f_ecm.c

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/*
 * f_ecm.c -- USB CDC Ethernet (ECM) link function driver
 *
 * 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.
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/etherdevice.h>

#include "u_ether.h"


/*
 * This function is a "CDC Ethernet Networking Control Model" (CDC ECM)
 * Ethernet link.  The data transfer model is simple (packets sent and
 * received over bulk endpoints using normal short packet termination),
 * and the control model exposes various data and optional notifications.
 *
 * ECM is well standardized and (except for Microsoft) supported by most
 * operating systems with USB host support.  It's the preferred interop
 * solution for Ethernet over USB, at least for firmware based solutions.
 * (Hardware solutions tend to be more minimalist.)  A newer and simpler
 * "Ethernet Emulation Model" (CDC EEM) hasn't yet caught on.
 *
 * Note that ECM 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.
 */


enum ecm_notify_state {
    ECM_NOTIFY_NONE,        /* don't notify */
    ECM_NOTIFY_CONNECT,     /* issue CONNECT next */
    ECM_NOTIFY_SPEED,       /* issue SPEED_CHANGE next */
};

struct f_ecm {
    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;

    /* FIXME is_open needs some irq-ish locking
     * ... possibly the same as port.ioport
     */
};

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

/* peak (theoretical) bulk transfer rate in bits-per-second */
static inline unsigned ecm_bitrate(struct usb_gadget *g)
{
    if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER)
        return 13 * 1024 * 8 * 1000 * 8;
    else if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
        return 13 * 512 * 8 * 1000 * 8;
    else
        return 19 * 64 * 1 * 1000 * 8;
}

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

/*
 * Include the status endpoint if we can, even though it's optional.
 *
 * 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.
 *
 * Some drivers (like Linux 2.4 cdc-ether!) "need" it to exist even
 * if they ignore the connect/disconnect notifications that real aether
 * can provide.  More advanced cdc configurations might want to support
 * encapsulated commands (vendor-specific, using control-OUT).
 */

#define LOG2_STATUS_INTERVAL_MSEC   5   /* 1 << 5 == 32 msec */
#define ECM_STATUS_BYTECOUNT        16  /* 8 byte header + data */


/* interface descriptor: */

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

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


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

    /* .bInterfaceNumber = DYNAMIC */
    /* status endpoint is optional; this could be patched later */
    .bNumEndpoints =    1,
    .bInterfaceClass =  USB_CLASS_COMM,
    .bInterfaceSubClass =   USB_CDC_SUBCLASS_ETHERNET,
    .bInterfaceProtocol =   USB_CDC_PROTO_NONE,
    /* .iInterface = DYNAMIC */
};

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

    .bcdCDC =       cpu_to_le16(0x0110),
};

static struct usb_cdc_union_desc ecm_union_desc = {
    .bLength =      sizeof(ecm_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,
};

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

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

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

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

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

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

/* full speed support: */

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

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_INT,
    .wMaxPacketSize =   cpu_to_le16(ECM_STATUS_BYTECOUNT),
    .bInterval =        1 << LOG2_STATUS_INTERVAL_MSEC,
};

static struct usb_endpoint_descriptor fs_ecm_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_ecm_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 *ecm_fs_function[] = {
    /* CDC ECM control descriptors */
    (struct usb_descriptor_header *) &ecm_iad_descriptor,
    (struct usb_descriptor_header *) &ecm_control_intf,
    (struct usb_descriptor_header *) &ecm_header_desc,
    (struct usb_descriptor_header *) &ecm_union_desc,
    (struct usb_descriptor_header *) &ecm_desc,

    /* NOTE: status endpoint might need to be removed */
    (struct usb_descriptor_header *) &fs_ecm_notify_desc,

    /* data interface, altsettings 0 and 1 */
    (struct usb_descriptor_header *) &ecm_data_nop_intf,
    (struct usb_descriptor_header *) &ecm_data_intf,
    (struct usb_descriptor_header *) &fs_ecm_in_desc,
    (struct usb_descriptor_header *) &fs_ecm_out_desc,
    NULL,
};

/* high speed support: */

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

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_INT,
    .wMaxPacketSize =   cpu_to_le16(ECM_STATUS_BYTECOUNT),
    .bInterval =        LOG2_STATUS_INTERVAL_MSEC + 4,
};

static struct usb_endpoint_descriptor hs_ecm_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_ecm_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 *ecm_hs_function[] = {
    /* CDC ECM control descriptors */
    (struct usb_descriptor_header *) &ecm_iad_descriptor,
    (struct usb_descriptor_header *) &ecm_control_intf,
    (struct usb_descriptor_header *) &ecm_header_desc,
    (struct usb_descriptor_header *) &ecm_union_desc,
    (struct usb_descriptor_header *) &ecm_desc,

    /* NOTE: status endpoint might need to be removed */
    (struct usb_descriptor_header *) &hs_ecm_notify_desc,

    /* data interface, altsettings 0 and 1 */
    (struct usb_descriptor_header *) &ecm_data_nop_intf,
    (struct usb_descriptor_header *) &ecm_data_intf,
    (struct usb_descriptor_header *) &hs_ecm_in_desc,
    (struct usb_descriptor_header *) &hs_ecm_out_desc,
    NULL,
};

/* super speed support: */

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

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_INT,
    .wMaxPacketSize =   cpu_to_le16(ECM_STATUS_BYTECOUNT),
    .bInterval =        LOG2_STATUS_INTERVAL_MSEC + 4,
};

static struct usb_ss_ep_comp_descriptor ss_ecm_intr_comp_desc = {
    .bLength =      sizeof ss_ecm_intr_comp_desc,
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,

    /* the following 3 values can be tweaked if necessary */
    /* .bMaxBurst =     0, */
    /* .bmAttributes =  0, */
    .wBytesPerInterval =    cpu_to_le16(ECM_STATUS_BYTECOUNT),
};

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

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(1024),
};

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

    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor ss_ecm_bulk_comp_desc = {
    .bLength =      sizeof ss_ecm_bulk_comp_desc,
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,

    /* the following 2 values can be tweaked if necessary */
    /* .bMaxBurst =     0, */
    /* .bmAttributes =  0, */
};

static struct usb_descriptor_header *ecm_ss_function[] = {
    /* CDC ECM control descriptors */
    (struct usb_descriptor_header *) &ecm_control_intf,
    (struct usb_descriptor_header *) &ecm_header_desc,
    (struct usb_descriptor_header *) &ecm_union_desc,
    (struct usb_descriptor_header *) &ecm_desc,

    /* NOTE: status endpoint might need to be removed */
    (struct usb_descriptor_header *) &ss_ecm_notify_desc,
    (struct usb_descriptor_header *) &ss_ecm_intr_comp_desc,

    /* data interface, altsettings 0 and 1 */
    (struct usb_descriptor_header *) &ecm_data_nop_intf,
    (struct usb_descriptor_header *) &ecm_data_intf,
    (struct usb_descriptor_header *) &ss_ecm_in_desc,
    (struct usb_descriptor_header *) &ss_ecm_bulk_comp_desc,
    (struct usb_descriptor_header *) &ss_ecm_out_desc,
    (struct usb_descriptor_header *) &ss_ecm_bulk_comp_desc,
    NULL,
};

/* string descriptors: */

static struct usb_string ecm_string_defs[] = {
    [0].s = "CDC Ethernet Control Model (ECM)",
    [1].s = NULL /* DYNAMIC */,
    [2].s = "CDC Ethernet Data",
    [3].s = "CDC ECM",
    {  } /* end of list */
};

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

static struct usb_gadget_strings *ecm_strings[] = {
    &ecm_string_table,
    NULL,
};

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

static void ecm_do_notify(struct f_ecm *ecm)
{
    struct usb_request      *req = ecm->notify_req;
    struct usb_cdc_notification *event;
    struct usb_composite_dev    *cdev = ecm->port.func.config->cdev;
    __le32              *data;
    int             status;

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

    event = req->buf;
    switch (ecm->notify_state) {
    case ECM_NOTIFY_NONE:
        return;

    case ECM_NOTIFY_CONNECT:
        event->bNotificationType = USB_CDC_NOTIFY_NETWORK_CONNECTION;
        if (ecm->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",
                ecm->is_open ? "true" : "false");
        ecm->notify_state = ECM_NOTIFY_SPEED;
        break;

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

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

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

    ecm->notify_req = NULL;
    status = usb_ep_queue(ecm->notify, req, GFP_ATOMIC);
    if (status < 0) {
        ecm->notify_req = req;
        DBG(cdev, "notify --> %d\n", status);
    }
}

static void ecm_notify(struct f_ecm *ecm)
{
    /* 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.
     */
    ecm->notify_state = ECM_NOTIFY_CONNECT;
    ecm_do_notify(ecm);
}

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

    switch (req->status) {
    case 0:
        /* no fault */
        break;
    case -ECONNRESET:
    case -ESHUTDOWN:
        ecm->notify_state = ECM_NOTIFY_NONE;
        break;
    default:
        DBG(cdev, "event %02x --> %d\n",
            event->bNotificationType, req->status);
        break;
    }
    ecm->notify_req = req;
    ecm_do_notify(ecm);
}

static int ecm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
    struct f_ecm        *ecm = func_to_ecm(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 != ecm->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...
         */
        ecm->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:
     */

    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, "ecm 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, "ecm req %02x.%02x response err %d\n",
                    ctrl->bRequestType, ctrl->bRequest,
                    value);
    }

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


static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
    struct f_ecm        *ecm = func_to_ecm(f);
    struct usb_composite_dev *cdev = f->config->cdev;

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

        if (ecm->notify->driver_data) {
            VDBG(cdev, "reset ecm control %d\n", intf);
            usb_ep_disable(ecm->notify);
        }
        if (!(ecm->notify->desc)) {
            VDBG(cdev, "init ecm ctrl %d\n", intf);
            if (config_ep_by_speed(cdev->gadget, f, ecm->notify))
                goto fail;
        }
        usb_ep_enable(ecm->notify);
        ecm->notify->driver_data = ecm;

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

        if (ecm->port.in_ep->driver_data) {
            DBG(cdev, "reset ecm\n");
            gether_disconnect(&ecm->port);
        }

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

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

            /* Enable zlps by default for ECM conformance;
             * override for musb_hdrc (avoids txdma ovhead).
             */
            ecm->port.is_zlp_ok = !(gadget_is_musbhdrc(cdev->gadget)
                );
            ecm->port.cdc_filter = DEFAULT_FILTER;
            DBG(cdev, "activate ecm\n");
            net = gether_connect(&ecm->port);
            if (IS_ERR(net))
                return PTR_ERR(net);
        }

        /* NOTE this can be a minor disagreement with the ECM spec,
         * which says speed notifications will "always" follow
         * connection notifications.  But we allow one connect to
         * follow another (if the first is in flight), and instead
         * just guarantee that a speed notification is always sent.
         */
        ecm_notify(ecm);
    } else
        goto fail;

    return 0;
fail:
    return -EINVAL;
}

/* Because the data interface supports multiple altsettings,
 * this ECM function *MUST* implement a get_alt() method.
 */
static int ecm_get_alt(struct usb_function *f, unsigned intf)
{
    struct f_ecm        *ecm = func_to_ecm(f);

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

static void ecm_disable(struct usb_function *f)
{
    struct f_ecm        *ecm = func_to_ecm(f);
    struct usb_composite_dev *cdev = f->config->cdev;

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

    if (ecm->port.in_ep->driver_data)
        gether_disconnect(&ecm->port);

    if (ecm->notify->driver_data) {
        usb_ep_disable(ecm->notify);
        ecm->notify->driver_data = NULL;
        ecm->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 ecm_open(struct gether *geth)
{
    struct f_ecm        *ecm = func_to_ecm(&geth->func);

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

    ecm->is_open = true;
    ecm_notify(ecm);
}

static void ecm_close(struct gether *geth)
{
    struct f_ecm        *ecm = func_to_ecm(&geth->func);

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

    ecm->is_open = false;
    ecm_notify(ecm);
}

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

/* ethernet function driver setup/binding */

static int
ecm_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct usb_composite_dev *cdev = c->cdev;
    struct f_ecm        *ecm = func_to_ecm(f);
    int         status;
    struct usb_ep       *ep;

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

    ecm_control_intf.bInterfaceNumber = status;
    ecm_union_desc.bMasterInterface0 = status;

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

    ecm_data_nop_intf.bInterfaceNumber = status;
    ecm_data_intf.bInterfaceNumber = status;
    ecm_union_desc.bSlaveInterface0 = status;

    status = -ENODEV;

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

    ep = usb_ep_autoconfig(cdev->gadget, &fs_ecm_out_desc);
    if (!ep)
        goto fail;
    ecm->port.out_ep = ep;
    ep->driver_data = cdev; /* claim */

    /* NOTE:  a status/notification endpoint is *OPTIONAL* but we
     * don't treat it that way.  It's simpler, and some newer CDC
     * profiles (wireless handsets) no longer treat it as optional.
     */
    ep = usb_ep_autoconfig(cdev->gadget, &fs_ecm_notify_desc);
    if (!ep)
        goto fail;
    ecm->notify = ep;
    ep->driver_data = cdev; /* claim */

    status = -ENOMEM;

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

    /* copy descriptors, and track endpoint copies */
    f->descriptors = usb_copy_descriptors(ecm_fs_function);
    if (!f->descriptors)
        goto fail;

    /* support all relevant hardware speeds... we expect that when
     * hardware is dual speed, all bulk-capable endpoints work at
     * both speeds
     */
    if (gadget_is_dualspeed(c->cdev->gadget)) {
        hs_ecm_in_desc.bEndpointAddress =
                fs_ecm_in_desc.bEndpointAddress;
        hs_ecm_out_desc.bEndpointAddress =
                fs_ecm_out_desc.bEndpointAddress;
        hs_ecm_notify_desc.bEndpointAddress =
                fs_ecm_notify_desc.bEndpointAddress;

        /* copy descriptors, and track endpoint copies */
        f->hs_descriptors = usb_copy_descriptors(ecm_hs_function);
        if (!f->hs_descriptors)
            goto fail;
    }

    if (gadget_is_superspeed(c->cdev->gadget)) {
        ss_ecm_in_desc.bEndpointAddress =
                fs_ecm_in_desc.bEndpointAddress;
        ss_ecm_out_desc.bEndpointAddress =
                fs_ecm_out_desc.bEndpointAddress;
        ss_ecm_notify_desc.bEndpointAddress =
                fs_ecm_notify_desc.bEndpointAddress;

        /* copy descriptors, and track endpoint copies */
        f->ss_descriptors = usb_copy_descriptors(ecm_ss_function);
        if (!f->ss_descriptors)
            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().
     */

    ecm->port.open = ecm_open;
    ecm->port.close = ecm_close;

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

fail:
    if (f->descriptors)
        usb_free_descriptors(f->descriptors);
    if (f->hs_descriptors)
        usb_free_descriptors(f->hs_descriptors);

    if (ecm->notify_req) {
        kfree(ecm->notify_req->buf);
        usb_ep_free_request(ecm->notify, ecm->notify_req);
    }

    /* we might as well release our claims on endpoints */
    if (ecm->notify)
        ecm->notify->driver_data = NULL;
    if (ecm->port.out_ep->desc)
        ecm->port.out_ep->driver_data = NULL;
    if (ecm->port.in_ep->desc)
        ecm->port.in_ep->driver_data = NULL;

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

    return status;
}

static void
ecm_unbind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_ecm        *ecm = func_to_ecm(f);

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

    if (gadget_is_superspeed(c->cdev->gadget))
        usb_free_descriptors(f->ss_descriptors);
    if (gadget_is_dualspeed(c->cdev->gadget))
        usb_free_descriptors(f->hs_descriptors);
    usb_free_descriptors(f->descriptors);

    kfree(ecm->notify_req->buf);
    usb_ep_free_request(ecm->notify, ecm->notify_req);

    ecm_string_defs[1].s = NULL;
    kfree(ecm);
}

int
ecm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
{
    struct f_ecm    *ecm;
    int     status;

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

    /* maybe allocate device-global string IDs */
    if (ecm_string_defs[0].id == 0) {

        /* control interface label */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ecm_string_defs[0].id = status;
        ecm_control_intf.iInterface = status;

        /* data interface label */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ecm_string_defs[2].id = status;
        ecm_data_intf.iInterface = status;

        /* MAC address */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ecm_string_defs[1].id = status;
        ecm_desc.iMACAddress = status;

        /* IAD label */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ecm_string_defs[3].id = status;
        ecm_iad_descriptor.iFunction = status;
    }

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

    /* export host's Ethernet address in CDC format */
    snprintf(ecm->ethaddr, sizeof ecm->ethaddr, "%pm", ethaddr);
    ecm_string_defs[1].s = ecm->ethaddr;

    ecm->port.cdc_filter = DEFAULT_FILTER;

    ecm->port.func.name = "cdc_ethernet";
    ecm->port.func.strings = ecm_strings;
    /* descriptors are per-instance copies */
    ecm->port.func.bind = ecm_bind;
    ecm->port.func.unbind = ecm_unbind;
    ecm->port.func.set_alt = ecm_set_alt;
    ecm->port.func.get_alt = ecm_get_alt;
    ecm->port.func.setup = ecm_setup;
    ecm->port.func.disable = ecm_disable;

    status = usb_add_function(c, &ecm->port.func);
    if (status) {
        ecm_string_defs[1].s = NULL;
        kfree(ecm);
    }
    return status;
}