On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:

[mmotm.git] / drivers / usb / gadget / f_rndis.c

/*
 * f_rndis.c -- RNDIS link function driver
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* #define VERBOSE_DEBUG */

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

#include <asm/atomic.h>

#include "u_ether.h"
#include "rndis.h"


/*
 * This function is an RNDIS Ethernet port -- a Microsoft protocol that's
 * been promoted instead of the standard CDC Ethernet.  The published RNDIS
 * spec is ambiguous, incomplete, and needlessly complex.  Variants such as
 * ActiveSync have even worse status in terms of specification.
 *
 * In short:  it's a protocol controlled by (and for) Microsoft, not for an
 * Open ecosystem or markets.  Linux supports it *only* because Microsoft
 * doesn't support the CDC Ethernet standard.
 *
 * The RNDIS data transfer model is complex, with multiple Ethernet packets
 * per USB message, and out of band data.  The control model is built around
 * what's essentially an "RNDIS RPC" protocol.  It's all wrapped in a CDC ACM
 * (modem, not Ethernet) veneer, with those ACM descriptors being entirely
 * useless (they're ignored).  RNDIS expects to be the only function in its
 * configuration, so it's no real help if you need composite devices; and
 * it expects to be the first configuration too.
 *
 * There is a single technical advantage of RNDIS over CDC Ethernet, if you
 * discount the fluff that its RPC can be made to deliver: it doesn't need
 * a NOP altsetting for the data interface.  That lets it work on some of the
 * "so smart it's stupid" hardware which takes over configuration changes
 * from the software, and adds restrictions like "no altsettings".
 *
 * Unfortunately MSFT's RNDIS drivers are buggy.  They hang or oops, and
 * have all sorts of contrary-to-specification oddities that can prevent
 * them from working sanely.  Since bugfixes (or accurate specs, letting
 * Linux work around those bugs) are unlikely to ever come from MSFT, you
 * may want to avoid using RNDIS on purely operational grounds.
 *
 * Omissions from the RNDIS 1.0 specification include:
 *
 *   - Power management ... references data that's scattered around lots
 *     of other documentation, which is incorrect/incomplete there too.
 *
 *   - There are various undocumented protocol requirements, like the need
 *     to send garbage in some control-OUT messages.
 *
 *   - MS-Windows drivers sometimes emit undocumented requests.
 */

struct rndis_ep_descs {
        struct usb_endpoint_descriptor  *in;
        struct usb_endpoint_descriptor  *out;
        struct usb_endpoint_descriptor  *notify;
};

struct f_rndis {
        struct gether                   port;
        u8                              ctrl_id, data_id;
        u8                              ethaddr[ETH_ALEN];
        int                             config;

        struct rndis_ep_descs           fs;
        struct rndis_ep_descs           hs;

        struct usb_ep                   *notify;
        struct usb_endpoint_descriptor  *notify_desc;
        struct usb_request              *notify_req;
        atomic_t                        notify_count;
};

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

/* peak (theoretical) bulk transfer rate in bits-per-second */
static unsigned int 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;
}

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

/*
 */

#define LOG2_STATUS_INTERVAL_MSEC       5       /* 1 << 5 == 32 msec */
#define STATUS_BYTECOUNT                8       /* 8 bytes data */


/* interface descriptor: */

static struct usb_interface_descriptor rndis_control_intf __initdata = {
        .bLength =              sizeof rndis_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_ACM,
        .bInterfaceProtocol =   USB_CDC_ACM_PROTO_VENDOR,
        /* .iInterface = DYNAMIC */
};

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

        .bcdCDC =               cpu_to_le16(0x0110),
};

static struct usb_cdc_call_mgmt_descriptor call_mgmt_descriptor __initdata = {
        .bLength =              sizeof call_mgmt_descriptor,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_CALL_MANAGEMENT_TYPE,

        .bmCapabilities =       0x00,
        .bDataInterface =       0x01,
};

static struct usb_cdc_acm_descriptor acm_descriptor __initdata = {
        .bLength =              sizeof acm_descriptor,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_ACM_TYPE,

        .bmCapabilities =       0x00,
};

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

/* the data interface has two bulk endpoints */

static struct usb_interface_descriptor rndis_data_intf __initdata = {
        .bLength =              sizeof rndis_data_intf,
        .bDescriptorType =      USB_DT_INTERFACE,

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

/* full speed support: */

static struct usb_endpoint_descriptor fs_notify_desc __initdata = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

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

static struct usb_endpoint_descriptor fs_in_desc __initdata = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

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

static struct usb_endpoint_descriptor fs_out_desc __initdata = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

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

static struct usb_descriptor_header *eth_fs_function[] __initdata = {
        /* control interface matches ACM, not Ethernet */
        (struct usb_descriptor_header *) &rndis_control_intf,
        (struct usb_descriptor_header *) &header_desc,
        (struct usb_descriptor_header *) &call_mgmt_descriptor,
        (struct usb_descriptor_header *) &acm_descriptor,
        (struct usb_descriptor_header *) &rndis_union_desc,
        (struct usb_descriptor_header *) &fs_notify_desc,
        /* data interface has no altsetting */
        (struct usb_descriptor_header *) &rndis_data_intf,
        (struct usb_descriptor_header *) &fs_in_desc,
        (struct usb_descriptor_header *) &fs_out_desc,
        NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor hs_notify_desc __initdata = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize =       cpu_to_le16(STATUS_BYTECOUNT),
        .bInterval =            LOG2_STATUS_INTERVAL_MSEC + 4,
};
static struct usb_endpoint_descriptor hs_in_desc __initdata = {
        .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_out_desc __initdata = {
        .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 *eth_hs_function[] __initdata = {
        /* control interface matches ACM, not Ethernet */
        (struct usb_descriptor_header *) &rndis_control_intf,
        (struct usb_descriptor_header *) &header_desc,
        (struct usb_descriptor_header *) &call_mgmt_descriptor,
        (struct usb_descriptor_header *) &acm_descriptor,
        (struct usb_descriptor_header *) &rndis_union_desc,
        (struct usb_descriptor_header *) &hs_notify_desc,
        /* data interface has no altsetting */
        (struct usb_descriptor_header *) &rndis_data_intf,
        (struct usb_descriptor_header *) &hs_in_desc,
        (struct usb_descriptor_header *) &hs_out_desc,
        NULL,
};

/* string descriptors: */

static struct usb_string rndis_string_defs[] = {
        [0].s = "RNDIS Communications Control",
        [1].s = "RNDIS Ethernet Data",
        {  } /* end of list */
};

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

static struct usb_gadget_strings *rndis_strings[] = {
        &rndis_string_table,
        NULL,
};

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

static struct sk_buff *rndis_add_header(struct gether *port,
                                        struct sk_buff *skb)
{
        struct sk_buff *skb2;

        skb2 = skb_realloc_headroom(skb, sizeof(struct rndis_packet_msg_type));
        if (skb2)
                rndis_add_hdr(skb2);

        dev_kfree_skb_any(skb);
        return skb2;
}

static void rndis_response_available(void *_rndis)
{
        struct f_rndis                  *rndis = _rndis;
        struct usb_request              *req = rndis->notify_req;
        struct usb_composite_dev        *cdev = rndis->port.func.config->cdev;
        __le32                          *data = req->buf;
        int                             status;

        if (atomic_inc_return(&rndis->notify_count) != 1)
                return;

        /* Send RNDIS RESPONSE_AVAILABLE notification; a
         * USB_CDC_NOTIFY_RESPONSE_AVAILABLE "should" work too
         *
         * This is the only notification defined by RNDIS.
         */
        data[0] = cpu_to_le32(1);
        data[1] = cpu_to_le32(0);

        status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
        if (status) {
                atomic_dec(&rndis->notify_count);
                DBG(cdev, "notify/0 --> %d\n", status);
        }
}

static void rndis_response_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_rndis                  *rndis = req->context;
        struct usb_composite_dev        *cdev = rndis->port.func.config->cdev;
        int                             status = req->status;

        /* after TX:
         *  - USB_CDC_GET_ENCAPSULATED_RESPONSE (ep0/control)
         *  - RNDIS_RESPONSE_AVAILABLE (status/irq)
         */
        switch (status) {
        case -ECONNRESET:
        case -ESHUTDOWN:
                /* connection gone */
                atomic_set(&rndis->notify_count, 0);
                break;
        default:
                DBG(cdev, "RNDIS %s response error %d, %d/%d\n",
                        ep->name, status,
                        req->actual, req->length);
                /* FALLTHROUGH */
        case 0:
                if (ep != rndis->notify)
                        break;

                /* handle multiple pending RNDIS_RESPONSE_AVAILABLE
                 * notifications by resending until we're done
                 */
                if (atomic_dec_and_test(&rndis->notify_count))
                        break;
                status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
                if (status) {
                        atomic_dec(&rndis->notify_count);
                        DBG(cdev, "notify/1 --> %d\n", status);
                }
                break;
        }
}

static void rndis_command_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_rndis                  *rndis = req->context;
        struct usb_composite_dev        *cdev = rndis->port.func.config->cdev;
        int                             status;

        /* received RNDIS command from USB_CDC_SEND_ENCAPSULATED_COMMAND */
//      spin_lock(&dev->lock);
        status = rndis_msg_parser(rndis->config, (u8 *) req->buf);
        if (status < 0)
                ERROR(cdev, "RNDIS command error %d, %d/%d\n",
                        status, req->actual, req->length);
//      spin_unlock(&dev->lock);
}

static int
rndis_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
        struct f_rndis          *rndis = func_to_rndis(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) {

        /* RNDIS uses the CDC command encapsulation mechanism to implement
         * an RPC scheme, with much getting/setting of attributes by OID.
         */
        case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                        | USB_CDC_SEND_ENCAPSULATED_COMMAND:
                if (w_length > req->length || w_value
                                || w_index != rndis->ctrl_id)
                        goto invalid;
                /* read the request; process it later */
                value = w_length;
                req->complete = rndis_command_complete;
                req->context = rndis;
                /* later, rndis_response_available() sends a notification */
                break;

        case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
                        | USB_CDC_GET_ENCAPSULATED_RESPONSE:
                if (w_value || w_index != rndis->ctrl_id)
                        goto invalid;
                else {
                        u8 *buf;
                        u32 n;

                        /* return the result */
                        buf = rndis_get_next_response(rndis->config, &n);
                        if (buf) {
                                memcpy(req->buf, buf, n);
                                req->complete = rndis_response_complete;
                                rndis_free_response(rndis->config, buf);
                                value = n;
                        }
                        /* else stalls ... spec says to avoid that */
                }
                break;

        default:
invalid:
                VDBG(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, "rndis req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        w_value, w_index, w_length);
                req->zero = (value < w_length);
                req->length = value;
                value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
                if (value < 0)
                        ERROR(cdev, "rndis response on err %d\n", value);
        }

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


static int rndis_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_rndis          *rndis = func_to_rndis(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        /* we know alt == 0 */

        if (intf == rndis->ctrl_id) {
                if (rndis->notify->driver_data) {
                        VDBG(cdev, "reset rndis control %d\n", intf);
                        usb_ep_disable(rndis->notify);
                } else {
                        VDBG(cdev, "init rndis ctrl %d\n", intf);
                        rndis->notify_desc = ep_choose(cdev->gadget,
                                        rndis->hs.notify,
                                        rndis->fs.notify);
                }
                usb_ep_enable(rndis->notify, rndis->notify_desc);
                rndis->notify->driver_data = rndis;

        } else if (intf == rndis->data_id) {
                struct net_device       *net;

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

                if (!rndis->port.in) {
                        DBG(cdev, "init rndis\n");
                        rndis->port.in = ep_choose(cdev->gadget,
                                        rndis->hs.in, rndis->fs.in);
                        rndis->port.out = ep_choose(cdev->gadget,
                                        rndis->hs.out, rndis->fs.out);
                }

                /* Avoid ZLPs; they can be troublesome. */
                rndis->port.is_zlp_ok = false;

                /* RNDIS should be in the "RNDIS uninitialized" state,
                 * either never activated or after rndis_uninit().
                 *
                 * We don't want data to flow here until a nonzero packet
                 * filter is set, at which point it enters "RNDIS data
                 * initialized" state ... but we do want the endpoints
                 * to be activated.  It's a strange little state.
                 *
                 * REVISIT the RNDIS gadget code has done this wrong for a
                 * very long time.  We need another call to the link layer
                 * code -- gether_updown(...bool) maybe -- to do it right.
                 */
                rndis->port.cdc_filter = 0;

                DBG(cdev, "RNDIS RX/TX early activation ... \n");
                net = gether_connect(&rndis->port);
                if (IS_ERR(net))
                        return PTR_ERR(net);

                rndis_set_param_dev(rndis->config, net,
                                &rndis->port.cdc_filter);
        } else
                goto fail;

        return 0;
fail:
        return -EINVAL;
}

static void rndis_disable(struct usb_function *f)
{
        struct f_rndis          *rndis = func_to_rndis(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        if (!rndis->notify->driver_data)
                return;

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

        rndis_uninit(rndis->config);
        gether_disconnect(&rndis->port);

        usb_ep_disable(rndis->notify);
        rndis->notify->driver_data = NULL;
}

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

/*
 * This isn't quite the same mechanism as CDC Ethernet, since the
 * notification scheme passes less data, but the same set of link
 * states must be tested.  A key difference is that altsettings are
 * not used to tell whether the link should send packets or not.
 */

static void rndis_open(struct gether *geth)
{
        struct f_rndis          *rndis = func_to_rndis(&geth->func);
        struct usb_composite_dev *cdev = geth->func.config->cdev;

        DBG(cdev, "%s\n", __func__);

        rndis_set_param_medium(rndis->config, NDIS_MEDIUM_802_3,
                                bitrate(cdev->gadget) / 100);
        rndis_signal_connect(rndis->config);
}

static void rndis_close(struct gether *geth)
{
        struct f_rndis          *rndis = func_to_rndis(&geth->func);

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

        rndis_set_param_medium(rndis->config, NDIS_MEDIUM_802_3, 0);
        rndis_signal_disconnect(rndis->config);
}

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

/* ethernet function driver setup/binding */

static int __init
rndis_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_rndis          *rndis = func_to_rndis(f);
        int                     status;
        struct usb_ep           *ep;

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

        rndis_control_intf.bInterfaceNumber = status;
        rndis_union_desc.bMasterInterface0 = status;

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

        rndis_data_intf.bInterfaceNumber = status;
        rndis_union_desc.bSlaveInterface0 = status;

        status = -ENODEV;

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

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

        /* NOTE:  a status/notification endpoint is, strictly speaking,
         * optional.  We don't treat it that way though!  It's simpler,
         * and some newer profiles don't treat it as optional.
         */
        ep = usb_ep_autoconfig(cdev->gadget, &fs_notify_desc);
        if (!ep)
                goto fail;
        rndis->notify = ep;
        ep->driver_data = cdev; /* claim */

        status = -ENOMEM;

        /* allocate notification request and buffer */
        rndis->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
        if (!rndis->notify_req)
                goto fail;
        rndis->notify_req->buf = kmalloc(STATUS_BYTECOUNT, GFP_KERNEL);
        if (!rndis->notify_req->buf)
                goto fail;
        rndis->notify_req->length = STATUS_BYTECOUNT;
        rndis->notify_req->context = rndis;
        rndis->notify_req->complete = rndis_response_complete;

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

        rndis->fs.in = usb_find_endpoint(eth_fs_function,
                        f->descriptors, &fs_in_desc);
        rndis->fs.out = usb_find_endpoint(eth_fs_function,
                        f->descriptors, &fs_out_desc);
        rndis->fs.notify = usb_find_endpoint(eth_fs_function,
                        f->descriptors, &fs_notify_desc);

        /* 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_in_desc.bEndpointAddress =
                                fs_in_desc.bEndpointAddress;
                hs_out_desc.bEndpointAddress =
                                fs_out_desc.bEndpointAddress;
                hs_notify_desc.bEndpointAddress =
                                fs_notify_desc.bEndpointAddress;

                /* copy descriptors, and track endpoint copies */
                f->hs_descriptors = usb_copy_descriptors(eth_hs_function);

                if (!f->hs_descriptors)
                        goto fail;

                rndis->hs.in = usb_find_endpoint(eth_hs_function,
                                f->hs_descriptors, &hs_in_desc);
                rndis->hs.out = usb_find_endpoint(eth_hs_function,
                                f->hs_descriptors, &hs_out_desc);
                rndis->hs.notify = usb_find_endpoint(eth_hs_function,
                                f->hs_descriptors, &hs_notify_desc);
        }

        rndis->port.open = rndis_open;
        rndis->port.close = rndis_close;

        status = rndis_register(rndis_response_available, rndis);
        if (status < 0)
                goto fail;
        rndis->config = status;

        rndis_set_param_medium(rndis->config, NDIS_MEDIUM_802_3, 0);
        rndis_set_host_mac(rndis->config, rndis->ethaddr);

#if 0
// FIXME
        if (rndis_set_param_vendor(rndis->config, vendorID,
                                manufacturer))
                goto fail0;
#endif

        /* 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().
         */

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

fail:
        if (gadget_is_dualspeed(c->cdev->gadget) && f->hs_descriptors)
                usb_free_descriptors(f->hs_descriptors);
        if (f->descriptors)
                usb_free_descriptors(f->descriptors);

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

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

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

        return status;
}

static void
rndis_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct f_rndis          *rndis = func_to_rndis(f);

        rndis_deregister(rndis->config);
        rndis_exit();

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

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

        kfree(rndis);
}

/* Some controllers can't support RNDIS ... */
static inline bool can_support_rndis(struct usb_configuration *c)
{
        /* only two endpoints on sa1100 */
        if (gadget_is_sa1100(c->cdev->gadget))
                return false;

        /* everything else is *presumably* fine */
        return true;
}

/**
 * rndis_bind_config - add RNDIS network link to a configuration
 * @c: the configuration to support the network link
 * @ethaddr: a buffer in which the ethernet address of the host side
 *      side of the link was recorded
 * Context: single threaded during gadget setup
 *
 * Returns zero on success, else negative errno.
 *
 * Caller must have called @gether_setup().  Caller is also responsible
 * for calling @gether_cleanup() before module unload.
 */
int __init rndis_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
{
        struct f_rndis  *rndis;
        int             status;

        if (!can_support_rndis(c) || !ethaddr)
                return -EINVAL;

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

                /* ... and setup RNDIS itself */
                status = rndis_init();
                if (status < 0)
                        return status;

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

                /* data interface label */
                status = usb_string_id(c->cdev);
                if (status < 0)
                        return status;
                rndis_string_defs[1].id = status;
                rndis_data_intf.iInterface = status;
        }

        /* allocate and initialize one new instance */
        status = -ENOMEM;
        rndis = kzalloc(sizeof *rndis, GFP_KERNEL);
        if (!rndis)
                goto fail;

        memcpy(rndis->ethaddr, ethaddr, ETH_ALEN);

        /* RNDIS activates when the host changes this filter */
        rndis->port.cdc_filter = 0;

        /* RNDIS has special (and complex) framing */
        rndis->port.header_len = sizeof(struct rndis_packet_msg_type);
        rndis->port.wrap = rndis_add_header;
        rndis->port.unwrap = rndis_rm_hdr;

        rndis->port.func.name = "rndis";
        rndis->port.func.strings = rndis_strings;
        /* descriptors are per-instance copies */
        rndis->port.func.bind = rndis_bind;
        rndis->port.func.unbind = rndis_unbind;
        rndis->port.func.set_alt = rndis_set_alt;
        rndis->port.func.setup = rndis_setup;
        rndis->port.func.disable = rndis_disable;

        status = usb_add_function(c, &rndis->port.func);
        if (status) {
                kfree(rndis);
fail:
                rndis_exit();
        }
        return status;
}