diff mbox

USB host CDC Phonet network interface driver

Message ID 1247824566-9141-1-git-send-email-remi.denis-courmont@nokia.com
State Superseded, archived
Delegated to: David Miller
Headers show

Commit Message

Rémi Denis-Courmont July 17, 2009, 9:56 a.m. UTC
From: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>

Many Nokia handsets support a Phonet interface to the cellular modem
via a vendor-specific USB interface. CDC Phonet follows the
Communications Device Class model, with one control interface, and
and a pair of inactive and active data alternative interface. The later
has two bulk endpoint, one per direction.

This was tested against Nokia E61, Nokia N95, and the existing Phonet
gadget function for the Linux composite USB gadget framework.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
---
 drivers/net/usb/Kconfig      |    8 +
 drivers/net/usb/Makefile     |    1 +
 drivers/net/usb/cdc-phonet.c |  454 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 463 insertions(+), 0 deletions(-)
 create mode 100644 drivers/net/usb/cdc-phonet.c

Comments

Oliver Neukum July 17, 2009, 1:47 p.m. UTC | #1
Am Freitag, 17. Juli 2009 11:56:06 schrieb Rémi Denis-Courmont:
> +       atomic_dec(&pnd->tx_queue);
> +       netif_wake_queue(dev);

Now that I think about it this seems to be a race condition.
What makes sure that your are still below the limit when you
wake the queue?

	Regards
		Oliver


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Rémi Denis-Courmont July 20, 2009, 6:35 a.m. UTC | #2
On Friday 17 July 2009 16:47:38 ext Oliver Neukum wrote:
> Am Freitag, 17. Juli 2009 11:56:06 schrieb Rémi Denis-Courmont:
> > +       atomic_dec(&pnd->tx_queue);
> > +       netif_wake_queue(dev);
>
> Now that I think about it this seems to be a race condition.
> What makes sure that your are still below the limit when you
> wake the queue?

The netif TX queue serializes usbpn_xmit() against itself. Then, at all times: 
tx_queue + !netif_queue_stopped() <= tx_queue_len (in other words either 
tx_queue = tx_queue_len and queue is stopped, or tx_queue < tx_queue_len).

Initially:
0 + 1 <= tx_queue_len, the assertion is initially true.

Recurrently:
If usbpn_xmit() is called, then the queue was not stopped, so tx_queue < 
tx_queue_len. Then the queue is stopped. In the race free cases, either 
tx_queue is incremented up to the limit, and the queue remains stopped; the 
assertion is still valid.
Alternatively tx_queue remains below limit and the queue gets woken again; the 
assertion is still valid.

In the racy case, tx_complete() fires, incrementation in usbpn_xmit() and 
decrementation in tx_complete() will cancel each other. So, regardless of 
their respective order, tx_queue will be unchanged, and the assertion remains 
valid. A fortiori, it works fine if usbpn_xmit() races with more than one call 
of tx_complete().

The cases that tx_complete() runs while the queue is not transmitting is 
evident.
Oliver Neukum July 20, 2009, 6:41 a.m. UTC | #3
Am Montag, 20. Juli 2009 08:35:18 schrieb Rémi Denis-Courmont:
> Recurrently:
> If usbpn_xmit() is called, then the queue was not stopped, so tx_queue <
> tx_queue_len. Then the queue is stopped. In the race free cases, either
> tx_queue is incremented up to the limit, and the queue remains stopped; the
> assertion is still valid.
> Alternatively tx_queue remains below limit and the queue gets woken again;
> the assertion is still valid.

Yes, you are correct. I find no flaws with the driver.

	Regards
		Oliver

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
David Miller July 20, 2009, 2:55 p.m. UTC | #4
From: "Rémi Denis-Courmont" <remi.denis-courmont@nokia.com>
Date: Mon, 20 Jul 2009 09:35:18 +0300

> In the racy case, tx_complete() fires, incrementation in
> usbpn_xmit() and decrementation in tx_complete() will cancel each
> other. So, regardless of their respective order, tx_queue will be
> unchanged, and the assertion remains valid. A fortiori, it works
> fine if usbpn_xmit() races with more than one call of tx_complete().

You can only do the wakeup race free without deadlocking the TX queue
state if you grab the TX path lock, as TG3 does:

	/* Need to make the tx_cons update visible to tg3_start_xmit()
	 * before checking for netif_queue_stopped().  Without the
	 * memory barrier, there is a small possibility that tg3_start_xmit()
	 * will miss it and cause the queue to be stopped forever.
	 */
	smp_mb();

	if (unlikely(netif_queue_stopped(tp->dev) &&
		     (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp)))) {
		netif_tx_lock(tp->dev);
		if (netif_queue_stopped(tp->dev) &&
		    (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp)))
			netif_wake_queue(tp->dev);
		netif_tx_unlock(tp->dev);
	}
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
David Miller July 21, 2009, 7:42 p.m. UTC | #5
From: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Date: Fri, 17 Jul 2009 12:56:06 +0300

> From: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
> 
> Many Nokia handsets support a Phonet interface to the cellular modem
> via a vendor-specific USB interface. CDC Phonet follows the
> Communications Device Class model, with one control interface, and
> and a pair of inactive and active data alternative interface. The later
> has two bulk endpoint, one per direction.
> 
> This was tested against Nokia E61, Nokia N95, and the existing Phonet
> gadget function for the Linux composite USB gadget framework.
> 
> Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>

Applied, thanks.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Marcel Holtmann July 21, 2009, 8:14 p.m. UTC | #6
Hi Dave,

> > Many Nokia handsets support a Phonet interface to the cellular modem
> > via a vendor-specific USB interface. CDC Phonet follows the
> > Communications Device Class model, with one control interface, and
> > and a pair of inactive and active data alternative interface. The later
> > has two bulk endpoint, one per direction.
> > 
> > This was tested against Nokia E61, Nokia N95, and the existing Phonet
> > gadget function for the Linux composite USB gadget framework.
> > 
> > Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
> 
> Applied, thanks.

I think that Remi sent an updated version today.

Regards

Marcel


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
David Miller July 21, 2009, 8:18 p.m. UTC | #7
From: Marcel Holtmann <marcel@holtmann.org>
Date: Tue, 21 Jul 2009 22:14:00 +0200

> Hi Dave,
> 
>> > Many Nokia handsets support a Phonet interface to the cellular modem
>> > via a vendor-specific USB interface. CDC Phonet follows the
>> > Communications Device Class model, with one control interface, and
>> > and a pair of inactive and active data alternative interface. The later
>> > has two bulk endpoint, one per direction.
>> > 
>> > This was tested against Nokia E61, Nokia N95, and the existing Phonet
>> > gadget function for the Linux composite USB gadget framework.
>> > 
>> > Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
>> 
>> Applied, thanks.
> 
> I think that Remi sent an updated version today.

I'm pretty sure I applied the updated patch.

I'll double check to make sure.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Marcel Holtmann July 21, 2009, 8:20 p.m. UTC | #8
Hi Dave,

> >> > Many Nokia handsets support a Phonet interface to the cellular modem
> >> > via a vendor-specific USB interface. CDC Phonet follows the
> >> > Communications Device Class model, with one control interface, and
> >> > and a pair of inactive and active data alternative interface. The later
> >> > has two bulk endpoint, one per direction.
> >> > 
> >> > This was tested against Nokia E61, Nokia N95, and the existing Phonet
> >> > gadget function for the Linux composite USB gadget framework.
> >> > 
> >> > Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
> >> 
> >> Applied, thanks.
> > 
> > I think that Remi sent an updated version today.
> 
> I'm pretty sure I applied the updated patch.
> 
> I'll double check to make sure.

I only mentioned it because your reply is to this patch and not the
other one from today. He sent 3 versions of it if I am not mis-counting.

Regards

Marcel


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
David Miller July 21, 2009, 8:20 p.m. UTC | #9
From: David Miller <davem@davemloft.net>
Date: Tue, 21 Jul 2009 13:18:16 -0700 (PDT)

> From: Marcel Holtmann <marcel@holtmann.org>
> Date: Tue, 21 Jul 2009 22:14:00 +0200
> 
>> Hi Dave,
>> 
>>> > Many Nokia handsets support a Phonet interface to the cellular modem
>>> > via a vendor-specific USB interface. CDC Phonet follows the
>>> > Communications Device Class model, with one control interface, and
>>> > and a pair of inactive and active data alternative interface. The later
>>> > has two bulk endpoint, one per direction.
>>> > 
>>> > This was tested against Nokia E61, Nokia N95, and the existing Phonet
>>> > gadget function for the Linux composite USB gadget framework.
>>> > 
>>> > Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
>>> 
>>> Applied, thanks.
>> 
>> I think that Remi sent an updated version today.
> 
> I'm pretty sure I applied the updated patch.
> 
> I'll double check to make sure.

I did apply the correct patch.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Rémi Denis-Courmont July 22, 2009, 6:57 a.m. UTC | #10
On Tuesday 21 July 2009 23:18:16 ext David Miller wrote:
> >> Applied, thanks.
> >
> > I think that Remi sent an updated version today.
>
> I'm pretty sure I applied the updated patch.
>
> I'll double check to make sure.

I guess I should put updated version as answers to older ones then?

Thanks every one for the reviews anyway!
diff mbox

Patch

diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index a906d39..c47237c 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -369,4 +369,12 @@  config USB_NET_INT51X1
 	  (Powerline Communications) solution with an Intellon
 	  INT51x1/INT5200 chip, like the "devolo dLan duo".
 
+config USB_CDC_PHONET
+	tristate "CDC Phonet support"
+	depends on PHONET
+	help
+	  Choose this option to support the Phonet interface to a Nokia
+	  cellular modem, as found on most Nokia handsets with the
+	  "PC suite" USB profile.
+
 endmenu
diff --git a/drivers/net/usb/Makefile b/drivers/net/usb/Makefile
index b870b0b..e17afb7 100644
--- a/drivers/net/usb/Makefile
+++ b/drivers/net/usb/Makefile
@@ -21,4 +21,5 @@  obj-$(CONFIG_USB_NET_ZAURUS)	+= zaurus.o
 obj-$(CONFIG_USB_NET_MCS7830)	+= mcs7830.o
 obj-$(CONFIG_USB_USBNET)	+= usbnet.o
 obj-$(CONFIG_USB_NET_INT51X1)	+= int51x1.o
+obj-$(CONFIG_USB_CDC_PHONET)	+= cdc-phonet.o
 
diff --git a/drivers/net/usb/cdc-phonet.c b/drivers/net/usb/cdc-phonet.c
new file mode 100644
index 0000000..a22d2c9
--- /dev/null
+++ b/drivers/net/usb/cdc-phonet.c
@@ -0,0 +1,454 @@ 
+/*
+ * phonet.c -- USB CDC Phonet host driver
+ *
+ * Copyright (C) 2008-2009 Nokia Corporation. All rights reserved.
+ *
+ * Author: Rémi Denis-Courmont
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/cdc.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/if_phonet.h>
+
+#define PN_MEDIA_USB	0x1B
+
+static const unsigned rxq_size = 17;
+
+struct usbpn_dev {
+	struct net_device	*dev;
+	atomic_t		tx_queue;
+
+	struct usb_interface	*intf, *data_intf;
+	struct usb_device	*usb;
+	unsigned int		tx_pipe, rx_pipe;
+	u8 active_setting;
+	u8 disconnected;
+
+	spinlock_t		rx_lock;
+	struct sk_buff		*rx_skb;
+	struct urb		*urbs[0];
+};
+
+static void tx_complete(struct urb *req);
+static void rx_complete(struct urb *req);
+
+/*
+ * Network device callbacks
+ */
+static int usbpn_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct usbpn_dev *pnd = netdev_priv(dev);
+	struct urb *req = NULL;
+	int err;
+
+	if (skb->protocol != htons(ETH_P_PHONET))
+		goto drop;
+
+	req = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!req)
+		goto drop;
+	usb_fill_bulk_urb(req, pnd->usb, pnd->tx_pipe, skb->data, skb->len,
+				tx_complete, skb);
+	req->transfer_flags = URB_ZERO_PACKET;
+	err = usb_submit_urb(req, GFP_ATOMIC);
+	if (err) {
+		usb_free_urb(req);
+		goto drop;
+	}
+
+	netif_stop_queue(dev);
+	if (atomic_inc_return(&pnd->tx_queue) < dev->tx_queue_len)
+		netif_wake_queue(dev);
+	return 0;
+
+drop:
+	dev_kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return 0;
+}
+
+static void tx_complete(struct urb *req)
+{
+	struct sk_buff *skb = req->context;
+	struct net_device *dev = skb->dev;
+	struct usbpn_dev *pnd = netdev_priv(dev);
+
+	switch (req->status) {
+	case 0:
+		dev->stats.tx_bytes += skb->len;
+		break;
+
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		dev->stats.tx_aborted_errors++;
+	default:
+		dev->stats.tx_errors++;
+		dev_dbg(&dev->dev, "TX error (%d)\n", req->status);
+	}
+	dev->stats.tx_packets++;
+
+	atomic_dec(&pnd->tx_queue);
+	netif_wake_queue(dev);
+
+	dev_kfree_skb_any(skb);
+	usb_free_urb(req);
+}
+
+static int rx_submit(struct usbpn_dev *pnd, struct urb *req, gfp_t gfp_flags)
+{
+	struct net_device *dev = pnd->dev;
+	struct page *page;
+	int err;
+
+	page = __netdev_alloc_page(dev, gfp_flags);
+	if (!page)
+		return -ENOMEM;
+
+	usb_fill_bulk_urb(req, pnd->usb, pnd->rx_pipe, page_address(page),
+				PAGE_SIZE, rx_complete, dev);
+	req->transfer_flags = 0;
+	err = usb_submit_urb(req, gfp_flags);
+	if (unlikely(err)) {
+		dev_dbg(&dev->dev, "RX submit error (%d)\n", err);
+		netdev_free_page(dev, page);
+	}
+	return err;
+}
+
+static void rx_complete(struct urb *req)
+{
+	struct net_device *dev = req->context;
+	struct usbpn_dev *pnd = netdev_priv(dev);
+	struct page *page = virt_to_page(req->transfer_buffer);
+	struct sk_buff *skb;
+	unsigned long flags;
+
+	switch (req->status) {
+	case 0:
+		spin_lock_irqsave(&pnd->rx_lock, flags);
+		skb = pnd->rx_skb;
+		if (!skb) {
+			skb = pnd->rx_skb = netdev_alloc_skb(dev, 12);
+			if (likely(skb)) {
+				/* Can't use pskb_pull() on page in IRQ */
+				memcpy(skb_put(skb, 1), page_address(page), 1);
+				skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+						page, 1, req->actual_length);
+				page = NULL;
+			}
+		} else {
+			skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+					page, 0, req->actual_length);
+			page = NULL;
+		}
+		if (req->actual_length < PAGE_SIZE)
+			pnd->rx_skb = NULL; /* Last fragment */
+		else
+			skb = NULL;
+		spin_unlock_irqrestore(&pnd->rx_lock, flags);
+		if (skb) {
+			skb->protocol = htons(ETH_P_PHONET);
+			skb_reset_mac_header(skb);
+			__skb_pull(skb, 1);
+			skb->dev = dev;
+			dev->stats.rx_packets++;
+			dev->stats.rx_bytes += skb->len;
+
+			netif_rx(skb);
+		}
+		goto resubmit;
+
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		req = NULL;
+		break;
+
+	case -EOVERFLOW:
+		dev->stats.rx_over_errors++;
+		dev_dbg(&dev->dev, "RX overflow\n");
+		break;
+
+	case -EILSEQ:
+		dev->stats.rx_crc_errors++;
+		break;
+	}
+
+	dev->stats.rx_errors++;
+resubmit:
+	if (page)
+		netdev_free_page(dev, page);
+	if (req)
+		rx_submit(pnd, req, GFP_ATOMIC);
+}
+
+static int usbpn_close(struct net_device *dev);
+
+static int usbpn_open(struct net_device *dev)
+{
+	struct usbpn_dev *pnd = netdev_priv(dev);
+	int err;
+	unsigned i;
+	unsigned num = pnd->data_intf->cur_altsetting->desc.bInterfaceNumber;
+
+	err = usb_set_interface(pnd->usb, num, pnd->active_setting);
+	if (err)
+		return err;
+
+	for (i = 0; i < rxq_size; i++) {
+		struct urb *req = usb_alloc_urb(0, GFP_KERNEL);
+
+		if (!req || rx_submit(pnd, req, GFP_KERNEL)) {
+			usbpn_close(dev);
+			return -ENOMEM;
+		}
+		pnd->urbs[i] = req;
+	}
+
+	netif_wake_queue(dev);
+	return 0;
+}
+
+static int usbpn_close(struct net_device *dev)
+{
+	struct usbpn_dev *pnd = netdev_priv(dev);
+	unsigned i;
+	unsigned num = pnd->data_intf->cur_altsetting->desc.bInterfaceNumber;
+
+	netif_stop_queue(dev);
+
+	for (i = 0; i < rxq_size; i++) {
+		struct urb *req = pnd->urbs[i];
+
+		if (!req)
+			continue;
+		usb_kill_urb(req);
+		usb_free_urb(req);
+		pnd->urbs[i] = NULL;
+	}
+
+	return usb_set_interface(pnd->usb, num, !pnd->active_setting);
+}
+
+static int usbpn_set_mtu(struct net_device *dev, int new_mtu)
+{
+	if ((new_mtu < PHONET_MIN_MTU) || (new_mtu > PHONET_MAX_MTU))
+		return -EINVAL;
+
+	dev->mtu = new_mtu;
+	return 0;
+}
+
+static const struct net_device_ops usbpn_ops = {
+	.ndo_open	= usbpn_open,
+	.ndo_stop	= usbpn_close,
+	.ndo_start_xmit = usbpn_xmit,
+	.ndo_change_mtu = usbpn_set_mtu,
+};
+
+static void usbpn_setup(struct net_device *dev)
+{
+	dev->features		= 0;
+	dev->netdev_ops		= &usbpn_ops,
+	dev->header_ops		= &phonet_header_ops;
+	dev->type		= ARPHRD_PHONET;
+	dev->flags		= IFF_POINTOPOINT | IFF_NOARP;
+	dev->mtu		= PHONET_MAX_MTU;
+	dev->hard_header_len	= 1;
+	dev->dev_addr[0]	= PN_MEDIA_USB;
+	dev->addr_len		= 1;
+	dev->tx_queue_len	= 3;
+
+	dev->destructor		= free_netdev;
+}
+
+/*
+ * USB driver callbacks
+ */
+static struct usb_device_id usbpn_ids[] = {
+	{
+		.match_flags = USB_DEVICE_ID_MATCH_VENDOR
+			| USB_DEVICE_ID_MATCH_INT_CLASS
+			| USB_DEVICE_ID_MATCH_INT_SUBCLASS,
+		.idVendor = 0x0421, /* Nokia */
+		.bInterfaceClass = USB_CLASS_COMM,
+		.bInterfaceSubClass = 0xFE,
+	},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(usb, usbpn_ids);
+
+static struct usb_driver usbpn_driver;
+
+int usbpn_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	static const char ifname[] = "usbpn%d";
+	const struct usb_cdc_union_desc *union_header = NULL;
+	const struct usb_cdc_header_desc *phonet_header = NULL;
+	const struct usb_host_interface *data_desc;
+	struct usb_interface *data_intf;
+	struct usb_device *usbdev = interface_to_usbdev(intf);
+	struct net_device *dev;
+	struct usbpn_dev *pnd;
+	u8 *data;
+	int len, err;
+
+	data = intf->altsetting->extra;
+	len = intf->altsetting->extralen;
+	while (len >= 3) {
+		u8 dlen = data[0];
+		if (dlen < 3)
+			return -EINVAL;
+
+		/* bDescriptorType */
+		if (data[1] == USB_DT_CS_INTERFACE) {
+			/* bDescriptorSubType */
+			switch (data[2]) {
+			case USB_CDC_UNION_TYPE:
+				if (union_header || dlen < 5)
+					break;
+				union_header =
+					(struct usb_cdc_union_desc *)data;
+				break;
+			case 0xAB:
+				if (phonet_header || dlen < 5)
+					break;
+				phonet_header =
+					(struct usb_cdc_header_desc *)data;
+				break;
+			}
+		}
+		data += dlen;
+		len -= dlen;
+	}
+
+	if (!union_header || !phonet_header)
+		return -EINVAL;
+
+	data_intf = usb_ifnum_to_if(usbdev, union_header->bSlaveInterface0);
+	if (data_intf == NULL)
+		return -ENODEV;
+	/* Data interface has one inactive and one active setting */
+	if (data_intf->num_altsetting != 2)
+		return -EINVAL;
+	if (data_intf->altsetting[0].desc.bNumEndpoints == 0
+	 && data_intf->altsetting[1].desc.bNumEndpoints == 2)
+		data_desc = data_intf->altsetting + 1;
+	else
+	if (data_intf->altsetting[0].desc.bNumEndpoints == 2
+	 && data_intf->altsetting[1].desc.bNumEndpoints == 0)
+		data_desc = data_intf->altsetting;
+	else
+		return -EINVAL;
+
+	dev = alloc_netdev(sizeof(*pnd) + sizeof(pnd->urbs[0]) * rxq_size,
+				ifname, usbpn_setup);
+	if (!dev)
+		return -ENOMEM;
+
+	pnd = netdev_priv(dev);
+	SET_NETDEV_DEV(dev, &intf->dev);
+	netif_stop_queue(dev);
+
+	pnd->dev = dev;
+	atomic_set(&pnd->tx_queue, 0);
+	pnd->usb = usb_get_dev(usbdev);
+	pnd->intf = intf;
+	pnd->data_intf = data_intf;
+	spin_lock_init(&pnd->rx_lock);
+	/* Endpoints */
+	if (usb_pipein(data_desc->endpoint[0].desc.bEndpointAddress)) {
+		pnd->rx_pipe = usb_rcvbulkpipe(usbdev,
+			data_desc->endpoint[0].desc.bEndpointAddress);
+		pnd->tx_pipe = usb_sndbulkpipe(usbdev,
+			data_desc->endpoint[1].desc.bEndpointAddress);
+	} else {
+		pnd->rx_pipe = usb_rcvbulkpipe(usbdev,
+			data_desc->endpoint[1].desc.bEndpointAddress);
+		pnd->tx_pipe = usb_sndbulkpipe(usbdev,
+			data_desc->endpoint[0].desc.bEndpointAddress);
+	}
+	pnd->active_setting = data_desc - data_intf->altsetting;
+
+	err = usb_driver_claim_interface(&usbpn_driver, data_intf, pnd);
+	if (err)
+		goto out;
+
+	/* Force inactive mode until the network device is brought UP */
+	usb_set_interface(usbdev, union_header->bSlaveInterface0,
+				!pnd->active_setting);
+	usb_set_intfdata(intf, pnd);
+
+	err = register_netdev(dev);
+	if (err) {
+		usb_driver_release_interface(&usbpn_driver, data_intf);
+		goto out;
+	}
+
+	dev_dbg(&dev->dev, "USB CDC Phonet device found\n");
+	return 0;
+
+out:
+	usb_set_intfdata(intf, NULL);
+	free_netdev(dev);
+	return err;
+}
+
+static void usbpn_disconnect(struct usb_interface *intf)
+{
+	struct usbpn_dev *pnd = usb_get_intfdata(intf);
+	struct usb_device *usb = pnd->usb;
+
+	if (pnd->disconnected)
+		return;
+
+	pnd->disconnected = 1;
+	usb_driver_release_interface(&usbpn_driver,
+			(pnd->intf == intf) ? pnd->data_intf : pnd->intf);
+	unregister_netdev(pnd->dev);
+	usb_put_dev(usb);
+}
+
+static struct usb_driver usbpn_driver = {
+	.name =		"cdc_phonet",
+	.probe =	usbpn_probe,
+	.disconnect =	usbpn_disconnect,
+	.id_table =	usbpn_ids,
+};
+
+static int __init usbpn_init(void)
+{
+	return usb_register(&usbpn_driver);
+}
+
+static void __exit usbpn_exit(void)
+{
+	usb_deregister(&usbpn_driver);
+}
+
+module_init(usbpn_init);
+module_exit(usbpn_exit);
+
+MODULE_AUTHOR("Remi Denis-Courmont");
+MODULE_DESCRIPTION("USB CDC Phonet host interface");
+MODULE_LICENSE("GPL");