Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc

[mirror_ubuntu-bionic-kernel.git] / drivers / net / usb / cdc_ncm.c

/*
 * cdc_ncm.c
 *
 * Copyright (C) ST-Ericsson 2010-2011
 * Contact: Alexey Orishko <alexey.orishko@stericsson.com>
 * Original author: Hans Petter Selasky <hans.petter.selasky@stericsson.com>
 *
 * USB Host Driver for Network Control Model (NCM)
 * http://www.usb.org/developers/devclass_docs/NCM10.zip
 *
 * The NCM encoding, decoding and initialization logic
 * derives from FreeBSD 8.x. if_cdce.c and if_cdcereg.h
 *
 * This software is available to you under a choice of one of two
 * licenses. You may choose this file to be licensed under the terms
 * of the GNU General Public License (GPL) Version 2 or the 2-clause
 * BSD license listed below:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/ctype.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/crc32.h>
#include <linux/usb.h>
#include <linux/timer.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/usb/usbnet.h>
#include <linux/usb/cdc.h>

#define DRIVER_VERSION                          "04-Aug-2011"

/* CDC NCM subclass 3.2.1 */
#define USB_CDC_NCM_NDP16_LENGTH_MIN            0x10

/* Maximum NTB length */
#define CDC_NCM_NTB_MAX_SIZE_TX                 16384   /* bytes */
#define CDC_NCM_NTB_MAX_SIZE_RX                 16384   /* bytes */

/* Minimum value for MaxDatagramSize, ch. 6.2.9 */
#define CDC_NCM_MIN_DATAGRAM_SIZE               1514    /* bytes */

#define CDC_NCM_MIN_TX_PKT                      512     /* bytes */

/* Default value for MaxDatagramSize */
#define CDC_NCM_MAX_DATAGRAM_SIZE               2048    /* bytes */

/*
 * Maximum amount of datagrams in NCM Datagram Pointer Table, not counting
 * the last NULL entry. Any additional datagrams in NTB would be discarded.
 */
#define CDC_NCM_DPT_DATAGRAMS_MAX               32

/* Maximum amount of IN datagrams in NTB */
#define CDC_NCM_DPT_DATAGRAMS_IN_MAX            0 /* unlimited */

/* Restart the timer, if amount of datagrams is less than given value */
#define CDC_NCM_RESTART_TIMER_DATAGRAM_CNT      3

/* The following macro defines the minimum header space */
#define CDC_NCM_MIN_HDR_SIZE \
        (sizeof(struct usb_cdc_ncm_nth16) + sizeof(struct usb_cdc_ncm_ndp16) + \
        (CDC_NCM_DPT_DATAGRAMS_MAX + 1) * sizeof(struct usb_cdc_ncm_dpe16))

struct cdc_ncm_data {
        struct usb_cdc_ncm_nth16 nth16;
        struct usb_cdc_ncm_ndp16 ndp16;
        struct usb_cdc_ncm_dpe16 dpe16[CDC_NCM_DPT_DATAGRAMS_MAX + 1];
};

struct cdc_ncm_ctx {
        struct cdc_ncm_data rx_ncm;
        struct cdc_ncm_data tx_ncm;
        struct usb_cdc_ncm_ntb_parameters ncm_parm;
        struct timer_list tx_timer;

        const struct usb_cdc_ncm_desc *func_desc;
        const struct usb_cdc_header_desc *header_desc;
        const struct usb_cdc_union_desc *union_desc;
        const struct usb_cdc_ether_desc *ether_desc;

        struct net_device *netdev;
        struct usb_device *udev;
        struct usb_host_endpoint *in_ep;
        struct usb_host_endpoint *out_ep;
        struct usb_host_endpoint *status_ep;
        struct usb_interface *intf;
        struct usb_interface *control;
        struct usb_interface *data;

        struct sk_buff *tx_curr_skb;
        struct sk_buff *tx_rem_skb;

        spinlock_t mtx;

        u32 tx_timer_pending;
        u32 tx_curr_offset;
        u32 tx_curr_last_offset;
        u32 tx_curr_frame_num;
        u32 rx_speed;
        u32 tx_speed;
        u32 rx_max;
        u32 tx_max;
        u32 max_datagram_size;
        u16 tx_max_datagrams;
        u16 tx_remainder;
        u16 tx_modulus;
        u16 tx_ndp_modulus;
        u16 tx_seq;
        u16 connected;
};

static void cdc_ncm_tx_timeout(unsigned long arg);
static const struct driver_info cdc_ncm_info;
static struct usb_driver cdc_ncm_driver;
static struct ethtool_ops cdc_ncm_ethtool_ops;

static const struct usb_device_id cdc_devs[] = {
        { USB_INTERFACE_INFO(USB_CLASS_COMM,
                USB_CDC_SUBCLASS_NCM, USB_CDC_PROTO_NONE),
                .driver_info = (unsigned long)&cdc_ncm_info,
        },
        {
        },
};

MODULE_DEVICE_TABLE(usb, cdc_devs);

static void
cdc_ncm_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *info)
{
        struct usbnet *dev = netdev_priv(net);

        strncpy(info->driver, dev->driver_name, sizeof(info->driver));
        strncpy(info->version, DRIVER_VERSION, sizeof(info->version));
        strncpy(info->fw_version, dev->driver_info->description,
                sizeof(info->fw_version));
        usb_make_path(dev->udev, info->bus_info, sizeof(info->bus_info));
}

static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)
{
        u32 val;
        u8 flags;
        u8 iface_no;
        int err;
        u16 ntb_fmt_supported;

        iface_no = ctx->control->cur_altsetting->desc.bInterfaceNumber;

        err = usb_control_msg(ctx->udev,
                                usb_rcvctrlpipe(ctx->udev, 0),
                                USB_CDC_GET_NTB_PARAMETERS,
                                USB_TYPE_CLASS | USB_DIR_IN
                                 | USB_RECIP_INTERFACE,
                                0, iface_no, &ctx->ncm_parm,
                                sizeof(ctx->ncm_parm), 10000);
        if (err < 0) {
                pr_debug("failed GET_NTB_PARAMETERS\n");
                return 1;
        }

        /* read correct set of parameters according to device mode */
        ctx->rx_max = le32_to_cpu(ctx->ncm_parm.dwNtbInMaxSize);
        ctx->tx_max = le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize);
        ctx->tx_remainder = le16_to_cpu(ctx->ncm_parm.wNdpOutPayloadRemainder);
        ctx->tx_modulus = le16_to_cpu(ctx->ncm_parm.wNdpOutDivisor);
        ctx->tx_ndp_modulus = le16_to_cpu(ctx->ncm_parm.wNdpOutAlignment);
        /* devices prior to NCM Errata shall set this field to zero */
        ctx->tx_max_datagrams = le16_to_cpu(ctx->ncm_parm.wNtbOutMaxDatagrams);
        ntb_fmt_supported = le16_to_cpu(ctx->ncm_parm.bmNtbFormatsSupported);

        if (ctx->func_desc != NULL)
                flags = ctx->func_desc->bmNetworkCapabilities;
        else
                flags = 0;

        pr_debug("dwNtbInMaxSize=%u dwNtbOutMaxSize=%u "
                 "wNdpOutPayloadRemainder=%u wNdpOutDivisor=%u "
                 "wNdpOutAlignment=%u wNtbOutMaxDatagrams=%u flags=0x%x\n",
                 ctx->rx_max, ctx->tx_max, ctx->tx_remainder, ctx->tx_modulus,
                 ctx->tx_ndp_modulus, ctx->tx_max_datagrams, flags);

        /* max count of tx datagrams */
        if ((ctx->tx_max_datagrams == 0) ||
                        (ctx->tx_max_datagrams > CDC_NCM_DPT_DATAGRAMS_MAX))
                ctx->tx_max_datagrams = CDC_NCM_DPT_DATAGRAMS_MAX;

        /* verify maximum size of received NTB in bytes */
        if (ctx->rx_max < USB_CDC_NCM_NTB_MIN_IN_SIZE) {
                pr_debug("Using min receive length=%d\n",
                                                USB_CDC_NCM_NTB_MIN_IN_SIZE);
                ctx->rx_max = USB_CDC_NCM_NTB_MIN_IN_SIZE;
        }

        if (ctx->rx_max > CDC_NCM_NTB_MAX_SIZE_RX) {
                pr_debug("Using default maximum receive length=%d\n",
                                                CDC_NCM_NTB_MAX_SIZE_RX);
                ctx->rx_max = CDC_NCM_NTB_MAX_SIZE_RX;
        }

        /* inform device about NTB input size changes */
        if (ctx->rx_max != le32_to_cpu(ctx->ncm_parm.dwNtbInMaxSize)) {

                if (flags & USB_CDC_NCM_NCAP_NTB_INPUT_SIZE) {
                        struct usb_cdc_ncm_ndp_input_size *ndp_in_sz;

                        ndp_in_sz = kzalloc(sizeof(*ndp_in_sz), GFP_KERNEL);
                        if (!ndp_in_sz) {
                                err = -ENOMEM;
                                goto size_err;
                        }

                        err = usb_control_msg(ctx->udev,
                                        usb_sndctrlpipe(ctx->udev, 0),
                                        USB_CDC_SET_NTB_INPUT_SIZE,
                                        USB_TYPE_CLASS | USB_DIR_OUT
                                         | USB_RECIP_INTERFACE,
                                        0, iface_no, ndp_in_sz, 8, 1000);
                        kfree(ndp_in_sz);
                } else {
                        __le32 *dwNtbInMaxSize;
                        dwNtbInMaxSize = kzalloc(sizeof(*dwNtbInMaxSize),
                                        GFP_KERNEL);
                        if (!dwNtbInMaxSize) {
                                err = -ENOMEM;
                                goto size_err;
                        }
                        *dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);

                        err = usb_control_msg(ctx->udev,
                                        usb_sndctrlpipe(ctx->udev, 0),
                                        USB_CDC_SET_NTB_INPUT_SIZE,
                                        USB_TYPE_CLASS | USB_DIR_OUT
                                         | USB_RECIP_INTERFACE,
                                        0, iface_no, dwNtbInMaxSize, 4, 1000);
                        kfree(dwNtbInMaxSize);
                }
size_err:
                if (err < 0)
                        pr_debug("Setting NTB Input Size failed\n");
        }

        /* verify maximum size of transmitted NTB in bytes */
        if ((ctx->tx_max <
            (CDC_NCM_MIN_HDR_SIZE + CDC_NCM_MIN_DATAGRAM_SIZE)) ||
            (ctx->tx_max > CDC_NCM_NTB_MAX_SIZE_TX)) {
                pr_debug("Using default maximum transmit length=%d\n",
                                                CDC_NCM_NTB_MAX_SIZE_TX);
                ctx->tx_max = CDC_NCM_NTB_MAX_SIZE_TX;
        }

        /*
         * verify that the structure alignment is:
         * - power of two
         * - not greater than the maximum transmit length
         * - not less than four bytes
         */
        val = ctx->tx_ndp_modulus;

        if ((val < USB_CDC_NCM_NDP_ALIGN_MIN_SIZE) ||
            (val != ((-val) & val)) || (val >= ctx->tx_max)) {
                pr_debug("Using default alignment: 4 bytes\n");
                ctx->tx_ndp_modulus = USB_CDC_NCM_NDP_ALIGN_MIN_SIZE;
        }

        /*
         * verify that the payload alignment is:
         * - power of two
         * - not greater than the maximum transmit length
         * - not less than four bytes
         */
        val = ctx->tx_modulus;

        if ((val < USB_CDC_NCM_NDP_ALIGN_MIN_SIZE) ||
            (val != ((-val) & val)) || (val >= ctx->tx_max)) {
                pr_debug("Using default transmit modulus: 4 bytes\n");
                ctx->tx_modulus = USB_CDC_NCM_NDP_ALIGN_MIN_SIZE;
        }

        /* verify the payload remainder */
        if (ctx->tx_remainder >= ctx->tx_modulus) {
                pr_debug("Using default transmit remainder: 0 bytes\n");
                ctx->tx_remainder = 0;
        }

        /* adjust TX-remainder according to NCM specification. */
        ctx->tx_remainder = ((ctx->tx_remainder - ETH_HLEN) &
                                                (ctx->tx_modulus - 1));

        /* additional configuration */

        /* set CRC Mode */
        if (flags & USB_CDC_NCM_NCAP_CRC_MODE) {
                err = usb_control_msg(ctx->udev, usb_sndctrlpipe(ctx->udev, 0),
                                USB_CDC_SET_CRC_MODE,
                                USB_TYPE_CLASS | USB_DIR_OUT
                                 | USB_RECIP_INTERFACE,
                                USB_CDC_NCM_CRC_NOT_APPENDED,
                                iface_no, NULL, 0, 1000);
                if (err < 0)
                        pr_debug("Setting CRC mode off failed\n");
        }

        /* set NTB format, if both formats are supported */
        if (ntb_fmt_supported & USB_CDC_NCM_NTH32_SIGN) {
                err = usb_control_msg(ctx->udev, usb_sndctrlpipe(ctx->udev, 0),
                                USB_CDC_SET_NTB_FORMAT, USB_TYPE_CLASS
                                 | USB_DIR_OUT | USB_RECIP_INTERFACE,
                                USB_CDC_NCM_NTB16_FORMAT,
                                iface_no, NULL, 0, 1000);
                if (err < 0)
                        pr_debug("Setting NTB format to 16-bit failed\n");
        }

        ctx->max_datagram_size = CDC_NCM_MIN_DATAGRAM_SIZE;

        /* set Max Datagram Size (MTU) */
        if (flags & USB_CDC_NCM_NCAP_MAX_DATAGRAM_SIZE) {
                __le16 *max_datagram_size;
                u16 eth_max_sz = le16_to_cpu(ctx->ether_desc->wMaxSegmentSize);

                max_datagram_size = kzalloc(sizeof(*max_datagram_size),
                                GFP_KERNEL);
                if (!max_datagram_size) {
                        err = -ENOMEM;
                        goto max_dgram_err;
                }

                err = usb_control_msg(ctx->udev, usb_rcvctrlpipe(ctx->udev, 0),
                                USB_CDC_GET_MAX_DATAGRAM_SIZE,
                                USB_TYPE_CLASS | USB_DIR_IN
                                 | USB_RECIP_INTERFACE,
                                0, iface_no, max_datagram_size,
                                2, 1000);
                if (err < 0) {
                        pr_debug("GET_MAX_DATAGRAM_SIZE failed, use size=%u\n",
                                                CDC_NCM_MIN_DATAGRAM_SIZE);
                        kfree(max_datagram_size);
                } else {
                        ctx->max_datagram_size =
                                le16_to_cpu(*max_datagram_size);
                        /* Check Eth descriptor value */
                        if (eth_max_sz < CDC_NCM_MAX_DATAGRAM_SIZE) {
                                if (ctx->max_datagram_size > eth_max_sz)
                                        ctx->max_datagram_size = eth_max_sz;
                        } else {
                                if (ctx->max_datagram_size >
                                                CDC_NCM_MAX_DATAGRAM_SIZE)
                                        ctx->max_datagram_size =
                                                CDC_NCM_MAX_DATAGRAM_SIZE;
                        }

                        if (ctx->max_datagram_size < CDC_NCM_MIN_DATAGRAM_SIZE)
                                ctx->max_datagram_size =
                                        CDC_NCM_MIN_DATAGRAM_SIZE;

                        /* if value changed, update device */
                        err = usb_control_msg(ctx->udev,
                                                usb_sndctrlpipe(ctx->udev, 0),
                                                USB_CDC_SET_MAX_DATAGRAM_SIZE,
                                                USB_TYPE_CLASS | USB_DIR_OUT
                                                 | USB_RECIP_INTERFACE,
                                                0,
                                                iface_no, max_datagram_size,
                                                2, 1000);
                        kfree(max_datagram_size);
max_dgram_err:
                        if (err < 0)
                                pr_debug("SET_MAX_DATAGRAM_SIZE failed\n");
                }

        }

        if (ctx->netdev->mtu != (ctx->max_datagram_size - ETH_HLEN))
                ctx->netdev->mtu = ctx->max_datagram_size - ETH_HLEN;

        return 0;
}

static void
cdc_ncm_find_endpoints(struct cdc_ncm_ctx *ctx, struct usb_interface *intf)
{
        struct usb_host_endpoint *e;
        u8 ep;

        for (ep = 0; ep < intf->cur_altsetting->desc.bNumEndpoints; ep++) {

                e = intf->cur_altsetting->endpoint + ep;
                switch (e->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
                case USB_ENDPOINT_XFER_INT:
                        if (usb_endpoint_dir_in(&e->desc)) {
                                if (ctx->status_ep == NULL)
                                        ctx->status_ep = e;
                        }
                        break;

                case USB_ENDPOINT_XFER_BULK:
                        if (usb_endpoint_dir_in(&e->desc)) {
                                if (ctx->in_ep == NULL)
                                        ctx->in_ep = e;
                        } else {
                                if (ctx->out_ep == NULL)
                                        ctx->out_ep = e;
                        }
                        break;

                default:
                        break;
                }
        }
}

static void cdc_ncm_free(struct cdc_ncm_ctx *ctx)
{
        if (ctx == NULL)
                return;

        del_timer_sync(&ctx->tx_timer);

        if (ctx->tx_rem_skb != NULL) {
                dev_kfree_skb_any(ctx->tx_rem_skb);
                ctx->tx_rem_skb = NULL;
        }

        if (ctx->tx_curr_skb != NULL) {
                dev_kfree_skb_any(ctx->tx_curr_skb);
                ctx->tx_curr_skb = NULL;
        }

        kfree(ctx);
}

static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)
{
        struct cdc_ncm_ctx *ctx;
        struct usb_driver *driver;
        u8 *buf;
        int len;
        int temp;
        u8 iface_no;

        ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
        if (ctx == NULL)
                return -ENODEV;

        memset(ctx, 0, sizeof(*ctx));

        init_timer(&ctx->tx_timer);
        spin_lock_init(&ctx->mtx);
        ctx->netdev = dev->net;

        /* store ctx pointer in device data field */
        dev->data[0] = (unsigned long)ctx;

        /* get some pointers */
        driver = driver_of(intf);
        buf = intf->cur_altsetting->extra;
        len = intf->cur_altsetting->extralen;

        ctx->udev = dev->udev;
        ctx->intf = intf;

        /* parse through descriptors associated with control interface */
        while ((len > 0) && (buf[0] > 2) && (buf[0] <= len)) {

                if (buf[1] != USB_DT_CS_INTERFACE)
                        goto advance;

                switch (buf[2]) {
                case USB_CDC_UNION_TYPE:
                        if (buf[0] < sizeof(*(ctx->union_desc)))
                                break;

                        ctx->union_desc =
                                        (const struct usb_cdc_union_desc *)buf;

                        ctx->control = usb_ifnum_to_if(dev->udev,
                                        ctx->union_desc->bMasterInterface0);
                        ctx->data = usb_ifnum_to_if(dev->udev,
                                        ctx->union_desc->bSlaveInterface0);
                        break;

                case USB_CDC_ETHERNET_TYPE:
                        if (buf[0] < sizeof(*(ctx->ether_desc)))
                                break;

                        ctx->ether_desc =
                                        (const struct usb_cdc_ether_desc *)buf;
                        dev->hard_mtu =
                                le16_to_cpu(ctx->ether_desc->wMaxSegmentSize);

                        if (dev->hard_mtu < CDC_NCM_MIN_DATAGRAM_SIZE)
                                dev->hard_mtu = CDC_NCM_MIN_DATAGRAM_SIZE;
                        else if (dev->hard_mtu > CDC_NCM_MAX_DATAGRAM_SIZE)
                                dev->hard_mtu = CDC_NCM_MAX_DATAGRAM_SIZE;
                        break;

                case USB_CDC_NCM_TYPE:
                        if (buf[0] < sizeof(*(ctx->func_desc)))
                                break;

                        ctx->func_desc = (const struct usb_cdc_ncm_desc *)buf;
                        break;

                default:
                        break;
                }
advance:
                /* advance to next descriptor */
                temp = buf[0];
                buf += temp;
                len -= temp;
        }

        /* check if we got everything */
        if ((ctx->control == NULL) || (ctx->data == NULL) ||
            (ctx->ether_desc == NULL) || (ctx->control != intf))
                goto error;

        /* claim interfaces, if any */
        temp = usb_driver_claim_interface(driver, ctx->data, dev);
        if (temp)
                goto error;

        iface_no = ctx->data->cur_altsetting->desc.bInterfaceNumber;

        /* reset data interface */
        temp = usb_set_interface(dev->udev, iface_no, 0);
        if (temp)
                goto error2;

        /* initialize data interface */
        if (cdc_ncm_setup(ctx))
                goto error2;

        /* configure data interface */
        temp = usb_set_interface(dev->udev, iface_no, 1);
        if (temp)
                goto error2;

        cdc_ncm_find_endpoints(ctx, ctx->data);
        cdc_ncm_find_endpoints(ctx, ctx->control);

        if ((ctx->in_ep == NULL) || (ctx->out_ep == NULL) ||
            (ctx->status_ep == NULL))
                goto error2;

        dev->net->ethtool_ops = &cdc_ncm_ethtool_ops;

        usb_set_intfdata(ctx->data, dev);
        usb_set_intfdata(ctx->control, dev);
        usb_set_intfdata(ctx->intf, dev);

        temp = usbnet_get_ethernet_addr(dev, ctx->ether_desc->iMACAddress);
        if (temp)
                goto error2;

        dev_info(&dev->udev->dev, "MAC-Address: "
                                "0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x\n",
                                dev->net->dev_addr[0], dev->net->dev_addr[1],
                                dev->net->dev_addr[2], dev->net->dev_addr[3],
                                dev->net->dev_addr[4], dev->net->dev_addr[5]);

        dev->in = usb_rcvbulkpipe(dev->udev,
                ctx->in_ep->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
        dev->out = usb_sndbulkpipe(dev->udev,
                ctx->out_ep->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
        dev->status = ctx->status_ep;
        dev->rx_urb_size = ctx->rx_max;

        /*
         * We should get an event when network connection is "connected" or
         * "disconnected". Set network connection in "disconnected" state
         * (carrier is OFF) during attach, so the IP network stack does not
         * start IPv6 negotiation and more.
         */
        netif_carrier_off(dev->net);
        ctx->tx_speed = ctx->rx_speed = 0;
        return 0;

error2:
        usb_set_intfdata(ctx->control, NULL);
        usb_set_intfdata(ctx->data, NULL);
        usb_driver_release_interface(driver, ctx->data);
error:
        cdc_ncm_free((struct cdc_ncm_ctx *)dev->data[0]);
        dev->data[0] = 0;
        dev_info(&dev->udev->dev, "bind() failure\n");
        return -ENODEV;
}

static void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf)
{
        struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
        struct usb_driver *driver = driver_of(intf);

        if (ctx == NULL)
                return;         /* no setup */

        /* disconnect master --> disconnect slave */
        if (intf == ctx->control && ctx->data) {
                usb_set_intfdata(ctx->data, NULL);
                usb_driver_release_interface(driver, ctx->data);
                ctx->data = NULL;

        } else if (intf == ctx->data && ctx->control) {
                usb_set_intfdata(ctx->control, NULL);
                usb_driver_release_interface(driver, ctx->control);
                ctx->control = NULL;
        }

        usb_set_intfdata(ctx->intf, NULL);
        cdc_ncm_free(ctx);
}

static void cdc_ncm_zero_fill(u8 *ptr, u32 first, u32 end, u32 max)
{
        if (first >= max)
                return;
        if (first >= end)
                return;
        if (end > max)
                end = max;
        memset(ptr + first, 0, end - first);
}

static struct sk_buff *
cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb)
{
        struct sk_buff *skb_out;
        u32 rem;
        u32 offset;
        u32 last_offset;
        u16 n = 0, index;
        u8 ready2send = 0;

        /* if there is a remaining skb, it gets priority */
        if (skb != NULL)
                swap(skb, ctx->tx_rem_skb);
        else
                ready2send = 1;

        /*
         * +----------------+
         * | skb_out        |
         * +----------------+
         *           ^ offset
         *        ^ last_offset
         */

        /* check if we are resuming an OUT skb */
        if (ctx->tx_curr_skb != NULL) {
                /* pop variables */
                skb_out = ctx->tx_curr_skb;
                offset = ctx->tx_curr_offset;
                last_offset = ctx->tx_curr_last_offset;
                n = ctx->tx_curr_frame_num;

        } else {
                /* reset variables */
                skb_out = alloc_skb((ctx->tx_max + 1), GFP_ATOMIC);
                if (skb_out == NULL) {
                        if (skb != NULL) {
                                dev_kfree_skb_any(skb);
                                ctx->netdev->stats.tx_dropped++;
                        }
                        goto exit_no_skb;
                }

                /* make room for NTH and NDP */
                offset = ALIGN(sizeof(struct usb_cdc_ncm_nth16),
                                        ctx->tx_ndp_modulus) +
                                        sizeof(struct usb_cdc_ncm_ndp16) +
                                        (ctx->tx_max_datagrams + 1) *
                                        sizeof(struct usb_cdc_ncm_dpe16);

                /* store last valid offset before alignment */
                last_offset = offset;
                /* align first Datagram offset correctly */
                offset = ALIGN(offset, ctx->tx_modulus) + ctx->tx_remainder;
                /* zero buffer till the first IP datagram */
                cdc_ncm_zero_fill(skb_out->data, 0, offset, offset);
                n = 0;
                ctx->tx_curr_frame_num = 0;
        }

        for (; n < ctx->tx_max_datagrams; n++) {
                /* check if end of transmit buffer is reached */
                if (offset >= ctx->tx_max) {
                        ready2send = 1;
                        break;
                }
                /* compute maximum buffer size */
                rem = ctx->tx_max - offset;

                if (skb == NULL) {
                        skb = ctx->tx_rem_skb;
                        ctx->tx_rem_skb = NULL;

                        /* check for end of skb */
                        if (skb == NULL)
                                break;
                }

                if (skb->len > rem) {
                        if (n == 0) {
                                /* won't fit, MTU problem? */
                                dev_kfree_skb_any(skb);
                                skb = NULL;
                                ctx->netdev->stats.tx_dropped++;
                        } else {
                                /* no room for skb - store for later */
                                if (ctx->tx_rem_skb != NULL) {
                                        dev_kfree_skb_any(ctx->tx_rem_skb);
                                        ctx->netdev->stats.tx_dropped++;
                                }
                                ctx->tx_rem_skb = skb;
                                skb = NULL;
                                ready2send = 1;
                        }
                        break;
                }

                memcpy(((u8 *)skb_out->data) + offset, skb->data, skb->len);

                ctx->tx_ncm.dpe16[n].wDatagramLength = cpu_to_le16(skb->len);
                ctx->tx_ncm.dpe16[n].wDatagramIndex = cpu_to_le16(offset);

                /* update offset */
                offset += skb->len;

                /* store last valid offset before alignment */
                last_offset = offset;

                /* align offset correctly */
                offset = ALIGN(offset, ctx->tx_modulus) + ctx->tx_remainder;

                /* zero padding */
                cdc_ncm_zero_fill(skb_out->data, last_offset, offset,
                                                                ctx->tx_max);
                dev_kfree_skb_any(skb);
                skb = NULL;
        }

        /* free up any dangling skb */
        if (skb != NULL) {
                dev_kfree_skb_any(skb);
                skb = NULL;
                ctx->netdev->stats.tx_dropped++;
        }

        ctx->tx_curr_frame_num = n;

        if (n == 0) {
                /* wait for more frames */
                /* push variables */
                ctx->tx_curr_skb = skb_out;
                ctx->tx_curr_offset = offset;
                ctx->tx_curr_last_offset = last_offset;
                goto exit_no_skb;

        } else if ((n < ctx->tx_max_datagrams) && (ready2send == 0)) {
                /* wait for more frames */
                /* push variables */
                ctx->tx_curr_skb = skb_out;
                ctx->tx_curr_offset = offset;
                ctx->tx_curr_last_offset = last_offset;
                /* set the pending count */
                if (n < CDC_NCM_RESTART_TIMER_DATAGRAM_CNT)
                        ctx->tx_timer_pending = 2;
                goto exit_no_skb;

        } else {
                /* frame goes out */
                /* variables will be reset at next call */
        }

        /* check for overflow */
        if (last_offset > ctx->tx_max)
                last_offset = ctx->tx_max;

        /* revert offset */
        offset = last_offset;

        /*
         * If collected data size is less or equal CDC_NCM_MIN_TX_PKT bytes,
         * we send buffers as it is. If we get more data, it would be more
         * efficient for USB HS mobile device with DMA engine to receive a full
         * size NTB, than canceling DMA transfer and receiving a short packet.
         */
        if (offset > CDC_NCM_MIN_TX_PKT)
                offset = ctx->tx_max;

        /* final zero padding */
        cdc_ncm_zero_fill(skb_out->data, last_offset, offset, ctx->tx_max);

        /* store last offset */
        last_offset = offset;

        if (((last_offset < ctx->tx_max) && ((last_offset %
                        le16_to_cpu(ctx->out_ep->desc.wMaxPacketSize)) == 0)) ||
            (((last_offset == ctx->tx_max) && ((ctx->tx_max %
                le16_to_cpu(ctx->out_ep->desc.wMaxPacketSize)) == 0)) &&
                (ctx->tx_max < le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize)))) {
                /* force short packet */
                *(((u8 *)skb_out->data) + last_offset) = 0;
                last_offset++;
        }

        /* zero the rest of the DPEs plus the last NULL entry */
        for (; n <= CDC_NCM_DPT_DATAGRAMS_MAX; n++) {
                ctx->tx_ncm.dpe16[n].wDatagramLength = 0;
                ctx->tx_ncm.dpe16[n].wDatagramIndex = 0;
        }

        /* fill out 16-bit NTB header */
        ctx->tx_ncm.nth16.dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);
        ctx->tx_ncm.nth16.wHeaderLength =
                                        cpu_to_le16(sizeof(ctx->tx_ncm.nth16));
        ctx->tx_ncm.nth16.wSequence = cpu_to_le16(ctx->tx_seq);
        ctx->tx_ncm.nth16.wBlockLength = cpu_to_le16(last_offset);
        index = ALIGN(sizeof(struct usb_cdc_ncm_nth16), ctx->tx_ndp_modulus);
        ctx->tx_ncm.nth16.wNdpIndex = cpu_to_le16(index);

        memcpy(skb_out->data, &(ctx->tx_ncm.nth16), sizeof(ctx->tx_ncm.nth16));
        ctx->tx_seq++;

        /* fill out 16-bit NDP table */
        ctx->tx_ncm.ndp16.dwSignature =
                                cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN);
        rem = sizeof(ctx->tx_ncm.ndp16) + ((ctx->tx_curr_frame_num + 1) *
                                        sizeof(struct usb_cdc_ncm_dpe16));
        ctx->tx_ncm.ndp16.wLength = cpu_to_le16(rem);
        ctx->tx_ncm.ndp16.wNextNdpIndex = 0; /* reserved */

        memcpy(((u8 *)skb_out->data) + index,
                                                &(ctx->tx_ncm.ndp16),
                                                sizeof(ctx->tx_ncm.ndp16));

        memcpy(((u8 *)skb_out->data) + index + sizeof(ctx->tx_ncm.ndp16),
                                        &(ctx->tx_ncm.dpe16),
                                        (ctx->tx_curr_frame_num + 1) *
                                        sizeof(struct usb_cdc_ncm_dpe16));

        /* set frame length */
        skb_put(skb_out, last_offset);

        /* return skb */
        ctx->tx_curr_skb = NULL;
        return skb_out;

exit_no_skb:
        return NULL;
}

static void cdc_ncm_tx_timeout_start(struct cdc_ncm_ctx *ctx)
{
        /* start timer, if not already started */
        if (timer_pending(&ctx->tx_timer) == 0) {
                ctx->tx_timer.function = &cdc_ncm_tx_timeout;
                ctx->tx_timer.data = (unsigned long)ctx;
                ctx->tx_timer.expires = jiffies + ((HZ + 999) / 1000);
                add_timer(&ctx->tx_timer);
        }
}

static void cdc_ncm_tx_timeout(unsigned long arg)
{
        struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)arg;
        u8 restart;

        spin_lock(&ctx->mtx);
        if (ctx->tx_timer_pending != 0) {
                ctx->tx_timer_pending--;
                restart = 1;
        } else {
                restart = 0;
        }

        spin_unlock(&ctx->mtx);

        if (restart) {
                spin_lock(&ctx->mtx);
                cdc_ncm_tx_timeout_start(ctx);
                spin_unlock(&ctx->mtx);
        } else if (ctx->netdev != NULL) {
                usbnet_start_xmit(NULL, ctx->netdev);
        }
}

static struct sk_buff *
cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
        struct sk_buff *skb_out;
        struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
        u8 need_timer = 0;

        /*
         * The Ethernet API we are using does not support transmitting
         * multiple Ethernet frames in a single call. This driver will
         * accumulate multiple Ethernet frames and send out a larger
         * USB frame when the USB buffer is full or when a single jiffies
         * timeout happens.
         */
        if (ctx == NULL)
                goto error;

        spin_lock(&ctx->mtx);
        skb_out = cdc_ncm_fill_tx_frame(ctx, skb);
        if (ctx->tx_curr_skb != NULL)
                need_timer = 1;

        /* Start timer, if there is a remaining skb */
        if (need_timer)
                cdc_ncm_tx_timeout_start(ctx);

        if (skb_out)
                dev->net->stats.tx_packets += ctx->tx_curr_frame_num;

        spin_unlock(&ctx->mtx);
        return skb_out;

error:
        if (skb != NULL)
                dev_kfree_skb_any(skb);

        return NULL;
}

static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
{
        struct sk_buff *skb;
        struct cdc_ncm_ctx *ctx;
        int sumlen;
        int actlen;
        int temp;
        int nframes;
        int x;
        int offset;

        ctx = (struct cdc_ncm_ctx *)dev->data[0];
        if (ctx == NULL)
                goto error;

        actlen = skb_in->len;
        sumlen = CDC_NCM_NTB_MAX_SIZE_RX;

        if (actlen < (sizeof(ctx->rx_ncm.nth16) + sizeof(ctx->rx_ncm.ndp16))) {
                pr_debug("frame too short\n");
                goto error;
        }

        memcpy(&(ctx->rx_ncm.nth16), ((u8 *)skb_in->data),
                                                sizeof(ctx->rx_ncm.nth16));

        if (le32_to_cpu(ctx->rx_ncm.nth16.dwSignature) !=
            USB_CDC_NCM_NTH16_SIGN) {
                pr_debug("invalid NTH16 signature <%u>\n",
                         le32_to_cpu(ctx->rx_ncm.nth16.dwSignature));
                goto error;
        }

        temp = le16_to_cpu(ctx->rx_ncm.nth16.wBlockLength);
        if (temp > sumlen) {
                pr_debug("unsupported NTB block length %u/%u\n", temp, sumlen);
                goto error;
        }

        temp = le16_to_cpu(ctx->rx_ncm.nth16.wNdpIndex);
        if ((temp + sizeof(ctx->rx_ncm.ndp16)) > actlen) {
                pr_debug("invalid DPT16 index\n");
                goto error;
        }

        memcpy(&(ctx->rx_ncm.ndp16), ((u8 *)skb_in->data) + temp,
                                                sizeof(ctx->rx_ncm.ndp16));

        if (le32_to_cpu(ctx->rx_ncm.ndp16.dwSignature) !=
            USB_CDC_NCM_NDP16_NOCRC_SIGN) {
                pr_debug("invalid DPT16 signature <%u>\n",
                         le32_to_cpu(ctx->rx_ncm.ndp16.dwSignature));
                goto error;
        }

        if (le16_to_cpu(ctx->rx_ncm.ndp16.wLength) <
            USB_CDC_NCM_NDP16_LENGTH_MIN) {
                pr_debug("invalid DPT16 length <%u>\n",
                         le32_to_cpu(ctx->rx_ncm.ndp16.dwSignature));
                goto error;
        }

        nframes = ((le16_to_cpu(ctx->rx_ncm.ndp16.wLength) -
                                        sizeof(struct usb_cdc_ncm_ndp16)) /
                                        sizeof(struct usb_cdc_ncm_dpe16));
        nframes--; /* we process NDP entries except for the last one */

        pr_debug("nframes = %u\n", nframes);

        temp += sizeof(ctx->rx_ncm.ndp16);

        if ((temp + nframes * (sizeof(struct usb_cdc_ncm_dpe16))) > actlen) {
                pr_debug("Invalid nframes = %d\n", nframes);
                goto error;
        }

        if (nframes > CDC_NCM_DPT_DATAGRAMS_MAX) {
                pr_debug("Truncating number of frames from %u to %u\n",
                                        nframes, CDC_NCM_DPT_DATAGRAMS_MAX);
                nframes = CDC_NCM_DPT_DATAGRAMS_MAX;
        }

        memcpy(&(ctx->rx_ncm.dpe16), ((u8 *)skb_in->data) + temp,
                                nframes * (sizeof(struct usb_cdc_ncm_dpe16)));

        for (x = 0; x < nframes; x++) {
                offset = le16_to_cpu(ctx->rx_ncm.dpe16[x].wDatagramIndex);
                temp = le16_to_cpu(ctx->rx_ncm.dpe16[x].wDatagramLength);

                /*
                 * CDC NCM ch. 3.7
                 * All entries after first NULL entry are to be ignored
                 */
                if ((offset == 0) || (temp == 0)) {
                        if (!x)
                                goto error; /* empty NTB */
                        break;
                }

                /* sanity checking */
                if (((offset + temp) > actlen) ||
                    (temp > CDC_NCM_MAX_DATAGRAM_SIZE) || (temp < ETH_HLEN)) {
                        pr_debug("invalid frame detected (ignored)"
                                        "offset[%u]=%u, length=%u, skb=%p\n",
                                        x, offset, temp, skb_in);
                        if (!x)
                                goto error;
                        break;

                } else {
                        skb = skb_clone(skb_in, GFP_ATOMIC);
                        if (!skb)
                                goto error;
                        skb->len = temp;
                        skb->data = ((u8 *)skb_in->data) + offset;
                        skb_set_tail_pointer(skb, temp);
                        usbnet_skb_return(dev, skb);
                }
        }
        return 1;
error:
        return 0;
}

static void
cdc_ncm_speed_change(struct cdc_ncm_ctx *ctx,
                     struct usb_cdc_speed_change *data)
{
        uint32_t rx_speed = le32_to_cpu(data->DLBitRRate);
        uint32_t tx_speed = le32_to_cpu(data->ULBitRate);

        /*
         * Currently the USB-NET API does not support reporting the actual
         * device speed. Do print it instead.
         */
        if ((tx_speed != ctx->tx_speed) || (rx_speed != ctx->rx_speed)) {
                ctx->tx_speed = tx_speed;
                ctx->rx_speed = rx_speed;

                if ((tx_speed > 1000000) && (rx_speed > 1000000)) {
                        printk(KERN_INFO KBUILD_MODNAME
                                ": %s: %u mbit/s downlink "
                                "%u mbit/s uplink\n",
                                ctx->netdev->name,
                                (unsigned int)(rx_speed / 1000000U),
                                (unsigned int)(tx_speed / 1000000U));
                } else {
                        printk(KERN_INFO KBUILD_MODNAME
                                ": %s: %u kbit/s downlink "
                                "%u kbit/s uplink\n",
                                ctx->netdev->name,
                                (unsigned int)(rx_speed / 1000U),
                                (unsigned int)(tx_speed / 1000U));
                }
        }
}

static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
{
        struct cdc_ncm_ctx *ctx;
        struct usb_cdc_notification *event;

        ctx = (struct cdc_ncm_ctx *)dev->data[0];

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

        /* test for split data in 8-byte chunks */
        if (test_and_clear_bit(EVENT_STS_SPLIT, &dev->flags)) {
                cdc_ncm_speed_change(ctx,
                      (struct usb_cdc_speed_change *)urb->transfer_buffer);
                return;
        }

        event = urb->transfer_buffer;

        switch (event->bNotificationType) {
        case USB_CDC_NOTIFY_NETWORK_CONNECTION:
                /*
                 * According to the CDC NCM specification ch.7.1
                 * USB_CDC_NOTIFY_NETWORK_CONNECTION notification shall be
                 * sent by device after USB_CDC_NOTIFY_SPEED_CHANGE.
                 */
                ctx->connected = event->wValue;

                printk(KERN_INFO KBUILD_MODNAME ": %s: network connection:"
                        " %sconnected\n",
                        ctx->netdev->name, ctx->connected ? "" : "dis");

                if (ctx->connected)
                        netif_carrier_on(dev->net);
                else {
                        netif_carrier_off(dev->net);
                        ctx->tx_speed = ctx->rx_speed = 0;
                }
                break;

        case USB_CDC_NOTIFY_SPEED_CHANGE:
                if (urb->actual_length < (sizeof(*event) +
                                        sizeof(struct usb_cdc_speed_change)))
                        set_bit(EVENT_STS_SPLIT, &dev->flags);
                else
                        cdc_ncm_speed_change(ctx,
                                (struct usb_cdc_speed_change *) &event[1]);
                break;

        default:
                dev_err(&dev->udev->dev, "NCM: unexpected "
                        "notification 0x%02x!\n", event->bNotificationType);
                break;
        }
}

static int cdc_ncm_check_connect(struct usbnet *dev)
{
        struct cdc_ncm_ctx *ctx;

        ctx = (struct cdc_ncm_ctx *)dev->data[0];
        if (ctx == NULL)
                return 1;       /* disconnected */

        return !ctx->connected;
}

static int
cdc_ncm_probe(struct usb_interface *udev, const struct usb_device_id *prod)
{
        return usbnet_probe(udev, prod);
}

static void cdc_ncm_disconnect(struct usb_interface *intf)
{
        struct usbnet *dev = usb_get_intfdata(intf);

        if (dev == NULL)
                return;         /* already disconnected */

        usbnet_disconnect(intf);
}

static int cdc_ncm_manage_power(struct usbnet *dev, int status)
{
        dev->intf->needs_remote_wakeup = status;
        return 0;
}

static const struct driver_info cdc_ncm_info = {
        .description = "CDC NCM",
        .flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET,
        .bind = cdc_ncm_bind,
        .unbind = cdc_ncm_unbind,
        .check_connect = cdc_ncm_check_connect,
        .manage_power = cdc_ncm_manage_power,
        .status = cdc_ncm_status,
        .rx_fixup = cdc_ncm_rx_fixup,
        .tx_fixup = cdc_ncm_tx_fixup,
};

static struct usb_driver cdc_ncm_driver = {
        .name = "cdc_ncm",
        .id_table = cdc_devs,
        .probe = cdc_ncm_probe,
        .disconnect = cdc_ncm_disconnect,
        .suspend = usbnet_suspend,
        .resume = usbnet_resume,
        .reset_resume = usbnet_resume,
        .supports_autosuspend = 1,
};

static struct ethtool_ops cdc_ncm_ethtool_ops = {
        .get_drvinfo = cdc_ncm_get_drvinfo,
        .get_link = usbnet_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,
};

static int __init cdc_ncm_init(void)
{
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION "\n");
        return usb_register(&cdc_ncm_driver);
}

module_init(cdc_ncm_init);

static void __exit cdc_ncm_exit(void)
{
        usb_deregister(&cdc_ncm_driver);
}

module_exit(cdc_ncm_exit);

MODULE_AUTHOR("Hans Petter Selasky");
MODULE_DESCRIPTION("USB CDC NCM host driver");
MODULE_LICENSE("Dual BSD/GPL");