Date:	Tue, 21 Jul 2009 09:52:53 -0400
From:	Dan Williams <dcbw@...hat.com>
To:	Rémi Denis-Courmont 
	<remi.denis-courmont@...ia.com>
Cc:	netdev@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] USB host CDC Phonet network interface driver

On Tue, 2009-07-21 at 14:58 +0300, Rémi Denis-Courmont wrote:
> From: Rémi Denis-Courmont <remi.denis-courmont@...ia.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.

Is there an example somewhere of how to use Phonet to get a mobile
broadband connection in place of usb-serial and PPP?  I've read the
Phonet protocol description and other random docs I can find, but can't
figure out how that would work.  Or does "PC Suite" mode not support
that?

Thanks!
Dan


> Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@...ia.com>
> ---
>  drivers/net/usb/Kconfig      |    8 +
>  drivers/net/usb/Makefile     |    1 +
>  drivers/net/usb/cdc-phonet.c |  461 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 470 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/net/usb/cdc-phonet.c
> 
> 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..792af72
> --- /dev/null
> +++ b/drivers/net/usb/cdc-phonet.c
> @@ -0,0 +1,461 @@
> +/*
> + * 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;
> +
> +	struct usb_interface	*intf, *data_intf;
> +	struct usb_device	*usb;
> +	unsigned int		tx_pipe, rx_pipe;
> +	u8 active_setting;
> +	u8 disconnected;
> +
> +	unsigned		tx_queue;
> +	spinlock_t		tx_lock;
> +
> +	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;
> +	unsigned long flags;
> +	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;
> +	}
> +
> +	spin_lock_irqsave(&pnd->tx_lock, flags);
> +	pnd->tx_queue++;
> +	if (pnd->tx_queue >= dev->tx_queue_len)
> +		netif_stop_queue(dev);
> +	spin_unlock_irqrestore(&pnd->tx_lock, flags);
> +	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++;
> +
> +	spin_lock(&pnd->tx_lock);
> +	pnd->tx_queue--;
> +	netif_wake_queue(dev);
> +	spin_unlock(&pnd->tx_lock);
> +
> +	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;
> +	pnd->usb = usb_get_dev(usbdev);
> +	pnd->intf = intf;
> +	pnd->data_intf = data_intf;
> +	spin_lock_init(&pnd->tx_lock);
> +	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");

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