Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 820 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_acm.c b/drivers/usb/gadget/function/f_acm.c
new file mode 100644
index 000000000..add0f7ead
--- /dev/null
+++ b/drivers/usb/gadget/function/f_acm.c
@@ -0,0 +1,820 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * f_acm.c -- USB CDC serial (ACM) function driver
+ *
+ * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
+ * Copyright (C) 2008 by David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ * Copyright (C) 2009 by Samsung Electronics
+ * Author: Michal Nazarewicz (mina86@mina86.com)
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+
+#include "u_serial.h"
+
+
+/*
+ * This CDC ACM function support just wraps control functions and
+ * notifications around the generic serial-over-usb code.
+ *
+ * Because CDC ACM is standardized by the USB-IF, many host operating
+ * systems have drivers for it.  Accordingly, ACM is the preferred
+ * interop solution for serial-port type connections.  The control
+ * models are often not necessary, and in any case don't do much in
+ * this bare-bones implementation.
+ *
+ * Note that even MS-Windows has some support for ACM.  However, that
+ * support is somewhat broken because when you use ACM in a composite
+ * device, having multiple interfaces confuses the poor OS.  It doesn't
+ * seem to understand CDC Union descriptors.  The new "association"
+ * descriptors (roughly equivalent to CDC Unions) may sometimes help.
+ */
+
+struct f_acm {
+	struct gserial			port;
+	u8				ctrl_id, data_id;
+	u8				port_num;
+
+	u8				pending;
+
+	/* lock is mostly for pending and notify_req ... they get accessed
+	 * by callbacks both from tty (open/close/break) under its spinlock,
+	 * and notify_req.complete() which can't use that lock.
+	 */
+	spinlock_t			lock;
+
+	struct usb_ep			*notify;
+	struct usb_request		*notify_req;
+
+	struct usb_cdc_line_coding	port_line_coding;	/* 8-N-1 etc */
+
+	/* SetControlLineState request -- CDC 1.1 section 6.2.14 (INPUT) */
+	u16				port_handshake_bits;
+#define ACM_CTRL_RTS	(1 << 1)	/* unused with full duplex */
+#define ACM_CTRL_DTR	(1 << 0)	/* host is ready for data r/w */
+
+	/* SerialState notification -- CDC 1.1 section 6.3.5 (OUTPUT) */
+	u16				serial_state;
+#define ACM_CTRL_OVERRUN	(1 << 6)
+#define ACM_CTRL_PARITY		(1 << 5)
+#define ACM_CTRL_FRAMING	(1 << 4)
+#define ACM_CTRL_RI		(1 << 3)
+#define ACM_CTRL_BRK		(1 << 2)
+#define ACM_CTRL_DSR		(1 << 1)
+#define ACM_CTRL_DCD		(1 << 0)
+};
+
+static inline struct f_acm *func_to_acm(struct usb_function *f)
+{
+	return container_of(f, struct f_acm, port.func);
+}
+
+static inline struct f_acm *port_to_acm(struct gserial *p)
+{
+	return container_of(p, struct f_acm, port);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* notification endpoint uses smallish and infrequent fixed-size messages */
+
+#define GS_NOTIFY_INTERVAL_MS		32
+#define GS_NOTIFY_MAXPACKET		10	/* notification + 2 bytes */
+
+/* interface and class descriptors: */
+
+static struct usb_interface_assoc_descriptor
+acm_iad_descriptor = {
+	.bLength =		sizeof acm_iad_descriptor,
+	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
+
+	/* .bFirstInterface =	DYNAMIC, */
+	.bInterfaceCount = 	2,	// control + data
+	.bFunctionClass =	USB_CLASS_COMM,
+	.bFunctionSubClass =	USB_CDC_SUBCLASS_ACM,
+	.bFunctionProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
+	/* .iFunction =		DYNAMIC */
+};
+
+
+static struct usb_interface_descriptor acm_control_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	/* .bInterfaceNumber = DYNAMIC */
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_COMM,
+	.bInterfaceSubClass =	USB_CDC_SUBCLASS_ACM,
+	.bInterfaceProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_interface_descriptor acm_data_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	/* .bInterfaceNumber = DYNAMIC */
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	0,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc acm_header_desc = {
+	.bLength =		sizeof(acm_header_desc),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
+	.bcdCDC =		cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_call_mgmt_descriptor
+acm_call_mgmt_descriptor = {
+	.bLength =		sizeof(acm_call_mgmt_descriptor),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
+	.bmCapabilities =	0,
+	/* .bDataInterface = DYNAMIC */
+};
+
+static struct usb_cdc_acm_descriptor acm_descriptor = {
+	.bLength =		sizeof(acm_descriptor),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
+	.bmCapabilities =	USB_CDC_CAP_LINE,
+};
+
+static struct usb_cdc_union_desc acm_union_desc = {
+	.bLength =		sizeof(acm_union_desc),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
+	/* .bMasterInterface0 =	DYNAMIC */
+	/* .bSlaveInterface0 =	DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor acm_fs_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
+	.bInterval =		GS_NOTIFY_INTERVAL_MS,
+};
+
+static struct usb_endpoint_descriptor acm_fs_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor acm_fs_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *acm_fs_function[] = {
+	(struct usb_descriptor_header *) &acm_iad_descriptor,
+	(struct usb_descriptor_header *) &acm_control_interface_desc,
+	(struct usb_descriptor_header *) &acm_header_desc,
+	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &acm_descriptor,
+	(struct usb_descriptor_header *) &acm_union_desc,
+	(struct usb_descriptor_header *) &acm_fs_notify_desc,
+	(struct usb_descriptor_header *) &acm_data_interface_desc,
+	(struct usb_descriptor_header *) &acm_fs_in_desc,
+	(struct usb_descriptor_header *) &acm_fs_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+static struct usb_endpoint_descriptor acm_hs_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
+	.bInterval =		USB_MS_TO_HS_INTERVAL(GS_NOTIFY_INTERVAL_MS),
+};
+
+static struct usb_endpoint_descriptor acm_hs_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor acm_hs_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *acm_hs_function[] = {
+	(struct usb_descriptor_header *) &acm_iad_descriptor,
+	(struct usb_descriptor_header *) &acm_control_interface_desc,
+	(struct usb_descriptor_header *) &acm_header_desc,
+	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &acm_descriptor,
+	(struct usb_descriptor_header *) &acm_union_desc,
+	(struct usb_descriptor_header *) &acm_hs_notify_desc,
+	(struct usb_descriptor_header *) &acm_data_interface_desc,
+	(struct usb_descriptor_header *) &acm_hs_in_desc,
+	(struct usb_descriptor_header *) &acm_hs_out_desc,
+	NULL,
+};
+
+static struct usb_endpoint_descriptor acm_ss_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_endpoint_descriptor acm_ss_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor acm_ss_bulk_comp_desc = {
+	.bLength =              sizeof acm_ss_bulk_comp_desc,
+	.bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_descriptor_header *acm_ss_function[] = {
+	(struct usb_descriptor_header *) &acm_iad_descriptor,
+	(struct usb_descriptor_header *) &acm_control_interface_desc,
+	(struct usb_descriptor_header *) &acm_header_desc,
+	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &acm_descriptor,
+	(struct usb_descriptor_header *) &acm_union_desc,
+	(struct usb_descriptor_header *) &acm_hs_notify_desc,
+	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
+	(struct usb_descriptor_header *) &acm_data_interface_desc,
+	(struct usb_descriptor_header *) &acm_ss_in_desc,
+	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
+	(struct usb_descriptor_header *) &acm_ss_out_desc,
+	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+#define ACM_CTRL_IDX	0
+#define ACM_DATA_IDX	1
+#define ACM_IAD_IDX	2
+
+/* static strings, in UTF-8 */
+static struct usb_string acm_string_defs[] = {
+	[ACM_CTRL_IDX].s = "CDC Abstract Control Model (ACM)",
+	[ACM_DATA_IDX].s = "CDC ACM Data",
+	[ACM_IAD_IDX ].s = "CDC Serial",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings acm_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		acm_string_defs,
+};
+
+static struct usb_gadget_strings *acm_strings[] = {
+	&acm_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* ACM control ... data handling is delegated to tty library code.
+ * The main task of this function is to activate and deactivate
+ * that code based on device state; track parameters like line
+ * speed, handshake state, and so on; and issue notifications.
+ */
+
+static void acm_complete_set_line_coding(struct usb_ep *ep,
+		struct usb_request *req)
+{
+	struct f_acm	*acm = ep->driver_data;
+	struct usb_composite_dev *cdev = acm->port.func.config->cdev;
+
+	if (req->status != 0) {
+		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d completion, err %d\n",
+			acm->port_num, req->status);
+		return;
+	}
+
+	/* normal completion */
+	if (req->actual != sizeof(acm->port_line_coding)) {
+		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d short resp, len %d\n",
+			acm->port_num, req->actual);
+		usb_ep_set_halt(ep);
+	} else {
+		struct usb_cdc_line_coding	*value = req->buf;
+
+		/* REVISIT:  we currently just remember this data.
+		 * If we change that, (a) validate it first, then
+		 * (b) update whatever hardware needs updating,
+		 * (c) worry about locking.  This is information on
+		 * the order of 9600-8-N-1 ... most of which means
+		 * nothing unless we control a real RS232 line.
+		 */
+		acm->port_line_coding = *value;
+	}
+}
+
+static int acm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct f_acm		*acm = func_to_acm(f);
+	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
+	 * CDC class messages; interface activation uses set_alt().
+	 *
+	 * Note CDC spec table 4 lists the ACM request profile.  It requires
+	 * encapsulated command support ... we don't handle any, and respond
+	 * to them by stalling.  Options include get/set/clear comm features
+	 * (not that useful) and SEND_BREAK.
+	 */
+	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
+
+	/* SET_LINE_CODING ... just read and save what the host sends */
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_REQ_SET_LINE_CODING:
+		if (w_length != sizeof(struct usb_cdc_line_coding)
+				|| w_index != acm->ctrl_id)
+			goto invalid;
+
+		value = w_length;
+		cdev->gadget->ep0->driver_data = acm;
+		req->complete = acm_complete_set_line_coding;
+		break;
+
+	/* GET_LINE_CODING ... return what host sent, or initial value */
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_REQ_GET_LINE_CODING:
+		if (w_index != acm->ctrl_id)
+			goto invalid;
+
+		value = min_t(unsigned, w_length,
+				sizeof(struct usb_cdc_line_coding));
+		memcpy(req->buf, &acm->port_line_coding, value);
+		break;
+
+	/* SET_CONTROL_LINE_STATE ... save what the host sent */
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_REQ_SET_CONTROL_LINE_STATE:
+		if (w_index != acm->ctrl_id)
+			goto invalid;
+
+		value = 0;
+
+		/* FIXME we should not allow data to flow until the
+		 * host sets the ACM_CTRL_DTR bit; and when it clears
+		 * that bit, we should return to that no-flow state.
+		 */
+		acm->port_handshake_bits = w_value;
+		break;
+
+	default:
+invalid:
+		dev_vdbg(&cdev->gadget->dev,
+			 "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) {
+		dev_dbg(&cdev->gadget->dev,
+			"acm ttyGS%d req%02x.%02x v%04x i%04x l%d\n",
+			acm->port_num, 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, "acm response on ttyGS%d, err %d\n",
+					acm->port_num, value);
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+static int acm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_acm		*acm = func_to_acm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	/* we know alt == 0, so this is an activation or a reset */
+
+	if (intf == acm->ctrl_id) {
+		dev_vdbg(&cdev->gadget->dev,
+				"reset acm control interface %d\n", intf);
+		usb_ep_disable(acm->notify);
+
+		if (!acm->notify->desc)
+			if (config_ep_by_speed(cdev->gadget, f, acm->notify))
+				return -EINVAL;
+
+		usb_ep_enable(acm->notify);
+
+	} else if (intf == acm->data_id) {
+		if (acm->notify->enabled) {
+			dev_dbg(&cdev->gadget->dev,
+				"reset acm ttyGS%d\n", acm->port_num);
+			gserial_disconnect(&acm->port);
+		}
+		if (!acm->port.in->desc || !acm->port.out->desc) {
+			dev_dbg(&cdev->gadget->dev,
+				"activate acm ttyGS%d\n", acm->port_num);
+			if (config_ep_by_speed(cdev->gadget, f,
+					       acm->port.in) ||
+			    config_ep_by_speed(cdev->gadget, f,
+					       acm->port.out)) {
+				acm->port.in->desc = NULL;
+				acm->port.out->desc = NULL;
+				return -EINVAL;
+			}
+		}
+		gserial_connect(&acm->port, acm->port_num);
+
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+
+static void acm_disable(struct usb_function *f)
+{
+	struct f_acm	*acm = func_to_acm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	dev_dbg(&cdev->gadget->dev, "acm ttyGS%d deactivated\n", acm->port_num);
+	gserial_disconnect(&acm->port);
+	usb_ep_disable(acm->notify);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * acm_cdc_notify - issue CDC notification to host
+ * @acm: wraps host to be notified
+ * @type: notification type
+ * @value: Refer to cdc specs, wValue field.
+ * @data: data to be sent
+ * @length: size of data
+ * Context: irqs blocked, acm->lock held, acm_notify_req non-null
+ *
+ * Returns zero on success or a negative errno.
+ *
+ * See section 6.3.5 of the CDC 1.1 specification for information
+ * about the only notification we issue:  SerialState change.
+ */
+static int acm_cdc_notify(struct f_acm *acm, u8 type, u16 value,
+		void *data, unsigned length)
+{
+	struct usb_ep			*ep = acm->notify;
+	struct usb_request		*req;
+	struct usb_cdc_notification	*notify;
+	const unsigned			len = sizeof(*notify) + length;
+	void				*buf;
+	int				status;
+
+	req = acm->notify_req;
+	acm->notify_req = NULL;
+	acm->pending = false;
+
+	req->length = len;
+	notify = req->buf;
+	buf = notify + 1;
+
+	notify->bmRequestType = USB_DIR_IN | USB_TYPE_CLASS
+			| USB_RECIP_INTERFACE;
+	notify->bNotificationType = type;
+	notify->wValue = cpu_to_le16(value);
+	notify->wIndex = cpu_to_le16(acm->ctrl_id);
+	notify->wLength = cpu_to_le16(length);
+	memcpy(buf, data, length);
+
+	/* ep_queue() can complete immediately if it fills the fifo... */
+	spin_unlock(&acm->lock);
+	status = usb_ep_queue(ep, req, GFP_ATOMIC);
+	spin_lock(&acm->lock);
+
+	if (status < 0) {
+		ERROR(acm->port.func.config->cdev,
+				"acm ttyGS%d can't notify serial state, %d\n",
+				acm->port_num, status);
+		acm->notify_req = req;
+	}
+
+	return status;
+}
+
+static int acm_notify_serial_state(struct f_acm *acm)
+{
+	struct usb_composite_dev *cdev = acm->port.func.config->cdev;
+	int			status;
+	__le16			serial_state;
+
+	spin_lock(&acm->lock);
+	if (acm->notify_req) {
+		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d serial state %04x\n",
+			acm->port_num, acm->serial_state);
+		serial_state = cpu_to_le16(acm->serial_state);
+		status = acm_cdc_notify(acm, USB_CDC_NOTIFY_SERIAL_STATE,
+				0, &serial_state, sizeof(acm->serial_state));
+	} else {
+		acm->pending = true;
+		status = 0;
+	}
+	spin_unlock(&acm->lock);
+	return status;
+}
+
+static void acm_cdc_notify_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_acm		*acm = req->context;
+	u8			doit = false;
+
+	/* on this call path we do NOT hold the port spinlock,
+	 * which is why ACM needs its own spinlock
+	 */
+	spin_lock(&acm->lock);
+	if (req->status != -ESHUTDOWN)
+		doit = acm->pending;
+	acm->notify_req = req;
+	spin_unlock(&acm->lock);
+
+	if (doit)
+		acm_notify_serial_state(acm);
+}
+
+/* connect == the TTY link is open */
+
+static void acm_connect(struct gserial *port)
+{
+	struct f_acm		*acm = port_to_acm(port);
+
+	acm->serial_state |= ACM_CTRL_DSR | ACM_CTRL_DCD;
+	acm_notify_serial_state(acm);
+}
+
+static void acm_disconnect(struct gserial *port)
+{
+	struct f_acm		*acm = port_to_acm(port);
+
+	acm->serial_state &= ~(ACM_CTRL_DSR | ACM_CTRL_DCD);
+	acm_notify_serial_state(acm);
+}
+
+static int acm_send_break(struct gserial *port, int duration)
+{
+	struct f_acm		*acm = port_to_acm(port);
+	u16			state;
+
+	state = acm->serial_state;
+	state &= ~ACM_CTRL_BRK;
+	if (duration)
+		state |= ACM_CTRL_BRK;
+
+	acm->serial_state = state;
+	return acm_notify_serial_state(acm);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ACM function driver setup/binding */
+static int
+acm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_acm		*acm = func_to_acm(f);
+	struct usb_string	*us;
+	int			status;
+	struct usb_ep		*ep;
+
+	/* REVISIT might want instance-specific strings to help
+	 * distinguish instances ...
+	 */
+
+	/* maybe allocate device-global string IDs, and patch descriptors */
+	us = usb_gstrings_attach(cdev, acm_strings,
+			ARRAY_SIZE(acm_string_defs));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+	acm_control_interface_desc.iInterface = us[ACM_CTRL_IDX].id;
+	acm_data_interface_desc.iInterface = us[ACM_DATA_IDX].id;
+	acm_iad_descriptor.iFunction = us[ACM_IAD_IDX].id;
+
+	/* allocate instance-specific interface IDs, and patch descriptors */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	acm->ctrl_id = status;
+	acm_iad_descriptor.bFirstInterface = status;
+
+	acm_control_interface_desc.bInterfaceNumber = status;
+	acm_union_desc .bMasterInterface0 = status;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	acm->data_id = status;
+
+	acm_data_interface_desc.bInterfaceNumber = status;
+	acm_union_desc.bSlaveInterface0 = status;
+	acm_call_mgmt_descriptor.bDataInterface = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_in_desc);
+	if (!ep)
+		goto fail;
+	acm->port.in = ep;
+
+	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_out_desc);
+	if (!ep)
+		goto fail;
+	acm->port.out = ep;
+
+	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_notify_desc);
+	if (!ep)
+		goto fail;
+	acm->notify = ep;
+
+	/* allocate notification */
+	acm->notify_req = gs_alloc_req(ep,
+			sizeof(struct usb_cdc_notification) + 2,
+			GFP_KERNEL);
+	if (!acm->notify_req)
+		goto fail;
+
+	acm->notify_req->complete = acm_cdc_notify_complete;
+	acm->notify_req->context = acm;
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	acm_hs_in_desc.bEndpointAddress = acm_fs_in_desc.bEndpointAddress;
+	acm_hs_out_desc.bEndpointAddress = acm_fs_out_desc.bEndpointAddress;
+	acm_hs_notify_desc.bEndpointAddress =
+		acm_fs_notify_desc.bEndpointAddress;
+
+	acm_ss_in_desc.bEndpointAddress = acm_fs_in_desc.bEndpointAddress;
+	acm_ss_out_desc.bEndpointAddress = acm_fs_out_desc.bEndpointAddress;
+
+	status = usb_assign_descriptors(f, acm_fs_function, acm_hs_function,
+			acm_ss_function, acm_ss_function);
+	if (status)
+		goto fail;
+
+	dev_dbg(&cdev->gadget->dev,
+		"acm ttyGS%d: %s speed IN/%s OUT/%s NOTIFY/%s\n",
+		acm->port_num,
+		gadget_is_superspeed(c->cdev->gadget) ? "super" :
+		gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+		acm->port.in->name, acm->port.out->name,
+		acm->notify->name);
+	return 0;
+
+fail:
+	if (acm->notify_req)
+		gs_free_req(acm->notify, acm->notify_req);
+
+	ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
+
+	return status;
+}
+
+static void acm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_acm		*acm = func_to_acm(f);
+
+	acm_string_defs[0].id = 0;
+	usb_free_all_descriptors(f);
+	if (acm->notify_req)
+		gs_free_req(acm->notify, acm->notify_req);
+}
+
+static void acm_free_func(struct usb_function *f)
+{
+	struct f_acm		*acm = func_to_acm(f);
+
+	kfree(acm);
+}
+
+static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
+{
+	struct f_serial_opts *opts;
+	struct f_acm *acm;
+
+	acm = kzalloc(sizeof(*acm), GFP_KERNEL);
+	if (!acm)
+		return ERR_PTR(-ENOMEM);
+
+	spin_lock_init(&acm->lock);
+
+	acm->port.connect = acm_connect;
+	acm->port.disconnect = acm_disconnect;
+	acm->port.send_break = acm_send_break;
+
+	acm->port.func.name = "acm";
+	acm->port.func.strings = acm_strings;
+	/* descriptors are per-instance copies */
+	acm->port.func.bind = acm_bind;
+	acm->port.func.set_alt = acm_set_alt;
+	acm->port.func.setup = acm_setup;
+	acm->port.func.disable = acm_disable;
+
+	opts = container_of(fi, struct f_serial_opts, func_inst);
+	acm->port_num = opts->port_num;
+	acm->port.func.unbind = acm_unbind;
+	acm->port.func.free_func = acm_free_func;
+
+	return &acm->port.func;
+}
+
+static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_serial_opts,
+			func_inst.group);
+}
+
+static void acm_attr_release(struct config_item *item)
+{
+	struct f_serial_opts *opts = to_f_serial_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations acm_item_ops = {
+	.release                = acm_attr_release,
+};
+
+static ssize_t f_acm_port_num_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%u\n", to_f_serial_opts(item)->port_num);
+}
+
+CONFIGFS_ATTR_RO(f_acm_, port_num);
+
+static struct configfs_attribute *acm_attrs[] = {
+	&f_acm_attr_port_num,
+	NULL,
+};
+
+static const struct config_item_type acm_func_type = {
+	.ct_item_ops    = &acm_item_ops,
+	.ct_attrs	= acm_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
+static void acm_free_instance(struct usb_function_instance *fi)
+{
+	struct f_serial_opts *opts;
+
+	opts = container_of(fi, struct f_serial_opts, func_inst);
+	gserial_free_line(opts->port_num);
+	kfree(opts);
+}
+
+static struct usb_function_instance *acm_alloc_instance(void)
+{
+	struct f_serial_opts *opts;
+	int ret;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+	opts->func_inst.free_func_inst = acm_free_instance;
+	ret = gserial_alloc_line(&opts->port_num);
+	if (ret) {
+		kfree(opts);
+		return ERR_PTR(ret);
+	}
+	config_group_init_type_name(&opts->func_inst.group, "",
+			&acm_func_type);
+	return &opts->func_inst;
+}
+DECLARE_USB_FUNCTION_INIT(acm, acm_alloc_instance, acm_alloc_func);
+MODULE_LICENSE("GPL");