usb: gadget: f_ncm.c added

Initial submittion of NCM link function driver.

The driver's logic is based on f_ecm driver and does not
use most of the NCM advantages like frame grouping and alignment.
Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_ncm.c

+/*
+ * f_ncm.c -- USB CDC Network (NCM) link function driver
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ * Contact: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
+ *
+ * The driver borrows from f_ecm.c which is:
+ *
+ * Copyright (C) 2003-2005,2008 David Brownell
+ * Copyright (C) 2008 Nokia Corporation
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/etherdevice.h>
+#include <linux/crc32.h>
+
+#include <linux/usb/cdc.h>
+
+#include "u_ether.h"
+
+/*
+ * This function is a "CDC Network Control Model" (CDC NCM) Ethernet link.
+ * NCM is intended to be used with high-speed network attachments.
+ *
+ * Note that NCM requires the use of "alternate settings" for its data
+ * interface.  This means that the set_alt() method has real work to do,
+ * and also means that a get_alt() method is required.
+ */
+
+/* to trigger crc/non-crc ndp signature */
+
+#define NCM_NDP_HDR_CRC_MASK	0x01000000
+#define NCM_NDP_HDR_CRC		0x01000000
+#define NCM_NDP_HDR_NOCRC	0x00000000
+
+struct ncm_ep_descs {
+	struct usb_endpoint_descriptor	*in;
+	struct usb_endpoint_descriptor	*out;
+	struct usb_endpoint_descriptor	*notify;
+};
+
+enum ncm_notify_state {
+	NCM_NOTIFY_NONE,		/* don't notify */
+	NCM_NOTIFY_CONNECT,		/* issue CONNECT next */
+	NCM_NOTIFY_SPEED,		/* issue SPEED_CHANGE next */
+};
+
+struct f_ncm {
+	struct gether			port;
+	u8				ctrl_id, data_id;
+
+	char				ethaddr[14];
+
+	struct ncm_ep_descs		fs;
+	struct ncm_ep_descs		hs;
+
+	struct usb_ep			*notify;
+	struct usb_endpoint_descriptor	*notify_desc;
+	struct usb_request		*notify_req;
+	u8				notify_state;
+	bool				is_open;
+
+	struct ndp_parser_opts		*parser_opts;
+	bool				is_crc;
+
+	/*
+	 * for notification, it is accessed from both
+	 * callback and ethernet open/close
+	 */
+	spinlock_t			lock;
+};
+
+static inline struct f_ncm *func_to_ncm(struct usb_function *f)
+{
+	return container_of(f, struct f_ncm, port.func);
+}
+
+/* peak (theoretical) bulk transfer rate in bits-per-second */
+static inline unsigned ncm_bitrate(struct usb_gadget *g)
+{
+	if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
+		return 13 * 512 * 8 * 1000 * 8;
+	else
+		return 19 *  64 * 1 * 1000 * 8;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * We cannot group frames so use just the minimal size which ok to put
+ * one max-size ethernet frame.
+ * If the host can group frames, allow it to do that, 16K is selected,
+ * because it's used by default by the current linux host driver
+ */
+#define NTB_DEFAULT_IN_SIZE	USB_CDC_NCM_NTB_MIN_IN_SIZE
+#define NTB_OUT_SIZE		16384
+
+/*
+ * skbs of size less than that will not be alligned
+ * to NCM's dwNtbInMaxSize to save bus bandwidth
+ */
+
+#define	MAX_TX_NONFIXED		(512 * 3)
+
+#define FORMATS_SUPPORTED	(USB_CDC_NCM_NTB16_SUPPORTED |	\
+				 USB_CDC_NCM_NTB32_SUPPORTED)
+
+static struct usb_cdc_ncm_ntb_parameters ntb_parameters = {
+	.wLength = sizeof ntb_parameters,
+	.bmNtbFormatsSupported = cpu_to_le16(FORMATS_SUPPORTED),
+	.dwNtbInMaxSize = cpu_to_le32(NTB_DEFAULT_IN_SIZE),
+	.wNdpInDivisor = cpu_to_le16(4),
+	.wNdpInPayloadRemainder = cpu_to_le16(0),
+	.wNdpInAlignment = cpu_to_le16(4),
+
+	.dwNtbOutMaxSize = cpu_to_le32(NTB_OUT_SIZE),
+	.wNdpOutDivisor = cpu_to_le16(4),
+	.wNdpOutPayloadRemainder = cpu_to_le16(0),
+	.wNdpOutAlignment = cpu_to_le16(4),
+};
+
+/*
+ * Use wMaxPacketSize big enough to fit CDC_NOTIFY_SPEED_CHANGE in one
+ * packet, to simplify cancellation; and a big transfer interval, to
+ * waste less bandwidth.
+ */
+
+#define LOG2_STATUS_INTERVAL_MSEC	5	/* 1 << 5 == 32 msec */
+#define NCM_STATUS_BYTECOUNT		16	/* 8 byte header + data */
+
+static struct usb_interface_assoc_descriptor ncm_iad_desc __initdata = {
+	.bLength =		sizeof ncm_iad_desc,
+	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
+
+	/* .bFirstInterface =	DYNAMIC, */
+	.bInterfaceCount =	2,	/* control + data */
+	.bFunctionClass =	USB_CLASS_COMM,
+	.bFunctionSubClass =	USB_CDC_SUBCLASS_NCM,
+	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
+	/* .iFunction =		DYNAMIC */
+};
+
+/* interface descriptor: */
+
+static struct usb_interface_descriptor ncm_control_intf __initdata = {
+	.bLength =		sizeof ncm_control_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_COMM,
+	.bInterfaceSubClass =	USB_CDC_SUBCLASS_NCM,
+	.bInterfaceProtocol =	USB_CDC_PROTO_NONE,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc ncm_header_desc __initdata = {
+	.bLength =		sizeof ncm_header_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
+
+	.bcdCDC =		cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_union_desc ncm_union_desc __initdata = {
+	.bLength =		sizeof(ncm_union_desc),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
+	/* .bMasterInterface0 =	DYNAMIC */
+	/* .bSlaveInterface0 =	DYNAMIC */
+};
+
+static struct usb_cdc_ether_desc ecm_desc __initdata = {
+	.bLength =		sizeof ecm_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_ETHERNET_TYPE,
+
+	/* this descriptor actually adds value, surprise! */
+	/* .iMACAddress = DYNAMIC */
+	.bmEthernetStatistics =	cpu_to_le32(0), /* no statistics */
+	.wMaxSegmentSize =	cpu_to_le16(ETH_FRAME_LEN),
+	.wNumberMCFilters =	cpu_to_le16(0),
+	.bNumberPowerFilters =	0,
+};
+
+#define NCAPS	(USB_CDC_NCM_NCAP_ETH_FILTER | USB_CDC_NCM_NCAP_CRC_MODE)
+
+static struct usb_cdc_ncm_desc ncm_desc __initdata = {
+	.bLength =		sizeof ncm_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_NCM_TYPE,
+
+	.bcdNcmVersion =	cpu_to_le16(0x0100),
+	/* can process SetEthernetPacketFilter */
+	.bmNetworkCapabilities = NCAPS,
+};
+
+/* the default data interface has no endpoints ... */
+
+static struct usb_interface_descriptor ncm_data_nop_intf __initdata = {
+	.bLength =		sizeof ncm_data_nop_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bInterfaceNumber =	1,
+	.bAlternateSetting =	0,
+	.bNumEndpoints =	0,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	USB_CDC_NCM_PROTO_NTB,
+	/* .iInterface = DYNAMIC */
+};
+
+/* ... but the "real" data interface has two bulk endpoints */
+
+static struct usb_interface_descriptor ncm_data_intf __initdata = {
+	.bLength =		sizeof ncm_data_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bInterfaceNumber =	1,
+	.bAlternateSetting =	1,
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	USB_CDC_NCM_PROTO_NTB,
+	/* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_ncm_notify_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(NCM_STATUS_BYTECOUNT),
+	.bInterval =		1 << LOG2_STATUS_INTERVAL_MSEC,
+};
+
+static struct usb_endpoint_descriptor fs_ncm_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_ncm_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *ncm_fs_function[] __initdata = {
+	(struct usb_descriptor_header *) &ncm_iad_desc,
+	/* CDC NCM control descriptors */
+	(struct usb_descriptor_header *) &ncm_control_intf,
+	(struct usb_descriptor_header *) &ncm_header_desc,
+	(struct usb_descriptor_header *) &ncm_union_desc,
+	(struct usb_descriptor_header *) &ecm_desc,
+	(struct usb_descriptor_header *) &ncm_desc,
+	(struct usb_descriptor_header *) &fs_ncm_notify_desc,
+	/* data interface, altsettings 0 and 1 */
+	(struct usb_descriptor_header *) &ncm_data_nop_intf,
+	(struct usb_descriptor_header *) &ncm_data_intf,
+	(struct usb_descriptor_header *) &fs_ncm_in_desc,
+	(struct usb_descriptor_header *) &fs_ncm_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_ncm_notify_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(NCM_STATUS_BYTECOUNT),
+	.bInterval =		LOG2_STATUS_INTERVAL_MSEC + 4,
+};
+static struct usb_endpoint_descriptor hs_ncm_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_ncm_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *ncm_hs_function[] __initdata = {
+	(struct usb_descriptor_header *) &ncm_iad_desc,
+	/* CDC NCM control descriptors */
+	(struct usb_descriptor_header *) &ncm_control_intf,
+	(struct usb_descriptor_header *) &ncm_header_desc,
+	(struct usb_descriptor_header *) &ncm_union_desc,
+	(struct usb_descriptor_header *) &ecm_desc,
+	(struct usb_descriptor_header *) &ncm_desc,
+	(struct usb_descriptor_header *) &hs_ncm_notify_desc,
+	/* data interface, altsettings 0 and 1 */
+	(struct usb_descriptor_header *) &ncm_data_nop_intf,
+	(struct usb_descriptor_header *) &ncm_data_intf,
+	(struct usb_descriptor_header *) &hs_ncm_in_desc,
+	(struct usb_descriptor_header *) &hs_ncm_out_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+#define STRING_CTRL_IDX	0
+#define STRING_MAC_IDX	1
+#define STRING_DATA_IDX	2
+#define STRING_IAD_IDX	3
+
+static struct usb_string ncm_string_defs[] = {
+	[STRING_CTRL_IDX].s = "CDC Network Control Model (NCM)",
+	[STRING_MAC_IDX].s = NULL /* DYNAMIC */,
+	[STRING_DATA_IDX].s = "CDC Network Data",
+	[STRING_IAD_IDX].s = "CDC NCM",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings ncm_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		ncm_string_defs,
+};
+
+static struct usb_gadget_strings *ncm_strings[] = {
+	&ncm_string_table,
+	NULL,
+};
+
+/*
+ * Here are options for NCM Datagram Pointer table (NDP) parser.
+ * There are 2 different formats: NDP16 and NDP32 in the spec (ch. 3),
+ * in NDP16 offsets and sizes fields are 1 16bit word wide,
+ * in NDP32 -- 2 16bit words wide. Also signatures are different.
+ * To make the parser code the same, put the differences in the structure,
+ * and switch pointers to the structures when the format is changed.
+ */
+
+struct ndp_parser_opts {
+	u32		nth_sign;
+	u32		ndp_sign;
+	unsigned	nth_size;
+	unsigned	ndp_size;
+	unsigned	ndplen_align;
+	/* sizes in u16 units */
+	unsigned	dgram_item_len; /* index or length */
+	unsigned	block_length;
+	unsigned	fp_index;
+	unsigned	reserved1;
+	unsigned	reserved2;
+	unsigned	next_fp_index;
+};
+
+#define INIT_NDP16_OPTS {					\
+		.nth_sign = USB_CDC_NCM_NTH16_SIGN,		\
+		.ndp_sign = USB_CDC_NCM_NDP16_NOCRC_SIGN,	\
+		.nth_size = sizeof(struct usb_cdc_ncm_nth16),	\
+		.ndp_size = sizeof(struct usb_cdc_ncm_ndp16),	\
+		.ndplen_align = 4,				\
+		.dgram_item_len = 1,				\
+		.block_length = 1,				\
+		.fp_index = 1,					\
+		.reserved1 = 0,					\
+		.reserved2 = 0,					\
+		.next_fp_index = 1,				\
+	}
+
+
+#define INIT_NDP32_OPTS {					\
+		.nth_sign = USB_CDC_NCM_NTH32_SIGN,		\
+		.ndp_sign = USB_CDC_NCM_NDP32_NOCRC_SIGN,	\
+		.nth_size = sizeof(struct usb_cdc_ncm_nth32),	\
+		.ndp_size = sizeof(struct usb_cdc_ncm_ndp32),	\
+		.ndplen_align = 8,				\
+		.dgram_item_len = 2,				\
+		.block_length = 2,				\
+		.fp_index = 2,					\
+		.reserved1 = 1,					\
+		.reserved2 = 2,					\
+		.next_fp_index = 2,				\
+	}
+
+static struct ndp_parser_opts ndp16_opts = INIT_NDP16_OPTS;
+static struct ndp_parser_opts ndp32_opts = INIT_NDP32_OPTS;
+
+static inline void put_ncm(__le16 **p, unsigned size, unsigned val)
+{
+	switch (size) {
+	case 1:
+		put_unaligned_le16((u16)val, *p);
+		break;
+	case 2:
+		put_unaligned_le32((u32)val, *p);
+
+		break;
+	default:
+		BUG();
+	}
+
+	*p += size;
+}
+
+static inline unsigned get_ncm(__le16 **p, unsigned size)
+{
+	unsigned tmp;
+
+	switch (size) {
+	case 1:
+		tmp = get_unaligned_le16(*p);
+		break;
+	case 2:
+		tmp = get_unaligned_le32(*p);
+		break;
+	default:
+		BUG();
+	}
+
+	*p += size;
+	return tmp;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static inline void ncm_reset_values(struct f_ncm *ncm)
+{
+	ncm->parser_opts = &ndp16_opts;
+	ncm->is_crc = false;
+	ncm->port.cdc_filter = DEFAULT_FILTER;
+
+	/* doesn't make sense for ncm, fixed size used */
+	ncm->port.header_len = 0;
+
+	ncm->port.fixed_out_len = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
+	ncm->port.fixed_in_len = NTB_DEFAULT_IN_SIZE;
+}
+
+/*
+ * Context: ncm->lock held
+ */
+static void ncm_do_notify(struct f_ncm *ncm)
+{
+	struct usb_request		*req = ncm->notify_req;
+	struct usb_cdc_notification	*event;
+	struct usb_composite_dev	*cdev = ncm->port.func.config->cdev;
+	__le32				*data;
+	int				status;
+
+	/* notification already in flight? */
+	if (!req)
+		return;
+
+	event = req->buf;
+	switch (ncm->notify_state) {
+	case NCM_NOTIFY_NONE:
+		return;
+
+	case NCM_NOTIFY_CONNECT:
+		event->bNotificationType = USB_CDC_NOTIFY_NETWORK_CONNECTION;
+		if (ncm->is_open)
+			event->wValue = cpu_to_le16(1);
+		else
+			event->wValue = cpu_to_le16(0);
+		event->wLength = 0;
+		req->length = sizeof *event;
+
+		DBG(cdev, "notify connect %s\n",
+				ncm->is_open ? "true" : "false");
+		ncm->notify_state = NCM_NOTIFY_NONE;
+		break;
+
+	case NCM_NOTIFY_SPEED:
+		event->bNotificationType = USB_CDC_NOTIFY_SPEED_CHANGE;
+		event->wValue = cpu_to_le16(0);
+		event->wLength = cpu_to_le16(8);
+		req->length = NCM_STATUS_BYTECOUNT;
+
+		/* SPEED_CHANGE data is up/down speeds in bits/sec */
+		data = req->buf + sizeof *event;
+		data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));
+		data[1] = data[0];
+
+		DBG(cdev, "notify speed %d\n", ncm_bitrate(cdev->gadget));
+		ncm->notify_state = NCM_NOTIFY_CONNECT;
+		break;
+	}
+	event->bmRequestType = 0xA1;
+	event->wIndex = cpu_to_le16(ncm->ctrl_id);
+
+	ncm->notify_req = NULL;
+	/*
+	 * In double buffering if there is a space in FIFO,
+	 * completion callback can be called right after the call,
+	 * so unlocking
+	 */
+	spin_unlock(&ncm->lock);
+	status = usb_ep_queue(ncm->notify, req, GFP_ATOMIC);
+	spin_lock(&ncm->lock);
+	if (status < 0) {
+		ncm->notify_req = req;
+		DBG(cdev, "notify --> %d\n", status);
+	}
+}
+
+/*
+ * Context: ncm->lock held
+ */
+static void ncm_notify(struct f_ncm *ncm)
+{
+	/*
+	 * NOTE on most versions of Linux, host side cdc-ethernet
+	 * won't listen for notifications until its netdevice opens.
+	 * The first notification then sits in the FIFO for a long
+	 * time, and the second one is queued.
+	 *
+	 * If ncm_notify() is called before the second (CONNECT)
+	 * notification is sent, then it will reset to send the SPEED
+	 * notificaion again (and again, and again), but it's not a problem
+	 */
+	ncm->notify_state = NCM_NOTIFY_SPEED;
+	ncm_do_notify(ncm);
+}
+
+static void ncm_notify_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_ncm			*ncm = req->context;
+	struct usb_composite_dev	*cdev = ncm->port.func.config->cdev;
+	struct usb_cdc_notification	*event = req->buf;
+
+	spin_lock(&ncm->lock);
+	switch (req->status) {
+	case 0:
+		VDBG(cdev, "Notification %02x sent\n",
+		     event->bNotificationType);
+		break;
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		ncm->notify_state = NCM_NOTIFY_NONE;
+		break;
+	default:
+		DBG(cdev, "event %02x --> %d\n",
+			event->bNotificationType, req->status);
+		break;
+	}
+	ncm->notify_req = req;
+	ncm_do_notify(ncm);
+	spin_unlock(&ncm->lock);
+}
+
+static void ncm_ep0out_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	/* now for SET_NTB_INPUT_SIZE only */
+	unsigned		in_size;
+	struct usb_function	*f = req->context;
+	struct f_ncm		*ncm = func_to_ncm(f);
+	struct usb_composite_dev *cdev = ep->driver_data;
+
+	req->context = NULL;
+	if (req->status || req->actual != req->length) {
+		DBG(cdev, "Bad control-OUT transfer\n");
+		goto invalid;
+	}
+
+	in_size = get_unaligned_le32(req->buf);
+	if (in_size < USB_CDC_NCM_NTB_MIN_IN_SIZE ||
+	    in_size > le32_to_cpu(ntb_parameters.dwNtbInMaxSize)) {
+		DBG(cdev, "Got wrong INPUT SIZE (%d) from host\n", in_size);
+		goto invalid;
+	}
+
+	ncm->port.fixed_in_len = in_size;
+	VDBG(cdev, "Set NTB INPUT SIZE %d\n", in_size);
+	return;
+
+invalid:
+	usb_ep_set_halt(ep);
+	return;
+}
+
+static int ncm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct f_ncm		*ncm = func_to_ncm(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().
+	 */
+	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_SET_ETHERNET_PACKET_FILTER:
+		/*
+		 * see 6.2.30: no data, wIndex = interface,
+		 * wValue = packet filter bitmap
+		 */
+		if (w_length != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		DBG(cdev, "packet filter %02x\n", w_value);
+		/*
+		 * REVISIT locking of cdc_filter.  This assumes the UDC
+		 * driver won't have a concurrent packet TX irq running on
+		 * another CPU; or that if it does, this write is atomic...
+		 */
+		ncm->port.cdc_filter = w_value;
+		value = 0;
+		break;
+	/*
+	 * and optionally:
+	 * case USB_CDC_SEND_ENCAPSULATED_COMMAND:
+	 * case USB_CDC_GET_ENCAPSULATED_RESPONSE:
+	 * case USB_CDC_SET_ETHERNET_MULTICAST_FILTERS:
+	 * case USB_CDC_SET_ETHERNET_PM_PATTERN_FILTER:
+	 * case USB_CDC_GET_ETHERNET_PM_PATTERN_FILTER:
+	 * case USB_CDC_GET_ETHERNET_STATISTIC:
+	 */
+
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_GET_NTB_PARAMETERS:
+
+		if (w_length == 0 || w_value != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		value = w_length > sizeof ntb_parameters ?
+			sizeof ntb_parameters : w_length;
+		memcpy(req->buf, &ntb_parameters, value);
+		VDBG(cdev, "Host asked NTB parameters\n");
+		break;
+
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_GET_NTB_INPUT_SIZE:
+
+		if (w_length < 4 || w_value != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		put_unaligned_le32(ncm->port.fixed_in_len, req->buf);
+		value = 4;
+		VDBG(cdev, "Host asked INPUT SIZE, sending %d\n",
+		     ncm->port.fixed_in_len);
+		break;
+
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_SET_NTB_INPUT_SIZE:
+	{
+		if (w_length != 4 || w_value != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		req->complete = ncm_ep0out_complete;
+		req->length = w_length;
+		req->context = f;
+
+		value = req->length;
+		break;
+	}
+
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_GET_NTB_FORMAT:
+	{
+		uint16_t format;
+
+		if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		format = (ncm->parser_opts == &ndp16_opts) ? 0x0000 : 0x0001;
+		put_unaligned_le16(format, req->buf);
+		value = 2;
+		VDBG(cdev, "Host asked NTB FORMAT, sending %d\n", format);
+		break;
+	}
+
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_SET_NTB_FORMAT:
+	{
+		if (w_length != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		switch (w_value) {
+		case 0x0000:
+			ncm->parser_opts = &ndp16_opts;
+			DBG(cdev, "NCM16 selected\n");
+			break;
+		case 0x0001:
+			ncm->parser_opts = &ndp32_opts;
+			DBG(cdev, "NCM32 selected\n");
+			break;
+		default:
+			goto invalid;
+		}
+		value = 0;
+		break;
+	}
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_GET_CRC_MODE:
+	{
+		uint16_t is_crc;
+
+		if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		is_crc = ncm->is_crc ? 0x0001 : 0x0000;
+		put_unaligned_le16(is_crc, req->buf);
+		value = 2;
+		VDBG(cdev, "Host asked CRC MODE, sending %d\n", is_crc);
+		break;
+	}
+
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+		| USB_CDC_SET_CRC_MODE:
+	{
+		int ndp_hdr_crc = 0;
+
+		if (w_length != 0 || w_index != ncm->ctrl_id)
+			goto invalid;
+		switch (w_value) {
+		case 0x0000:
+			ncm->is_crc = false;
+			ndp_hdr_crc = NCM_NDP_HDR_NOCRC;
+			DBG(cdev, "non-CRC mode selected\n");
+			break;
+		case 0x0001:
+			ncm->is_crc = true;
+			ndp_hdr_crc = NCM_NDP_HDR_CRC;
+			DBG(cdev, "CRC mode selected\n");
+			break;
+		default:
+			goto invalid;
+		}
+		ncm->parser_opts->ndp_sign &= ~NCM_NDP_HDR_CRC_MASK;
+		ncm->parser_opts->ndp_sign |= ndp_hdr_crc;
+		value = 0;
+		break;
+	}
+
+	/* and disabled in ncm descriptor: */
+	/* case USB_CDC_GET_NET_ADDRESS: */
+	/* case USB_CDC_SET_NET_ADDRESS: */
+	/* case USB_CDC_GET_MAX_DATAGRAM_SIZE: */
+	/* case USB_CDC_SET_MAX_DATAGRAM_SIZE: */
+
+	default:
+invalid:
+		DBG(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, "ncm 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, "ncm req %02x.%02x response err %d\n",
+					ctrl->bRequestType, ctrl->bRequest,
+					value);
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+
+static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_ncm		*ncm = func_to_ncm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	/* Control interface has only altsetting 0 */
+	if (intf == ncm->ctrl_id) {
+		if (alt != 0)
+			goto fail;
+
+		if (ncm->notify->driver_data) {
+			DBG(cdev, "reset ncm control %d\n", intf);
+			usb_ep_disable(ncm->notify);
+		} else {
+			DBG(cdev, "init ncm ctrl %d\n", intf);
+			ncm->notify_desc = ep_choose(cdev->gadget,
+					ncm->hs.notify,
+					ncm->fs.notify);
+		}
+		usb_ep_enable(ncm->notify, ncm->notify_desc);
+		ncm->notify->driver_data = ncm;
+
+	/* Data interface has two altsettings, 0 and 1 */
+	} else if (intf == ncm->data_id) {
+		if (alt > 1)
+			goto fail;
+
+		if (ncm->port.in_ep->driver_data) {
+			DBG(cdev, "reset ncm\n");
+			gether_disconnect(&ncm->port);
+			ncm_reset_values(ncm);
+		}
+
+		/*
+		 * CDC Network only sends data in non-default altsettings.
+		 * Changing altsettings resets filters, statistics, etc.
+		 */
+		if (alt == 1) {
+			struct net_device	*net;
+
+			if (!ncm->port.in) {
+				DBG(cdev, "init ncm\n");
+				ncm->port.in = ep_choose(cdev->gadget,
+							 ncm->hs.in,
+							 ncm->fs.in);
+				ncm->port.out = ep_choose(cdev->gadget,
+							  ncm->hs.out,
+							  ncm->fs.out);
+			}
+
+			/* TODO */
+			/* Enable zlps by default for NCM conformance;
+			 * override for musb_hdrc (avoids txdma ovhead)
+			 */
+			ncm->port.is_zlp_ok = !(
+				gadget_is_musbhdrc(cdev->gadget)
+				);
+			ncm->port.cdc_filter = DEFAULT_FILTER;
+			DBG(cdev, "activate ncm\n");
+			net = gether_connect(&ncm->port);
+			if (IS_ERR(net))
+				return PTR_ERR(net);
+		}
+
+		spin_lock(&ncm->lock);
+		ncm_notify(ncm);
+		spin_unlock(&ncm->lock);
+	} else
+		goto fail;
+
+	return 0;
+fail:
+	return -EINVAL;
+}
+
+/*
+ * Because the data interface supports multiple altsettings,
+ * this NCM function *MUST* implement a get_alt() method.
+ */
+static int ncm_get_alt(struct usb_function *f, unsigned intf)
+{
+	struct f_ncm		*ncm = func_to_ncm(f);
+
+	if (intf == ncm->ctrl_id)
+		return 0;
+	return ncm->port.in_ep->driver_data ? 1 : 0;
+}
+
+static struct sk_buff *ncm_wrap_ntb(struct gether *port,
+				    struct sk_buff *skb)
+{
+	struct f_ncm	*ncm = func_to_ncm(&port->func);
+	struct sk_buff	*skb2;
+	int		ncb_len = 0;
+	__le16		*tmp;
+	int		div = ntb_parameters.wNdpInDivisor;
+	int		rem = ntb_parameters.wNdpInPayloadRemainder;
+	int		pad;
+	int		ndp_align = ntb_parameters.wNdpInAlignment;
+	int		ndp_pad;
+	unsigned	max_size = ncm->port.fixed_in_len;
+	struct ndp_parser_opts *opts = ncm->parser_opts;
+	unsigned	crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
+
+	ncb_len += opts->nth_size;
+	ndp_pad = ALIGN(ncb_len, ndp_align) - ncb_len;
+	ncb_len += ndp_pad;
+	ncb_len += opts->ndp_size;
+	ncb_len += 2 * 2 * opts->dgram_item_len; /* Datagram entry */
+	ncb_len += 2 * 2 * opts->dgram_item_len; /* Zero datagram entry */
+	pad = ALIGN(ncb_len, div) + rem - ncb_len;
+	ncb_len += pad;
+
+	if (ncb_len + skb->len + crc_len > max_size) {
+		dev_kfree_skb_any(skb);
+		return NULL;
+	}
+
+	skb2 = skb_copy_expand(skb, ncb_len,
+			       max_size - skb->len - ncb_len - crc_len,
+			       GFP_ATOMIC);
+	dev_kfree_skb_any(skb);
+	if (!skb2)
+		return NULL;
+
+	skb = skb2;
+
+	tmp = (void *) skb_push(skb, ncb_len);
+	memset(tmp, 0, ncb_len);
+
+	put_unaligned_le32(opts->nth_sign, tmp); /* dwSignature */
+	tmp += 2;
+	/* wHeaderLength */
+	put_unaligned_le16(opts->nth_size, tmp++);
+	tmp++; /* skip wSequence */
+	put_ncm(&tmp, opts->block_length, skb->len); /* (d)wBlockLength */
+	/* (d)wFpIndex */
+	/* the first pointer is right after the NTH + align */
+	put_ncm(&tmp, opts->fp_index, opts->nth_size + ndp_pad);
+
+	tmp = (void *)tmp + ndp_pad;
+
+	/* NDP */
+	put_unaligned_le32(opts->ndp_sign, tmp); /* dwSignature */
+	tmp += 2;
+	/* wLength */
+	put_unaligned_le16(ncb_len - opts->nth_size - pad, tmp++);
+
+	tmp += opts->reserved1;
+	tmp += opts->next_fp_index; /* skip reserved (d)wNextFpIndex */
+	tmp += opts->reserved2;
+
+	if (ncm->is_crc) {
+		uint32_t crc;
+
+		crc = ~crc32_le(~0,
+				skb->data + ncb_len,
+				skb->len - ncb_len);
+		put_unaligned_le32(crc, skb->data + skb->len);
+		skb_put(skb, crc_len);
+	}
+
+	/* (d)wDatagramIndex[0] */
+	put_ncm(&tmp, opts->dgram_item_len, ncb_len);
+	/* (d)wDatagramLength[0] */
+	put_ncm(&tmp, opts->dgram_item_len, skb->len - ncb_len);
+	/* (d)wDatagramIndex[1] and  (d)wDatagramLength[1] already zeroed */
+
+	if (skb->len > MAX_TX_NONFIXED)
+		memset(skb_put(skb, max_size - skb->len),
+		       0, max_size - skb->len);
+
+	return skb;
+}
+
+static int ncm_unwrap_ntb(struct gether *port,
+			  struct sk_buff *skb,
+			  struct sk_buff_head *list)
+{
+	struct f_ncm	*ncm = func_to_ncm(&port->func);
+	__le16		*tmp = (void *) skb->data;
+	unsigned	index, index2;
+	unsigned	dg_len, dg_len2;
+	unsigned	ndp_len;
+	struct sk_buff	*skb2;
+	int		ret = -EINVAL;
+	unsigned	max_size = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
+	struct ndp_parser_opts *opts = ncm->parser_opts;
+	unsigned	crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
+	int		dgram_counter;
+
+	/* dwSignature */
+	if (get_unaligned_le32(tmp) != opts->nth_sign) {
+		INFO(port->func.config->cdev, "Wrong NTH SIGN, skblen %d\n",
+			skb->len);
+		print_hex_dump(KERN_INFO, "HEAD:", DUMP_PREFIX_ADDRESS, 32, 1,
+			       skb->data, 32, false);
+
+		goto err;
+	}
+	tmp += 2;
+	/* wHeaderLength */
+	if (get_unaligned_le16(tmp++) != opts->nth_size) {
+		INFO(port->func.config->cdev, "Wrong NTB headersize\n");
+		goto err;
+	}
+	tmp++; /* skip wSequence */
+
+	/* (d)wBlockLength */
+	if (get_ncm(&tmp, opts->block_length) > max_size) {
+		INFO(port->func.config->cdev, "OUT size exceeded\n");
+		goto err;
+	}
+
+	index = get_ncm(&tmp, opts->fp_index);
+	/* NCM 3.2 */
+	if (((index % 4) != 0) && (index < opts->nth_size)) {
+		INFO(port->func.config->cdev, "Bad index: %x\n",
+			index);
+		goto err;
+	}
+
+	/* walk through NDP */
+	tmp = ((void *)skb->data) + index;
+	if (get_unaligned_le32(tmp) != opts->ndp_sign) {
+		INFO(port->func.config->cdev, "Wrong NDP SIGN\n");
+		goto err;
+	}
+	tmp += 2;
+
+	ndp_len = get_unaligned_le16(tmp++);
+	/*
+	 * NCM 3.3.1
+	 * entry is 2 items
+	 * item size is 16/32 bits, opts->dgram_item_len * 2 bytes
+	 * minimal: struct usb_cdc_ncm_ndpX + normal entry + zero entry
+	 */
+	if ((ndp_len < opts->ndp_size + 2 * 2 * (opts->dgram_item_len * 2))
+	    || (ndp_len % opts->ndplen_align != 0)) {
+		INFO(port->func.config->cdev, "Bad NDP length: %x\n", ndp_len);
+		goto err;
+	}
+	tmp += opts->reserved1;
+	tmp += opts->next_fp_index; /* skip reserved (d)wNextFpIndex */
+	tmp += opts->reserved2;
+
+	ndp_len -= opts->ndp_size;
+	index2 = get_ncm(&tmp, opts->dgram_item_len);
+	dg_len2 = get_ncm(&tmp, opts->dgram_item_len);
+	dgram_counter = 0;
+
+	do {
+		index = index2;
+		dg_len = dg_len2;
+		if (dg_len < 14 + crc_len) { /* ethernet header + crc */
+			INFO(port->func.config->cdev, "Bad dgram length: %x\n",
+			     dg_len);
+			goto err;
+		}
+		if (ncm->is_crc) {
+			uint32_t crc, crc2;
+
+			crc = get_unaligned_le32(skb->data +
+						 index + dg_len - crc_len);
+			crc2 = ~crc32_le(~0,
+					 skb->data + index,
+					 dg_len - crc_len);
+			if (crc != crc2) {
+				INFO(port->func.config->cdev, "Bad CRC\n");
+				goto err;
+			}
+		}
+
+		index2 = get_ncm(&tmp, opts->dgram_item_len);
+		dg_len2 = get_ncm(&tmp, opts->dgram_item_len);
+
+		if (index2 == 0 || dg_len2 == 0) {
+			skb2 = skb;
+		} else {
+			skb2 = skb_clone(skb, GFP_ATOMIC);
+			if (skb2 == NULL)
+				goto err;
+		}
+
+		if (!skb_pull(skb2, index)) {
+			ret = -EOVERFLOW;
+			goto err;
+		}
+
+		skb_trim(skb2, dg_len - crc_len);
+		skb_queue_tail(list, skb2);
+
+		ndp_len -= 2 * (opts->dgram_item_len * 2);
+
+		dgram_counter++;
+
+		if (index2 == 0 || dg_len2 == 0)
+			break;
+	} while (ndp_len > 2 * (opts->dgram_item_len * 2)); /* zero entry */
+
+	VDBG(port->func.config->cdev,
+	     "Parsed NTB with %d frames\n", dgram_counter);
+	return 0;
+err:
+	skb_queue_purge(list);
+	dev_kfree_skb_any(skb);
+	return ret;
+}
+
+static void ncm_disable(struct usb_function *f)
+{
+	struct f_ncm		*ncm = func_to_ncm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	DBG(cdev, "ncm deactivated\n");
+
+	if (ncm->port.in_ep->driver_data)
+		gether_disconnect(&ncm->port);
+
+	if (ncm->notify->driver_data) {
+		usb_ep_disable(ncm->notify);
+		ncm->notify->driver_data = NULL;
+		ncm->notify_desc = NULL;
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Callbacks let us notify the host about connect/disconnect when the
+ * net device is opened or closed.
+ *
+ * For testing, note that link states on this side include both opened
+ * and closed variants of:
+ *
+ *   - disconnected/unconfigured
+ *   - configured but inactive (data alt 0)
+ *   - configured and active (data alt 1)
+ *
+ * Each needs to be tested with unplug, rmmod, SET_CONFIGURATION, and
+ * SET_INTERFACE (altsetting).  Remember also that "configured" doesn't
+ * imply the host is actually polling the notification endpoint, and
+ * likewise that "active" doesn't imply it's actually using the data
+ * endpoints for traffic.
+ */
+
+static void ncm_open(struct gether *geth)
+{
+	struct f_ncm		*ncm = func_to_ncm(&geth->func);
+
+	DBG(ncm->port.func.config->cdev, "%s\n", __func__);
+
+	spin_lock(&ncm->lock);
+	ncm->is_open = true;
+	ncm_notify(ncm);
+	spin_unlock(&ncm->lock);
+}
+
+static void ncm_close(struct gether *geth)
+{
+	struct f_ncm		*ncm = func_to_ncm(&geth->func);
+
+	DBG(ncm->port.func.config->cdev, "%s\n", __func__);
+
+	spin_lock(&ncm->lock);
+	ncm->is_open = false;
+	ncm_notify(ncm);
+	spin_unlock(&ncm->lock);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ethernet function driver setup/binding */
+
+static int __init
+ncm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_ncm		*ncm = func_to_ncm(f);
+	int			status;
+	struct usb_ep		*ep;
+
+	/* allocate instance-specific interface IDs */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	ncm->ctrl_id = status;
+	ncm_iad_desc.bFirstInterface = status;
+
+	ncm_control_intf.bInterfaceNumber = status;
+	ncm_union_desc.bMasterInterface0 = status;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	ncm->data_id = status;
+
+	ncm_data_nop_intf.bInterfaceNumber = status;
+	ncm_data_intf.bInterfaceNumber = status;
+	ncm_union_desc.bSlaveInterface0 = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_in_desc);
+	if (!ep)
+		goto fail;
+	ncm->port.in_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_out_desc);
+	if (!ep)
+		goto fail;
+	ncm->port.out_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_notify_desc);
+	if (!ep)
+		goto fail;
+	ncm->notify = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	status = -ENOMEM;
+
+	/* allocate notification request and buffer */
+	ncm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!ncm->notify_req)
+		goto fail;
+	ncm->notify_req->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL);
+	if (!ncm->notify_req->buf)
+		goto fail;
+	ncm->notify_req->context = ncm;
+	ncm->notify_req->complete = ncm_notify_complete;
+
+	/* copy descriptors, and track endpoint copies */
+	f->descriptors = usb_copy_descriptors(ncm_fs_function);
+	if (!f->descriptors)
+		goto fail;
+
+	ncm->fs.in = usb_find_endpoint(ncm_fs_function,
+			f->descriptors, &fs_ncm_in_desc);
+	ncm->fs.out = usb_find_endpoint(ncm_fs_function,
+			f->descriptors, &fs_ncm_out_desc);
+	ncm->fs.notify = usb_find_endpoint(ncm_fs_function,
+			f->descriptors, &fs_ncm_notify_desc);
+
+	/*
+	 * support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+		hs_ncm_in_desc.bEndpointAddress =
+				fs_ncm_in_desc.bEndpointAddress;
+		hs_ncm_out_desc.bEndpointAddress =
+				fs_ncm_out_desc.bEndpointAddress;
+		hs_ncm_notify_desc.bEndpointAddress =
+				fs_ncm_notify_desc.bEndpointAddress;
+
+		/* copy descriptors, and track endpoint copies */
+		f->hs_descriptors = usb_copy_descriptors(ncm_hs_function);
+		if (!f->hs_descriptors)
+			goto fail;
+
+		ncm->hs.in = usb_find_endpoint(ncm_hs_function,
+				f->hs_descriptors, &hs_ncm_in_desc);
+		ncm->hs.out = usb_find_endpoint(ncm_hs_function,
+				f->hs_descriptors, &hs_ncm_out_desc);
+		ncm->hs.notify = usb_find_endpoint(ncm_hs_function,
+				f->hs_descriptors, &hs_ncm_notify_desc);
+	}
+
+	/*
+	 * NOTE:  all that is done without knowing or caring about
+	 * the network link ... which is unavailable to this code
+	 * until we're activated via set_alt().
+	 */
+
+	ncm->port.open = ncm_open;
+	ncm->port.close = ncm_close;
+
+	DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			ncm->port.in_ep->name, ncm->port.out_ep->name,
+			ncm->notify->name);
+	return 0;
+
+fail:
+	if (f->descriptors)
+		usb_free_descriptors(f->descriptors);
+
+	if (ncm->notify_req) {
+		kfree(ncm->notify_req->buf);
+		usb_ep_free_request(ncm->notify, ncm->notify_req);
+	}
+
+	/* we might as well release our claims on endpoints */
+	if (ncm->notify)
+		ncm->notify->driver_data = NULL;
+	if (ncm->port.out)
+		ncm->port.out_ep->driver_data = NULL;
+	if (ncm->port.in)
+		ncm->port.in_ep->driver_data = NULL;
+
+	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+	return status;
+}
+
+static void
+ncm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_ncm		*ncm = func_to_ncm(f);
+
+	DBG(c->cdev, "ncm unbind\n");
+
+	if (gadget_is_dualspeed(c->cdev->gadget))
+		usb_free_descriptors(f->hs_descriptors);
+	usb_free_descriptors(f->descriptors);
+
+	kfree(ncm->notify_req->buf);
+	usb_ep_free_request(ncm->notify, ncm->notify_req);
+
+	ncm_string_defs[1].s = NULL;
+	kfree(ncm);
+}
+
+/**
+ * ncm_bind_config - add CDC Network link to a configuration
+ * @c: the configuration to support the network link
+ * @ethaddr: a buffer in which the ethernet address of the host side
+ *	side of the link was recorded
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @gether_setup().  Caller is also responsible
+ * for calling @gether_cleanup() before module unload.
+ */
+int __init ncm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
+{
+	struct f_ncm	*ncm;
+	int		status;
+
+	if (!can_support_ecm(c->cdev->gadget) || !ethaddr)
+		return -EINVAL;
+
+	/* maybe allocate device-global string IDs */
+	if (ncm_string_defs[0].id == 0) {
+
+		/* control interface label */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		ncm_string_defs[STRING_CTRL_IDX].id = status;
+		ncm_control_intf.iInterface = status;
+
+		/* data interface label */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		ncm_string_defs[STRING_DATA_IDX].id = status;
+		ncm_data_nop_intf.iInterface = status;
+		ncm_data_intf.iInterface = status;
+
+		/* MAC address */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		ncm_string_defs[STRING_MAC_IDX].id = status;
+		ecm_desc.iMACAddress = status;
+
+		/* IAD */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		ncm_string_defs[STRING_IAD_IDX].id = status;
+		ncm_iad_desc.iFunction = status;
+	}
+
+	/* allocate and initialize one new instance */
+	ncm = kzalloc(sizeof *ncm, GFP_KERNEL);
+	if (!ncm)
+		return -ENOMEM;
+
+	/* export host's Ethernet address in CDC format */
+	snprintf(ncm->ethaddr, sizeof ncm->ethaddr,
+		"%02X%02X%02X%02X%02X%02X",
+		ethaddr[0], ethaddr[1], ethaddr[2],
+		ethaddr[3], ethaddr[4], ethaddr[5]);
+	ncm_string_defs[1].s = ncm->ethaddr;
+
+	spin_lock_init(&ncm->lock);
+	ncm_reset_values(ncm);
+	ncm->port.is_fixed = true;
+
+	ncm->port.func.name = "cdc_network";
+	ncm->port.func.strings = ncm_strings;
+	/* descriptors are per-instance copies */
+	ncm->port.func.bind = ncm_bind;
+	ncm->port.func.unbind = ncm_unbind;
+	ncm->port.func.set_alt = ncm_set_alt;
+	ncm->port.func.get_alt = ncm_get_alt;
+	ncm->port.func.setup = ncm_setup;
+	ncm->port.func.disable = ncm_disable;
+
+	ncm->port.wrap = ncm_wrap_ntb;
+	ncm->port.unwrap = ncm_unwrap_ntb;
+
+	status = usb_add_function(c, &ncm->port.func);
+	if (status) {
+		ncm_string_defs[1].s = NULL;
+		kfree(ncm);
+	}
+	return status;
+}

drivers/usb/gadget/u_ether.h

@@ -107,6 +107,7 @@ static inline bool can_support_ecm(struct usb_gadget *gadget)
 /* each configuration may bind one instance of an ethernet link */
 int geth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
 int ecm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
+int ncm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
 int eem_bind_config(struct usb_configuration *c);
 
 #ifdef USB_ETH_RNDIS