Merge branch 'linus' into tracing/urgent

1 files changed, 967 insertions, 0 deletions

diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
new file mode 100644
index 000000000000..5458f43a8668
--- /dev/null
+++ b/drivers/usb/gadget/u_ether.c
@@ -0,0 +1,967 @@
+/*
+ * u_ether.c -- Ethernet-over-USB link layer utilities for Gadget stack
+ *
+ * Copyright (C) 2003-2005,2008 David Brownell
+ * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
+ * Copyright (C) 2008 Nokia Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+#include <linux/ctype.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+
+#include "u_ether.h"
+
+
+/*
+ * This component encapsulates the Ethernet link glue needed to provide
+ * one (!) network link through the USB gadget stack, normally "usb0".
+ *
+ * The control and data models are handled by the function driver which
+ * connects to this code; such as CDC Ethernet, "CDC Subset", or RNDIS.
+ * That includes all descriptor and endpoint management.
+ *
+ * Link level addressing is handled by this component using module
+ * parameters; if no such parameters are provided, random link level
+ * addresses are used.  Each end of the link uses one address.  The
+ * host end address is exported in various ways, and is often recorded
+ * in configuration databases.
+ *
+ * The driver which assembles each configuration using such a link is
+ * responsible for ensuring that each configuration includes at most one
+ * instance of is network link.  (The network layer provides ways for
+ * this single "physical" link to be used by multiple virtual links.)
+ */
+
+#define DRIVER_VERSION	"29-May-2008"
+
+struct eth_dev {
+	/* lock is held while accessing port_usb
+	 * or updating its backlink port_usb->ioport
+	 */
+	spinlock_t		lock;
+	struct gether		*port_usb;
+
+	struct net_device	*net;
+	struct usb_gadget	*gadget;
+
+	spinlock_t		req_lock;	/* guard {rx,tx}_reqs */
+	struct list_head	tx_reqs, rx_reqs;
+	atomic_t		tx_qlen;
+
+	unsigned		header_len;
+	struct sk_buff		*(*wrap)(struct sk_buff *skb);
+	int			(*unwrap)(struct sk_buff *skb);
+
+	struct work_struct	work;
+
+	unsigned long		todo;
+#define	WORK_RX_MEMORY		0
+
+	bool			zlp;
+	u8			host_mac[ETH_ALEN];
+};
+
+/*-------------------------------------------------------------------------*/
+
+#define RX_EXTRA	20	/* bytes guarding against rx overflows */
+
+#define DEFAULT_QLEN	2	/* double buffering by default */
+
+
+#ifdef CONFIG_USB_GADGET_DUALSPEED
+
+static unsigned qmult = 5;
+module_param(qmult, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(qmult, "queue length multiplier at high speed");
+
+#else	/* full speed (low speed doesn't do bulk) */
+#define qmult		1
+#endif
+
+/* for dual-speed hardware, use deeper queues at highspeed */
+static inline int qlen(struct usb_gadget *gadget)
+{
+	if (gadget_is_dualspeed(gadget) && gadget->speed == USB_SPEED_HIGH)
+		return qmult * DEFAULT_QLEN;
+	else
+		return DEFAULT_QLEN;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* REVISIT there must be a better way than having two sets
+ * of debug calls ...
+ */
+
+#undef DBG
+#undef VDBG
+#undef ERROR
+#undef WARN
+#undef INFO
+
+#define xprintk(d, level, fmt, args...) \
+	printk(level "%s: " fmt , (d)->net->name , ## args)
+
+#ifdef DEBUG
+#undef DEBUG
+#define DBG(dev, fmt, args...) \
+	xprintk(dev , KERN_DEBUG , fmt , ## args)
+#else
+#define DBG(dev, fmt, args...) \
+	do { } while (0)
+#endif /* DEBUG */
+
+#ifdef VERBOSE_DEBUG
+#define VDBG	DBG
+#else
+#define VDBG(dev, fmt, args...) \
+	do { } while (0)
+#endif /* DEBUG */
+
+#define ERROR(dev, fmt, args...) \
+	xprintk(dev , KERN_ERR , fmt , ## args)
+#define WARN(dev, fmt, args...) \
+	xprintk(dev , KERN_WARNING , fmt , ## args)
+#define INFO(dev, fmt, args...) \
+	xprintk(dev , KERN_INFO , fmt , ## args)
+
+/*-------------------------------------------------------------------------*/
+
+/* NETWORK DRIVER HOOKUP (to the layer above this driver) */
+
+static int eth_change_mtu(struct net_device *net, int new_mtu)
+{
+	struct eth_dev	*dev = netdev_priv(net);
+	unsigned long	flags;
+	int		status = 0;
+
+	/* don't change MTU on "live" link (peer won't know) */
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->port_usb)
+		status = -EBUSY;
+	else if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
+		status = -ERANGE;
+	else
+		net->mtu = new_mtu;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return status;
+}
+
+static void eth_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *p)
+{
+	struct eth_dev	*dev = netdev_priv(net);
+
+	strlcpy(p->driver, "g_ether", sizeof p->driver);
+	strlcpy(p->version, DRIVER_VERSION, sizeof p->version);
+	strlcpy(p->fw_version, dev->gadget->name, sizeof p->fw_version);
+	strlcpy(p->bus_info, dev_name(&dev->gadget->dev), sizeof p->bus_info);
+}
+
+static u32 eth_get_link(struct net_device *net)
+{
+	struct eth_dev	*dev = netdev_priv(net);
+	return dev->gadget->speed != USB_SPEED_UNKNOWN;
+}
+
+/* REVISIT can also support:
+ *   - WOL (by tracking suspends and issuing remote wakeup)
+ *   - msglevel (implies updated messaging)
+ *   - ... probably more ethtool ops
+ */
+
+static struct ethtool_ops ops = {
+	.get_drvinfo = eth_get_drvinfo,
+	.get_link = eth_get_link
+};
+
+static void defer_kevent(struct eth_dev *dev, int flag)
+{
+	if (test_and_set_bit(flag, &dev->todo))
+		return;
+	if (!schedule_work(&dev->work))
+		ERROR(dev, "kevent %d may have been dropped\n", flag);
+	else
+		DBG(dev, "kevent %d scheduled\n", flag);
+}
+
+static void rx_complete(struct usb_ep *ep, struct usb_request *req);
+
+static int
+rx_submit(struct eth_dev *dev, struct usb_request *req, gfp_t gfp_flags)
+{
+	struct sk_buff	*skb;
+	int		retval = -ENOMEM;
+	size_t		size = 0;
+	struct usb_ep	*out;
+	unsigned long	flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->port_usb)
+		out = dev->port_usb->out_ep;
+	else
+		out = NULL;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (!out)
+		return -ENOTCONN;
+
+
+	/* Padding up to RX_EXTRA handles minor disagreements with host.
+	 * Normally we use the USB "terminate on short read" convention;
+	 * so allow up to (N*maxpacket), since that memory is normally
+	 * already allocated.  Some hardware doesn't deal well with short
+	 * reads (e.g. DMA must be N*maxpacket), so for now don't trim a
+	 * byte off the end (to force hardware errors on overflow).
+	 *
+	 * RNDIS uses internal framing, and explicitly allows senders to
+	 * pad to end-of-packet.  That's potentially nice for speed, but
+	 * means receivers can't recover lost synch on their own (because
+	 * new packets don't only start after a short RX).
+	 */
+	size += sizeof(struct ethhdr) + dev->net->mtu + RX_EXTRA;
+	size += dev->port_usb->header_len;
+	size += out->maxpacket - 1;
+	size -= size % out->maxpacket;
+
+	skb = alloc_skb(size + NET_IP_ALIGN, gfp_flags);
+	if (skb == NULL) {
+		DBG(dev, "no rx skb\n");
+		goto enomem;
+	}
+
+	/* Some platforms perform better when IP packets are aligned,
+	 * but on at least one, checksumming fails otherwise.  Note:
+	 * RNDIS headers involve variable numbers of LE32 values.
+	 */
+	skb_reserve(skb, NET_IP_ALIGN);
+
+	req->buf = skb->data;
+	req->length = size;
+	req->complete = rx_complete;
+	req->context = skb;
+
+	retval = usb_ep_queue(out, req, gfp_flags);
+	if (retval == -ENOMEM)
+enomem:
+		defer_kevent(dev, WORK_RX_MEMORY);
+	if (retval) {
+		DBG(dev, "rx submit --> %d\n", retval);
+		if (skb)
+			dev_kfree_skb_any(skb);
+		spin_lock_irqsave(&dev->req_lock, flags);
+		list_add(&req->list, &dev->rx_reqs);
+		spin_unlock_irqrestore(&dev->req_lock, flags);
+	}
+	return retval;
+}
+
+static void rx_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct sk_buff	*skb = req->context;
+	struct eth_dev	*dev = ep->driver_data;
+	int		status = req->status;
+
+	switch (status) {
+
+	/* normal completion */
+	case 0:
+		skb_put(skb, req->actual);
+		if (dev->unwrap)
+			status = dev->unwrap(skb);
+		if (status < 0
+				|| ETH_HLEN > skb->len
+				|| skb->len > ETH_FRAME_LEN) {
+			dev->net->stats.rx_errors++;
+			dev->net->stats.rx_length_errors++;
+			DBG(dev, "rx length %d\n", skb->len);
+			break;
+		}
+
+		skb->protocol = eth_type_trans(skb, dev->net);
+		dev->net->stats.rx_packets++;
+		dev->net->stats.rx_bytes += skb->len;
+
+		/* no buffer copies needed, unless hardware can't
+		 * use skb buffers.
+		 */
+		status = netif_rx(skb);
+		skb = NULL;
+		break;
+
+	/* software-driven interface shutdown */
+	case -ECONNRESET:		/* unlink */
+	case -ESHUTDOWN:		/* disconnect etc */
+		VDBG(dev, "rx shutdown, code %d\n", status);
+		goto quiesce;
+
+	/* for hardware automagic (such as pxa) */
+	case -ECONNABORTED:		/* endpoint reset */
+		DBG(dev, "rx %s reset\n", ep->name);
+		defer_kevent(dev, WORK_RX_MEMORY);
+quiesce:
+		dev_kfree_skb_any(skb);
+		goto clean;
+
+	/* data overrun */
+	case -EOVERFLOW:
+		dev->net->stats.rx_over_errors++;
+		/* FALLTHROUGH */
+
+	default:
+		dev->net->stats.rx_errors++;
+		DBG(dev, "rx status %d\n", status);
+		break;
+	}
+
+	if (skb)
+		dev_kfree_skb_any(skb);
+	if (!netif_running(dev->net)) {
+clean:
+		spin_lock(&dev->req_lock);
+		list_add(&req->list, &dev->rx_reqs);
+		spin_unlock(&dev->req_lock);
+		req = NULL;
+	}
+	if (req)
+		rx_submit(dev, req, GFP_ATOMIC);
+}
+
+static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
+{
+	unsigned		i;
+	struct usb_request	*req;
+
+	if (!n)
+		return -ENOMEM;
+
+	/* queue/recycle up to N requests */
+	i = n;
+	list_for_each_entry(req, list, list) {
+		if (i-- == 0)
+			goto extra;
+	}
+	while (i--) {
+		req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+		if (!req)
+			return list_empty(list) ? -ENOMEM : 0;
+		list_add(&req->list, list);
+	}
+	return 0;
+
+extra:
+	/* free extras */
+	for (;;) {
+		struct list_head	*next;
+
+		next = req->list.next;
+		list_del(&req->list);
+		usb_ep_free_request(ep, req);
+
+		if (next == list)
+			break;
+
+		req = container_of(next, struct usb_request, list);
+	}
+	return 0;
+}
+
+static int alloc_requests(struct eth_dev *dev, struct gether *link, unsigned n)
+{
+	int	status;
+
+	spin_lock(&dev->req_lock);
+	status = prealloc(&dev->tx_reqs, link->in_ep, n);
+	if (status < 0)
+		goto fail;
+	status = prealloc(&dev->rx_reqs, link->out_ep, n);
+	if (status < 0)
+		goto fail;
+	goto done;
+fail:
+	DBG(dev, "can't alloc requests\n");
+done:
+	spin_unlock(&dev->req_lock);
+	return status;
+}
+
+static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
+{
+	struct usb_request	*req;
+	unsigned long		flags;
+
+	/* fill unused rxq slots with some skb */
+	spin_lock_irqsave(&dev->req_lock, flags);
+	while (!list_empty(&dev->rx_reqs)) {
+		req = container_of(dev->rx_reqs.next,
+				struct usb_request, list);
+		list_del_init(&req->list);
+		spin_unlock_irqrestore(&dev->req_lock, flags);
+
+		if (rx_submit(dev, req, gfp_flags) < 0) {
+			defer_kevent(dev, WORK_RX_MEMORY);
+			return;
+		}
+
+		spin_lock_irqsave(&dev->req_lock, flags);
+	}
+	spin_unlock_irqrestore(&dev->req_lock, flags);
+}
+
+static void eth_work(struct work_struct *work)
+{
+	struct eth_dev	*dev = container_of(work, struct eth_dev, work);
+
+	if (test_and_clear_bit(WORK_RX_MEMORY, &dev->todo)) {
+		if (netif_running(dev->net))
+			rx_fill(dev, GFP_KERNEL);
+	}
+
+	if (dev->todo)
+		DBG(dev, "work done, flags = 0x%lx\n", dev->todo);
+}
+
+static void tx_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct sk_buff	*skb = req->context;
+	struct eth_dev	*dev = ep->driver_data;
+
+	switch (req->status) {
+	default:
+		dev->net->stats.tx_errors++;
+		VDBG(dev, "tx err %d\n", req->status);
+		/* FALLTHROUGH */
+	case -ECONNRESET:		/* unlink */
+	case -ESHUTDOWN:		/* disconnect etc */
+		break;
+	case 0:
+		dev->net->stats.tx_bytes += skb->len;
+	}
+	dev->net->stats.tx_packets++;
+
+	spin_lock(&dev->req_lock);
+	list_add(&req->list, &dev->tx_reqs);
+	spin_unlock(&dev->req_lock);
+	dev_kfree_skb_any(skb);
+
+	atomic_dec(&dev->tx_qlen);
+	if (netif_carrier_ok(dev->net))
+		netif_wake_queue(dev->net);
+}
+
+static inline int is_promisc(u16 cdc_filter)
+{
+	return cdc_filter & USB_CDC_PACKET_TYPE_PROMISCUOUS;
+}
+
+static int eth_start_xmit(struct sk_buff *skb, struct net_device *net)
+{
+	struct eth_dev		*dev = netdev_priv(net);
+	int			length = skb->len;
+	int			retval;
+	struct usb_request	*req = NULL;
+	unsigned long		flags;
+	struct usb_ep		*in;
+	u16			cdc_filter;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->port_usb) {
+		in = dev->port_usb->in_ep;
+		cdc_filter = dev->port_usb->cdc_filter;
+	} else {
+		in = NULL;
+		cdc_filter = 0;
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (!in) {
+		dev_kfree_skb_any(skb);
+		return 0;
+	}
+
+	/* apply outgoing CDC or RNDIS filters */
+	if (!is_promisc(cdc_filter)) {
+		u8		*dest = skb->data;
+
+		if (is_multicast_ether_addr(dest)) {
+			u16	type;
+
+			/* ignores USB_CDC_PACKET_TYPE_MULTICAST and host
+			 * SET_ETHERNET_MULTICAST_FILTERS requests
+			 */
+			if (is_broadcast_ether_addr(dest))
+				type = USB_CDC_PACKET_TYPE_BROADCAST;
+			else
+				type = USB_CDC_PACKET_TYPE_ALL_MULTICAST;
+			if (!(cdc_filter & type)) {
+				dev_kfree_skb_any(skb);
+				return 0;
+			}
+		}
+		/* ignores USB_CDC_PACKET_TYPE_DIRECTED */
+	}
+
+	spin_lock_irqsave(&dev->req_lock, flags);
+	/*
+	 * this freelist can be empty if an interrupt triggered disconnect()
+	 * and reconfigured the gadget (shutting down this queue) after the
+	 * network stack decided to xmit but before we got the spinlock.
+	 */
+	if (list_empty(&dev->tx_reqs)) {
+		spin_unlock_irqrestore(&dev->req_lock, flags);
+		return 1;
+	}
+
+	req = container_of(dev->tx_reqs.next, struct usb_request, list);
+	list_del(&req->list);
+
+	/* temporarily stop TX queue when the freelist empties */
+	if (list_empty(&dev->tx_reqs))
+		netif_stop_queue(net);
+	spin_unlock_irqrestore(&dev->req_lock, flags);
+
+	/* no buffer copies needed, unless the network stack did it
+	 * or the hardware can't use skb buffers.
+	 * or there's not enough space for extra headers we need
+	 */
+	if (dev->wrap) {
+		struct sk_buff	*skb_new;
+
+		skb_new = dev->wrap(skb);
+		if (!skb_new)
+			goto drop;
+
+		dev_kfree_skb_any(skb);
+		skb = skb_new;
+		length = skb->len;
+	}
+	req->buf = skb->data;
+	req->context = skb;
+	req->complete = tx_complete;
+
+	/* use zlp framing on tx for strict CDC-Ether conformance,
+	 * though any robust network rx path ignores extra padding.
+	 * and some hardware doesn't like to write zlps.
+	 */
+	req->zero = 1;
+	if (!dev->zlp && (length % in->maxpacket) == 0)
+		length++;
+
+	req->length = length;
+
+	/* throttle highspeed IRQ rate back slightly */
+	if (gadget_is_dualspeed(dev->gadget))
+		req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH)
+			? ((atomic_read(&dev->tx_qlen) % qmult) != 0)
+			: 0;
+
+	retval = usb_ep_queue(in, req, GFP_ATOMIC);
+	switch (retval) {
+	default:
+		DBG(dev, "tx queue err %d\n", retval);
+		break;
+	case 0:
+		net->trans_start = jiffies;
+		atomic_inc(&dev->tx_qlen);
+	}
+
+	if (retval) {
+drop:
+		dev->net->stats.tx_dropped++;
+		dev_kfree_skb_any(skb);
+		spin_lock_irqsave(&dev->req_lock, flags);
+		if (list_empty(&dev->tx_reqs))
+			netif_start_queue(net);
+		list_add(&req->list, &dev->tx_reqs);
+		spin_unlock_irqrestore(&dev->req_lock, flags);
+	}
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void eth_start(struct eth_dev *dev, gfp_t gfp_flags)
+{
+	DBG(dev, "%s\n", __func__);
+
+	/* fill the rx queue */
+	rx_fill(dev, gfp_flags);
+
+	/* and open the tx floodgates */
+	atomic_set(&dev->tx_qlen, 0);
+	netif_wake_queue(dev->net);
+}
+
+static int eth_open(struct net_device *net)
+{
+	struct eth_dev	*dev = netdev_priv(net);
+	struct gether	*link;
+
+	DBG(dev, "%s\n", __func__);
+	if (netif_carrier_ok(dev->net))
+		eth_start(dev, GFP_KERNEL);
+
+	spin_lock_irq(&dev->lock);
+	link = dev->port_usb;
+	if (link && link->open)
+		link->open(link);
+	spin_unlock_irq(&dev->lock);
+
+	return 0;
+}
+
+static int eth_stop(struct net_device *net)
+{
+	struct eth_dev	*dev = netdev_priv(net);
+	unsigned long	flags;
+
+	VDBG(dev, "%s\n", __func__);
+	netif_stop_queue(net);
+
+	DBG(dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld\n",
+		dev->net->stats.rx_packets, dev->net->stats.tx_packets,
+		dev->net->stats.rx_errors, dev->net->stats.tx_errors
+		);
+
+	/* ensure there are no more active requests */
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->port_usb) {
+		struct gether	*link = dev->port_usb;
+
+		if (link->close)
+			link->close(link);
+
+		/* NOTE:  we have no abort-queue primitive we could use
+		 * to cancel all pending I/O.  Instead, we disable then
+		 * reenable the endpoints ... this idiom may leave toggle
+		 * wrong, but that's a self-correcting error.
+		 *
+		 * REVISIT:  we *COULD* just let the transfers complete at
+		 * their own pace; the network stack can handle old packets.
+		 * For the moment we leave this here, since it works.
+		 */
+		usb_ep_disable(link->in_ep);
+		usb_ep_disable(link->out_ep);
+		if (netif_carrier_ok(net)) {
+			DBG(dev, "host still using in/out endpoints\n");
+			usb_ep_enable(link->in_ep, link->in);
+			usb_ep_enable(link->out_ep, link->out);
+		}
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* initial value, changed by "ifconfig usb0 hw ether xx:xx:xx:xx:xx:xx" */
+static char *dev_addr;
+module_param(dev_addr, charp, S_IRUGO);
+MODULE_PARM_DESC(dev_addr, "Device Ethernet Address");
+
+/* this address is invisible to ifconfig */
+static char *host_addr;
+module_param(host_addr, charp, S_IRUGO);
+MODULE_PARM_DESC(host_addr, "Host Ethernet Address");
+
+
+static u8 __init nibble(unsigned char c)
+{
+	if (isdigit(c))
+		return c - '0';
+	c = toupper(c);
+	if (isxdigit(c))
+		return 10 + c - 'A';
+	return 0;
+}
+
+static int __init get_ether_addr(const char *str, u8 *dev_addr)
+{
+	if (str) {
+		unsigned	i;
+
+		for (i = 0; i < 6; i++) {
+			unsigned char num;
+
+			if ((*str == '.') || (*str == ':'))
+				str++;
+			num = nibble(*str++) << 4;
+			num |= (nibble(*str++));
+			dev_addr [i] = num;
+		}
+		if (is_valid_ether_addr(dev_addr))
+			return 0;
+	}
+	random_ether_addr(dev_addr);
+	return 1;
+}
+
+static struct eth_dev *the_dev;
+
+
+/**
+ * gether_setup - initialize one ethernet-over-usb link
+ * @g: gadget to associated with these links
+ * @ethaddr: NULL, or a buffer in which the ethernet address of the
+ *	host side of the link is recorded
+ * Context: may sleep
+ *
+ * This sets up the single network link that may be exported by a
+ * gadget driver using this framework.  The link layer addresses are
+ * set up using module parameters.
+ *
+ * Returns negative errno, or zero on success
+ */
+int __init gether_setup(struct usb_gadget *g, u8 ethaddr[ETH_ALEN])
+{
+	struct eth_dev		*dev;
+	struct net_device	*net;
+	int			status;
+
+	if (the_dev)
+		return -EBUSY;
+
+	net = alloc_etherdev(sizeof *dev);
+	if (!net)
+		return -ENOMEM;
+
+	dev = netdev_priv(net);
+	spin_lock_init(&dev->lock);
+	spin_lock_init(&dev->req_lock);
+	INIT_WORK(&dev->work, eth_work);
+	INIT_LIST_HEAD(&dev->tx_reqs);
+	INIT_LIST_HEAD(&dev->rx_reqs);
+
+	/* network device setup */
+	dev->net = net;
+	strcpy(net->name, "usb%d");
+
+	if (get_ether_addr(dev_addr, net->dev_addr))
+		dev_warn(&g->dev,
+			"using random %s ethernet address\n", "self");
+	if (get_ether_addr(host_addr, dev->host_mac))
+		dev_warn(&g->dev,
+			"using random %s ethernet address\n", "host");
+
+	if (ethaddr)
+		memcpy(ethaddr, dev->host_mac, ETH_ALEN);
+
+	net->change_mtu = eth_change_mtu;
+	net->hard_start_xmit = eth_start_xmit;
+	net->open = eth_open;
+	net->stop = eth_stop;
+	/* watchdog_timeo, tx_timeout ... */
+	/* set_multicast_list */
+	SET_ETHTOOL_OPS(net, &ops);
+
+	/* two kinds of host-initiated state changes:
+	 *  - iff DATA transfer is active, carrier is "on"
+	 *  - tx queueing enabled if open *and* carrier is "on"
+	 */
+	netif_stop_queue(net);
+	netif_carrier_off(net);
+
+	dev->gadget = g;
+	SET_NETDEV_DEV(net, &g->dev);
+
+	status = register_netdev(net);
+	if (status < 0) {
+		dev_dbg(&g->dev, "register_netdev failed, %d\n", status);
+		free_netdev(net);
+	} else {
+		DECLARE_MAC_BUF(tmp);
+
+		INFO(dev, "MAC %s\n", print_mac(tmp, net->dev_addr));
+		INFO(dev, "HOST MAC %s\n", print_mac(tmp, dev->host_mac));
+
+		the_dev = dev;
+	}
+
+	return status;
+}
+
+/**
+ * gether_cleanup - remove Ethernet-over-USB device
+ * Context: may sleep
+ *
+ * This is called to free all resources allocated by @gether_setup().
+ */
+void gether_cleanup(void)
+{
+	if (!the_dev)
+		return;
+
+	unregister_netdev(the_dev->net);
+	free_netdev(the_dev->net);
+
+	/* assuming we used keventd, it must quiesce too */
+	flush_scheduled_work();
+
+	the_dev = NULL;
+}
+
+
+/**
+ * gether_connect - notify network layer that USB link is active
+ * @link: the USB link, set up with endpoints, descriptors matching
+ *	current device speed, and any framing wrapper(s) set up.
+ * Context: irqs blocked
+ *
+ * This is called to activate endpoints and let the network layer know
+ * the connection is active ("carrier detect").  It may cause the I/O
+ * queues to open and start letting network packets flow, but will in
+ * any case activate the endpoints so that they respond properly to the
+ * USB host.
+ *
+ * Verify net_device pointer returned using IS_ERR().  If it doesn't
+ * indicate some error code (negative errno), ep->driver_data values
+ * have been overwritten.
+ */
+struct net_device *gether_connect(struct gether *link)
+{
+	struct eth_dev		*dev = the_dev;
+	int			result = 0;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	link->in_ep->driver_data = dev;
+	result = usb_ep_enable(link->in_ep, link->in);
+	if (result != 0) {
+		DBG(dev, "enable %s --> %d\n",
+			link->in_ep->name, result);
+		goto fail0;
+	}
+
+	link->out_ep->driver_data = dev;
+	result = usb_ep_enable(link->out_ep, link->out);
+	if (result != 0) {
+		DBG(dev, "enable %s --> %d\n",
+			link->out_ep->name, result);
+		goto fail1;
+	}
+
+	if (result == 0)
+		result = alloc_requests(dev, link, qlen(dev->gadget));
+
+	if (result == 0) {
+		dev->zlp = link->is_zlp_ok;
+		DBG(dev, "qlen %d\n", qlen(dev->gadget));
+
+		dev->header_len = link->header_len;
+		dev->unwrap = link->unwrap;
+		dev->wrap = link->wrap;
+
+		spin_lock(&dev->lock);
+		dev->port_usb = link;
+		link->ioport = dev;
+		spin_unlock(&dev->lock);
+
+		netif_carrier_on(dev->net);
+		if (netif_running(dev->net))
+			eth_start(dev, GFP_ATOMIC);
+
+	/* on error, disable any endpoints  */
+	} else {
+		(void) usb_ep_disable(link->out_ep);
+fail1:
+		(void) usb_ep_disable(link->in_ep);
+	}
+fail0:
+	/* caller is responsible for cleanup on error */
+	if (result < 0)
+		return ERR_PTR(result);
+	return dev->net;
+}
+
+/**
+ * gether_disconnect - notify network layer that USB link is inactive
+ * @link: the USB link, on which gether_connect() was called
+ * Context: irqs blocked
+ *
+ * This is called to deactivate endpoints and let the network layer know
+ * the connection went inactive ("no carrier").
+ *
+ * On return, the state is as if gether_connect() had never been called.
+ * The endpoints are inactive, and accordingly without active USB I/O.
+ * Pointers to endpoint descriptors and endpoint private data are nulled.
+ */
+void gether_disconnect(struct gether *link)
+{
+	struct eth_dev		*dev = link->ioport;
+	struct usb_request	*req;
+
+	WARN_ON(!dev);
+	if (!dev)
+		return;
+
+	DBG(dev, "%s\n", __func__);
+
+	netif_stop_queue(dev->net);
+	netif_carrier_off(dev->net);
+
+	/* disable endpoints, forcing (synchronous) completion
+	 * of all pending i/o.  then free the request objects
+	 * and forget about the endpoints.
+	 */
+	usb_ep_disable(link->in_ep);
+	spin_lock(&dev->req_lock);
+	while (!list_empty(&dev->tx_reqs)) {
+		req = container_of(dev->tx_reqs.next,
+					struct usb_request, list);
+		list_del(&req->list);
+
+		spin_unlock(&dev->req_lock);
+		usb_ep_free_request(link->in_ep, req);
+		spin_lock(&dev->req_lock);
+	}
+	spin_unlock(&dev->req_lock);
+	link->in_ep->driver_data = NULL;
+	link->in = NULL;
+
+	usb_ep_disable(link->out_ep);
+	spin_lock(&dev->req_lock);
+	while (!list_empty(&dev->rx_reqs)) {
+		req = container_of(dev->rx_reqs.next,
+					struct usb_request, list);
+		list_del(&req->list);
+
+		spin_unlock(&dev->req_lock);
+		usb_ep_free_request(link->out_ep, req);
+		spin_lock(&dev->req_lock);
+	}
+	spin_unlock(&dev->req_lock);
+	link->out_ep->driver_data = NULL;
+	link->out = NULL;
+
+	/* finish forgetting about this USB link episode */
+	dev->header_len = 0;
+	dev->unwrap = NULL;
+	dev->wrap = NULL;
+
+	spin_lock(&dev->lock);
+	dev->port_usb = NULL;
+	link->ioport = NULL;
+	spin_unlock(&dev->lock);
+}