text: /*
   * 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.
   */
  
  /* #define VERBOSE_DEBUG */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/gfp.h>
  #include <linux/device.h>
  #include <linux/ctype.h>
  #include <linux/etherdevice.h>
  #include <linux/ethtool.h>
  #include <linux/if_vlan.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 (ECM or EEM),
   * "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 UETH__VERSION	"29-May-2008"
  
  struct eth_dev {
  	/* lock is held while accessing port_usb
  	 */
  	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;
  
  	struct sk_buff_head	rx_frames;
  
  	unsigned		qmult;
  
  	unsigned		header_len;
  	struct sk_buff		*(*wrap)(struct gether *, struct sk_buff *skb);
  	int			(*unwrap)(struct gether *,
  						struct sk_buff *skb,
  						struct sk_buff_head *list);
  
  	struct work_struct	work;
  
  	unsigned long		todo;
  #define	WORK_RX_MEMORY		0
  
  	bool			zlp;
  	u8			host_mac[ETH_ALEN];
  	u8			dev_mac[ETH_ALEN];
  };
  
  /*-------------------------------------------------------------------------*/
  
  #define RX_EXTRA	20	/* bytes guarding against rx overflows */
  
  #define DEFAULT_QLEN	2	/* double buffering by default */
  
  /* for dual-speed hardware, use deeper queues at high/super speed */
  static inline int qlen(struct usb_gadget *gadget, unsigned qmult)
  {
  	if (gadget_is_dualspeed(gadget) && (gadget->speed == USB_SPEED_HIGH ||
  					    gadget->speed == USB_SPEED_SUPER))
  		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 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 INFO(dev, fmt, args...) \
  	xprintk(dev , KERN_INFO , fmt , ## args)
  
  /*-------------------------------------------------------------------------*/
  
  /* NETWORK DRIVER HOOKUP (to the layer above this driver) */
  
  static int ueth_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, UETH__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));
  }
  
  /* REVISIT can also support:
   *   - WOL (by tracking suspends and issuing remote wakeup)
   *   - msglevel (implies updated messaging)
   *   - ... probably more ethtool ops
   */
  
  static const struct ethtool_ops ops = {
  	.get_drvinfo = eth_get_drvinfo,
  	.get_link = ethtool_op_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;
  
  	if (dev->port_usb->is_fixed)
  		size = max_t(size_t, size, dev->port_usb->fixed_out_len);
  
  	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, *skb2;
  	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) {
  			unsigned long	flags;
  
  			spin_lock_irqsave(&dev->lock, flags);
  			if (dev->port_usb) {
  				status = dev->unwrap(dev->port_usb,
  							skb,
  							&dev->rx_frames);
  			} else {
  				dev_kfree_skb_any(skb);
  				status = -ENOTCONN;
  			}
  			spin_unlock_irqrestore(&dev->lock, flags);
  		} else {
  			skb_queue_tail(&dev->rx_frames, skb);
  		}
  		skb = NULL;
  
  		skb2 = skb_dequeue(&dev->rx_frames);
  		while (skb2) {
  			if (status < 0
  					|| ETH_HLEN > skb2->len
  					|| skb2->len > VLAN_ETH_FRAME_LEN) {
  				dev->net->stats.rx_errors++;
  				dev->net->stats.rx_length_errors++;
  				DBG(dev, "rx length %d\n", skb2->len);
  				dev_kfree_skb_any(skb2);
  				goto next_frame;
  			}
  			skb2->protocol = eth_type_trans(skb2, dev->net);
  			dev->net->stats.rx_packets++;
  			dev->net->stats.rx_bytes += skb2->len;
  
  			/* no buffer copies needed, unless hardware can't
  			 * use skb buffers.
  			 */
  			status = netif_rx(skb2);
  next_frame:
  			skb2 = skb_dequeue(&dev->rx_frames);
  		}
  		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 netdev_tx_t 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 NETDEV_TX_OK;
  	}
  
  	/* 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 NETDEV_TX_OK;
  			}
  		}
  		/* 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 NETDEV_TX_BUSY;
  	}
  
  	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) {
  		unsigned long	flags;
  
  		spin_lock_irqsave(&dev->lock, flags);
  		if (dev->port_usb)
  			skb = dev->wrap(dev->port_usb, skb);
  		spin_unlock_irqrestore(&dev->lock, flags);
  		if (!skb)
  			goto drop;
  
  		length = skb->len;
  	}
  	req->buf = skb->data;
  	req->context = skb;
  	req->complete = tx_complete;
  
  	/* NCM requires no zlp if transfer is dwNtbInMaxSize */
  	if (dev->port_usb->is_fixed &&
  	    length == dev->port_usb->fixed_in_len &&
  	    (length % in->maxpacket) == 0)
  		req->zero = 0;
  	else
  		req->zero = 1;
  
  	/* 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.
  	 */
  	if (req->zero && !dev->zlp && (length % in->maxpacket) == 0)
  		length++;
  
  	req->length = length;
  
  	/* throttle high/super speed IRQ rate back slightly */
  	if (gadget_is_dualspeed(dev->gadget))
  		req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH ||
  				     dev->gadget->speed == USB_SPEED_SUPER)
  			? ((atomic_read(&dev->tx_qlen) % dev->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) {
  		dev_kfree_skb_any(skb);
  drop:
  		dev->net->stats.tx_dropped++;
  		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 NETDEV_TX_OK;
  }
  
  /*-------------------------------------------------------------------------*/
  
  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;
  		const struct usb_endpoint_descriptor *in;
  		const struct usb_endpoint_descriptor *out;
  
  		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.
  		 */
  		in = link->in_ep->desc;
  		out = link->out_ep->desc;
  		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");
  			link->in_ep->desc = in;
  			link->out_ep->desc = out;
  			usb_ep_enable(link->in_ep);
  			usb_ep_enable(link->out_ep);
  		}
  	}
  	spin_unlock_irqrestore(&dev->lock, flags);
  
  	return 0;
  }
  
  /*-------------------------------------------------------------------------*/
  
  static int 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 = hex_to_bin(*str++) << 4;
  			num |= hex_to_bin(*str++);
  			dev_addr [i] = num;
  		}
  		if (is_valid_ether_addr(dev_addr))
  			return 0;
  	}
  	eth_random_addr(dev_addr);
  	return 1;
  }
  
  static int get_ether_addr_str(u8 dev_addr[ETH_ALEN], char *str, int len)
  {
  	if (len < 18)
  		return -EINVAL;
  
  	snprintf(str, len, "%02x:%02x:%02x:%02x:%02x:%02x",
  		 dev_addr[0], dev_addr[1], dev_addr[2],
  		 dev_addr[3], dev_addr[4], dev_addr[5]);
  	return 18;
  }
  
  static const struct net_device_ops eth_netdev_ops = {
  	.ndo_open		= eth_open,
  	.ndo_stop		= eth_stop,
  	.ndo_start_xmit		= eth_start_xmit,
  	.ndo_change_mtu		= ueth_change_mtu,
  	.ndo_set_mac_address 	= eth_mac_addr,
  	.ndo_validate_addr	= eth_validate_addr,
  };
  
  static struct device_type gadget_type = {
  	.name	= "gadget",
  };
  
  /**
   * gether_setup_name - 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
   * @netname: name for network device (for example, "usb")
   * 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 an eth_dev pointer on success, or an ERR_PTR on failure.
   */
  struct eth_dev *gether_setup_name(struct usb_gadget *g,
  		const char *dev_addr, const char *host_addr,
  		u8 ethaddr[ETH_ALEN], unsigned qmult, const char *netname)
  {
  	struct eth_dev		*dev;
  	struct net_device	*net;
  	int			status;
  
  	net = alloc_etherdev(sizeof *dev);
  	if (!net)
  		return ERR_PTR(-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);
  
  	skb_queue_head_init(&dev->rx_frames);
  
  	/* network device setup */
  	dev->net = net;
  	dev->qmult = qmult;
  	snprintf(net->name, sizeof(net->name), "%s%%d", netname);
  
  	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->netdev_ops = &eth_netdev_ops;
  
  	SET_ETHTOOL_OPS(net, &ops);
  
  	dev->gadget = g;
  	SET_NETDEV_DEV(net, &g->dev);
  	SET_NETDEV_DEVTYPE(net, &gadget_type);
  
  	status = register_netdev(net);
  	if (status < 0) {
  		dev_dbg(&g->dev, "register_netdev failed, %d\n", status);
  		free_netdev(net);
  		dev = ERR_PTR(status);
  	} else {
  		INFO(dev, "MAC %pM\n", net->dev_addr);
  		INFO(dev, "HOST MAC %pM\n", dev->host_mac);
  
  		/*
  		 * 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_carrier_off(net);
  	}
  
  	return dev;
  }
  EXPORT_SYMBOL(gether_setup_name);
  
  struct net_device *gether_setup_name_default(const char *netname)
  {
  	struct net_device	*net;
  	struct eth_dev		*dev;
  
  	net = alloc_etherdev(sizeof(*dev));
  	if (!net)
  		return ERR_PTR(-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);
  
  	skb_queue_head_init(&dev->rx_frames);
  
  	/* network device setup */
  	dev->net = net;
  	dev->qmult = QMULT_DEFAULT;
  	snprintf(net->name, sizeof(net->name), "%s%%d", netname);
  
  	eth_random_addr(dev->dev_mac);
  	pr_warn("using random %s ethernet address\n", "self");
  	eth_random_addr(dev->host_mac);
  	pr_warn("using random %s ethernet address\n", "host");
  
  	net->netdev_ops = &eth_netdev_ops;
  
  	SET_ETHTOOL_OPS(net, &ops);
  	SET_NETDEV_DEVTYPE(net, &gadget_type);
  
  	return net;
  }
  EXPORT_SYMBOL(gether_setup_name_default);
  
  int gether_register_netdev(struct net_device *net)
  {
  	struct eth_dev *dev;
  	struct usb_gadget *g;
  	struct sockaddr sa;
  	int status;
  
  	if (!net->dev.parent)
  		return -EINVAL;
  	dev = netdev_priv(net);
  	g = dev->gadget;
  	status = register_netdev(net);
  	if (status < 0) {
  		dev_dbg(&g->dev, "register_netdev failed, %d\n", status);
  		return status;
  	} else {
  		INFO(dev, "HOST MAC %pM\n", dev->host_mac);
  
  		/* 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_carrier_off(net);
  	}
  	sa.sa_family = net->type;
  	memcpy(sa.sa_data, dev->dev_mac, ETH_ALEN);
  	rtnl_lock();
  	status = dev_set_mac_address(net, &sa);
  	rtnl_unlock();
  	if (status)
  		pr_warn("cannot set self ethernet address: %d\n", status);
  	else
  		INFO(dev, "MAC %pM\n", dev->dev_mac);
  
  	return status;
  }
  EXPORT_SYMBOL(gether_register_netdev);
  
  void gether_set_gadget(struct net_device *net, struct usb_gadget *g)
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	dev->gadget = g;
  	SET_NETDEV_DEV(net, &g->dev);
  }
  EXPORT_SYMBOL(gether_set_gadget);
  
  int gether_set_dev_addr(struct net_device *net, const char *dev_addr)
  {
  	struct eth_dev *dev;
  	u8 new_addr[ETH_ALEN];
  
  	dev = netdev_priv(net);
  	if (get_ether_addr(dev_addr, new_addr))
  		return -EINVAL;
  	memcpy(dev->dev_mac, new_addr, ETH_ALEN);
  	return 0;
  }
  EXPORT_SYMBOL(gether_set_dev_addr);
  
  int gether_get_dev_addr(struct net_device *net, char *dev_addr, int len)
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	return get_ether_addr_str(dev->dev_mac, dev_addr, len);
  }
  EXPORT_SYMBOL(gether_get_dev_addr);
  
  int gether_set_host_addr(struct net_device *net, const char *host_addr)
  {
  	struct eth_dev *dev;
  	u8 new_addr[ETH_ALEN];
  
  	dev = netdev_priv(net);
  	if (get_ether_addr(host_addr, new_addr))
  		return -EINVAL;
  	memcpy(dev->host_mac, new_addr, ETH_ALEN);
  	return 0;
  }
  EXPORT_SYMBOL(gether_set_host_addr);
  
  int gether_get_host_addr(struct net_device *net, char *host_addr, int len)
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	return get_ether_addr_str(dev->host_mac, host_addr, len);
  }
  EXPORT_SYMBOL(gether_get_host_addr);
  
  int gether_get_host_addr_cdc(struct net_device *net, char *host_addr, int len)
  {
  	struct eth_dev *dev;
  
  	if (len < 13)
  		return -EINVAL;
  
  	dev = netdev_priv(net);
  	snprintf(host_addr, len, "%pm", dev->host_mac);
  
  	return strlen(host_addr);
  }
  EXPORT_SYMBOL(gether_get_host_addr_cdc);
  
  void gether_get_host_addr_u8(struct net_device *net, u8 host_mac[ETH_ALEN])
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	memcpy(host_mac, dev->host_mac, ETH_ALEN);
  }
  EXPORT_SYMBOL(gether_get_host_addr_u8);
  
  void gether_set_qmult(struct net_device *net, unsigned qmult)
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	dev->qmult = qmult;
  }
  EXPORT_SYMBOL(gether_set_qmult);
  
  unsigned gether_get_qmult(struct net_device *net)
  {
  	struct eth_dev *dev;
  
  	dev = netdev_priv(net);
  	return dev->qmult;
  }
  EXPORT_SYMBOL(gether_get_qmult);
  
  int gether_get_ifname(struct net_device *net, char *name, int len)
  {
  	rtnl_lock();
  	strlcpy(name, netdev_name(net), len);
  	rtnl_unlock();
  	return strlen(name);
  }
  EXPORT_SYMBOL(gether_get_ifname);
  
  /**
   * gether_cleanup - remove Ethernet-over-USB device
   * Context: may sleep
   *
   * This is called to free all resources allocated by @gether_setup().
   */
  void gether_cleanup(struct eth_dev *dev)
  {
  	if (!dev)
  		return;
  
  	unregister_netdev(dev->net);
  	flush_work(&dev->work);
  	free_netdev(dev->net);
  }
  EXPORT_SYMBOL(gether_cleanup);
  
  /**
   * 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 = link->ioport;
  	int			result = 0;
  
  	if (!dev)
  		return ERR_PTR(-EINVAL);
  
  	link->in_ep->driver_data = dev;
  	result = usb_ep_enable(link->in_ep);
  	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);
  	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,
  					dev->qmult));
  
  	if (result == 0) {
  		dev->zlp = link->is_zlp_ok;
  		DBG(dev, "qlen %d\n", qlen(dev->gadget, dev->qmult));
  
  		dev->header_len = link->header_len;
  		dev->unwrap = link->unwrap;
  		dev->wrap = link->wrap;
  
  		spin_lock(&dev->lock);
  		dev->port_usb = link;
  		if (netif_running(dev->net)) {
  			if (link->open)
  				link->open(link);
  		} else {
  			if (link->close)
  				link->close(link);
  		}
  		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;
  }
  EXPORT_SYMBOL(gether_connect);
  
  /**
   * 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_ep->desc = 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_ep->desc = 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;
  	spin_unlock(&dev->lock);
  }
  EXPORT_SYMBOL(gether_disconnect);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("David Brownell");
  