sierra_net.c

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/*
 * USB-to-WWAN Driver for Sierra Wireless modems
 *
 * Copyright (C) 2008, 2009, 2010 Paxton Smith, Matthew Safar, Rory Filer
 *                          <[email protected]>
 *
 * Portions of this based on the cdc_ether driver by David Brownell (2003-2005)
 * and Ole Andre Vadla Ravnas (ActiveSync) (2006).
 *
 * IMPORTANT DISCLAIMER: This driver is not commercially supported by
 * Sierra Wireless. Use at your own risk.
 *
 * 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 DRIVER_VERSION "v.2.0"
#define DRIVER_AUTHOR "Paxton Smith, Matthew Safar, Rory Filer"
#define DRIVER_DESC "USB-to-WWAN Driver for Sierra Wireless modems"
static const char driver_name[] = "sierra_net";

/* if defined debug messages enabled */
/*#define   DEBUG*/

#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/mii.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <net/ip.h>
#include <net/udp.h>
#include <asm/unaligned.h>
#include <linux/usb/usbnet.h>

#define SWI_USB_REQUEST_GET_FW_ATTR 0x06
#define SWI_GET_FW_ATTR_MASK        0x08

/* atomic counter partially included in MAC address to make sure 2 devices
 * do not end up with the same MAC - concept breaks in case of > 255 ifaces
 */
static  atomic_t iface_counter = ATOMIC_INIT(0);

/*
 * SYNC Timer Delay definition used to set the expiry time
 */
#define SIERRA_NET_SYNCDELAY (2*HZ)

/* Max. MTU supported. The modem buffers are limited to 1500 */
#define SIERRA_NET_MAX_SUPPORTED_MTU    1500

/* The SIERRA_NET_USBCTL_BUF_LEN defines a buffer size allocated for control
 * message reception ... and thus the max. received packet.
 * (May be the cause for parse_hip returning -EINVAL)
 */
#define SIERRA_NET_USBCTL_BUF_LEN   1024

/* Overriding the default usbnet rx_urb_size */
#define SIERRA_NET_RX_URB_SIZE      (8 * 1024)

/* Private data structure */
struct sierra_net_data {

    u8 ethr_hdr_tmpl[ETH_HLEN]; /* ethernet header template for rx'd pkts */

    u16 link_up;        /* air link up or down */
    u8 tx_hdr_template[4];  /* part of HIP hdr for tx'd packets */

    u8 sync_msg[4];     /* SYNC message */
    u8 shdwn_msg[4];    /* Shutdown message */

    /* Backpointer to the container */
    struct usbnet *usbnet;

    u8 ifnum;   /* interface number */

/* Bit masks, must be a power of 2 */
#define SIERRA_NET_EVENT_RESP_AVAIL    0x01
#define SIERRA_NET_TIMER_EXPIRY        0x02
    unsigned long kevent_flags;
    struct work_struct sierra_net_kevent;
    struct timer_list sync_timer; /* For retrying SYNC sequence */
};

struct param {
    int is_present;
    union {
        void  *ptr;
        u32    dword;
        u16    word;
        u8     byte;
    };
};

/* HIP message type */
#define SIERRA_NET_HIP_EXTENDEDID   0x7F
#define SIERRA_NET_HIP_HSYNC_ID     0x60    /* Modem -> host */
#define SIERRA_NET_HIP_RESTART_ID   0x62    /* Modem -> host */
#define SIERRA_NET_HIP_MSYNC_ID     0x20    /* Host -> modem */
#define SIERRA_NET_HIP_SHUTD_ID     0x26    /* Host -> modem */

#define SIERRA_NET_HIP_EXT_IP_IN_ID   0x0202
#define SIERRA_NET_HIP_EXT_IP_OUT_ID  0x0002

/* 3G UMTS Link Sense Indication definitions */
#define SIERRA_NET_HIP_LSI_UMTSID   0x78

/* Reverse Channel Grant Indication HIP message */
#define SIERRA_NET_HIP_RCGI     0x64

/* LSI Protocol types */
#define SIERRA_NET_PROTOCOL_UMTS      0x01
/* LSI Coverage */
#define SIERRA_NET_COVERAGE_NONE      0x00
#define SIERRA_NET_COVERAGE_NOPACKET  0x01

/* LSI Session */
#define SIERRA_NET_SESSION_IDLE       0x00
/* LSI Link types */
#define SIERRA_NET_AS_LINK_TYPE_IPv4  0x00

struct lsi_umts {
    u8 protocol;
    u8 unused1;
    __be16 length;
    /* eventually use a union for the rest - assume umts for now */
    u8 coverage;
    u8 unused2[41];
    u8 session_state;
    u8 unused3[33];
    u8 link_type;
    u8 pdp_addr_len; /* NW-supplied PDP address len */
    u8 pdp_addr[16]; /* NW-supplied PDP address (bigendian)) */
    u8 unused4[23];
    u8 dns1_addr_len; /* NW-supplied 1st DNS address len (bigendian) */
    u8 dns1_addr[16]; /* NW-supplied 1st DNS address */
    u8 dns2_addr_len; /* NW-supplied 2nd DNS address len */
    u8 dns2_addr[16]; /* NW-supplied 2nd DNS address (bigendian)*/
    u8 wins1_addr_len; /* NW-supplied 1st Wins address len */
    u8 wins1_addr[16]; /* NW-supplied 1st Wins address (bigendian)*/
    u8 wins2_addr_len; /* NW-supplied 2nd Wins address len */
    u8 wins2_addr[16]; /* NW-supplied 2nd Wins address (bigendian) */
    u8 unused5[4];
    u8 gw_addr_len; /* NW-supplied GW address len */
    u8 gw_addr[16]; /* NW-supplied GW address (bigendian) */
    u8 reserved[8];
} __packed;

#define SIERRA_NET_LSI_COMMON_LEN      4
#define SIERRA_NET_LSI_UMTS_LEN        (sizeof(struct lsi_umts))
#define SIERRA_NET_LSI_UMTS_STATUS_LEN \
    (SIERRA_NET_LSI_UMTS_LEN - SIERRA_NET_LSI_COMMON_LEN)

/* Forward definitions */
static void sierra_sync_timer(unsigned long syncdata);
static int sierra_net_change_mtu(struct net_device *net, int new_mtu);

/* Our own net device operations structure */
static const struct net_device_ops sierra_net_device_ops = {
    .ndo_open               = usbnet_open,
    .ndo_stop               = usbnet_stop,
    .ndo_start_xmit         = usbnet_start_xmit,
    .ndo_tx_timeout         = usbnet_tx_timeout,
    .ndo_change_mtu         = sierra_net_change_mtu,
    .ndo_set_mac_address    = eth_mac_addr,
    .ndo_validate_addr      = eth_validate_addr,
};

/* get private data associated with passed in usbnet device */
static inline struct sierra_net_data *sierra_net_get_private(struct usbnet *dev)
{
    return (struct sierra_net_data *)dev->data[0];
}

/* set private data associated with passed in usbnet device */
static inline void sierra_net_set_private(struct usbnet *dev,
            struct sierra_net_data *priv)
{
    dev->data[0] = (unsigned long)priv;
}

/* is packet IPv4 */
static inline int is_ip(struct sk_buff *skb)
{
    return skb->protocol == cpu_to_be16(ETH_P_IP);
}

/*
 * check passed in packet and make sure that:
 *  - it is linear (no scatter/gather)
 *  - it is ethernet (mac_header properly set)
 */
static int check_ethip_packet(struct sk_buff *skb, struct usbnet *dev)
{
    skb_reset_mac_header(skb); /* ethernet header */

    if (skb_is_nonlinear(skb)) {
        netdev_err(dev->net, "Non linear buffer-dropping\n");
        return 0;
    }

    if (!pskb_may_pull(skb, ETH_HLEN))
        return 0;
    skb->protocol = eth_hdr(skb)->h_proto;

    return 1;
}

static const u8 *save16bit(struct param *p, const u8 *datap)
{
    p->is_present = 1;
    p->word = get_unaligned_be16(datap);
    return datap + sizeof(p->word);
}

static const u8 *save8bit(struct param *p, const u8 *datap)
{
    p->is_present = 1;
    p->byte = *datap;
    return datap + sizeof(p->byte);
}

/*----------------------------------------------------------------------------*
 *                              BEGIN HIP                                     *
 *----------------------------------------------------------------------------*/
/* HIP header */
#define SIERRA_NET_HIP_HDR_LEN 4
/* Extended HIP header */
#define SIERRA_NET_HIP_EXT_HDR_LEN 6

struct hip_hdr {
    int    hdrlen;
    struct param payload_len;
    struct param msgid;
    struct param msgspecific;
    struct param extmsgid;
};

static int parse_hip(const u8 *buf, const u32 buflen, struct hip_hdr *hh)
{
    const u8 *curp = buf;
    int    padded;

    if (buflen < SIERRA_NET_HIP_HDR_LEN)
        return -EPROTO;

    curp = save16bit(&hh->payload_len, curp);
    curp = save8bit(&hh->msgid, curp);
    curp = save8bit(&hh->msgspecific, curp);

    padded = hh->msgid.byte & 0x80;
    hh->msgid.byte &= 0x7F;         /* 7 bits */

    hh->extmsgid.is_present = (hh->msgid.byte == SIERRA_NET_HIP_EXTENDEDID);
    if (hh->extmsgid.is_present) {
        if (buflen < SIERRA_NET_HIP_EXT_HDR_LEN)
            return -EPROTO;

        hh->payload_len.word &= 0x3FFF; /* 14 bits */

        curp = save16bit(&hh->extmsgid, curp);
        hh->extmsgid.word &= 0x03FF;    /* 10 bits */

        hh->hdrlen = SIERRA_NET_HIP_EXT_HDR_LEN;
    } else {
        hh->payload_len.word &= 0x07FF; /* 11 bits */
        hh->hdrlen = SIERRA_NET_HIP_HDR_LEN;
    }

    if (padded) {
        hh->hdrlen++;
        hh->payload_len.word--;
    }

    /* if real packet shorter than the claimed length */
    if (buflen < (hh->hdrlen + hh->payload_len.word))
        return -EINVAL;

    return 0;
}

static void build_hip(u8 *buf, const u16 payloadlen,
        struct sierra_net_data *priv)
{
    /* the following doesn't have the full functionality. We
     * currently build only one kind of header, so it is faster this way
     */
    put_unaligned_be16(payloadlen, buf);
    memcpy(buf+2, priv->tx_hdr_template, sizeof(priv->tx_hdr_template));
}
/*----------------------------------------------------------------------------*
 *                              END HIP                                       *
 *----------------------------------------------------------------------------*/

static int sierra_net_send_cmd(struct usbnet *dev,
        u8 *cmd, int cmdlen, const char * cmd_name)
{
    struct sierra_net_data *priv = sierra_net_get_private(dev);
    int  status;

    status = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
            USB_CDC_SEND_ENCAPSULATED_COMMAND,
            USB_DIR_OUT|USB_TYPE_CLASS|USB_RECIP_INTERFACE, 0,
            priv->ifnum, cmd, cmdlen, USB_CTRL_SET_TIMEOUT);

    if (status != cmdlen && status != -ENODEV)
        netdev_err(dev->net, "Submit %s failed %d\n", cmd_name, status);

    return status;
}

static int sierra_net_send_sync(struct usbnet *dev)
{
    int  status;
    struct sierra_net_data *priv = sierra_net_get_private(dev);

    dev_dbg(&dev->udev->dev, "%s", __func__);

    status = sierra_net_send_cmd(dev, priv->sync_msg,
            sizeof(priv->sync_msg), "SYNC");

    return status;
}

static void sierra_net_set_ctx_index(struct sierra_net_data *priv, u8 ctx_ix)
{
    dev_dbg(&(priv->usbnet->udev->dev), "%s %d", __func__, ctx_ix);
    priv->tx_hdr_template[0] = 0x3F;
    priv->tx_hdr_template[1] = ctx_ix;
    *((u16 *)&priv->tx_hdr_template[2]) =
        cpu_to_be16(SIERRA_NET_HIP_EXT_IP_OUT_ID);
}

static inline int sierra_net_is_valid_addrlen(u8 len)
{
    return len == sizeof(struct in_addr);
}

static int sierra_net_parse_lsi(struct usbnet *dev, char *data, int datalen)
{
    struct lsi_umts *lsi = (struct lsi_umts *)data;

    if (datalen < sizeof(struct lsi_umts)) {
        netdev_err(dev->net, "%s: Data length %d, exp %Zu\n",
                __func__, datalen,
                sizeof(struct lsi_umts));
        return -1;
    }

    if (lsi->length != cpu_to_be16(SIERRA_NET_LSI_UMTS_STATUS_LEN)) {
        netdev_err(dev->net, "%s: LSI_UMTS_STATUS_LEN %d, exp %u\n",
                __func__, be16_to_cpu(lsi->length),
                (u32)SIERRA_NET_LSI_UMTS_STATUS_LEN);
        return -1;
    }

    /* Validate the protocol  - only support UMTS for now */
    if (lsi->protocol != SIERRA_NET_PROTOCOL_UMTS) {
        netdev_err(dev->net, "Protocol unsupported, 0x%02x\n",
            lsi->protocol);
        return -1;
    }

    /* Validate the link type */
    if (lsi->link_type != SIERRA_NET_AS_LINK_TYPE_IPv4) {
        netdev_err(dev->net, "Link type unsupported: 0x%02x\n",
            lsi->link_type);
        return -1;
    }

    /* Validate the coverage */
    if (lsi->coverage == SIERRA_NET_COVERAGE_NONE
       || lsi->coverage == SIERRA_NET_COVERAGE_NOPACKET) {
        netdev_err(dev->net, "No coverage, 0x%02x\n", lsi->coverage);
        return 0;
    }

    /* Validate the session state */
    if (lsi->session_state == SIERRA_NET_SESSION_IDLE) {
        netdev_err(dev->net, "Session idle, 0x%02x\n",
            lsi->session_state);
        return 0;
    }

    /* Set link_sense true */
    return 1;
}

static void sierra_net_handle_lsi(struct usbnet *dev, char *data,
        struct hip_hdr  *hh)
{
    struct sierra_net_data *priv = sierra_net_get_private(dev);
    int link_up;

    link_up = sierra_net_parse_lsi(dev, data + hh->hdrlen,
                    hh->payload_len.word);
    if (link_up < 0) {
        netdev_err(dev->net, "Invalid LSI\n");
        return;
    }
    if (link_up) {
        sierra_net_set_ctx_index(priv, hh->msgspecific.byte);
        priv->link_up = 1;
        netif_carrier_on(dev->net);
    } else {
        priv->link_up = 0;
        netif_carrier_off(dev->net);
    }
}

static void sierra_net_dosync(struct usbnet *dev)
{
    int status;
    struct sierra_net_data *priv = sierra_net_get_private(dev);

    dev_dbg(&dev->udev->dev, "%s", __func__);

    /* tell modem we are ready */
    status = sierra_net_send_sync(dev);
    if (status < 0)
        netdev_err(dev->net,
            "Send SYNC failed, status %d\n", status);
    status = sierra_net_send_sync(dev);
    if (status < 0)
        netdev_err(dev->net,
            "Send SYNC failed, status %d\n", status);

    /* Now, start a timer and make sure we get the Restart Indication */
    priv->sync_timer.function = sierra_sync_timer;
    priv->sync_timer.data = (unsigned long) dev;
    priv->sync_timer.expires = jiffies + SIERRA_NET_SYNCDELAY;
    add_timer(&priv->sync_timer);
}

static void sierra_net_kevent(struct work_struct *work)
{
    struct sierra_net_data *priv =
        container_of(work, struct sierra_net_data, sierra_net_kevent);
    struct usbnet *dev = priv->usbnet;
    int  len;
    int  err;
    u8  *buf;
    u8   ifnum;

    if (test_bit(SIERRA_NET_EVENT_RESP_AVAIL, &priv->kevent_flags)) {
        clear_bit(SIERRA_NET_EVENT_RESP_AVAIL, &priv->kevent_flags);

        /* Query the modem for the LSI message */
        buf = kzalloc(SIERRA_NET_USBCTL_BUF_LEN, GFP_KERNEL);
        if (!buf) {
            netdev_err(dev->net,
                "failed to allocate buf for LS msg\n");
            return;
        }
        ifnum = priv->ifnum;
        len = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
                USB_CDC_GET_ENCAPSULATED_RESPONSE,
                USB_DIR_IN|USB_TYPE_CLASS|USB_RECIP_INTERFACE,
                0, ifnum, buf, SIERRA_NET_USBCTL_BUF_LEN,
                USB_CTRL_SET_TIMEOUT);

        if (len < 0) {
            netdev_err(dev->net,
                "usb_control_msg failed, status %d\n", len);
        } else {
            struct hip_hdr  hh;

            dev_dbg(&dev->udev->dev, "%s: Received status message,"
                " %04x bytes", __func__, len);

            err = parse_hip(buf, len, &hh);
            if (err) {
                netdev_err(dev->net, "%s: Bad packet,"
                    " parse result %d\n", __func__, err);
                kfree(buf);
                return;
            }

            /* Validate packet length */
            if (len != hh.hdrlen + hh.payload_len.word) {
                netdev_err(dev->net, "%s: Bad packet, received"
                    " %d, expected %d\n",   __func__, len,
                    hh.hdrlen + hh.payload_len.word);
                kfree(buf);
                return;
            }

            /* Switch on received message types */
            switch (hh.msgid.byte) {
            case SIERRA_NET_HIP_LSI_UMTSID:
                dev_dbg(&dev->udev->dev, "LSI for ctx:%d",
                    hh.msgspecific.byte);
                sierra_net_handle_lsi(dev, buf, &hh);
                break;
            case SIERRA_NET_HIP_RESTART_ID:
                dev_dbg(&dev->udev->dev, "Restart reported: %d,"
                        " stopping sync timer",
                        hh.msgspecific.byte);
                /* Got sync resp - stop timer & clear mask */
                del_timer_sync(&priv->sync_timer);
                clear_bit(SIERRA_NET_TIMER_EXPIRY,
                      &priv->kevent_flags);
                break;
            case SIERRA_NET_HIP_HSYNC_ID:
                dev_dbg(&dev->udev->dev, "SYNC received");
                err = sierra_net_send_sync(dev);
                if (err < 0)
                    netdev_err(dev->net,
                        "Send SYNC failed %d\n", err);
                break;
            case SIERRA_NET_HIP_EXTENDEDID:
                netdev_err(dev->net, "Unrecognized HIP msg, "
                    "extmsgid 0x%04x\n", hh.extmsgid.word);
                break;
            case SIERRA_NET_HIP_RCGI:
                /* Ignored */
                break;
            default:
                netdev_err(dev->net, "Unrecognized HIP msg, "
                    "msgid 0x%02x\n", hh.msgid.byte);
                break;
            }
        }
        kfree(buf);
    }
    /* The sync timer bit might be set */
    if (test_bit(SIERRA_NET_TIMER_EXPIRY, &priv->kevent_flags)) {
        clear_bit(SIERRA_NET_TIMER_EXPIRY, &priv->kevent_flags);
        dev_dbg(&dev->udev->dev, "Deferred sync timer expiry");
        sierra_net_dosync(priv->usbnet);
    }

    if (priv->kevent_flags)
        dev_dbg(&dev->udev->dev, "sierra_net_kevent done, "
            "kevent_flags = 0x%lx", priv->kevent_flags);
}

static void sierra_net_defer_kevent(struct usbnet *dev, int work)
{
    struct sierra_net_data *priv = sierra_net_get_private(dev);

    set_bit(work, &priv->kevent_flags);
    schedule_work(&priv->sierra_net_kevent);
}

/*
 * Sync Retransmit Timer Handler. On expiry, kick the work queue
 */
static void sierra_sync_timer(unsigned long syncdata)
{
    struct usbnet *dev = (struct usbnet *)syncdata;

    dev_dbg(&dev->udev->dev, "%s", __func__);
    /* Kick the tasklet */
    sierra_net_defer_kevent(dev, SIERRA_NET_TIMER_EXPIRY);
}

static void sierra_net_status(struct usbnet *dev, struct urb *urb)
{
    struct usb_cdc_notification *event;

    dev_dbg(&dev->udev->dev, "%s", __func__);

    if (urb->actual_length < sizeof *event)
        return;

    /* Add cases to handle other standard notifications. */
    event = urb->transfer_buffer;
    switch (event->bNotificationType) {
    case USB_CDC_NOTIFY_NETWORK_CONNECTION:
    case USB_CDC_NOTIFY_SPEED_CHANGE:
        /* USB 305 sends those */
        break;
    case USB_CDC_NOTIFY_RESPONSE_AVAILABLE:
        sierra_net_defer_kevent(dev, SIERRA_NET_EVENT_RESP_AVAIL);
        break;
    default:
        netdev_err(dev->net, ": unexpected notification %02x!\n",
                event->bNotificationType);
        break;
    }
}

static void sierra_net_get_drvinfo(struct net_device *net,
        struct ethtool_drvinfo *info)
{
    /* Inherit standard device info */
    usbnet_get_drvinfo(net, info);
    strncpy(info->driver, driver_name, sizeof info->driver);
    strncpy(info->version, DRIVER_VERSION, sizeof info->version);
}

static u32 sierra_net_get_link(struct net_device *net)
{
    struct usbnet *dev = netdev_priv(net);
    /* Report link is down whenever the interface is down */
    return sierra_net_get_private(dev)->link_up && netif_running(net);
}

static const struct ethtool_ops sierra_net_ethtool_ops = {
    .get_drvinfo = sierra_net_get_drvinfo,
    .get_link = sierra_net_get_link,
    .get_msglevel = usbnet_get_msglevel,
    .set_msglevel = usbnet_set_msglevel,
    .get_settings = usbnet_get_settings,
    .set_settings = usbnet_set_settings,
    .nway_reset = usbnet_nway_reset,
};

/* MTU can not be more than 1500 bytes, enforce it. */
static int sierra_net_change_mtu(struct net_device *net, int new_mtu)
{
    if (new_mtu > SIERRA_NET_MAX_SUPPORTED_MTU)
        return -EINVAL;

    return usbnet_change_mtu(net, new_mtu);
}

static int sierra_net_get_fw_attr(struct usbnet *dev, u16 *datap)
{
    int result = 0;
    u16 *attrdata;

    attrdata = kmalloc(sizeof(*attrdata), GFP_KERNEL);
    if (!attrdata)
        return -ENOMEM;

    result = usb_control_msg(
            dev->udev,
            usb_rcvctrlpipe(dev->udev, 0),
            /* _u8 vendor specific request */
            SWI_USB_REQUEST_GET_FW_ATTR,
            USB_DIR_IN | USB_TYPE_VENDOR,   /* __u8 request type */
            0x0000,     /* __u16 value not used */
            0x0000,     /* __u16 index  not used */
            attrdata,   /* char *data */
            sizeof(*attrdata),      /* __u16 size */
            USB_CTRL_SET_TIMEOUT);  /* int timeout */

    if (result < 0) {
        kfree(attrdata);
        return -EIO;
    }

    *datap = le16_to_cpu(*attrdata);

    kfree(attrdata);
    return result;
}

/*
 * collects the bulk endpoints, the status endpoint.
 */
static int sierra_net_bind(struct usbnet *dev, struct usb_interface *intf)
{
    u8  ifacenum;
    u8  numendpoints;
    u16 fwattr = 0;
    int status;
    struct ethhdr *eth;
    struct sierra_net_data *priv;
    static const u8 sync_tmplate[sizeof(priv->sync_msg)] = {
        0x00, 0x00, SIERRA_NET_HIP_MSYNC_ID, 0x00};
    static const u8 shdwn_tmplate[sizeof(priv->shdwn_msg)] = {
        0x00, 0x00, SIERRA_NET_HIP_SHUTD_ID, 0x00};

    dev_dbg(&dev->udev->dev, "%s", __func__);

    ifacenum = intf->cur_altsetting->desc.bInterfaceNumber;
    numendpoints = intf->cur_altsetting->desc.bNumEndpoints;
    /* We have three endpoints, bulk in and out, and a status */
    if (numendpoints != 3) {
        dev_err(&dev->udev->dev, "Expected 3 endpoints, found: %d",
            numendpoints);
        return -ENODEV;
    }
    /* Status endpoint set in usbnet_get_endpoints() */
    dev->status = NULL;
    status = usbnet_get_endpoints(dev, intf);
    if (status < 0) {
        dev_err(&dev->udev->dev, "Error in usbnet_get_endpoints (%d)",
            status);
        return -ENODEV;
    }
    /* Initialize sierra private data */
    priv = kzalloc(sizeof *priv, GFP_KERNEL);
    if (!priv) {
        dev_err(&dev->udev->dev, "No memory");
        return -ENOMEM;
    }

    priv->usbnet = dev;
    priv->ifnum = ifacenum;
    dev->net->netdev_ops = &sierra_net_device_ops;

    /* change MAC addr to include, ifacenum, and to be unique */
    dev->net->dev_addr[ETH_ALEN-2] = atomic_inc_return(&iface_counter);
    dev->net->dev_addr[ETH_ALEN-1] = ifacenum;

    /* we will have to manufacture ethernet headers, prepare template */
    eth = (struct ethhdr *)priv->ethr_hdr_tmpl;
    memcpy(&eth->h_dest, dev->net->dev_addr, ETH_ALEN);
    eth->h_proto = cpu_to_be16(ETH_P_IP);

    /* prepare shutdown message template */
    memcpy(priv->shdwn_msg, shdwn_tmplate, sizeof(priv->shdwn_msg));
    /* set context index initially to 0 - prepares tx hdr template */
    sierra_net_set_ctx_index(priv, 0);

    /* decrease the rx_urb_size and max_tx_size to 4k on USB 1.1 */
    dev->rx_urb_size  = SIERRA_NET_RX_URB_SIZE;
    if (dev->udev->speed != USB_SPEED_HIGH)
        dev->rx_urb_size  = min_t(size_t, 4096, SIERRA_NET_RX_URB_SIZE);

    dev->net->hard_header_len += SIERRA_NET_HIP_EXT_HDR_LEN;
    dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;

    /* Set up the netdev */
    dev->net->flags |= IFF_NOARP;
    dev->net->ethtool_ops = &sierra_net_ethtool_ops;
    netif_carrier_off(dev->net);

    sierra_net_set_private(dev, priv);

    priv->kevent_flags = 0;

    /* Use the shared workqueue */
    INIT_WORK(&priv->sierra_net_kevent, sierra_net_kevent);

    /* Only need to do this once */
    init_timer(&priv->sync_timer);

    /* verify fw attributes */
    status = sierra_net_get_fw_attr(dev, &fwattr);
    dev_dbg(&dev->udev->dev, "Fw attr: %x\n", fwattr);

    /* test whether firmware supports DHCP */
    if (!(status == sizeof(fwattr) && (fwattr & SWI_GET_FW_ATTR_MASK))) {
        /* found incompatible firmware version */
        dev_err(&dev->udev->dev, "Incompatible driver and firmware"
            " versions\n");
        kfree(priv);
        return -ENODEV;
    }
    /* prepare sync message from template */
    memcpy(priv->sync_msg, sync_tmplate, sizeof(priv->sync_msg));

    /* initiate the sync sequence */
    sierra_net_dosync(dev);

    return 0;
}

static void sierra_net_unbind(struct usbnet *dev, struct usb_interface *intf)
{
    int status;
    struct sierra_net_data *priv = sierra_net_get_private(dev);

    dev_dbg(&dev->udev->dev, "%s", __func__);

    /* kill the timer and work */
    del_timer_sync(&priv->sync_timer);
    cancel_work_sync(&priv->sierra_net_kevent);

    /* tell modem we are going away */
    status = sierra_net_send_cmd(dev, priv->shdwn_msg,
            sizeof(priv->shdwn_msg), "Shutdown");
    if (status < 0)
        netdev_err(dev->net,
            "usb_control_msg failed, status %d\n", status);

    sierra_net_set_private(dev, NULL);

    kfree(priv);
}

static struct sk_buff *sierra_net_skb_clone(struct usbnet *dev,
        struct sk_buff *skb, int len)
{
    struct sk_buff *new_skb;

    /* clone skb */
    new_skb = skb_clone(skb, GFP_ATOMIC);

    /* remove len bytes from original */
    skb_pull(skb, len);

    /* trim next packet to it's length */
    if (new_skb) {
        skb_trim(new_skb, len);
    } else {
        if (netif_msg_rx_err(dev))
            netdev_err(dev->net, "failed to get skb\n");
        dev->net->stats.rx_dropped++;
    }

    return new_skb;
}

/* ---------------------------- Receive data path ----------------------*/
static int sierra_net_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
    int err;
    struct hip_hdr  hh;
    struct sk_buff *new_skb;

    dev_dbg(&dev->udev->dev, "%s", __func__);

    /* could contain multiple packets */
    while (likely(skb->len)) {
        err = parse_hip(skb->data, skb->len, &hh);
        if (err) {
            if (netif_msg_rx_err(dev))
                netdev_err(dev->net, "Invalid HIP header %d\n",
                    err);
            /* dev->net->stats.rx_errors incremented by caller */
            dev->net->stats.rx_length_errors++;
            return 0;
        }

        /* Validate Extended HIP header */
        if (!hh.extmsgid.is_present
            || hh.extmsgid.word != SIERRA_NET_HIP_EXT_IP_IN_ID) {
            if (netif_msg_rx_err(dev))
                netdev_err(dev->net, "HIP/ETH: Invalid pkt\n");

            dev->net->stats.rx_frame_errors++;
            /* dev->net->stats.rx_errors incremented by caller */
            return 0;
        }

        skb_pull(skb, hh.hdrlen);

        /* We are going to accept this packet, prepare it */
        memcpy(skb->data, sierra_net_get_private(dev)->ethr_hdr_tmpl,
            ETH_HLEN);

        /* Last packet in batch handled by usbnet */
        if (hh.payload_len.word == skb->len)
            return 1;

        new_skb = sierra_net_skb_clone(dev, skb, hh.payload_len.word);
        if (new_skb)
            usbnet_skb_return(dev, new_skb);

    } /* while */

    return 0;
}

/* ---------------------------- Transmit data path ----------------------*/
static struct sk_buff *sierra_net_tx_fixup(struct usbnet *dev,
                       struct sk_buff *skb, gfp_t flags)
{
    struct sierra_net_data *priv = sierra_net_get_private(dev);
    u16 len;
    bool need_tail;

    BUILD_BUG_ON(FIELD_SIZEOF(struct usbnet, data)
                < sizeof(struct cdc_state));

    dev_dbg(&dev->udev->dev, "%s", __func__);
    if (priv->link_up && check_ethip_packet(skb, dev) && is_ip(skb)) {
        /* enough head room as is? */
        if (SIERRA_NET_HIP_EXT_HDR_LEN <= skb_headroom(skb)) {
            /* Save the Eth/IP length and set up HIP hdr */
            len = skb->len;
            skb_push(skb, SIERRA_NET_HIP_EXT_HDR_LEN);
            /* Handle ZLP issue */
            need_tail = ((len + SIERRA_NET_HIP_EXT_HDR_LEN)
                % dev->maxpacket == 0);
            if (need_tail) {
                if (unlikely(skb_tailroom(skb) == 0)) {
                    netdev_err(dev->net, "tx_fixup:"
                        "no room for packet\n");
                    dev_kfree_skb_any(skb);
                    return NULL;
                } else {
                    skb->data[skb->len] = 0;
                    __skb_put(skb, 1);
                    len = len + 1;
                }
            }
            build_hip(skb->data, len, priv);
            return skb;
        } else {
            /*
             * compensate in the future if necessary
             */
            netdev_err(dev->net, "tx_fixup: no room for HIP\n");
        } /* headroom */
    }

    if (!priv->link_up)
        dev->net->stats.tx_carrier_errors++;

    /* tx_dropped incremented by usbnet */

    /* filter the packet out, release it  */
    dev_kfree_skb_any(skb);
    return NULL;
}

static const struct driver_info sierra_net_info_direct_ip = {
    .description = "Sierra Wireless USB-to-WWAN Modem",
    .flags = FLAG_WWAN | FLAG_SEND_ZLP,
    .bind = sierra_net_bind,
    .unbind = sierra_net_unbind,
    .status = sierra_net_status,
    .rx_fixup = sierra_net_rx_fixup,
    .tx_fixup = sierra_net_tx_fixup,
};

#define DIRECT_IP_DEVICE(vend, prod) \
    {USB_DEVICE_INTERFACE_NUMBER(vend, prod, 7), \
    .driver_info = (unsigned long)&sierra_net_info_direct_ip}, \
    {USB_DEVICE_INTERFACE_NUMBER(vend, prod, 10), \
    .driver_info = (unsigned long)&sierra_net_info_direct_ip}, \
    {USB_DEVICE_INTERFACE_NUMBER(vend, prod, 11), \
    .driver_info = (unsigned long)&sierra_net_info_direct_ip}

static const struct usb_device_id products[] = {
    DIRECT_IP_DEVICE(0x1199, 0x68A3), /* Sierra Wireless USB-to-WWAN modem */
    DIRECT_IP_DEVICE(0x0F3D, 0x68A3), /* AT&T Direct IP modem */
    DIRECT_IP_DEVICE(0x1199, 0x68AA), /* Sierra Wireless Direct IP LTE modem */
    DIRECT_IP_DEVICE(0x0F3D, 0x68AA), /* AT&T Direct IP LTE modem */

    {}, /* last item */
};
MODULE_DEVICE_TABLE(usb, products);

/* We are based on usbnet, so let it handle the USB driver specifics */
static struct usb_driver sierra_net_driver = {
    .name = "sierra_net",
    .id_table = products,
    .probe = usbnet_probe,
    .disconnect = usbnet_disconnect,
    .suspend = usbnet_suspend,
    .resume = usbnet_resume,
    .no_dynamic_id = 1,
    .disable_hub_initiated_lpm = 1,
};

module_usb_driver(sierra_net_driver);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");