descriptor(struct f_uac1_opts *opts)
 		io_out_ot_desc.bTerminalID = i++;
 	if (EPIN_EN(opts))
 		usb_in_ot_desc.bTerminalID = i++;
-
-	usb_in_ot_desc.bSourceID = io_in_it_desc.bTerminalID;
-	io_out_ot_desc.bSourceID = usb_out_it_desc.bTerminalID;
+	if (FUOUT_EN(opts))
+		out_feature_unit_desc->bUnitID = i++;
+	if (FUIN_EN(opts))
+		in_feature_unit_desc->bUnitID = i++;
+
+	if (FUIN_EN(opts)) {
+		usb_in_ot_desc.bSourceID = in_feature_unit_desc->bUnitID;
+		in_feature_unit_desc->bSourceID = io_in_it_desc.bTerminalID;
+	} else {
+		usb_in_ot_desc.bSourceID = io_in_it_desc.bTerminalID;
+	}
+	if (FUOUT_EN(opts)) {
+		io_out_ot_desc.bSourceID = out_feature_unit_desc->bUnitID;
+		out_feature_unit_desc->bSourceID = usb_out_it_desc.bTerminalID;
+	} else {
+		io_out_ot_desc.bSourceID = usb_out_it_desc.bTerminalID;
+	}
 
 	as_out_header_desc.bTerminalLink = usb_out_it_desc.bTerminalID;
 	as_in_header_desc.bTerminalLink = usb_in_ot_desc.bTerminalID;
@@ -544,6 +1001,8 @@ static void setup_descriptor(struct f_uac1_opts *opts)
 
 		len += sizeof(usb_in_ot_desc);
 		len += sizeof(io_in_it_desc);
+		if (FUIN_EN(opts))
+			len += in_feature_unit_desc->bLength;
 		ac_header_desc->wTotalLength = cpu_to_le16(len);
 	}
 	if (EPOUT_EN(opts)) {
@@ -551,6 +1010,8 @@ static void setup_descriptor(struct f_uac1_opts *opts)
 
 		len += sizeof(usb_out_it_desc);
 		len += sizeof(io_out_ot_desc);
+		if (FUOUT_EN(opts))
+			len += out_feature_unit_desc->bLength;
 		ac_header_desc->wTotalLength = cpu_to_le16(len);
 	}
 
@@ -561,13 +1022,20 @@ static void setup_descriptor(struct f_uac1_opts *opts)
 	if (EPOUT_EN(opts)) {
 		f_audio_desc[i++] = USBDHDR(&usb_out_it_desc);
 		f_audio_desc[i++] = USBDHDR(&io_out_ot_desc);
+		if (FUOUT_EN(opts))
+			f_audio_desc[i++] = USBDHDR(out_feature_unit_desc);
 	}
 
 	if (EPIN_EN(opts)) {
 		f_audio_desc[i++] = USBDHDR(&io_in_it_desc);
 		f_audio_desc[i++] = USBDHDR(&usb_in_ot_desc);
+		if (FUIN_EN(opts))
+			f_audio_desc[i++] = USBDHDR(in_feature_unit_desc);
 	}
 
+	if (FUOUT_EN(opts) || FUIN_EN(opts))
+		f_audio_desc[i++] = USBDHDR(&ac_int_ep_desc);
+
 	if (EPOUT_EN(opts)) {
 		f_audio_desc[i++] = USBDHDR(&as_out_interface_alt_0_desc);
 		f_audio_desc[i++] = USBDHDR(&as_out_interface_alt_1_desc);
@@ -614,6 +1082,28 @@ static int f_audio_validate_opts(struct g_audio *audio, struct device *dev)
 		return -EINVAL;
 	}
 
+	if (opts->p_volume_max <= opts->p_volume_min) {
+		dev_err(dev, "Error: incorrect playback volume max/min\n");
+			return -EINVAL;
+	} else if (opts->c_volume_max <= opts->c_volume_min) {
+		dev_err(dev, "Error: incorrect capture volume max/min\n");
+			return -EINVAL;
+	} else if (opts->p_volume_res <= 0) {
+		dev_err(dev, "Error: negative/zero playback volume resolution\n");
+			return -EINVAL;
+	} else if (opts->c_volume_res <= 0) {
+		dev_err(dev, "Error: negative/zero capture volume resolution\n");
+			return -EINVAL;
+	}
+
+	if ((opts->p_volume_max - opts->p_volume_min) % opts->p_volume_res) {
+		dev_err(dev, "Error: incorrect playback volume resolution\n");
+			return -EINVAL;
+	} else if ((opts->c_volume_max - opts->c_volume_min) % opts->c_volume_res) {
+		dev_err(dev, "Error: incorrect capture volume resolution\n");
+			return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -647,6 +1137,21 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	if (!ac_header_desc)
 		return -ENOMEM;
 
+	if (FUOUT_EN(audio_opts)) {
+		out_feature_unit_desc = build_fu_desc(audio_opts->c_chmask);
+		if (!out_feature_unit_desc) {
+			status = -ENOMEM;
+			goto fail;
+		}
+	}
+	if (FUIN_EN(audio_opts)) {
+		in_feature_unit_desc = build_fu_desc(audio_opts->p_chmask);
+		if (!in_feature_unit_desc) {
+			status = -ENOMEM;
+			goto err_free_fu;
+		}
+	}
+
 	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;
@@ -659,6 +1164,21 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	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;
 
+	if (FUOUT_EN(audio_opts)) {
+		u8 *i_feature;
+
+		i_feature = (u8 *)out_feature_unit_desc +
+					out_feature_unit_desc->bLength - 1;
+		*i_feature = us[STR_FU_OUT].id;
+	}
+	if (FUIN_EN(audio_opts)) {
+		u8 *i_feature;
+
+		i_feature = (u8 *)in_feature_unit_desc +
+					in_feature_unit_desc->bLength - 1;
+		*i_feature = us[STR_FU_IN].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);
@@ -671,6 +1191,27 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	as_in_type_i_desc.bSubframeSize = audio_opts->p_ssize;
 	as_in_type_i_desc.bBitResolution = audio_opts->p_ssize * 8;
 
+	if (FUOUT_EN(audio_opts)) {
+		__le16 *bma = (__le16 *)&out_feature_unit_desc->bmaControls[0];
+		u32 control = 0;
+
+		if (audio_opts->c_mute_present)
+			control |= UAC_FU_MUTE;
+		if (audio_opts->c_volume_present)
+			control |= UAC_FU_VOLUME;
+		*bma = cpu_to_le16(control);
+	}
+	if (FUIN_EN(audio_opts)) {
+		__le16 *bma = (__le16 *)&in_feature_unit_desc->bmaControls[0];
+		u32 control = 0;
+
+		if (audio_opts->p_mute_present)
+			control |= UAC_FU_MUTE;
+		if (audio_opts->p_volume_present)
+			control |= UAC_FU_VOLUME;
+		*bma = cpu_to_le16(control);
+	}
+
 	/* Set sample rates */
 	rate = audio_opts->c_srate;
 	sam_freq = as_out_type_i_desc.tSamFreq[0];
@@ -682,7 +1223,7 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	/* allocate instance-specific interface IDs, and patch descriptors */
 	status = usb_interface_id(c, f);
 	if (status < 0)
-		goto fail;
+		goto err_free_fu;
 	ac_interface_desc.bInterfaceNumber = status;
 	uac1->ac_intf = status;
 	uac1->ac_alt = 0;
@@ -692,7 +1233,7 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	if (EPOUT_EN(audio_opts)) {
 		status = usb_interface_id(c, f);
 		if (status < 0)
-			goto fail;
+			goto err_free_fu;
 		as_out_interface_alt_0_desc.bInterfaceNumber = status;
 		as_out_interface_alt_1_desc.bInterfaceNumber = status;
 		ac_header_desc->baInterfaceNr[ba_iface_id++] = status;
@@ -703,7 +1244,7 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	if (EPIN_EN(audio_opts)) {
 		status = usb_interface_id(c, f);
 		if (status < 0)
-			goto fail;
+			goto err_free_fu;
 		as_in_interface_alt_0_desc.bInterfaceNumber = status;
 		as_in_interface_alt_1_desc.bInterfaceNumber = status;
 		ac_header_desc->baInterfaceNr[ba_iface_id++] = status;
@@ -715,11 +1256,24 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 
 	status = -ENODEV;
 
+	ac_interface_desc.bNumEndpoints = 0;
+
+	/* allocate AC interrupt endpoint */
+	if (FUOUT_EN(audio_opts) || FUIN_EN(audio_opts)) {
+		ep = usb_ep_autoconfig(cdev->gadget, &ac_int_ep_desc);
+		if (!ep)
+			goto err_free_fu;
+		uac1->int_ep = ep;
+		uac1->int_ep->desc = &ac_int_ep_desc;
+
+		ac_interface_desc.bNumEndpoints = 1;
+	}
+
 	/* allocate instance-specific endpoints */
 	if (EPOUT_EN(audio_opts)) {
 		ep = usb_ep_autoconfig(cdev->gadget, &as_out_ep_desc);
 		if (!ep)
-			goto fail;
+			goto err_free_fu;
 		audio->out_ep = ep;
 		audio->out_ep->desc = &as_out_ep_desc;
 	}
@@ -727,7 +1281,7 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	if (EPIN_EN(audio_opts)) {
 		ep = usb_ep_autoconfig(cdev->gadget, &as_in_ep_desc);
 		if (!ep)
-			goto fail;
+			goto err_free_fu;
 		audio->in_ep = ep;
 		audio->in_ep->desc = &as_in_ep_desc;
 	}
@@ -738,17 +1292,37 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	status = usb_assign_descriptors(f, f_audio_desc, f_audio_desc, NULL,
 					NULL);
 	if (status)
-		goto fail;
+		goto err_free_fu;
 
 	audio->out_ep_maxpsize = le16_to_cpu(as_out_ep_desc.wMaxPacketSize);
 	audio->in_ep_maxpsize = le16_to_cpu(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;
+	if (FUIN_EN(audio_opts)) {
+		audio->params.p_fu.id = USB_IN_FU_ID;
+		audio->params.p_fu.mute_present = audio_opts->p_mute_present;
+		audio->params.p_fu.volume_present =
+				audio_opts->p_volume_present;
+		audio->params.p_fu.volume_min = audio_opts->p_volume_min;
+		audio->params.p_fu.volume_max = audio_opts->p_volume_max;
+		audio->params.p_fu.volume_res = audio_opts->p_volume_res;
+	}
 	audio->params.p_chmask = audio_opts->p_chmask;
 	audio->params.p_srate = audio_opts->p_srate;
 	audio->params.p_ssize = audio_opts->p_ssize;
+	if (FUOUT_EN(audio_opts)) {
+		audio->params.c_fu.id = USB_OUT_FU_ID;
+		audio->params.c_fu.mute_present = audio_opts->c_mute_present;
+		audio->params.c_fu.volume_present =
+				audio_opts->c_volume_present;
+		audio->params.c_fu.volume_min = audio_opts->c_volume_min;
+		audio->params.c_fu.volume_max = audio_opts->c_volume_max;
+		audio->params.c_fu.volume_res = audio_opts->c_volume_res;
+	}
 	audio->params.req_number = audio_opts->req_number;
+	if (FUOUT_EN(audio_opts) || FUIN_EN(audio_opts))
+		audio->notify = audio_notify;
 
 	status = g_audio_setup(audio, "UAC1_PCM", "UAC1_Gadget");
 	if (status)
@@ -758,6 +1332,11 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 
 err_card_register:
 	usb_free_all_descriptors(f);
+err_free_fu:
+	kfree(out_feature_unit_desc);
+	out_feature_unit_desc = NULL;
+	kfree(in_feature_unit_desc);
+	in_feature_unit_desc = NULL;
 fail:
 	kfree(ac_header_desc);
 	ac_header_desc = NULL;
@@ -783,7 +1362,15 @@ static struct configfs_item_operations f_uac1_item_ops = {
 	.release	= f_uac1_attr_release,
 };
 
-#define UAC1_ATTRIBUTE(name)						\
+#define uac1_kstrtou32			kstrtou32
+#define uac1_kstrtos16			kstrtos16
+#define uac1_kstrtobool(s, base, res)	kstrtobool((s), (res))
+
+static const char *u32_fmt = "%u\n";
+static const char *s16_fmt = "%hd\n";
+static const char *bool_fmt = "%u\n";
+
+#define UAC1_ATTRIBUTE(type, name)					\
 static ssize_t f_uac1_opts_##name##_show(				\
 					  struct config_item *item,	\
 					  char *page)			\
@@ -792,7 +1379,7 @@ static ssize_t f_uac1_opts_##name##_show(				\
 	int result;							\
 									\
 	mutex_lock(&opts->lock);					\
-	result = sprintf(page, "%u\n", opts->name);			\
+	result = sprintf(page, type##_fmt, opts->name);			\
 	mutex_unlock(&opts->lock);					\
 									\
 	return result;							\
@@ -804,7 +1391,7 @@ static ssize_t f_uac1_opts_##name##_store(				\
 {									\
 	struct f_uac1_opts *opts = to_f_uac1_opts(item);		\
 	int ret;							\
-	u32 num;							\
+	type num;							\
 									\
 	mutex_lock(&opts->lock);					\
 	if (opts->refcnt) {						\
@@ -812,7 +1399,7 @@ static ssize_t f_uac1_opts_##name##_store(				\
 		goto end;						\
 	}								\
 									\
-	ret = kstrtou32(page, 0, &num);					\
+	ret = uac1_kstrto##type(page, 0, &num);				\
 	if (ret)							\
 		goto end;						\
 									\
@@ -826,13 +1413,25 @@ end:									\
 									\
 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);
+UAC1_ATTRIBUTE(u32, c_chmask);
+UAC1_ATTRIBUTE(u32, c_srate);
+UAC1_ATTRIBUTE(u32, c_ssize);
+UAC1_ATTRIBUTE(u32, p_chmask);
+UAC1_ATTRIBUTE(u32, p_srate);
+UAC1_ATTRIBUTE(u32, p_ssize);
+UAC1_ATTRIBUTE(u32, req_number);
+
+UAC1_ATTRIBUTE(bool, p_mute_present);
+UAC1_ATTRIBUTE(bool, p_volume_present);
+UAC1_ATTRIBUTE(s16, p_volume_min);
+UAC1_ATTRIBUTE(s16, p_volume_max);
+UAC1_ATTRIBUTE(s16, p_volume_res);
+
+UAC1_ATTRIBUTE(bool, c_mute_present);
+UAC1_ATTRIBUTE(bool, c_volume_present);
+UAC1_ATTRIBUTE(s16, c_volume_min);
+UAC1_ATTRIBUTE(s16, c_volume_max);
+UAC1_ATTRIBUTE(s16, c_volume_res);
 
 static struct configfs_attribute *f_uac1_attrs[] = {
 	&f_uac1_opts_attr_c_chmask,
@@ -842,6 +1441,19 @@ static struct configfs_attribute *f_uac1_attrs[] = {
 	&f_uac1_opts_attr_p_srate,
 	&f_uac1_opts_attr_p_ssize,
 	&f_uac1_opts_attr_req_number,
+
+	&f_uac1_opts_attr_p_mute_present,
+	&f_uac1_opts_attr_p_volume_present,
+	&f_uac1_opts_attr_p_volume_min,
+	&f_uac1_opts_attr_p_volume_max,
+	&f_uac1_opts_attr_p_volume_res,
+
+	&f_uac1_opts_attr_c_mute_present,
+	&f_uac1_opts_attr_c_volume_present,
+	&f_uac1_opts_attr_c_volume_min,
+	&f_uac1_opts_attr_c_volume_max,
+	&f_uac1_opts_attr_c_volume_res,
+
 	NULL,
 };
 
@@ -879,6 +1491,19 @@ static struct usb_function_instance *f_audio_alloc_inst(void)
 	opts->p_chmask = UAC1_DEF_PCHMASK;
 	opts->p_srate = UAC1_DEF_PSRATE;
 	opts->p_ssize = UAC1_DEF_PSSIZE;
+
+	opts->p_mute_present = UAC1_DEF_MUTE_PRESENT;
+	opts->p_volume_present = UAC1_DEF_VOLUME_PRESENT;
+	opts->p_volume_min = UAC1_DEF_MIN_DB;
+	opts->p_volume_max = UAC1_DEF_MAX_DB;
+	opts->p_volume_res = UAC1_DEF_RES_DB;
+
+	opts->c_mute_present = UAC1_DEF_MUTE_PRESENT;
+	opts->c_volume_present = UAC1_DEF_VOLUME_PRESENT;
+	opts->c_volume_min = UAC1_DEF_MIN_DB;
+	opts->c_volume_max = UAC1_DEF_MAX_DB;
+	opts->c_volume_res = UAC1_DEF_RES_DB;
+
 	opts->req_number = UAC1_DEF_REQ_NUM;
 	return &opts->func_inst;
 }
@@ -903,6 +1528,11 @@ static void f_audio_unbind(struct usb_configuration *c, struct usb_function *f)
 	g_audio_cleanup(audio);
 	usb_free_all_descriptors(f);
 
+	kfree(out_feature_unit_desc);
+	out_feature_unit_desc = NULL;
+	kfree(in_feature_unit_desc);
+	in_feature_unit_desc = NULL;
+
 	kfree(ac_header_desc);
 	ac_header_desc = NULL;