drivers/net/usb/cdc_ether.c - kernel/msm-4.9 - Gitiles

 /*
  * CDC Ethernet based networking peripherals
  * Copyright (C) 2003-2005 by David Brownell
  * Copyright (C) 2006 by Ole Andre Vadla Ravnas (ActiveSync)
  *
  * 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
  */

 // #define	DEBUG			// error path messages, extra info
 // #define	VERBOSE			// more; success messages

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/workqueue.h>
 #include <linux/mii.h>
 #include <linux/usb.h>
 #include <linux/usb/cdc.h>
 #include <linux/usb/usbnet.h>


 #if defined(CONFIG_USB_NET_RNDIS_HOST) || defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)

 static int is_rndis(struct usb_interface_descriptor *desc)
 {
 	return desc->bInterfaceClass == USB_CLASS_COMM
 		&& desc->bInterfaceSubClass == 2
 		&& desc->bInterfaceProtocol == 0xff;
 }

 static int is_activesync(struct usb_interface_descriptor *desc)
 {
 	return desc->bInterfaceClass == USB_CLASS_MISC
 		&& desc->bInterfaceSubClass == 1
 		&& desc->bInterfaceProtocol == 1;
 }

 static int is_wireless_rndis(struct usb_interface_descriptor *desc)
 {
 	return desc->bInterfaceClass == USB_CLASS_WIRELESS_CONTROLLER
 		&& desc->bInterfaceSubClass == 1
 		&& desc->bInterfaceProtocol == 3;
 }

 #else

 #define is_rndis(desc)		0
 #define is_activesync(desc)	0
 #define is_wireless_rndis(desc)	0

 #endif

 /*
  * probes control interface, claims data interface, collects the bulk
  * endpoints, activates data interface (if needed), maybe sets MTU.
  * all pure cdc, except for certain firmware workarounds, and knowing
  * that rndis uses one different rule.
  */
 int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	u8				*buf = intf->cur_altsetting->extra;
 	int				len = intf->cur_altsetting->extralen;
 	struct usb_interface_descriptor	*d;
 	struct cdc_state		*info = (void *) &dev->data;
 	int				status;
 	int				rndis;
 	struct usb_driver		*driver = driver_of(intf);

 	if (sizeof dev->data < sizeof *info)
 		return -EDOM;

 	/* expect strict spec conformance for the descriptors, but
 	 * cope with firmware which stores them in the wrong place
 	 */
 	if (len == 0 && dev->udev->actconfig->extralen) {
 		/* Motorola SB4100 (and others: Brad Hards says it's
 		 * from a Broadcom design) put CDC descriptors here
 		 */
 		buf = dev->udev->actconfig->extra;
 		len = dev->udev->actconfig->extralen;
 		if (len)
 			dev_dbg(&intf->dev,
 				"CDC descriptors on config\n");
 	}

 	/* Maybe CDC descriptors are after the endpoint?  This bug has
 	 * been seen on some 2Wire Inc RNDIS-ish products.
 	 */
 	if (len == 0) {
 		struct usb_host_endpoint	*hep;

 		hep = intf->cur_altsetting->endpoint;
 		if (hep) {
 			buf = hep->extra;
 			len = hep->extralen;
 		}
 		if (len)
 			dev_dbg(&intf->dev,
 				"CDC descriptors on endpoint\n");
 	}

 	/* this assumes that if there's a non-RNDIS vendor variant
 	 * of cdc-acm, it'll fail RNDIS requests cleanly.
 	 */
 	rndis = is_rndis(&intf->cur_altsetting->desc)
 		|| is_activesync(&intf->cur_altsetting->desc)
 		|| is_wireless_rndis(&intf->cur_altsetting->desc);

 	memset(info, 0, sizeof *info);
 	info->control = intf;
 	while (len > 3) {
 		if (buf [1] != USB_DT_CS_INTERFACE)
 			goto next_desc;

 		/* use bDescriptorSubType to identify the CDC descriptors.
 		 * We expect devices with CDC header and union descriptors.
 		 * For CDC Ethernet we need the ethernet descriptor.
 		 * For RNDIS, ignore two (pointless) CDC modem descriptors
 		 * in favor of a complicated OID-based RPC scheme doing what
 		 * CDC Ethernet achieves with a simple descriptor.
 		 */
 		switch (buf [2]) {
 		case USB_CDC_HEADER_TYPE:
 			if (info->header) {
 				dev_dbg(&intf->dev, "extra CDC header\n");
 				goto bad_desc;
 			}
 			info->header = (void *) buf;
 			if (info->header->bLength != sizeof *info->header) {
 				dev_dbg(&intf->dev, "CDC header len %u\n",
 					info->header->bLength);
 				goto bad_desc;
 			}
 			break;
 		case USB_CDC_ACM_TYPE:
 			/* paranoia:  disambiguate a "real" vendor-specific
 			 * modem interface from an RNDIS non-modem.
 			 */
 			if (rndis) {
 				struct usb_cdc_acm_descriptor *acm;

 				acm = (void *) buf;
 				if (acm->bmCapabilities) {
 					dev_dbg(&intf->dev,
 						"ACM capabilities %02x, "
 						"not really RNDIS?\n",
 						acm->bmCapabilities);
 					goto bad_desc;
 				}
 			}
 			break;
 		case USB_CDC_UNION_TYPE:
 			if (info->u) {
 				dev_dbg(&intf->dev, "extra CDC union\n");
 				goto bad_desc;
 			}
 			info->u = (void *) buf;
 			if (info->u->bLength != sizeof *info->u) {
 				dev_dbg(&intf->dev, "CDC union len %u\n",
 					info->u->bLength);
 				goto bad_desc;
 			}

 			/* we need a master/control interface (what we're
 			 * probed with) and a slave/data interface; union
 			 * descriptors sort this all out.
 			 */
 			info->control = usb_ifnum_to_if(dev->udev,
 						info->u->bMasterInterface0);
 			info->data = usb_ifnum_to_if(dev->udev,
 						info->u->bSlaveInterface0);
 			if (!info->control || !info->data) {
 				dev_dbg(&intf->dev,
 					"master #%u/%p slave #%u/%p\n",
 					info->u->bMasterInterface0,
 					info->control,
 					info->u->bSlaveInterface0,
 					info->data);
 				goto bad_desc;
 			}
 			if (info->control != intf) {
 				dev_dbg(&intf->dev, "bogus CDC Union\n");
 				/* Ambit USB Cable Modem (and maybe others)
 				 * interchanges master and slave interface.
 				 */
 				if (info->data == intf) {
 					info->data = info->control;
 					info->control = intf;
 				} else
 					goto bad_desc;
 			}

 			/* a data interface altsetting does the real i/o */
 			d = &info->data->cur_altsetting->desc;
 			if (d->bInterfaceClass != USB_CLASS_CDC_DATA) {
 				dev_dbg(&intf->dev, "slave class %u\n",
 					d->bInterfaceClass);
 				goto bad_desc;
 			}
 			break;
 		case USB_CDC_ETHERNET_TYPE:
 			if (info->ether) {
 				dev_dbg(&intf->dev, "extra CDC ether\n");
 				goto bad_desc;
 			}
 			info->ether = (void *) buf;
 			if (info->ether->bLength != sizeof *info->ether) {
 				dev_dbg(&intf->dev, "CDC ether len %u\n",
 					info->ether->bLength);
 				goto bad_desc;
 			}
 			dev->hard_mtu = le16_to_cpu(
 						info->ether->wMaxSegmentSize);
 			/* because of Zaurus, we may be ignoring the host
 			 * side link address we were given.
 			 */
 			break;
 		}
 next_desc:
 		len -= buf [0];	/* bLength */
 		buf += buf [0];
 	}

 	/* Microsoft ActiveSync based and some regular RNDIS devices lack the
 	 * CDC descriptors, so we'll hard-wire the interfaces and not check
 	 * for descriptors.
 	 */
 	if (rndis && !info->u) {
 		info->control = usb_ifnum_to_if(dev->udev, 0);
 		info->data = usb_ifnum_to_if(dev->udev, 1);
 		if (!info->control || !info->data) {
 			dev_dbg(&intf->dev,
 				"rndis: master #0/%p slave #1/%p\n",
 				info->control,
 				info->data);
 			goto bad_desc;
 		}

 	} else if (!info->header || !info->u || (!rndis && !info->ether)) {
 		dev_dbg(&intf->dev, "missing cdc %s%s%sdescriptor\n",
 			info->header ? "" : "header ",
 			info->u ? "" : "union ",
 			info->ether ? "" : "ether ");
 		goto bad_desc;
 	}

 	/* claim data interface and set it up ... with side effects.
 	 * network traffic can't flow until an altsetting is enabled.
 	 */
 	status = usb_driver_claim_interface(driver, info->data, dev);
 	if (status < 0)
 		return status;
 	status = usbnet_get_endpoints(dev, info->data);
 	if (status < 0) {
 		/* ensure immediate exit from usbnet_disconnect */
 		usb_set_intfdata(info->data, NULL);
 		usb_driver_release_interface(driver, info->data);
 		return status;
 	}

 	/* status endpoint: optional for CDC Ethernet, not RNDIS (or ACM) */
 	dev->status = NULL;
 	if (info->control->cur_altsetting->desc.bNumEndpoints == 1) {
 		struct usb_endpoint_descriptor	*desc;

 		dev->status = &info->control->cur_altsetting->endpoint [0];
 		desc = &dev->status->desc;
 		if (!usb_endpoint_is_int_in(desc)
 				|| (le16_to_cpu(desc->wMaxPacketSize)
 					< sizeof(struct usb_cdc_notification))
 				|| !desc->bInterval) {
 			dev_dbg(&intf->dev, "bad notification endpoint\n");
 			dev->status = NULL;
 		}
 	}
 	if (rndis && !dev->status) {
 		dev_dbg(&intf->dev, "missing RNDIS status endpoint\n");
 		usb_set_intfdata(info->data, NULL);
 		usb_driver_release_interface(driver, info->data);
 		return -ENODEV;
 	}
 	return 0;

 bad_desc:
 	dev_info(&dev->udev->dev, "bad CDC descriptors\n");
 	return -ENODEV;
 }
 EXPORT_SYMBOL_GPL(usbnet_generic_cdc_bind);

 void usbnet_cdc_unbind(struct usbnet *dev, struct usb_interface *intf)
 {
 	struct cdc_state		*info = (void *) &dev->data;
 	struct usb_driver		*driver = driver_of(intf);

 	/* disconnect master --> disconnect slave */
 	if (intf == info->control && info->data) {
 		/* ensure immediate exit from usbnet_disconnect */
 		usb_set_intfdata(info->data, NULL);
 		usb_driver_release_interface(driver, info->data);
 		info->data = NULL;
 	}

 	/* and vice versa (just in case) */
 	else if (intf == info->data && info->control) {
 		/* ensure immediate exit from usbnet_disconnect */
 		usb_set_intfdata(info->control, NULL);
 		usb_driver_release_interface(driver, info->control);
 		info->control = NULL;
 	}
 }
 EXPORT_SYMBOL_GPL(usbnet_cdc_unbind);

 /*-------------------------------------------------------------------------
  *
  * Communications Device Class, Ethernet Control model
  *
  * Takes two interfaces.  The DATA interface is inactive till an altsetting
  * is selected.  Configuration data includes class descriptors.  There's
  * an optional status endpoint on the control interface.
  *
  * This should interop with whatever the 2.4 "CDCEther.c" driver
  * (by Brad Hards) talked with, with more functionality.
  *
  *-------------------------------------------------------------------------*/

 static void dumpspeed(struct usbnet *dev, __le32 *speeds)
 {
 	if (netif_msg_timer(dev))
 		devinfo(dev, "link speeds: %u kbps up, %u kbps down",
 			__le32_to_cpu(speeds[0]) / 1000,
 		__le32_to_cpu(speeds[1]) / 1000);
 }

 static void cdc_status(struct usbnet *dev, struct urb *urb)
 {
 	struct usb_cdc_notification	*event;

 	if (urb->actual_length < sizeof *event)
 		return;

 	/* SPEED_CHANGE can get split into two 8-byte packets */
 	if (test_and_clear_bit(EVENT_STS_SPLIT, &dev->flags)) {
 		dumpspeed(dev, (__le32 *) urb->transfer_buffer);
 		return;
 	}

 	event = urb->transfer_buffer;
 	switch (event->bNotificationType) {
 	case USB_CDC_NOTIFY_NETWORK_CONNECTION:
 		if (netif_msg_timer(dev))
 			devdbg(dev, "CDC: carrier %s",
 					event->wValue ? "on" : "off");
 		if (event->wValue)
 			netif_carrier_on(dev->net);
 		else
 			netif_carrier_off(dev->net);
 		break;
 	case USB_CDC_NOTIFY_SPEED_CHANGE:	/* tx/rx rates */
 		if (netif_msg_timer(dev))
 			devdbg(dev, "CDC: speed change (len %d)",
 					urb->actual_length);
 		if (urb->actual_length != (sizeof *event + 8))
 			set_bit(EVENT_STS_SPLIT, &dev->flags);
 		else
 			dumpspeed(dev, (__le32 *) &event[1]);
 		break;
 	/* USB_CDC_NOTIFY_RESPONSE_AVAILABLE can happen too (e.g. RNDIS),
 	 * but there are no standard formats for the response data.
 	 */
 	default:
 		deverr(dev, "CDC: unexpected notification %02x!",
 				 event->bNotificationType);
 		break;
 	}
 }

 static int cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	int				status;
 	struct cdc_state		*info = (void *) &dev->data;

 	status = usbnet_generic_cdc_bind(dev, intf);
 	if (status < 0)
 		return status;

 	status = usbnet_get_ethernet_addr(dev, info->ether->iMACAddress);
 	if (status < 0) {
 		usb_set_intfdata(info->data, NULL);
 		usb_driver_release_interface(driver_of(intf), info->data);
 		return status;
 	}

 	/* FIXME cdc-ether has some multicast code too, though it complains
 	 * in routine cases.  info->ether describes the multicast support.
 	 * Implement that here, manipulating the cdc filter as needed.
 	 */
 	return 0;
 }

 static const struct driver_info	cdc_info = {
 	.description =	"CDC Ethernet Device",
 	.flags =	FLAG_ETHER,
 	// .check_connect = cdc_check_connect,
 	.bind =		cdc_bind,
 	.unbind =	usbnet_cdc_unbind,
 	.status =	cdc_status,
 };

 /*-------------------------------------------------------------------------*/


 static const struct usb_device_id	products [] = {
 /*
  * BLACKLIST !!
  *
  * First blacklist any products that are egregiously nonconformant
  * with the CDC Ethernet specs.  Minor braindamage we cope with; when
  * they're not even trying, needing a separate driver is only the first
  * of the differences to show up.
  */

 #define	ZAURUS_MASTER_INTERFACE \
 	.bInterfaceClass	= USB_CLASS_COMM, \
 	.bInterfaceSubClass	= USB_CDC_SUBCLASS_ETHERNET, \
 	.bInterfaceProtocol	= USB_CDC_PROTO_NONE

 /* SA-1100 based Sharp Zaurus ("collie"), or compatible;
  * wire-incompatible with true CDC Ethernet implementations.
  * (And, it seems, needlessly so...)
  */
 {
 	.match_flags	=   USB_DEVICE_ID_MATCH_INT_INFO
 			  | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor		= 0x04DD,
 	.idProduct		= 0x8004,
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 },

 /* PXA-25x based Sharp Zaurii.  Note that it seems some of these
  * (later models especially) may have shipped only with firmware
  * advertising false "CDC MDLM" compatibility ... but we're not
  * clear which models did that, so for now let's assume the worst.
  */
 {
 	.match_flags	=   USB_DEVICE_ID_MATCH_INT_INFO
 			  | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor		= 0x04DD,
 	.idProduct		= 0x8005,	/* A-300 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 }, {
 	.match_flags	=   USB_DEVICE_ID_MATCH_INT_INFO
 			  | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor		= 0x04DD,
 	.idProduct		= 0x8006,	/* B-500/SL-5600 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 }, {
 	.match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 	          | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor		= 0x04DD,
 	.idProduct		= 0x8007,	/* C-700 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 }, {
 	.match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 		 | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor               = 0x04DD,
 	.idProduct              = 0x9031,	/* C-750 C-760 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 }, {
 	.match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 		 | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor               = 0x04DD,
 	.idProduct              = 0x9032,	/* SL-6000 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 }, {
 	.match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 		 | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor               = 0x04DD,
 	/* reported with some C860 units */
 	.idProduct              = 0x9050,	/* C-860 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 },

 /* Olympus has some models with a Zaurus-compatible option.
  * R-1000 uses a FreeScale i.MXL cpu (ARMv4T)
  */
 {
 	.match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 		 | USB_DEVICE_ID_MATCH_DEVICE,
 	.idVendor               = 0x07B4,
 	.idProduct              = 0x0F02,	/* R-1000 */
 	ZAURUS_MASTER_INTERFACE,
 	.driver_info		= 0,
 },

 /*
  * WHITELIST!!!
  *
  * CDC Ether uses two interfaces, not necessarily consecutive.
  * We match the main interface, ignoring the optional device
  * class so we could handle devices that aren't exclusively
  * CDC ether.
  *
  * NOTE:  this match must come AFTER entries blacklisting devices
  * because of bugs/quirks in a given product (like Zaurus, above).
  */
 {
 	USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ETHERNET,
 			USB_CDC_PROTO_NONE),
 	.driver_info = (unsigned long) &cdc_info,
 }, {
 	/* Ericsson F3507g */
 	USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1900, USB_CLASS_COMM,
 			USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 	.driver_info = (unsigned long) &cdc_info,
 },
 	{ },		// END
 };
 MODULE_DEVICE_TABLE(usb, products);

 static struct usb_driver cdc_driver = {
 	.name =		"cdc_ether",
 	.id_table =	products,
 	.probe =	usbnet_probe,
 	.disconnect =	usbnet_disconnect,
 	.suspend =	usbnet_suspend,
 	.resume =	usbnet_resume,
 };


 static int __init cdc_init(void)
 {
 	BUILD_BUG_ON((sizeof(((struct usbnet *)0)->data)
 			< sizeof(struct cdc_state)));

  	return usb_register(&cdc_driver);
 }
 module_init(cdc_init);

 static void __exit cdc_exit(void)
 {
  	usb_deregister(&cdc_driver);
 }
 module_exit(cdc_exit);

 MODULE_AUTHOR("David Brownell");
 MODULE_DESCRIPTION("USB CDC Ethernet devices");
 MODULE_LICENSE("GPL");
	/*
	* CDC Ethernet based networking peripherals
	* Copyright (C) 2003-2005 by David Brownell
	* Copyright (C) 2006 by Ole Andre Vadla Ravnas (ActiveSync)
	*
	* 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
	*/

	// #define DEBUG // error path messages, extra info
	// #define VERBOSE // more; success messages

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/netdevice.h>
	#include <linux/etherdevice.h>
	#include <linux/ethtool.h>
	#include <linux/workqueue.h>
	#include <linux/mii.h>
	#include <linux/usb.h>
	#include <linux/usb/cdc.h>
	#include <linux/usb/usbnet.h>


	#if defined(CONFIG_USB_NET_RNDIS_HOST) \|\| defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)

	static int is_rndis(struct usb_interface_descriptor *desc)
	{
	return desc->bInterfaceClass == USB_CLASS_COMM
	&& desc->bInterfaceSubClass == 2
	&& desc->bInterfaceProtocol == 0xff;
	}

	static int is_activesync(struct usb_interface_descriptor *desc)
	{
	return desc->bInterfaceClass == USB_CLASS_MISC
	&& desc->bInterfaceSubClass == 1
	&& desc->bInterfaceProtocol == 1;
	}

	static int is_wireless_rndis(struct usb_interface_descriptor *desc)
	{
	return desc->bInterfaceClass == USB_CLASS_WIRELESS_CONTROLLER
	&& desc->bInterfaceSubClass == 1
	&& desc->bInterfaceProtocol == 3;
	}

	#else

	#define is_rndis(desc) 0
	#define is_activesync(desc) 0
	#define is_wireless_rndis(desc) 0

	#endif

	/*
	* probes control interface, claims data interface, collects the bulk
	* endpoints, activates data interface (if needed), maybe sets MTU.
	* all pure cdc, except for certain firmware workarounds, and knowing
	* that rndis uses one different rule.
	*/
	int usbnet_generic_cdc_bind(struct usbnet dev, struct usb_interface intf)
	{
	u8 *buf = intf->cur_altsetting->extra;
	int len = intf->cur_altsetting->extralen;
	struct usb_interface_descriptor *d;
	struct cdc_state info = (void ) &dev->data;
	int status;
	int rndis;
	struct usb_driver *driver = driver_of(intf);

	if (sizeof dev->data < sizeof *info)
	return -EDOM;

	/* expect strict spec conformance for the descriptors, but
	* cope with firmware which stores them in the wrong place
	*/
	if (len == 0 && dev->udev->actconfig->extralen) {
	/* Motorola SB4100 (and others: Brad Hards says it's
	* from a Broadcom design) put CDC descriptors here
	*/
	buf = dev->udev->actconfig->extra;
	len = dev->udev->actconfig->extralen;
	if (len)
	dev_dbg(&intf->dev,
	"CDC descriptors on config\n");
	}

	/* Maybe CDC descriptors are after the endpoint? This bug has
	* been seen on some 2Wire Inc RNDIS-ish products.
	*/
	if (len == 0) {
	struct usb_host_endpoint *hep;

	hep = intf->cur_altsetting->endpoint;
	if (hep) {
	buf = hep->extra;
	len = hep->extralen;
	}
	if (len)
	dev_dbg(&intf->dev,
	"CDC descriptors on endpoint\n");
	}

	/* this assumes that if there's a non-RNDIS vendor variant
	* of cdc-acm, it'll fail RNDIS requests cleanly.
	*/
	rndis = is_rndis(&intf->cur_altsetting->desc)
	\|\| is_activesync(&intf->cur_altsetting->desc)
	\|\| is_wireless_rndis(&intf->cur_altsetting->desc);

	memset(info, 0, sizeof *info);
	info->control = intf;
	while (len > 3) {
	if (buf [1] != USB_DT_CS_INTERFACE)
	goto next_desc;

	/* use bDescriptorSubType to identify the CDC descriptors.
	* We expect devices with CDC header and union descriptors.
	* For CDC Ethernet we need the ethernet descriptor.
	* For RNDIS, ignore two (pointless) CDC modem descriptors
	* in favor of a complicated OID-based RPC scheme doing what
	* CDC Ethernet achieves with a simple descriptor.
	*/
	switch (buf [2]) {
	case USB_CDC_HEADER_TYPE:
	if (info->header) {
	dev_dbg(&intf->dev, "extra CDC header\n");
	goto bad_desc;
	}
	info->header = (void *) buf;
	if (info->header->bLength != sizeof *info->header) {
	dev_dbg(&intf->dev, "CDC header len %u\n",
	info->header->bLength);
	goto bad_desc;
	}
	break;
	case USB_CDC_ACM_TYPE:
	/* paranoia: disambiguate a "real" vendor-specific
	* modem interface from an RNDIS non-modem.
	*/
	if (rndis) {
	struct usb_cdc_acm_descriptor *acm;

	acm = (void *) buf;
	if (acm->bmCapabilities) {
	dev_dbg(&intf->dev,
	"ACM capabilities %02x, "
	"not really RNDIS?\n",
	acm->bmCapabilities);
	goto bad_desc;
	}
	}
	break;
	case USB_CDC_UNION_TYPE:
	if (info->u) {
	dev_dbg(&intf->dev, "extra CDC union\n");
	goto bad_desc;
	}
	info->u = (void *) buf;
	if (info->u->bLength != sizeof *info->u) {
	dev_dbg(&intf->dev, "CDC union len %u\n",
	info->u->bLength);
	goto bad_desc;
	}

	/* we need a master/control interface (what we're
	* probed with) and a slave/data interface; union
	* descriptors sort this all out.
	*/
	info->control = usb_ifnum_to_if(dev->udev,
	info->u->bMasterInterface0);
	info->data = usb_ifnum_to_if(dev->udev,
	info->u->bSlaveInterface0);
	if (!info->control \|\| !info->data) {
	dev_dbg(&intf->dev,
	"master #%u/%p slave #%u/%p\n",
	info->u->bMasterInterface0,
	info->control,
	info->u->bSlaveInterface0,
	info->data);
	goto bad_desc;
	}
	if (info->control != intf) {
	dev_dbg(&intf->dev, "bogus CDC Union\n");
	/* Ambit USB Cable Modem (and maybe others)
	* interchanges master and slave interface.
	*/
	if (info->data == intf) {
	info->data = info->control;
	info->control = intf;
	} else
	goto bad_desc;
	}

	/* a data interface altsetting does the real i/o */
	d = &info->data->cur_altsetting->desc;
	if (d->bInterfaceClass != USB_CLASS_CDC_DATA) {
	dev_dbg(&intf->dev, "slave class %u\n",
	d->bInterfaceClass);
	goto bad_desc;
	}
	break;
	case USB_CDC_ETHERNET_TYPE:
	if (info->ether) {
	dev_dbg(&intf->dev, "extra CDC ether\n");
	goto bad_desc;
	}
	info->ether = (void *) buf;
	if (info->ether->bLength != sizeof *info->ether) {
	dev_dbg(&intf->dev, "CDC ether len %u\n",
	info->ether->bLength);
	goto bad_desc;
	}
	dev->hard_mtu = le16_to_cpu(
	info->ether->wMaxSegmentSize);
	/* because of Zaurus, we may be ignoring the host
	* side link address we were given.
	*/
	break;
	}
	next_desc:
	len -= buf [0]; /* bLength */
	buf += buf [0];
	}

	/* Microsoft ActiveSync based and some regular RNDIS devices lack the
	* CDC descriptors, so we'll hard-wire the interfaces and not check
	* for descriptors.
	*/
	if (rndis && !info->u) {
	info->control = usb_ifnum_to_if(dev->udev, 0);
	info->data = usb_ifnum_to_if(dev->udev, 1);
	if (!info->control \|\| !info->data) {
	dev_dbg(&intf->dev,
	"rndis: master #0/%p slave #1/%p\n",
	info->control,
	info->data);
	goto bad_desc;
	}

	} else if (!info->header \|\| !info->u \|\| (!rndis && !info->ether)) {
	dev_dbg(&intf->dev, "missing cdc %s%s%sdescriptor\n",
	info->header ? "" : "header ",
	info->u ? "" : "union ",
	info->ether ? "" : "ether ");
	goto bad_desc;
	}

	/* claim data interface and set it up ... with side effects.
	* network traffic can't flow until an altsetting is enabled.
	*/
	status = usb_driver_claim_interface(driver, info->data, dev);
	if (status < 0)
	return status;
	status = usbnet_get_endpoints(dev, info->data);
	if (status < 0) {
	/* ensure immediate exit from usbnet_disconnect */
	usb_set_intfdata(info->data, NULL);
	usb_driver_release_interface(driver, info->data);
	return status;
	}

	/* status endpoint: optional for CDC Ethernet, not RNDIS (or ACM) */
	dev->status = NULL;
	if (info->control->cur_altsetting->desc.bNumEndpoints == 1) {
	struct usb_endpoint_descriptor *desc;

	dev->status = &info->control->cur_altsetting->endpoint [0];
	desc = &dev->status->desc;
	if (!usb_endpoint_is_int_in(desc)
	\|\| (le16_to_cpu(desc->wMaxPacketSize)
	< sizeof(struct usb_cdc_notification))
	\|\| !desc->bInterval) {
	dev_dbg(&intf->dev, "bad notification endpoint\n");
	dev->status = NULL;
	}
	}
	if (rndis && !dev->status) {
	dev_dbg(&intf->dev, "missing RNDIS status endpoint\n");
	usb_set_intfdata(info->data, NULL);
	usb_driver_release_interface(driver, info->data);
	return -ENODEV;
	}
	return 0;

	bad_desc:
	dev_info(&dev->udev->dev, "bad CDC descriptors\n");
	return -ENODEV;
	}
	EXPORT_SYMBOL_GPL(usbnet_generic_cdc_bind);

	void usbnet_cdc_unbind(struct usbnet dev, struct usb_interface intf)
	{
	struct cdc_state info = (void ) &dev->data;
	struct usb_driver *driver = driver_of(intf);

	/* disconnect master --> disconnect slave */
	if (intf == info->control && info->data) {
	/* ensure immediate exit from usbnet_disconnect */
	usb_set_intfdata(info->data, NULL);
	usb_driver_release_interface(driver, info->data);
	info->data = NULL;
	}

	/* and vice versa (just in case) */
	else if (intf == info->data && info->control) {
	/* ensure immediate exit from usbnet_disconnect */
	usb_set_intfdata(info->control, NULL);
	usb_driver_release_interface(driver, info->control);
	info->control = NULL;
	}
	}
	EXPORT_SYMBOL_GPL(usbnet_cdc_unbind);

	/*-------------------------------------------------------------------------
	*
	* Communications Device Class, Ethernet Control model
	*
	* Takes two interfaces. The DATA interface is inactive till an altsetting
	* is selected. Configuration data includes class descriptors. There's
	* an optional status endpoint on the control interface.
	*
	* This should interop with whatever the 2.4 "CDCEther.c" driver
	* (by Brad Hards) talked with, with more functionality.
	*
	-------------------------------------------------------------------------/

	static void dumpspeed(struct usbnet dev, __le32 speeds)
	{
	if (netif_msg_timer(dev))
	devinfo(dev, "link speeds: %u kbps up, %u kbps down",
	__le32_to_cpu(speeds[0]) / 1000,
	__le32_to_cpu(speeds[1]) / 1000);
	}

	static void cdc_status(struct usbnet dev, struct urb urb)
	{
	struct usb_cdc_notification *event;

	if (urb->actual_length < sizeof *event)
	return;

	/* SPEED_CHANGE can get split into two 8-byte packets */
	if (test_and_clear_bit(EVENT_STS_SPLIT, &dev->flags)) {
	dumpspeed(dev, (__le32 *) urb->transfer_buffer);
	return;
	}

	event = urb->transfer_buffer;
	switch (event->bNotificationType) {
	case USB_CDC_NOTIFY_NETWORK_CONNECTION:
	if (netif_msg_timer(dev))
	devdbg(dev, "CDC: carrier %s",
	event->wValue ? "on" : "off");
	if (event->wValue)
	netif_carrier_on(dev->net);
	else
	netif_carrier_off(dev->net);
	break;
	case USB_CDC_NOTIFY_SPEED_CHANGE: /* tx/rx rates */
	if (netif_msg_timer(dev))
	devdbg(dev, "CDC: speed change (len %d)",
	urb->actual_length);
	if (urb->actual_length != (sizeof *event + 8))
	set_bit(EVENT_STS_SPLIT, &dev->flags);
	else
	dumpspeed(dev, (__le32 *) &event[1]);
	break;
	/* USB_CDC_NOTIFY_RESPONSE_AVAILABLE can happen too (e.g. RNDIS),
	* but there are no standard formats for the response data.
	*/
	default:
	deverr(dev, "CDC: unexpected notification %02x!",
	event->bNotificationType);
	break;
	}
	}

	static int cdc_bind(struct usbnet dev, struct usb_interface intf)
	{
	int status;
	struct cdc_state info = (void ) &dev->data;

	status = usbnet_generic_cdc_bind(dev, intf);
	if (status < 0)
	return status;

	status = usbnet_get_ethernet_addr(dev, info->ether->iMACAddress);
	if (status < 0) {
	usb_set_intfdata(info->data, NULL);
	usb_driver_release_interface(driver_of(intf), info->data);
	return status;
	}

	/* FIXME cdc-ether has some multicast code too, though it complains
	* in routine cases. info->ether describes the multicast support.
	* Implement that here, manipulating the cdc filter as needed.
	*/
	return 0;
	}

	static const struct driver_info cdc_info = {
	.description = "CDC Ethernet Device",
	.flags = FLAG_ETHER,
	// .check_connect = cdc_check_connect,
	.bind = cdc_bind,
	.unbind = usbnet_cdc_unbind,
	.status = cdc_status,
	};

	/-------------------------------------------------------------------------/


	static const struct usb_device_id products [] = {
	/*
	* BLACKLIST !!
	*
	* First blacklist any products that are egregiously nonconformant
	* with the CDC Ethernet specs. Minor braindamage we cope with; when
	* they're not even trying, needing a separate driver is only the first
	* of the differences to show up.
	*/

	#define ZAURUS_MASTER_INTERFACE \
	.bInterfaceClass = USB_CLASS_COMM, \
	.bInterfaceSubClass = USB_CDC_SUBCLASS_ETHERNET, \
	.bInterfaceProtocol = USB_CDC_PROTO_NONE

	/* SA-1100 based Sharp Zaurus ("collie"), or compatible;
	* wire-incompatible with true CDC Ethernet implementations.
	* (And, it seems, needlessly so...)
	*/
	{
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x8004,
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	},

	/* PXA-25x based Sharp Zaurii. Note that it seems some of these
	* (later models especially) may have shipped only with firmware
	* advertising false "CDC MDLM" compatibility ... but we're not
	* clear which models did that, so for now let's assume the worst.
	*/
	{
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x8005, /* A-300 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	}, {
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x8006, /* B-500/SL-5600 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	}, {
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x8007, /* C-700 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	}, {
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x9031, /* C-750 C-760 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	}, {
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	.idProduct = 0x9032, /* SL-6000 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	}, {
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x04DD,
	/* reported with some C860 units */
	.idProduct = 0x9050, /* C-860 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	},

	/* Olympus has some models with a Zaurus-compatible option.
	* R-1000 uses a FreeScale i.MXL cpu (ARMv4T)
	*/
	{
	.match_flags = USB_DEVICE_ID_MATCH_INT_INFO
	\| USB_DEVICE_ID_MATCH_DEVICE,
	.idVendor = 0x07B4,
	.idProduct = 0x0F02, /* R-1000 */
	ZAURUS_MASTER_INTERFACE,
	.driver_info = 0,
	},

	/*
	* WHITELIST!!!
	*
	* CDC Ether uses two interfaces, not necessarily consecutive.
	* We match the main interface, ignoring the optional device
	* class so we could handle devices that aren't exclusively
	* CDC ether.
	*
	* NOTE: this match must come AFTER entries blacklisting devices
	* because of bugs/quirks in a given product (like Zaurus, above).
	*/
	{
	USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ETHERNET,
	USB_CDC_PROTO_NONE),
	.driver_info = (unsigned long) &cdc_info,
	}, {
	/* Ericsson F3507g */
	USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1900, USB_CLASS_COMM,
	USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
	.driver_info = (unsigned long) &cdc_info,
	},
	{ }, // END
	};
	MODULE_DEVICE_TABLE(usb, products);

	static struct usb_driver cdc_driver = {
	.name = "cdc_ether",
	.id_table = products,
	.probe = usbnet_probe,
	.disconnect = usbnet_disconnect,
	.suspend = usbnet_suspend,
	.resume = usbnet_resume,
	};


	static int __init cdc_init(void)
	{
	BUILD_BUG_ON((sizeof(((struct usbnet *)0)->data)
	< sizeof(struct cdc_state)));

	return usb_register(&cdc_driver);
	}
	module_init(cdc_init);

	static void __exit cdc_exit(void)
	{
	usb_deregister(&cdc_driver);
	}
	module_exit(cdc_exit);

	MODULE_AUTHOR("David Brownell");
	MODULE_DESCRIPTION("USB CDC Ethernet devices");
	MODULE_LICENSE("GPL");