drivers/usb/net/rndis_host.c - third_party/linux - Git at Google

 /*
  * 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/sched.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.
  *
  * 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.
  */
 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));

 /* RNDIS defines this (absurdly huge) control timeout */
 #define	RNDIS_CONTROL_TIMEOUT_MS	(10 * 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_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			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; don't bother byteswapping our xid */
 	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;
 	}
 	retval = usb_control_msg(dev->udev,
 		usb_sndctrlpipe(dev->udev, 0),
 		USB_CDC_SEND_ENCAPSULATED_COMMAND,
 		USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 		0, info->u->bMasterInterface0,
 		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, 1024);
 		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, info->u->bMasterInterface0,
 			buf, 1024,
 			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, info->u->bMasterInterface0,
 					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;
 }

 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	int			retval;
 	struct net_device	*net = dev->net;
 	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;

 	/* we can't rely on i/o from stack working, or stack allocation */
 	u.buf = kmalloc(1024, GFP_KERNEL);
 	if (!u.buf)
 		return -ENOMEM;
 	retval = usbnet_generic_cdc_bind(dev, intf);
 	if (retval < 0)
 		goto done;

 	net->hard_header_len += sizeof (struct rndis_data_hdr);

 	/* initialize; max transfer is 16KB at full speed */
 	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);
 	u.init->max_transfer_size = ccpu2(net->mtu + net->hard_header_len);

 	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);
 fail:
 		usb_driver_release_interface(driver_of(intf),
 			((struct cdc_state *)&(dev->data))->data);
 		goto done;
 	}
 	dev->hard_mtu = le32_to_cpu(u.init_c->max_transfer_size);
 	/* REVISIT:  peripheral "alignment" request is ignored ... */
 	dev_dbg(&intf->dev, "hard mtu %u, align %d\n", dev->hard_mtu,
 		1 << le32_to_cpu(u.init_c->packet_alignment));

 	/* get designated host ethernet address */
 	memset(u.get, 0, sizeof *u.get);
 	u.get->msg_type = RNDIS_MSG_QUERY;
 	u.get->msg_len = ccpu2(sizeof *u.get);
 	u.get->oid = OID_802_3_PERMANENT_ADDRESS;

 	retval = rndis_command(dev, u.header);
 	if (unlikely(retval < 0)) {
 		dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
 		goto fail;
 	}
 	tmp = le32_to_cpu(u.get_c->offset);
 	if (unlikely((tmp + 8) > (1024 - ETH_ALEN)
 			|| u.get_c->len != ccpu2(ETH_ALEN))) {
 		dev_err(&intf->dev, "rndis ethaddr off %d len %d ?\n",
 			tmp, le32_to_cpu(u.get_c->len));
 		retval = -EDOM;
 		goto fail;
 	}
 	memcpy(net->dev_addr, tmp + (char *)&u.get_c->request_id, 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;
 	}

 	retval = 0;
 done:
 	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->tail = skb->data + 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,
 	.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,
 },
 	{ },		// 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");
	/*
	* 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/sched.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.
	*
	* 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.
	*/
	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));

	/* RNDIS defines this (absurdly huge) control timeout */
	#define RNDIS_CONTROL_TIMEOUT_MS (10 * 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_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 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; don't bother byteswapping our xid */
	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;
	}
	retval = usb_control_msg(dev->udev,
	usb_sndctrlpipe(dev->udev, 0),
	USB_CDC_SEND_ENCAPSULATED_COMMAND,
	USB_TYPE_CLASS \| USB_RECIP_INTERFACE,
	0, info->u->bMasterInterface0,
	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, 1024);
	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, info->u->bMasterInterface0,
	buf, 1024,
	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, info->u->bMasterInterface0,
	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;
	}

	static int rndis_bind(struct usbnet dev, struct usb_interface intf)
	{
	int retval;
	struct net_device *net = dev->net;
	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;

	/* we can't rely on i/o from stack working, or stack allocation */
	u.buf = kmalloc(1024, GFP_KERNEL);
	if (!u.buf)
	return -ENOMEM;
	retval = usbnet_generic_cdc_bind(dev, intf);
	if (retval < 0)
	goto done;

	net->hard_header_len += sizeof (struct rndis_data_hdr);

	/* initialize; max transfer is 16KB at full speed */
	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);
	u.init->max_transfer_size = ccpu2(net->mtu + net->hard_header_len);

	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);
	fail:
	usb_driver_release_interface(driver_of(intf),
	((struct cdc_state *)&(dev->data))->data);
	goto done;
	}
	dev->hard_mtu = le32_to_cpu(u.init_c->max_transfer_size);
	/* REVISIT: peripheral "alignment" request is ignored ... */
	dev_dbg(&intf->dev, "hard mtu %u, align %d\n", dev->hard_mtu,
	1 << le32_to_cpu(u.init_c->packet_alignment));

	/* get designated host ethernet address */
	memset(u.get, 0, sizeof *u.get);
	u.get->msg_type = RNDIS_MSG_QUERY;
	u.get->msg_len = ccpu2(sizeof *u.get);
	u.get->oid = OID_802_3_PERMANENT_ADDRESS;

	retval = rndis_command(dev, u.header);
	if (unlikely(retval < 0)) {
	dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
	goto fail;
	}
	tmp = le32_to_cpu(u.get_c->offset);
	if (unlikely((tmp + 8) > (1024 - ETH_ALEN)
	\|\| u.get_c->len != ccpu2(ETH_ALEN))) {
	dev_err(&intf->dev, "rndis ethaddr off %d len %d ?\n",
	tmp, le32_to_cpu(u.get_c->len));
	retval = -EDOM;
	goto fail;
	}
	memcpy(net->dev_addr, tmp + (char *)&u.get_c->request_id, 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;
	}

	retval = 0;
	done:
	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->tail = skb->data + 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,
	.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,
	},
	{ }, // 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");