Move USB network drivers to drivers/net/usb.

It is preferable to group drivers by usage (net, scsi, ATA, ...) than
by bus.  When reviewing drivers, the [PCI|USB|PCMCIA|...] maintainer
is probably less qualified on networking issues than a networking
maintainer.  Also, from a practical standpoint, chips often
appear on multiple buses, which is why we do not put drivers into
drivers/pci/net.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 727 insertions, 0 deletions

diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c
new file mode 100644
index 000000000000..980e4aaa97aa
--- /dev/null
+++ b/drivers/net/usb/rndis_host.c
@@ -0,0 +1,727 @@
+/*
+ * Host Side support for RNDIS Networking Links
+ * Copyright (C) 2005 by David Brownell
+ *
+ * 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 "usbnet.h"
+
+
+/*
+ * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
+ * course ACM was intended for modems, not Ethernet links!  USB's standard
+ * for Ethernet links is "CDC Ethernet", which is significantly simpler.
+ *
+ * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
+ * include:
+ *    - Power management in particular relies on information that's scattered
+ *	through other documentation, and which is incomplete or incorrect even
+ *	there.
+ *    - There are various undocumented protocol requirements, such as the
+ *	need to send unused garbage in control-OUT messages.
+ *    - In some cases, MS-Windows will emit undocumented requests; this
+ *	matters more to peripheral implementations than host ones.
+ *
+ * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
+ *
+ * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
+ * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
+ * currently rare) "Ethernet Emulation Model" (EEM).
+ */
+
+/*
+ * CONTROL uses CDC "encapsulated commands" with funky notifications.
+ *  - control-out:  SEND_ENCAPSULATED
+ *  - interrupt-in:  RESPONSE_AVAILABLE
+ *  - control-in:  GET_ENCAPSULATED
+ *
+ * We'll try to ignore the RESPONSE_AVAILABLE notifications.
+ *
+ * REVISIT some RNDIS implementations seem to have curious issues still
+ * to be resolved.
+ */
+struct rndis_msg_hdr {
+	__le32	msg_type;			/* RNDIS_MSG_* */
+	__le32	msg_len;
+	// followed by data that varies between messages
+	__le32	request_id;
+	__le32	status;
+	// ... and more
+} __attribute__ ((packed));
+
+/* MS-Windows uses this strange size, but RNDIS spec says 1024 minimum */
+#define	CONTROL_BUFFER_SIZE		1025
+
+/* RNDIS defines an (absurdly huge) 10 second control timeout,
+ * but ActiveSync seems to use a more usual 5 second timeout
+ * (which matches the USB 2.0 spec).
+ */
+#define	RNDIS_CONTROL_TIMEOUT_MS	(5 * 1000)
+
+
+#define ccpu2 __constant_cpu_to_le32
+
+#define RNDIS_MSG_COMPLETION	ccpu2(0x80000000)
+
+/* codes for "msg_type" field of rndis messages;
+ * only the data channel uses packet messages (maybe batched);
+ * everything else goes on the control channel.
+ */
+#define RNDIS_MSG_PACKET	ccpu2(0x00000001)	/* 1-N packets */
+#define RNDIS_MSG_INIT		ccpu2(0x00000002)
+#define RNDIS_MSG_INIT_C	(RNDIS_MSG_INIT|RNDIS_MSG_COMPLETION)
+#define RNDIS_MSG_HALT		ccpu2(0x00000003)
+#define RNDIS_MSG_QUERY		ccpu2(0x00000004)
+#define RNDIS_MSG_QUERY_C	(RNDIS_MSG_QUERY|RNDIS_MSG_COMPLETION)
+#define RNDIS_MSG_SET		ccpu2(0x00000005)
+#define RNDIS_MSG_SET_C		(RNDIS_MSG_SET|RNDIS_MSG_COMPLETION)
+#define RNDIS_MSG_RESET		ccpu2(0x00000006)
+#define RNDIS_MSG_RESET_C	(RNDIS_MSG_RESET|RNDIS_MSG_COMPLETION)
+#define RNDIS_MSG_INDICATE	ccpu2(0x00000007)
+#define RNDIS_MSG_KEEPALIVE	ccpu2(0x00000008)
+#define RNDIS_MSG_KEEPALIVE_C	(RNDIS_MSG_KEEPALIVE|RNDIS_MSG_COMPLETION)
+
+/* codes for "status" field of completion messages */
+#define	RNDIS_STATUS_SUCCESS		ccpu2(0x00000000)
+#define	RNDIS_STATUS_FAILURE		ccpu2(0xc0000001)
+#define	RNDIS_STATUS_INVALID_DATA	ccpu2(0xc0010015)
+#define	RNDIS_STATUS_NOT_SUPPORTED	ccpu2(0xc00000bb)
+#define	RNDIS_STATUS_MEDIA_CONNECT	ccpu2(0x4001000b)
+#define	RNDIS_STATUS_MEDIA_DISCONNECT	ccpu2(0x4001000c)
+
+
+struct rndis_data_hdr {
+	__le32	msg_type;		/* RNDIS_MSG_PACKET */
+	__le32	msg_len;		// rndis_data_hdr + data_len + pad
+	__le32	data_offset;		// 36 -- right after header
+	__le32	data_len;		// ... real packet size
+
+	__le32	oob_data_offset;	// zero
+	__le32	oob_data_len;		// zero
+	__le32	num_oob;		// zero
+	__le32	packet_data_offset;	// zero
+
+	__le32	packet_data_len;	// zero
+	__le32	vc_handle;		// zero
+	__le32	reserved;		// zero
+} __attribute__ ((packed));
+
+struct rndis_init {		/* OUT */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_INIT */
+	__le32	msg_len;			// 24
+	__le32	request_id;
+	__le32	major_version;			// of rndis (1.0)
+	__le32	minor_version;
+	__le32	max_transfer_size;
+} __attribute__ ((packed));
+
+struct rndis_init_c {		/* IN */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_INIT_C */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	status;
+	__le32	major_version;			// of rndis (1.0)
+	__le32	minor_version;
+	__le32	device_flags;
+	__le32	medium;				// zero == 802.3
+	__le32	max_packets_per_message;
+	__le32	max_transfer_size;
+	__le32	packet_alignment;		// max 7; (1<<n) bytes
+	__le32	af_list_offset;			// zero
+	__le32	af_list_size;			// zero
+} __attribute__ ((packed));
+
+struct rndis_halt {		/* OUT (no reply) */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_HALT */
+	__le32	msg_len;
+	__le32	request_id;
+} __attribute__ ((packed));
+
+struct rndis_query {		/* OUT */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_QUERY */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	oid;
+	__le32	len;
+	__le32	offset;
+/*?*/	__le32	handle;				// zero
+} __attribute__ ((packed));
+
+struct rndis_query_c {		/* IN */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_QUERY_C */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	status;
+	__le32	len;
+	__le32	offset;
+} __attribute__ ((packed));
+
+struct rndis_set {		/* OUT */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_SET */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	oid;
+	__le32	len;
+	__le32	offset;
+/*?*/	__le32	handle;				// zero
+} __attribute__ ((packed));
+
+struct rndis_set_c {		/* IN */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_SET_C */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	status;
+} __attribute__ ((packed));
+
+struct rndis_reset {		/* IN */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_RESET */
+	__le32	msg_len;
+	__le32	reserved;
+} __attribute__ ((packed));
+
+struct rndis_reset_c {		/* OUT */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_RESET_C */
+	__le32	msg_len;
+	__le32	status;
+	__le32	addressing_lost;
+} __attribute__ ((packed));
+
+struct rndis_indicate {		/* IN (unrequested) */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_INDICATE */
+	__le32	msg_len;
+	__le32	status;
+	__le32	length;
+	__le32	offset;
+/**/	__le32	diag_status;
+	__le32	error_offset;
+/**/	__le32	message;
+} __attribute__ ((packed));
+
+struct rndis_keepalive {	/* OUT (optionally IN) */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_KEEPALIVE */
+	__le32	msg_len;
+	__le32	request_id;
+} __attribute__ ((packed));
+
+struct rndis_keepalive_c {	/* IN (optionally OUT) */
+	// header and:
+	__le32	msg_type;			/* RNDIS_MSG_KEEPALIVE_C */
+	__le32	msg_len;
+	__le32	request_id;
+	__le32	status;
+} __attribute__ ((packed));
+
+/* NOTE:  about 30 OIDs are "mandatory" for peripherals to support ... and
+ * there are gobs more that may optionally be supported.  We'll avoid as much
+ * of that mess as possible.
+ */
+#define OID_802_3_PERMANENT_ADDRESS	ccpu2(0x01010101)
+#define OID_GEN_MAXIMUM_FRAME_SIZE	ccpu2(0x00010106)
+#define OID_GEN_CURRENT_PACKET_FILTER	ccpu2(0x0001010e)
+
+/*
+ * RNDIS notifications from device: command completion; "reverse"
+ * keepalives; etc
+ */
+static void rndis_status(struct usbnet *dev, struct urb *urb)
+{
+	devdbg(dev, "rndis status urb, len %d stat %d",
+		urb->actual_length, urb->status);
+	// FIXME for keepalives, respond immediately (asynchronously)
+	// if not an RNDIS status, do like cdc_status(dev,urb) does
+}
+
+/*
+ * RPC done RNDIS-style.  Caller guarantees:
+ * - message is properly byteswapped
+ * - there's no other request pending
+ * - buf can hold up to 1KB response (required by RNDIS spec)
+ * On return, the first few entries are already byteswapped.
+ *
+ * Call context is likely probe(), before interface name is known,
+ * which is why we won't try to use it in the diagnostics.
+ */
+static int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf)
+{
+	struct cdc_state	*info = (void *) &dev->data;
+	int			master_ifnum;
+	int			retval;
+	unsigned		count;
+	__le32			rsp;
+	u32			xid = 0, msg_len, request_id;
+
+	/* REVISIT when this gets called from contexts other than probe() or
+	 * disconnect(): either serialize, or dispatch responses on xid
+	 */
+
+	/* Issue the request; xid is unique, don't bother byteswapping it */
+	if (likely(buf->msg_type != RNDIS_MSG_HALT
+			&& buf->msg_type != RNDIS_MSG_RESET)) {
+		xid = dev->xid++;
+		if (!xid)
+			xid = dev->xid++;
+		buf->request_id = (__force __le32) xid;
+	}
+	master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
+	retval = usb_control_msg(dev->udev,
+		usb_sndctrlpipe(dev->udev, 0),
+		USB_CDC_SEND_ENCAPSULATED_COMMAND,
+		USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		0, master_ifnum,
+		buf, le32_to_cpu(buf->msg_len),
+		RNDIS_CONTROL_TIMEOUT_MS);
+	if (unlikely(retval < 0 || xid == 0))
+		return retval;
+
+	// FIXME Seems like some devices discard responses when
+	// we time out and cancel our "get response" requests...
+	// so, this is fragile.  Probably need to poll for status.
+
+	/* ignore status endpoint, just poll the control channel;
+	 * the request probably completed immediately
+	 */
+	rsp = buf->msg_type | RNDIS_MSG_COMPLETION;
+	for (count = 0; count < 10; count++) {
+		memset(buf, 0, CONTROL_BUFFER_SIZE);
+		retval = usb_control_msg(dev->udev,
+			usb_rcvctrlpipe(dev->udev, 0),
+			USB_CDC_GET_ENCAPSULATED_RESPONSE,
+			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0, master_ifnum,
+			buf, CONTROL_BUFFER_SIZE,
+			RNDIS_CONTROL_TIMEOUT_MS);
+		if (likely(retval >= 8)) {
+			msg_len = le32_to_cpu(buf->msg_len);
+			request_id = (__force u32) buf->request_id;
+			if (likely(buf->msg_type == rsp)) {
+				if (likely(request_id == xid)) {
+					if (unlikely(rsp == RNDIS_MSG_RESET_C))
+						return 0;
+					if (likely(RNDIS_STATUS_SUCCESS
+							== buf->status))
+						return 0;
+					dev_dbg(&info->control->dev,
+						"rndis reply status %08x\n",
+						le32_to_cpu(buf->status));
+					return -EL3RST;
+				}
+				dev_dbg(&info->control->dev,
+					"rndis reply id %d expected %d\n",
+					request_id, xid);
+				/* then likely retry */
+			} else switch (buf->msg_type) {
+			case RNDIS_MSG_INDICATE: {	/* fault */
+				// struct rndis_indicate *msg = (void *)buf;
+				dev_info(&info->control->dev,
+					"rndis fault indication\n");
+				}
+				break;
+			case RNDIS_MSG_KEEPALIVE: {	/* ping */
+				struct rndis_keepalive_c *msg = (void *)buf;
+
+				msg->msg_type = RNDIS_MSG_KEEPALIVE_C;
+				msg->msg_len = ccpu2(sizeof *msg);
+				msg->status = RNDIS_STATUS_SUCCESS;
+				retval = usb_control_msg(dev->udev,
+					usb_sndctrlpipe(dev->udev, 0),
+					USB_CDC_SEND_ENCAPSULATED_COMMAND,
+					USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+					0, master_ifnum,
+					msg, sizeof *msg,
+					RNDIS_CONTROL_TIMEOUT_MS);
+				if (unlikely(retval < 0))
+					dev_dbg(&info->control->dev,
+						"rndis keepalive err %d\n",
+						retval);
+				}
+				break;
+			default:
+				dev_dbg(&info->control->dev,
+					"unexpected rndis msg %08x len %d\n",
+					le32_to_cpu(buf->msg_type), msg_len);
+			}
+		} else {
+			/* device probably issued a protocol stall; ignore */
+			dev_dbg(&info->control->dev,
+				"rndis response error, code %d\n", retval);
+		}
+		msleep(2);
+	}
+	dev_dbg(&info->control->dev, "rndis response timeout\n");
+	return -ETIMEDOUT;
+}
+
+/*
+ * rndis_query:
+ *
+ * Performs a query for @oid along with 0 or more bytes of payload as
+ * specified by @in_len. If @reply_len is not set to -1 then the reply
+ * length is checked against this value, resulting in an error if it
+ * doesn't match.
+ *
+ * NOTE: Adding a payload exactly or greater than the size of the expected
+ * response payload is an evident requirement MSFT added for ActiveSync.
+ *
+ * The only exception is for OIDs that return a variably sized response,
+ * in which case no payload should be added.  This undocumented (and
+ * nonsensical!) issue was found by sniffing protocol requests from the
+ * ActiveSync 4.1 Windows driver.
+ */
+static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
+		void *buf, u32 oid, u32 in_len,
+		void **reply, int *reply_len)
+{
+	int retval;
+	union {
+		void			*buf;
+		struct rndis_msg_hdr	*header;
+		struct rndis_query	*get;
+		struct rndis_query_c	*get_c;
+	} u;
+	u32 off, len;
+
+	u.buf = buf;
+
+	memset(u.get, 0, sizeof *u.get + in_len);
+	u.get->msg_type = RNDIS_MSG_QUERY;
+	u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
+	u.get->oid = oid;
+	u.get->len = cpu_to_le32(in_len);
+	u.get->offset = ccpu2(20);
+
+	retval = rndis_command(dev, u.header);
+	if (unlikely(retval < 0)) {
+		dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
+				oid, retval);
+		return retval;
+	}
+
+	off = le32_to_cpu(u.get_c->offset);
+	len = le32_to_cpu(u.get_c->len);
+	if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
+		goto response_error;
+
+	if (*reply_len != -1 && len != *reply_len)
+		goto response_error;
+
+	*reply = (unsigned char *) &u.get_c->request_id + off;
+	*reply_len = len;
+
+	return retval;
+
+response_error:
+	dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
+			"invalid response - off %d len %d\n",
+		oid, off, len);
+	return -EDOM;
+}
+
+static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
+{
+	int			retval;
+	struct net_device	*net = dev->net;
+	struct cdc_state	*info = (void *) &dev->data;
+	union {
+		void			*buf;
+		struct rndis_msg_hdr	*header;
+		struct rndis_init	*init;
+		struct rndis_init_c	*init_c;
+		struct rndis_query	*get;
+		struct rndis_query_c	*get_c;
+		struct rndis_set	*set;
+		struct rndis_set_c	*set_c;
+	} u;
+	u32			tmp;
+	int			reply_len;
+	unsigned char		*bp;
+
+	/* we can't rely on i/o from stack working, or stack allocation */
+	u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
+	if (!u.buf)
+		return -ENOMEM;
+	retval = usbnet_generic_cdc_bind(dev, intf);
+	if (retval < 0)
+		goto fail;
+
+	u.init->msg_type = RNDIS_MSG_INIT;
+	u.init->msg_len = ccpu2(sizeof *u.init);
+	u.init->major_version = ccpu2(1);
+	u.init->minor_version = ccpu2(0);
+
+	/* max transfer (in spec) is 0x4000 at full speed, but for
+	 * TX we'll stick to one Ethernet packet plus RNDIS framing.
+	 * For RX we handle drivers that zero-pad to end-of-packet.
+	 * Don't let userspace change these settings.
+	 *
+	 * NOTE: there still seems to be wierdness here, as if we need
+	 * to do some more things to make sure WinCE targets accept this.
+	 * They default to jumbograms of 8KB or 16KB, which is absurd
+	 * for such low data rates and which is also more than Linux
+	 * can usually expect to allocate for SKB data...
+	 */
+	net->hard_header_len += sizeof (struct rndis_data_hdr);
+	dev->hard_mtu = net->mtu + net->hard_header_len;
+
+	dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
+	dev->rx_urb_size &= ~(dev->maxpacket - 1);
+	u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
+
+	net->change_mtu = NULL;
+	retval = rndis_command(dev, u.header);
+	if (unlikely(retval < 0)) {
+		/* it might not even be an RNDIS device!! */
+		dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
+		goto fail_and_release;
+	}
+	tmp = le32_to_cpu(u.init_c->max_transfer_size);
+	if (tmp < dev->hard_mtu) {
+		dev_err(&intf->dev,
+			"dev can't take %u byte packets (max %u)\n",
+			dev->hard_mtu, tmp);
+		goto fail_and_release;
+	}
+
+	/* REVISIT:  peripheral "alignment" request is ignored ... */
+	dev_dbg(&intf->dev,
+		"hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
+		dev->hard_mtu, tmp, dev->rx_urb_size,
+		1 << le32_to_cpu(u.init_c->packet_alignment));
+
+	/* Get designated host ethernet address */
+	reply_len = ETH_ALEN;
+	retval = rndis_query(dev, intf, u.buf, OID_802_3_PERMANENT_ADDRESS,
+			48, (void **) &bp, &reply_len);
+	if (unlikely(retval< 0)) {
+		dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
+		goto fail_and_release;
+	}
+	memcpy(net->dev_addr, bp, ETH_ALEN);
+
+	/* set a nonzero filter to enable data transfers */
+	memset(u.set, 0, sizeof *u.set);
+	u.set->msg_type = RNDIS_MSG_SET;
+	u.set->msg_len = ccpu2(4 + sizeof *u.set);
+	u.set->oid = OID_GEN_CURRENT_PACKET_FILTER;
+	u.set->len = ccpu2(4);
+	u.set->offset = ccpu2((sizeof *u.set) - 8);
+	*(__le32 *)(u.buf + sizeof *u.set) = ccpu2(DEFAULT_FILTER);
+
+	retval = rndis_command(dev, u.header);
+	if (unlikely(retval < 0)) {
+		dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
+		goto fail_and_release;
+	}
+
+	retval = 0;
+
+	kfree(u.buf);
+	return retval;
+
+fail_and_release:
+	usb_set_intfdata(info->data, NULL);
+	usb_driver_release_interface(driver_of(intf), info->data);
+	info->data = NULL;
+fail:
+	kfree(u.buf);
+	return retval;
+}
+
+static void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
+{
+	struct rndis_halt	*halt;
+
+	/* try to clear any rndis state/activity (no i/o from stack!) */
+	halt = kzalloc(sizeof *halt, GFP_KERNEL);
+	if (halt) {
+		halt->msg_type = RNDIS_MSG_HALT;
+		halt->msg_len = ccpu2(sizeof *halt);
+		(void) rndis_command(dev, (void *)halt);
+		kfree(halt);
+	}
+
+	return usbnet_cdc_unbind(dev, intf);
+}
+
+/*
+ * DATA -- host must not write zlps
+ */
+static int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+	/* peripheral may have batched packets to us... */
+	while (likely(skb->len)) {
+		struct rndis_data_hdr	*hdr = (void *)skb->data;
+		struct sk_buff		*skb2;
+		u32			msg_len, data_offset, data_len;
+
+		msg_len = le32_to_cpu(hdr->msg_len);
+		data_offset = le32_to_cpu(hdr->data_offset);
+		data_len = le32_to_cpu(hdr->data_len);
+
+		/* don't choke if we see oob, per-packet data, etc */
+		if (unlikely(hdr->msg_type != RNDIS_MSG_PACKET
+				|| skb->len < msg_len
+				|| (data_offset + data_len + 8) > msg_len)) {
+			dev->stats.rx_frame_errors++;
+			devdbg(dev, "bad rndis message %d/%d/%d/%d, len %d",
+				le32_to_cpu(hdr->msg_type),
+				msg_len, data_offset, data_len, skb->len);
+			return 0;
+		}
+		skb_pull(skb, 8 + data_offset);
+
+		/* at most one packet left? */
+		if (likely((data_len - skb->len) <= sizeof *hdr)) {
+			skb_trim(skb, data_len);
+			break;
+		}
+
+		/* try to return all the packets in the batch */
+		skb2 = skb_clone(skb, GFP_ATOMIC);
+		if (unlikely(!skb2))
+			break;
+		skb_pull(skb, msg_len - sizeof *hdr);
+		skb_trim(skb2, data_len);
+		usbnet_skb_return(dev, skb2);
+	}
+
+	/* caller will usbnet_skb_return the remaining packet */
+	return 1;
+}
+
+static struct sk_buff *
+rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
+{
+	struct rndis_data_hdr	*hdr;
+	struct sk_buff		*skb2;
+	unsigned		len = skb->len;
+
+	if (likely(!skb_cloned(skb))) {
+		int	room = skb_headroom(skb);
+
+		/* enough head room as-is? */
+		if (unlikely((sizeof *hdr) <= room))
+			goto fill;
+
+		/* enough room, but needs to be readjusted? */
+		room += skb_tailroom(skb);
+		if (likely((sizeof *hdr) <= room)) {
+			skb->data = memmove(skb->head + sizeof *hdr,
+					    skb->data, len);
+			skb_set_tail_pointer(skb, len);
+			goto fill;
+		}
+	}
+
+	/* create a new skb, with the correct size (and tailpad) */
+	skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
+	dev_kfree_skb_any(skb);
+	if (unlikely(!skb2))
+		return skb2;
+	skb = skb2;
+
+	/* fill out the RNDIS header.  we won't bother trying to batch
+	 * packets; Linux minimizes wasted bandwidth through tx queues.
+	 */
+fill:
+	hdr = (void *) __skb_push(skb, sizeof *hdr);
+	memset(hdr, 0, sizeof *hdr);
+	hdr->msg_type = RNDIS_MSG_PACKET;
+	hdr->msg_len = cpu_to_le32(skb->len);
+	hdr->data_offset = ccpu2(sizeof(*hdr) - 8);
+	hdr->data_len = cpu_to_le32(len);
+
+	/* FIXME make the last packet always be short ... */
+	return skb;
+}
+
+
+static const struct driver_info	rndis_info = {
+	.description =	"RNDIS device",
+	.flags =	FLAG_ETHER | FLAG_FRAMING_RN | FLAG_NO_SETINT,
+	.bind =		rndis_bind,
+	.unbind =	rndis_unbind,
+	.status =	rndis_status,
+	.rx_fixup =	rndis_rx_fixup,
+	.tx_fixup =	rndis_tx_fixup,
+};
+
+#undef ccpu2
+
+
+/*-------------------------------------------------------------------------*/
+
+static const struct usb_device_id	products [] = {
+{
+	/* RNDIS is MSFT's un-official variant of CDC ACM */
+	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
+	.driver_info = (unsigned long) &rndis_info,
+}, {
+	/* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
+	USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
+	.driver_info = (unsigned long) &rndis_info,
+},
+	{ },		// END
+};
+MODULE_DEVICE_TABLE(usb, products);
+
+static struct usb_driver rndis_driver = {
+	.name =		"rndis_host",
+	.id_table =	products,
+	.probe =	usbnet_probe,
+	.disconnect =	usbnet_disconnect,
+	.suspend =	usbnet_suspend,
+	.resume =	usbnet_resume,
+};
+
+static int __init rndis_init(void)
+{
+	return usb_register(&rndis_driver);
+}
+module_init(rndis_init);
+
+static void __exit rndis_exit(void)
+{
+	usb_deregister(&rndis_driver);
+}
+module_exit(rndis_exit);
+
+MODULE_AUTHOR("David Brownell");
+MODULE_DESCRIPTION("USB Host side RNDIS driver");
+MODULE_LICENSE("GPL");