/*
 * f_ncm.c -- USB CDC Network (NCM) link function driver
 *
 * Copyright (C) 2010 Nokia Corporation
 * Contact: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
 *
 * The driver borrows from f_ecm.c which is:
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2008 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>

#include <linux/usb/cdc.h>

#include "u_ether.h"
#include "u_ether_configfs.h"
#include "u_ncm.h"

/*
 * This function is a "CDC Network Control Model" (CDC NCM) Ethernet link.
 * NCM is intended to be used with high-speed network attachments.
 *
 * Note that NCM requires the use of "alternate settings" for its data
 * interface.  This means that the set_alt() method has real work to do,
 * and also means that a get_alt() method is required.
 */

/* to trigger crc/non-crc ndp signature */

#define NCM_NDP_HDR_CRC_MASK    0x01000000
#define NCM_NDP_HDR_CRC         0x01000000
#define NCM_NDP_HDR_NOCRC       0x00000000

enum ncm_notify_state {
        NCM_NOTIFY_NONE,                /* don't notify */
        NCM_NOTIFY_CONNECT,             /* issue CONNECT next */
        NCM_NOTIFY_SPEED,               /* issue SPEED_CHANGE next */
};

struct f_ncm {
        struct gether                   port;
        u8                              ctrl_id, data_id;

        char                            ethaddr[14];

        struct usb_ep                   *notify;
        struct usb_request              *notify_req;
        u8                              notify_state;
        bool                            is_open;

        const struct ndp_parser_opts    *parser_opts;
        bool                            is_crc;
        u32                             ndp_sign;

        /*
         * for notification, it is accessed from both
         * callback and ethernet open/close
         */
        spinlock_t                      lock;

        struct net_device               *netdev;

        /* For multi-frame NDP TX */
        struct sk_buff                  *skb_tx_data;
        struct sk_buff                  *skb_tx_ndp;
        u16                             ndp_dgram_count;
        bool                            timer_force_tx;
        struct tasklet_struct           tx_tasklet;
        struct hrtimer                  task_timer;

        bool                            timer_stopping;
};

static inline struct f_ncm *func_to_ncm(struct usb_function *f)
{
        return container_of(f, struct f_ncm, port.func);
}

/* peak (theoretical) bulk transfer rate in bits-per-second */
static inline unsigned ncm_bitrate(struct usb_gadget *g)
{
        if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
                return 13 * 512 * 8 * 1000 * 8;
        else
                return 19 *  64 * 1 * 1000 * 8;
}

/*-------------------------------------------------------------------------*/

/*
 * We cannot group frames so use just the minimal size which ok to put
 * one max-size ethernet frame.
 * If the host can group frames, allow it to do that, 16K is selected,
 * because it's used by default by the current linux host driver
 */
#define NTB_DEFAULT_IN_SIZE     16384
#define NTB_OUT_SIZE            16384

/* Allocation for storing the NDP, 32 should suffice for a
 * 16k packet. This allows a maximum of 32 * 507 Byte packets to
 * be transmitted in a single 16kB skb, though when sending full size
 * packets this limit will be plenty.
 * Smaller packets are not likely to be trying to maximize the
 * throughput and will be mstly sending smaller infrequent frames.
 */
#define TX_MAX_NUM_DPE          32

/* Delay for the transmit to wait before sending an unfilled NTB frame. */
#define TX_TIMEOUT_NSECS        300000

#define FORMATS_SUPPORTED       (USB_CDC_NCM_NTB16_SUPPORTED |  \
                                 USB_CDC_NCM_NTB32_SUPPORTED)

static struct usb_cdc_ncm_ntb_parameters ntb_parameters = {
        .wLength = cpu_to_le16(sizeof(ntb_parameters)),
        .bmNtbFormatsSupported = cpu_to_le16(FORMATS_SUPPORTED),
        .dwNtbInMaxSize = cpu_to_le32(NTB_DEFAULT_IN_SIZE),
        .wNdpInDivisor = cpu_to_le16(4),
        .wNdpInPayloadRemainder = cpu_to_le16(0),
        .wNdpInAlignment = cpu_to_le16(4),

        .dwNtbOutMaxSize = cpu_to_le32(NTB_OUT_SIZE),
        .wNdpOutDivisor = cpu_to_le16(4),
        .wNdpOutPayloadRemainder = cpu_to_le16(0),
        .wNdpOutAlignment = cpu_to_le16(4),
};

/*
 * Use wMaxPacketSize big enough to fit CDC_NOTIFY_SPEED_CHANGE in one
 * packet, to simplify cancellation; and a big transfer interval, to
 * waste less bandwidth.
 */

#define NCM_STATUS_INTERVAL_MS          32
#define NCM_STATUS_BYTECOUNT            16      /* 8 byte header + data */

static struct usb_interface_assoc_descriptor ncm_iad_desc = {
        .bLength =              sizeof ncm_iad_desc,
        .bDescriptorType =      USB_DT_INTERFACE_ASSOCIATION,

        /* .bFirstInterface =   DYNAMIC, */
        .bInterfaceCount =      2,      /* control + data */
        .bFunctionClass =       USB_CLASS_COMM,
        .bFunctionSubClass =    USB_CDC_SUBCLASS_NCM,
        .bFunctionProtocol =    USB_CDC_PROTO_NONE,
        /* .iFunction =         DYNAMIC */
};

/* interface descriptor: */

static struct usb_interface_descriptor ncm_control_intf = {
        .bLength =              sizeof ncm_control_intf,
        .bDescriptorType =      USB_DT_INTERFACE,

        /* .bInterfaceNumber = DYNAMIC */
        .bNumEndpoints =        1,
        .bInterfaceClass =      USB_CLASS_COMM,
        .bInterfaceSubClass =   USB_CDC_SUBCLASS_NCM,
        .bInterfaceProtocol =   USB_CDC_PROTO_NONE,
        /* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc ncm_header_desc = {
        .bLength =              sizeof ncm_header_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_HEADER_TYPE,

        .bcdCDC =               cpu_to_le16(0x0110),
};

static struct usb_cdc_union_desc ncm_union_desc = {
        .bLength =              sizeof(ncm_union_desc),
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_UNION_TYPE,
        /* .bMasterInterface0 = DYNAMIC */
        /* .bSlaveInterface0 =  DYNAMIC */
};

static struct usb_cdc_ether_desc ecm_desc = {
        .bLength =              sizeof ecm_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_ETHERNET_TYPE,

        /* this descriptor actually adds value, surprise! */
        /* .iMACAddress = DYNAMIC */
        .bmEthernetStatistics = cpu_to_le32(0), /* no statistics */
        .wMaxSegmentSize =      cpu_to_le16(ETH_FRAME_LEN),
        .wNumberMCFilters =     cpu_to_le16(0),
        .bNumberPowerFilters =  0,
};

#define NCAPS   (USB_CDC_NCM_NCAP_ETH_FILTER | USB_CDC_NCM_NCAP_CRC_MODE)

static struct usb_cdc_ncm_desc ncm_desc = {
        .bLength =              sizeof ncm_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_NCM_TYPE,

        .bcdNcmVersion =        cpu_to_le16(0x0100),
        /* can process SetEthernetPacketFilter */
        .bmNetworkCapabilities = NCAPS,
};

/* the default data interface has no endpoints ... */

static struct usb_interface_descriptor ncm_data_nop_intf = {
        .bLength =              sizeof ncm_data_nop_intf,
        .bDescriptorType =      USB_DT_INTERFACE,

        .bInterfaceNumber =     1,
        .bAlternateSetting =    0,
        .bNumEndpoints =        0,
        .bInterfaceClass =      USB_CLASS_CDC_DATA,
        .bInterfaceSubClass =   0,
        .bInterfaceProtocol =   USB_CDC_NCM_PROTO_NTB,
        /* .iInterface = DYNAMIC */
};

/* ... but the "real" data interface has two bulk endpoints */

static struct usb_interface_descriptor ncm_data_intf = {
        .bLength =              sizeof ncm_data_intf,
        .bDescriptorType =      USB_DT_INTERFACE,

        .bInterfaceNumber =     1,
        .bAlternateSetting =    1,
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_CDC_DATA,
        .bInterfaceSubClass =   0,
        .bInterfaceProtocol =   USB_CDC_NCM_PROTO_NTB,
        /* .iInterface = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor fs_ncm_notify_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize =       cpu_to_le16(NCM_STATUS_BYTECOUNT),
        .bInterval =            NCM_STATUS_INTERVAL_MS,
};

static struct usb_endpoint_descriptor fs_ncm_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor fs_ncm_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *ncm_fs_function[] = {
        (struct usb_descriptor_header *) &ncm_iad_desc,
        /* CDC NCM control descriptors */
        (struct usb_descriptor_header *) &ncm_control_intf,
        (struct usb_descriptor_header *) &ncm_header_desc,
        (struct usb_descriptor_header *) &ncm_union_desc,
        (struct usb_descriptor_header *) &ecm_desc,
        (struct usb_descriptor_header *) &ncm_desc,
        (struct usb_descriptor_header *) &fs_ncm_notify_desc,
        /* data interface, altsettings 0 and 1 */
        (struct usb_descriptor_header *) &ncm_data_nop_intf,
        (struct usb_descriptor_header *) &ncm_data_intf,
        (struct usb_descriptor_header *) &fs_ncm_in_desc,
        (struct usb_descriptor_header *) &fs_ncm_out_desc,
        NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor hs_ncm_notify_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize =       cpu_to_le16(NCM_STATUS_BYTECOUNT),
        .bInterval =            USB_MS_TO_HS_INTERVAL(NCM_STATUS_INTERVAL_MS),
};
static struct usb_endpoint_descriptor hs_ncm_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_endpoint_descriptor hs_ncm_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_descriptor_header *ncm_hs_function[] = {
        (struct usb_descriptor_header *) &ncm_iad_desc,
        /* CDC NCM control descriptors */
        (struct usb_descriptor_header *) &ncm_control_intf,
        (struct usb_descriptor_header *) &ncm_header_desc,
        (struct usb_descriptor_header *) &ncm_union_desc,
        (struct usb_descriptor_header *) &ecm_desc,
        (struct usb_descriptor_header *) &ncm_desc,
        (struct usb_descriptor_header *) &hs_ncm_notify_desc,
        /* data interface, altsettings 0 and 1 */
        (struct usb_descriptor_header *) &ncm_data_nop_intf,
        (struct usb_descriptor_header *) &ncm_data_intf,
        (struct usb_descriptor_header *) &hs_ncm_in_desc,
        (struct usb_descriptor_header *) &hs_ncm_out_desc,
        NULL,
};

/* string descriptors: */

#define STRING_CTRL_IDX 0
#define STRING_MAC_IDX  1
#define STRING_DATA_IDX 2
#define STRING_IAD_IDX  3

static struct usb_string ncm_string_defs[] = {
        [STRING_CTRL_IDX].s = "CDC Network Control Model (NCM)",
        [STRING_MAC_IDX].s = "",
        [STRING_DATA_IDX].s = "CDC Network Data",
        [STRING_IAD_IDX].s = "CDC NCM",
        {  } /* end of list */
};

static struct usb_gadget_strings ncm_string_table = {
        .language =             0x0409, /* en-us */
        .strings =              ncm_string_defs,
};

static struct usb_gadget_strings *ncm_strings[] = {
        &ncm_string_table,
        NULL,
};

/*
 * Here are options for NCM Datagram Pointer table (NDP) parser.
 * There are 2 different formats: NDP16 and NDP32 in the spec (ch. 3),
 * in NDP16 offsets and sizes fields are 1 16bit word wide,
 * in NDP32 -- 2 16bit words wide. Also signatures are different.
 * To make the parser code the same, put the differences in the structure,
 * and switch pointers to the structures when the format is changed.
 */

struct ndp_parser_opts {
        u32             nth_sign;
        u32             ndp_sign;
        unsigned        nth_size;
        unsigned        ndp_size;
        unsigned        dpe_size;
        unsigned        ndplen_align;
        /* sizes in u16 units */
        unsigned        dgram_item_len; /* index or length */
        unsigned        block_length;
        unsigned        ndp_index;
        unsigned        reserved1;
        unsigned        reserved2;
        unsigned        next_ndp_index;
};

#define INIT_NDP16_OPTS {                                       \
                .nth_sign = USB_CDC_NCM_NTH16_SIGN,             \
                .ndp_sign = USB_CDC_NCM_NDP16_NOCRC_SIGN,       \
                .nth_size = sizeof(struct usb_cdc_ncm_nth16),   \
                .ndp_size = sizeof(struct usb_cdc_ncm_ndp16),   \
                .dpe_size = sizeof(struct usb_cdc_ncm_dpe16),   \
                .ndplen_align = 4,                              \
                .dgram_item_len = 1,                            \
                .block_length = 1,                              \
                .ndp_index = 1,                                 \
                .reserved1 = 0,                                 \
                .reserved2 = 0,                                 \
                .next_ndp_index = 1,                            \
        }


#define INIT_NDP32_OPTS {                                       \
                .nth_sign = USB_CDC_NCM_NTH32_SIGN,             \
                .ndp_sign = USB_CDC_NCM_NDP32_NOCRC_SIGN,       \
                .nth_size = sizeof(struct usb_cdc_ncm_nth32),   \
                .ndp_size = sizeof(struct usb_cdc_ncm_ndp32),   \
                .dpe_size = sizeof(struct usb_cdc_ncm_dpe32),   \
                .ndplen_align = 8,                              \
                .dgram_item_len = 2,                            \
                .block_length = 2,                              \
                .ndp_index = 2,                                 \
                .reserved1 = 1,                                 \
                .reserved2 = 2,                                 \
                .next_ndp_index = 2,                            \
        }

static const struct ndp_parser_opts ndp16_opts = INIT_NDP16_OPTS;
static const struct ndp_parser_opts ndp32_opts = INIT_NDP32_OPTS;

static inline void put_ncm(__le16 **p, unsigned size, unsigned val)
{
        switch (size) {
        case 1:
                put_unaligned_le16((u16)val, *p);
                break;
        case 2:
                put_unaligned_le32((u32)val, *p);

                break;
        default:
                BUG();
        }

        *p += size;
}

static inline unsigned get_ncm(__le16 **p, unsigned size)
{
        unsigned tmp;

        switch (size) {
        case 1:
                tmp = get_unaligned_le16(*p);
                break;
        case 2:
                tmp = get_unaligned_le32(*p);
                break;
        default:
                BUG();
        }

        *p += size;
        return tmp;
}

/*-------------------------------------------------------------------------*/

static inline void ncm_reset_values(struct f_ncm *ncm)
{
        ncm->parser_opts = &ndp16_opts;
        ncm->is_crc = false;
        ncm->port.cdc_filter = DEFAULT_FILTER;

        /* doesn't make sense for ncm, fixed size used */
        ncm->port.header_len = 0;

        ncm->port.fixed_out_len = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
        ncm->port.fixed_in_len = NTB_DEFAULT_IN_SIZE;
}

/*
 * Context: ncm->lock held
 */
static void ncm_do_notify(struct f_ncm *ncm)
{
        struct usb_request              *req = ncm->notify_req;
        struct usb_cdc_notification     *event;
        struct usb_composite_dev        *cdev = ncm->port.func.config->cdev;
        __le32                          *data;
        int                             status;

        /* notification already in flight? */
        if (!req)
                return;

        event = req->buf;
        switch (ncm->notify_state) {
        case NCM_NOTIFY_NONE:
                return;

        case NCM_NOTIFY_CONNECT:
                event->bNotificationType = USB_CDC_NOTIFY_NETWORK_CONNECTION;
                if (ncm->is_open)
                        event->wValue = cpu_to_le16(1);
                else
                        event->wValue = cpu_to_le16(0);
                event->wLength = 0;
                req->length = sizeof *event;

                DBG(cdev, "notify connect %s\n",
                                ncm->is_open ? "true" : "false");
                ncm->notify_state = NCM_NOTIFY_NONE;
                break;

        case NCM_NOTIFY_SPEED:
                event->bNotificationType = USB_CDC_NOTIFY_SPEED_CHANGE;
                event->wValue = cpu_to_le16(0);
                event->wLength = cpu_to_le16(8);
                req->length = NCM_STATUS_BYTECOUNT;

                /* SPEED_CHANGE data is up/down speeds in bits/sec */
                data = req->buf + sizeof *event;
                data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));
                data[1] = data[0];

                DBG(cdev, "notify speed %d\n", ncm_bitrate(cdev->gadget));
                ncm->notify_state = NCM_NOTIFY_CONNECT;
                break;
        }
        event->bmRequestType = 0xA1;
        event->wIndex = cpu_to_le16(ncm->ctrl_id);

        ncm->notify_req = NULL;
        /*
         * In double buffering if there is a space in FIFO,
         * completion callback can be called right after the call,
         * so unlocking
         */
        spin_unlock(&ncm->lock);
        status = usb_ep_queue(ncm->notify, req, GFP_ATOMIC);
        spin_lock(&ncm->lock);
        if (status < 0) {
                ncm->notify_req = req;
                DBG(cdev, "notify --> %d\n", status);
        }
}

/*
 * Context: ncm->lock held
 */
static void ncm_notify(struct f_ncm *ncm)
{
        /*
         * NOTE on most versions of Linux, host side cdc-ethernet
         * won't listen for notifications until its netdevice opens.
         * The first notification then sits in the FIFO for a long
         * time, and the second one is queued.
         *
         * If ncm_notify() is called before the second (CONNECT)
         * notification is sent, then it will reset to send the SPEED
         * notificaion again (and again, and again), but it's not a problem
         */
        ncm->notify_state = NCM_NOTIFY_SPEED;
        ncm_do_notify(ncm);
}

static void ncm_notify_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_ncm                    *ncm = req->context;
        struct usb_composite_dev        *cdev = ncm->port.func.config->cdev;
        struct usb_cdc_notification     *event = req->buf;

        spin_lock(&ncm->lock);
        switch (req->status) {
        case 0:
                VDBG(cdev, "Notification %02x sent\n",
                     event->bNotificationType);
                break;
        case -ECONNRESET:
        case -ESHUTDOWN:
                ncm->notify_state = NCM_NOTIFY_NONE;
                break;
        default:
                DBG(cdev, "event %02x --> %d\n",
                        event->bNotificationType, req->status);
                break;
        }
        ncm->notify_req = req;
        ncm_do_notify(ncm);
        spin_unlock(&ncm->lock);
}

static void ncm_ep0out_complete(struct usb_ep *ep, struct usb_request *req)
{
        /* now for SET_NTB_INPUT_SIZE only */
        unsigned                in_size;
        struct usb_function     *f = req->context;
        struct f_ncm            *ncm = func_to_ncm(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        req->context = NULL;
        if (req->status || req->actual != req->length) {
                DBG(cdev, "Bad control-OUT transfer\n");
                goto invalid;
        }

        in_size = get_unaligned_le32(req->buf);
        if (in_size < USB_CDC_NCM_NTB_MIN_IN_SIZE ||
            in_size > le32_to_cpu(ntb_parameters.dwNtbInMaxSize)) {
                DBG(cdev, "Got wrong INPUT SIZE (%d) from host\n", in_size);
                goto invalid;
        }

        ncm->port.fixed_in_len = in_size;
        VDBG(cdev, "Set NTB INPUT SIZE %d\n", in_size);
        return;

invalid:
        usb_ep_set_halt(ep);
        return;
}

static int ncm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
        struct f_ncm            *ncm = func_to_ncm(f);
        struct usb_composite_dev *cdev = f->config->cdev;
        struct usb_request      *req = cdev->req;
        int                     value = -EOPNOTSUPP;
        u16                     w_index = le16_to_cpu(ctrl->wIndex);
        u16                     w_value = le16_to_cpu(ctrl->wValue);
        u16                     w_length = le16_to_cpu(ctrl->wLength);

        /*
         * composite driver infrastructure handles everything except
         * CDC class messages; interface activation uses set_alt().
         */
        switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
        case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                        | USB_CDC_SET_ETHERNET_PACKET_FILTER:
                /*
                 * see 6.2.30: no data, wIndex = interface,
                 * wValue = packet filter bitmap
                 */
                if (w_length != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                DBG(cdev, "packet filter %02x\n", w_value);
                /*
                 * REVISIT locking of cdc_filter.  This assumes the UDC
                 * driver won't have a concurrent packet TX irq running on
                 * another CPU; or that if it does, this write is atomic...
                 */
                ncm->port.cdc_filter = w_value;
                value = 0;
                break;
        /*
         * and optionally:
         * case USB_CDC_SEND_ENCAPSULATED_COMMAND:
         * case USB_CDC_GET_ENCAPSULATED_RESPONSE:
         * case USB_CDC_SET_ETHERNET_MULTICAST_FILTERS:
         * case USB_CDC_SET_ETHERNET_PM_PATTERN_FILTER:
         * case USB_CDC_GET_ETHERNET_PM_PATTERN_FILTER:
         * case USB_CDC_GET_ETHERNET_STATISTIC:
         */

        case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_GET_NTB_PARAMETERS:

                if (w_length == 0 || w_value != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                value = w_length > sizeof ntb_parameters ?
                        sizeof ntb_parameters : w_length;
                memcpy(req->buf, &ntb_parameters, value);
                VDBG(cdev, "Host asked NTB parameters\n");
                break;

        case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_GET_NTB_INPUT_SIZE:

                if (w_length < 4 || w_value != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                put_unaligned_le32(ncm->port.fixed_in_len, req->buf);
                value = 4;
                VDBG(cdev, "Host asked INPUT SIZE, sending %d\n",
                     ncm->port.fixed_in_len);
                break;

        case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_SET_NTB_INPUT_SIZE:
        {
                if (w_length != 4 || w_value != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                req->complete = ncm_ep0out_complete;
                req->length = w_length;
                req->context = f;

                value = req->length;
                break;
        }

        case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_GET_NTB_FORMAT:
        {
                uint16_t format;

                if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                format = (ncm->parser_opts == &ndp16_opts) ? 0x0000 : 0x0001;
                put_unaligned_le16(format, req->buf);
                value = 2;
                VDBG(cdev, "Host asked NTB FORMAT, sending %d\n", format);
                break;
        }

        case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_SET_NTB_FORMAT:
        {
                if (w_length != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                switch (w_value) {
                case 0x0000:
                        ncm->parser_opts = &ndp16_opts;
                        DBG(cdev, "NCM16 selected\n");
                        break;
                case 0x0001:
                        ncm->parser_opts = &ndp32_opts;
                        DBG(cdev, "NCM32 selected\n");
                        break;
                default:
                        goto invalid;
                }
                value = 0;
                break;
        }
        case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_GET_CRC_MODE:
        {
                uint16_t is_crc;

                if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                is_crc = ncm->is_crc ? 0x0001 : 0x0000;
                put_unaligned_le16(is_crc, req->buf);
                value = 2;
                VDBG(cdev, "Host asked CRC MODE, sending %d\n", is_crc);
                break;
        }

        case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                | USB_CDC_SET_CRC_MODE:
        {
                int ndp_hdr_crc = 0;

                if (w_length != 0 || w_index != ncm->ctrl_id)
                        goto invalid;
                switch (w_value) {
                case 0x0000:
                        ncm->is_crc = false;
                        ndp_hdr_crc = NCM_NDP_HDR_NOCRC;
                        DBG(cdev, "non-CRC mode selected\n");
                        break;
                case 0x0001:
                        ncm->is_crc = true;
                        ndp_hdr_crc = NCM_NDP_HDR_CRC;
                        DBG(cdev, "CRC mode selected\n");
                        break;
                default:
                        goto invalid;
                }
                ncm->ndp_sign = ncm->parser_opts->ndp_sign | ndp_hdr_crc;
                value = 0;
                break;
        }

        /* and disabled in ncm descriptor: */
        /* case USB_CDC_GET_NET_ADDRESS: */
        /* case USB_CDC_SET_NET_ADDRESS: */
        /* case USB_CDC_GET_MAX_DATAGRAM_SIZE: */
        /* case USB_CDC_SET_MAX_DATAGRAM_SIZE: */

        default:
invalid:
                DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        w_value, w_index, w_length);
        }

        /* respond with data transfer or status phase? */
        if (value >= 0) {
                DBG(cdev, "ncm req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        w_value, w_index, w_length);
                req->zero = 0;
                req->length = value;
                value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
                if (value < 0)
                        ERROR(cdev, "ncm req %02x.%02x response err %d\n",
                                        ctrl->bRequestType, ctrl->bRequest,
                                        value);
        }

        /* device either stalls (value < 0) or reports success */
        return value;
}


static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_ncm            *ncm = func_to_ncm(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        /* Control interface has only altsetting 0 */
        if (intf == ncm->ctrl_id) {
                if (alt != 0)
                        goto fail;

                DBG(cdev, "reset ncm control %d\n", intf);
                usb_ep_disable(ncm->notify);

                if (!(ncm->notify->desc)) {
                        DBG(cdev, "init ncm ctrl %d\n", intf);
                        if (config_ep_by_speed(cdev->gadget, f, ncm->notify))
                                goto fail;
                }
                usb_ep_enable(ncm->notify);

        /* Data interface has two altsettings, 0 and 1 */
        } else if (intf == ncm->data_id) {
                if (alt > 1)
                        goto fail;

                if (ncm->port.in_ep->enabled) {
                        DBG(cdev, "reset ncm\n");
                        ncm->timer_stopping = true;
                        ncm->netdev = NULL;
                        gether_disconnect(&ncm->port);
                        ncm_reset_values(ncm);
                }

                /*
                 * CDC Network only sends data in non-default altsettings.
                 * Changing altsettings resets filters, statistics, etc.
                 */
                if (alt == 1) {
                        struct net_device       *net;

                        if (!ncm->port.in_ep->desc ||
                            !ncm->port.out_ep->desc) {
                                DBG(cdev, "init ncm\n");
                                if (config_ep_by_speed(cdev->gadget, f,
                                                       ncm->port.in_ep) ||
                                    config_ep_by_speed(cdev->gadget, f,
                                                       ncm->port.out_ep)) {
                                        ncm->port.in_ep->desc = NULL;
                                        ncm->port.out_ep->desc = NULL;
                                        goto fail;
                                }
                        }

                        /* TODO */
                        /* Enable zlps by default for NCM conformance;
                         * override for musb_hdrc (avoids txdma ovhead)
                         */
                        ncm->port.is_zlp_ok =
                                gadget_is_zlp_supported(cdev->gadget);
                        ncm->port.cdc_filter = DEFAULT_FILTER;
                        DBG(cdev, "activate ncm\n");
                        net = gether_connect(&ncm->port);
                        if (IS_ERR(net))
                                return PTR_ERR(net);
                        ncm->netdev = net;
                        ncm->timer_stopping = false;
                }

                spin_lock(&ncm->lock);
                ncm_notify(ncm);
                spin_unlock(&ncm->lock);
        } else
                goto fail;

        return 0;
fail:
        return -EINVAL;
}

/*
 * Because the data interface supports multiple altsettings,
 * this NCM function *MUST* implement a get_alt() method.
 */
static int ncm_get_alt(struct usb_function *f, unsigned intf)
{
        struct f_ncm            *ncm = func_to_ncm(f);

        if (intf == ncm->ctrl_id)
                return 0;
        return ncm->port.in_ep->enabled ? 1 : 0;
}

static struct sk_buff *package_for_tx(struct f_ncm *ncm)
{
        __le16          *ntb_iter;
        struct sk_buff  *skb2 = NULL;
        unsigned        ndp_pad;
        unsigned        ndp_index;
        unsigned        new_len;

        const struct ndp_parser_opts *opts = ncm->parser_opts;
        const int ndp_align = le16_to_cpu(ntb_parameters.wNdpInAlignment);
        const int dgram_idx_len = 2 * 2 * opts->dgram_item_len;

        /* Stop the timer */
        hrtimer_try_to_cancel(&ncm->task_timer);

        ndp_pad = ALIGN(ncm->skb_tx_data->len, ndp_align) -
                        ncm->skb_tx_data->len;
        ndp_index = ncm->skb_tx_data->len + ndp_pad;
        new_len = ndp_index + dgram_idx_len + ncm->skb_tx_ndp->len;

        /* Set the final BlockLength and wNdpIndex */
        ntb_iter = (void *) ncm->skb_tx_data->data;
        /* Increment pointer to BlockLength */
        ntb_iter += 2 + 1 + 1;
        put_ncm(&ntb_iter, opts->block_length, new_len);
        put_ncm(&ntb_iter, opts->ndp_index, ndp_index);

        /* Set the final NDP wLength */
        new_len = opts->ndp_size +
                        (ncm->ndp_dgram_count * dgram_idx_len);
        ncm->ndp_dgram_count = 0;
        /* Increment from start to wLength */
        ntb_iter = (void *) ncm->skb_tx_ndp->data;
        ntb_iter += 2;
        put_unaligned_le16(new_len, ntb_iter);

        /* Merge the skbs */
        swap(skb2, ncm->skb_tx_data);
        if (ncm->skb_tx_data) {
                dev_kfree_skb_any(ncm->skb_tx_data);
                ncm->skb_tx_data = NULL;
        }

        /* Insert NDP alignment. */
        ntb_iter = (void *) skb_put(skb2, ndp_pad);
        memset(ntb_iter, 0, ndp_pad);

        /* Copy NTB across. */
        ntb_iter = (void *) skb_put(skb2, ncm->skb_tx_ndp->len);
        memcpy(ntb_iter, ncm->skb_tx_ndp->data, ncm->skb_tx_ndp->len);
        dev_kfree_skb_any(ncm->skb_tx_ndp);
        ncm->skb_tx_ndp = NULL;

        /* Insert zero'd datagram. */
        ntb_iter = (void *) skb_put(skb2, dgram_idx_len);
        memset(ntb_iter, 0, dgram_idx_len);

        return skb2;
}

static struct sk_buff *ncm_wrap_ntb(struct gether *port,
                                    struct sk_buff *skb)
{
        struct f_ncm    *ncm = func_to_ncm(&port->func);
        struct sk_buff  *skb2 = NULL;
        int             ncb_len = 0;
        __le16          *ntb_data;
        __le16          *ntb_ndp;
        int             dgram_pad;

        unsigned        max_size = ncm->port.fixed_in_len;
        const struct ndp_parser_opts *opts = ncm->parser_opts;
        const int ndp_align = le16_to_cpu(ntb_parameters.wNdpInAlignment);
        const int div = le16_to_cpu(ntb_parameters.wNdpInDivisor);
        const int rem = le16_to_cpu(ntb_parameters.wNdpInPayloadRemainder);
        const int dgram_idx_len = 2 * 2 * opts->dgram_item_len;

        if (!skb && !ncm->skb_tx_data)
                return NULL;

        if (skb) {
                /* Add the CRC if required up front */
                if (ncm->is_crc) {
                        uint32_t        crc;
                        __le16          *crc_pos;

                        crc = ~crc32_le(~0,
                                        skb->data,
                                        skb->len);
                        crc_pos = (void *) skb_put(skb, sizeof(uint32_t));
                        put_unaligned_le32(crc, crc_pos);
                }

                /* If the new skb is too big for the current NCM NTB then
                 * set the current stored skb to be sent now and clear it
                 * ready for new data.
                 * NOTE: Assume maximum align for speed of calculation.
                 */
                if (ncm->skb_tx_data
                    && (ncm->ndp_dgram_count >= TX_MAX_NUM_DPE
                    || (ncm->skb_tx_data->len +
                    div + rem + skb->len +
                    ncm->skb_tx_ndp->len + ndp_align + (2 * dgram_idx_len))
                    > max_size)) {
                        skb2 = package_for_tx(ncm);
                        if (!skb2)
                                goto err;
                }

                if (!ncm->skb_tx_data) {
                        ncb_len = opts->nth_size;
                        dgram_pad = ALIGN(ncb_len, div) + rem - ncb_len;
                        ncb_len += dgram_pad;

                        /* Create a new skb for the NTH and datagrams. */
                        ncm->skb_tx_data = alloc_skb(max_size, GFP_ATOMIC);
                        if (!ncm->skb_tx_data)
                                goto err;

                        ntb_data = (void *) skb_put(ncm->skb_tx_data, ncb_len);
                        memset(ntb_data, 0, ncb_len);
                        /* dwSignature */
                        put_unaligned_le32(opts->nth_sign, ntb_data);
                        ntb_data += 2;
                        /* wHeaderLength */
                        put_unaligned_le16(opts->nth_size, ntb_data++);

                        /* Allocate an skb for storing the NDP,
                         * TX_MAX_NUM_DPE should easily suffice for a
                         * 16k packet.
                         */
                        ncm->skb_tx_ndp = alloc_skb((int)(opts->ndp_size
                                                    + opts->dpe_size
                                                    * TX_MAX_NUM_DPE),
                                                    GFP_ATOMIC);
                        if (!ncm->skb_tx_ndp)
                                goto err;
                        ntb_ndp = (void *) skb_put(ncm->skb_tx_ndp,
                                                    opts->ndp_size);
                        memset(ntb_ndp, 0, ncb_len);
                        /* dwSignature */
                        put_unaligned_le32(ncm->ndp_sign, ntb_ndp);
                        ntb_ndp += 2;

                        /* There is always a zeroed entry */
                        ncm->ndp_dgram_count = 1;

                        /* Note: we skip opts->next_ndp_index */
                }

                /* Delay the timer. */
                hrtimer_start(&ncm->task_timer,
                              ktime_set(0, TX_TIMEOUT_NSECS),
                              HRTIMER_MODE_REL);

                /* Add the datagram position entries */
                ntb_ndp = (void *) skb_put(ncm->skb_tx_ndp, dgram_idx_len);
                memset(ntb_ndp, 0, dgram_idx_len);

                ncb_len = ncm->skb_tx_data->len;
                dgram_pad = ALIGN(ncb_len, div) + rem - ncb_len;
                ncb_len += dgram_pad;

                /* (d)wDatagramIndex */
                put_ncm(&ntb_ndp, opts->dgram_item_len, ncb_len);
                /* (d)wDatagramLength */
                put_ncm(&ntb_ndp, opts->dgram_item_len, skb->len);
                ncm->ndp_dgram_count++;

                /* Add the new data to the skb */
                ntb_data = (void *) skb_put(ncm->skb_tx_data, dgram_pad);
                memset(ntb_data, 0, dgram_pad);
                ntb_data = (void *) skb_put(ncm->skb_tx_data, skb->len);
                memcpy(ntb_data, skb->data, skb->len);
                dev_kfree_skb_any(skb);
                skb = NULL;

        } else if (ncm->skb_tx_data && ncm->timer_force_tx) {
                /* If the tx was requested because of a timeout then send */
                skb2 = package_for_tx(ncm);
                if (!skb2)
                        goto err;
        }

        return skb2;

err:
        ncm->netdev->stats.tx_dropped++;

        if (skb)
                dev_kfree_skb_any(skb);
        if (ncm->skb_tx_data)
                dev_kfree_skb_any(ncm->skb_tx_data);
        if (ncm->skb_tx_ndp)
                dev_kfree_skb_any(ncm->skb_tx_ndp);

        return NULL;
}

/*
 * This transmits the NTB if there are frames waiting.
 */
static void ncm_tx_tasklet(unsigned long data)
{
        struct f_ncm    *ncm = (void *)data;

        if (ncm->timer_stopping)
                return;

        /* Only send if data is available. */
        if (ncm->skb_tx_data) {
                ncm->timer_force_tx = true;

                /* XXX This allowance of a NULL skb argument to ndo_start_xmit
                 * XXX is not sane.  The gadget layer should be redesigned so
                 * XXX that the dev->wrap() invocations to build SKBs is transparent
                 * XXX and performed in some way outside of the ndo_start_xmit
                 * XXX interface.
                 */
                ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);

                ncm->timer_force_tx = false;
        }
}

/*
 * The transmit should only be run if no skb data has been sent
 * for a certain duration.
 */
static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
{
        struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
        tasklet_schedule(&ncm->tx_tasklet);
        return HRTIMER_NORESTART;
}

static int ncm_unwrap_ntb(struct gether *port,
                          struct sk_buff *skb,
                          struct sk_buff_head *list)
{
        struct f_ncm    *ncm = func_to_ncm(&port->func);
        __le16          *tmp = (void *) skb->data;
        unsigned        index, index2;
        int             ndp_index;
        unsigned        dg_len, dg_len2;
        unsigned        ndp_len;
        struct sk_buff  *skb2;
        int             ret = -EINVAL;
        unsigned        max_size = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
        const struct ndp_parser_opts *opts = ncm->parser_opts;
        unsigned        crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
        int             dgram_counter;

        /* dwSignature */
        if (get_unaligned_le32(tmp) != opts->nth_sign) {
                INFO(port->func.config->cdev, "Wrong NTH SIGN, skblen %d\n",
                        skb->len);
                print_hex_dump(KERN_INFO, "HEAD:", DUMP_PREFIX_ADDRESS, 32, 1,
                               skb->data, 32, false);

                goto err;
        }
        tmp += 2;
        /* wHeaderLength */
        if (get_unaligned_le16(tmp++) != opts->nth_size) {
                INFO(port->func.config->cdev, "Wrong NTB headersize\n");
                goto err;
        }
        tmp++; /* skip wSequence */

        /* (d)wBlockLength */
        if (get_ncm(&tmp, opts->block_length) > max_size) {
                INFO(port->func.config->cdev, "OUT size exceeded\n");
                goto err;
        }

        ndp_index = get_ncm(&tmp, opts->ndp_index);

        /* Run through all the NDP's in the NTB */
        do {
                /* NCM 3.2 */
                if (((ndp_index % 4) != 0) &&
                                (ndp_index < opts->nth_size)) {
                        INFO(port->func.config->cdev, "Bad index: %#X\n",
                             ndp_index);
                        goto err;
                }

                /* walk through NDP */
                tmp = (void *)(skb->data + ndp_index);
                if (get_unaligned_le32(tmp) != ncm->ndp_sign) {
                        INFO(port->func.config->cdev, "Wrong NDP SIGN\n");
                        goto err;
                }
                tmp += 2;

                ndp_len = get_unaligned_le16(tmp++);
                /*
                 * NCM 3.3.1
                 * entry is 2 items
                 * item size is 16/32 bits, opts->dgram_item_len * 2 bytes
                 * minimal: struct usb_cdc_ncm_ndpX + normal entry + zero entry
                 * Each entry is a dgram index and a dgram length.
                 */
                if ((ndp_len < opts->ndp_size
                                + 2 * 2 * (opts->dgram_item_len * 2))
                                || (ndp_len % opts->ndplen_align != 0)) {
                        INFO(port->func.config->cdev, "Bad NDP length: %#X\n",
                             ndp_len);
                        goto err;
                }
                tmp += opts->reserved1;
                /* Check for another NDP (d)wNextNdpIndex */
                ndp_index = get_ncm(&tmp, opts->next_ndp_index);
                tmp += opts->reserved2;

                ndp_len -= opts->ndp_size;
                index2 = get_ncm(&tmp, opts->dgram_item_len);
                dg_len2 = get_ncm(&tmp, opts->dgram_item_len);
                dgram_counter = 0;

                do {
                        index = index2;
                        dg_len = dg_len2;
                        if (dg_len < 14 + crc_len) { /* ethernet hdr + crc */
                                INFO(port->func.config->cdev,
                                     "Bad dgram length: %#X\n", dg_len);
                                goto err;
                        }
                        if (ncm->is_crc) {
                                uint32_t crc, crc2;

                                crc = get_unaligned_le32(skb->data +
                                                         index + dg_len -
                                                         crc_len);
                                crc2 = ~crc32_le(~0,
                                                 skb->data + index,
                                                 dg_len - crc_len);
                                if (crc != crc2) {
                                        INFO(port->func.config->cdev,
                                             "Bad CRC\n");
                                        goto err;
                                }
                        }

                        index2 = get_ncm(&tmp, opts->dgram_item_len);
                        dg_len2 = get_ncm(&tmp, opts->dgram_item_len);

                        /*
                         * Copy the data into a new skb.
                         * This ensures the truesize is correct
                         */
                        skb2 = netdev_alloc_skb_ip_align(ncm->netdev,
                                                         dg_len - crc_len);
                        if (skb2 == NULL)
                                goto err;
                        memcpy(skb_put(skb2, dg_len - crc_len),
                               skb->data + index, dg_len - crc_len);

                        skb_queue_tail(list, skb2);

                        ndp_len -= 2 * (opts->dgram_item_len * 2);

                        dgram_counter++;

                        if (index2 == 0 || dg_len2 == 0)
                                break;
                } while (ndp_len > 2 * (opts->dgram_item_len * 2));
        } while (ndp_index);

        dev_kfree_skb_any(skb);

        VDBG(port->func.config->cdev,
             "Parsed NTB with %d frames\n", dgram_counter);
        return 0;
err:
        skb_queue_purge(list);
        dev_kfree_skb_any(skb);
        return ret;
}

static void ncm_disable(struct usb_function *f)
{
        struct f_ncm            *ncm = func_to_ncm(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        DBG(cdev, "ncm deactivated\n");

        if (ncm->port.in_ep->enabled) {
                ncm->timer_stopping = true;
                ncm->netdev = NULL;
                gether_disconnect(&ncm->port);
        }

        if (ncm->notify->enabled) {
                usb_ep_disable(ncm->notify);
                ncm->notify->desc = NULL;
        }
}

/*-------------------------------------------------------------------------*/

/*
 * Callbacks let us notify the host about connect/disconnect when the
 * net device is opened or closed.
 *
 * For testing, note that link states on this side include both opened
 * and closed variants of:
 *
 *   - disconnected/unconfigured
 *   - configured but inactive (data alt 0)
 *   - configured and active (data alt 1)
 *
 * Each needs to be tested with unplug, rmmod, SET_CONFIGURATION, and
 * SET_INTERFACE (altsetting).  Remember also that "configured" doesn't
 * imply the host is actually polling the notification endpoint, and
 * likewise that "active" doesn't imply it's actually using the data
 * endpoints for traffic.
 */

static void ncm_open(struct gether *geth)
{
        struct f_ncm            *ncm = func_to_ncm(&geth->func);

        DBG(ncm->port.func.config->cdev, "%s\n", __func__);

        spin_lock(&ncm->lock);
        ncm->is_open = true;
        ncm_notify(ncm);
        spin_unlock(&ncm->lock);
}

static void ncm_close(struct gether *geth)
{
        struct f_ncm            *ncm = func_to_ncm(&geth->func);

        DBG(ncm->port.func.config->cdev, "%s\n", __func__);

        spin_lock(&ncm->lock);
        ncm->is_open = false;
        ncm_notify(ncm);
        spin_unlock(&ncm->lock);
}

/*-------------------------------------------------------------------------*/

/* ethernet function driver setup/binding */

static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_ncm            *ncm = func_to_ncm(f);
        struct usb_string       *us;
        int                     status;
        struct usb_ep           *ep;
        struct f_ncm_opts       *ncm_opts;

        if (!can_support_ecm(cdev->gadget))
                return -EINVAL;

        ncm_opts = container_of(f->fi, struct f_ncm_opts, func_inst);
        /*
         * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
         * configurations are bound in sequence with list_for_each_entry,
         * in each configuration its functions are bound in sequence
         * with list_for_each_entry, so we assume no race condition
         * with regard to ncm_opts->bound access
         */
        if (!ncm_opts->bound) {
                mutex_lock(&ncm_opts->lock);
                gether_set_gadget(ncm_opts->net, cdev->gadget);
                status = gether_register_netdev(ncm_opts->net);
                mutex_unlock(&ncm_opts->lock);
                if (status)
                        return status;
                ncm_opts->bound = true;
        }
        us = usb_gstrings_attach(cdev, ncm_strings,
                                 ARRAY_SIZE(ncm_string_defs));
        if (IS_ERR(us))
                return PTR_ERR(us);
        ncm_control_intf.iInterface = us[STRING_CTRL_IDX].id;
        ncm_data_nop_intf.iInterface = us[STRING_DATA_IDX].id;
        ncm_data_intf.iInterface = us[STRING_DATA_IDX].id;
        ecm_desc.iMACAddress = us[STRING_MAC_IDX].id;
        ncm_iad_desc.iFunction = us[STRING_IAD_IDX].id;

        /* allocate instance-specific interface IDs */
        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        ncm->ctrl_id = status;
        ncm_iad_desc.bFirstInterface = status;

        ncm_control_intf.bInterfaceNumber = status;
        ncm_union_desc.bMasterInterface0 = status;

        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        ncm->data_id = status;

        ncm_data_nop_intf.bInterfaceNumber = status;
        ncm_data_intf.bInterfaceNumber = status;
        ncm_union_desc.bSlaveInterface0 = status;

        status = -ENODEV;

        /* allocate instance-specific endpoints */
        ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_in_desc);
        if (!ep)
                goto fail;
        ncm->port.in_ep = ep;

        ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_out_desc);
        if (!ep)
                goto fail;
        ncm->port.out_ep = ep;

        ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_notify_desc);
        if (!ep)
                goto fail;
        ncm->notify = ep;

        status = -ENOMEM;

        /* allocate notification request and buffer */
        ncm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
        if (!ncm->notify_req)
                goto fail;
        ncm->notify_req->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL);
        if (!ncm->notify_req->buf)
                goto fail;
        ncm->notify_req->context = ncm;
        ncm->notify_req->complete = ncm_notify_complete;

        /*
         * support all relevant hardware speeds... we expect that when
         * hardware is dual speed, all bulk-capable endpoints work at
         * both speeds
         */
        hs_ncm_in_desc.bEndpointAddress = fs_ncm_in_desc.bEndpointAddress;
        hs_ncm_out_desc.bEndpointAddress = fs_ncm_out_desc.bEndpointAddress;
        hs_ncm_notify_desc.bEndpointAddress =
                fs_ncm_notify_desc.bEndpointAddress;

        status = usb_assign_descriptors(f, ncm_fs_function, ncm_hs_function,
                        NULL);
        if (status)
                goto fail;

        /*
         * NOTE:  all that is done without knowing or caring about
         * the network link ... which is unavailable to this code
         * until we're activated via set_alt().
         */

        ncm->port.open = ncm_open;
        ncm->port.close = ncm_close;

        tasklet_init(&ncm->tx_tasklet, ncm_tx_tasklet, (unsigned long) ncm);
        hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        ncm->task_timer.function = ncm_tx_timeout;

        DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
                        gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
                        ncm->port.in_ep->name, ncm->port.out_ep->name,
                        ncm->notify->name);
        return 0;

fail:
        if (ncm->notify_req) {
                kfree(ncm->notify_req->buf);
                usb_ep_free_request(ncm->notify, ncm->notify_req);
        }

        ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);

        return status;
}

static inline struct f_ncm_opts *to_f_ncm_opts(struct config_item *item)
{
        return container_of(to_config_group(item), struct f_ncm_opts,
                            func_inst.group);
}

/* f_ncm_item_ops */
USB_ETHERNET_CONFIGFS_ITEM(ncm);

/* f_ncm_opts_dev_addr */
USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(ncm);

/* f_ncm_opts_host_addr */
USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(ncm);

/* f_ncm_opts_qmult */
USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(ncm);

/* f_ncm_opts_ifname */
USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(ncm);

static struct configfs_attribute *ncm_attrs[] = {
        &ncm_opts_attr_dev_addr,
        &ncm_opts_attr_host_addr,
        &ncm_opts_attr_qmult,
        &ncm_opts_attr_ifname,
        NULL,
};

static struct config_item_type ncm_func_type = {
        .ct_item_ops    = &ncm_item_ops,
        .ct_attrs       = ncm_attrs,
        .ct_owner       = THIS_MODULE,
};

static void ncm_free_inst(struct usb_function_instance *f)
{
        struct f_ncm_opts *opts;

        opts = container_of(f, struct f_ncm_opts, func_inst);
        if (opts->bound)
                gether_cleanup(netdev_priv(opts->net));
        else
                free_netdev(opts->net);
        kfree(opts);
}

static struct usb_function_instance *ncm_alloc_inst(void)
{
        struct f_ncm_opts *opts;

        opts = kzalloc(sizeof(*opts), GFP_KERNEL);
        if (!opts)
                return ERR_PTR(-ENOMEM);
        mutex_init(&opts->lock);
        opts->func_inst.free_func_inst = ncm_free_inst;
        opts->net = gether_setup_default();
        if (IS_ERR(opts->net)) {
                struct net_device *net = opts->net;
                kfree(opts);
                return ERR_CAST(net);
        }

        config_group_init_type_name(&opts->func_inst.group, "", &ncm_func_type);

        return &opts->func_inst;
}

static void ncm_free(struct usb_function *f)
{
        struct f_ncm *ncm;
        struct f_ncm_opts *opts;

        ncm = func_to_ncm(f);
        opts = container_of(f->fi, struct f_ncm_opts, func_inst);
        kfree(ncm);
        mutex_lock(&opts->lock);
        opts->refcnt--;
        mutex_unlock(&opts->lock);
}

static void ncm_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct f_ncm *ncm = func_to_ncm(f);

        DBG(c->cdev, "ncm unbind\n");

        hrtimer_cancel(&ncm->task_timer);
        tasklet_kill(&ncm->tx_tasklet);

        ncm_string_defs[0].id = 0;
        usb_free_all_descriptors(f);

        kfree(ncm->notify_req->buf);
        usb_ep_free_request(ncm->notify, ncm->notify_req);
}

static struct usb_function *ncm_alloc(struct usb_function_instance *fi)
{
        struct f_ncm            *ncm;
        struct f_ncm_opts       *opts;
        int status;

        /* allocate and initialize one new instance */
        ncm = kzalloc(sizeof(*ncm), GFP_KERNEL);
        if (!ncm)
                return ERR_PTR(-ENOMEM);

        opts = container_of(fi, struct f_ncm_opts, func_inst);
        mutex_lock(&opts->lock);
        opts->refcnt++;

        /* export host's Ethernet address in CDC format */
        status = gether_get_host_addr_cdc(opts->net, ncm->ethaddr,
                                      sizeof(ncm->ethaddr));
        if (status < 12) { /* strlen("01234567890a") */
                kfree(ncm);
                mutex_unlock(&opts->lock);
                return ERR_PTR(-EINVAL);
        }
        ncm_string_defs[STRING_MAC_IDX].s = ncm->ethaddr;

        spin_lock_init(&ncm->lock);
        ncm_reset_values(ncm);
        ncm->port.ioport = netdev_priv(opts->net);
        mutex_unlock(&opts->lock);
        ncm->port.is_fixed = true;
        ncm->port.supports_multi_frame = true;

        ncm->port.func.name = "cdc_network";
        /* descriptors are per-instance copies */
        ncm->port.func.bind = ncm_bind;
        ncm->port.func.unbind = ncm_unbind;
        ncm->port.func.set_alt = ncm_set_alt;
        ncm->port.func.get_alt = ncm_get_alt;
        ncm->port.func.setup = ncm_setup;
        ncm->port.func.disable = ncm_disable;
        ncm->port.func.free_func = ncm_free;

        ncm->port.wrap = ncm_wrap_ntb;
        ncm->port.unwrap = ncm_unwrap_ntb;

        return &ncm->port.func;
}

DECLARE_USB_FUNCTION_INIT(ncm, ncm_alloc_inst, ncm_alloc);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yauheni Kaliuta");