V4L/DVB (11242): allow v4l2 drivers to provide a get_unmapped_area handler

[linux-2.6] / drivers / uwb / hwa-rc.c

/*
 * WUSB Host Wire Adapter: Radio Control Interface (WUSB[8.6])
 * Radio Control command/event transport
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * Initialize the Radio Control interface Driver.
 *
 * For each device probed, creates an 'struct hwarc' which contains
 * just the representation of the UWB Radio Controller, and the logic
 * for reading notifications and passing them to the UWB Core.
 *
 * So we initialize all of those, register the UWB Radio Controller
 * and setup the notification/event handle to pipe the notifications
 * to the UWB management Daemon.
 *
 * Command and event filtering.
 *
 * This is the driver for the Radio Control Interface described in WUSB
 * 1.0. The core UWB module assumes that all drivers are compliant to the
 * WHCI 0.95 specification. We thus create a filter that parses all
 * incoming messages from the (WUSB 1.0) device and manipulate them to
 * conform to the WHCI 0.95 specification. Similarly, outgoing messages
 * are parsed and manipulated to conform to the WUSB 1.0 compliant messages
 * that the device expects. Only a few messages are affected:
 * Affected events:
 *    UWB_RC_EVT_BEACON
 *    UWB_RC_EVT_BP_SLOT_CHANGE
 *    UWB_RC_EVT_DRP_AVAIL
 *    UWB_RC_EVT_DRP
 * Affected commands:
 *    UWB_RC_CMD_SCAN
 *    UWB_RC_CMD_SET_DRP_IE
 *
 *
 *
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/wusb.h>
#include <linux/usb/wusb-wa.h>
#include <linux/uwb.h>

#include "uwb-internal.h"

/* The device uses commands and events from the WHCI specification, although
 * reporting itself as WUSB compliant. */
#define WUSB_QUIRK_WHCI_CMD_EVT         0x01

/**
 * Descriptor for an instance of the UWB Radio Control Driver that
 * attaches to the RCI interface of the Host Wired Adapter.
 *
 * Unless there is a lock specific to the 'data members', all access
 * is protected by uwb_rc->mutex.
 *
 * The NEEP (Notification/Event EndPoint) URB (@neep_urb) writes to
 * @rd_buffer. Note there is no locking because it is perfectly (heh!)
 * serialized--probe() submits an URB, callback is called, processes
 * the data (synchronously), submits another URB, and so on. There is
 * no concurrent access to the buffer.
 */
struct hwarc {
        struct usb_device *usb_dev;
        struct usb_interface *usb_iface;
        struct uwb_rc *uwb_rc;          /* UWB host controller */
        struct urb *neep_urb;           /* Notification endpoint handling */
        struct edc neep_edc;
        void *rd_buffer;                /* NEEP read buffer */
};


/* Beacon received notification (WUSB 1.0 [8.6.3.2]) */
struct uwb_rc_evt_beacon_WUSB_0100 {
        struct uwb_rceb rceb;
        u8      bChannelNumber;
        __le16  wBPSTOffset;
        u8      bLQI;
        u8      bRSSI;
        __le16  wBeaconInfoLength;
        u8      BeaconInfo[];
} __attribute__((packed));

/**
 * Filter WUSB 1.0 BEACON RCV notification to be WHCI 0.95
 *
 * @header: the incoming event
 * @buf_size: size of buffer containing incoming event
 * @new_size: size of event after filtering completed
 *
 * The WHCI 0.95 spec has a "Beacon Type" field. This value is unknown at
 * the time we receive the beacon from WUSB so we just set it to
 * UWB_RC_BEACON_TYPE_NEIGHBOR as a default.
 * The solution below allocates memory upon receipt of every beacon from a
 * WUSB device. This will deteriorate performance. What is the right way to
 * do this?
 */
static
int hwarc_filter_evt_beacon_WUSB_0100(struct uwb_rc *rc,
                                      struct uwb_rceb **header,
                                      const size_t buf_size,
                                      size_t *new_size)
{
        struct uwb_rc_evt_beacon_WUSB_0100 *be;
        struct uwb_rc_evt_beacon *newbe;
        size_t bytes_left, ielength;
        struct device *dev = &rc->uwb_dev.dev;

        be = container_of(*header, struct uwb_rc_evt_beacon_WUSB_0100, rceb);
        bytes_left = buf_size;
        if (bytes_left < sizeof(*be)) {
                dev_err(dev, "Beacon Received Notification: Not enough data "
                        "to decode for filtering (%zu vs %zu bytes needed)\n",
                        bytes_left, sizeof(*be));
                return -EINVAL;
        }
        bytes_left -= sizeof(*be);
        ielength = le16_to_cpu(be->wBeaconInfoLength);
        if (bytes_left < ielength) {
                dev_err(dev, "Beacon Received Notification: Not enough data "
                        "to decode IEs (%zu vs %zu bytes needed)\n",
                        bytes_left, ielength);
                return -EINVAL;
        }
        newbe = kzalloc(sizeof(*newbe) + ielength, GFP_ATOMIC);
        if (newbe == NULL)
                return -ENOMEM;
        newbe->rceb = be->rceb;
        newbe->bChannelNumber = be->bChannelNumber;
        newbe->bBeaconType = UWB_RC_BEACON_TYPE_NEIGHBOR;
        newbe->wBPSTOffset = be->wBPSTOffset;
        newbe->bLQI = be->bLQI;
        newbe->bRSSI = be->bRSSI;
        newbe->wBeaconInfoLength = be->wBeaconInfoLength;
        memcpy(newbe->BeaconInfo, be->BeaconInfo, ielength);
        *header = &newbe->rceb;
        *new_size = sizeof(*newbe) + ielength;
        return 1;  /* calling function will free memory */
}


/* DRP Availability change notification (WUSB 1.0 [8.6.3.8]) */
struct uwb_rc_evt_drp_avail_WUSB_0100 {
        struct uwb_rceb rceb;
        __le16 wIELength;
        u8 IEData[];
} __attribute__((packed));

/**
 * Filter WUSB 1.0 DRP AVAILABILITY CHANGE notification to be WHCI 0.95
 *
 * @header: the incoming event
 * @buf_size: size of buffer containing incoming event
 * @new_size: size of event after filtering completed
 */
static
int hwarc_filter_evt_drp_avail_WUSB_0100(struct uwb_rc *rc,
                                         struct uwb_rceb **header,
                                         const size_t buf_size,
                                         size_t *new_size)
{
        struct uwb_rc_evt_drp_avail_WUSB_0100 *da;
        struct uwb_rc_evt_drp_avail *newda;
        struct uwb_ie_hdr *ie_hdr;
        size_t bytes_left, ielength;
        struct device *dev = &rc->uwb_dev.dev;


        da = container_of(*header, struct uwb_rc_evt_drp_avail_WUSB_0100, rceb);
        bytes_left = buf_size;
        if (bytes_left < sizeof(*da)) {
                dev_err(dev, "Not enough data to decode DRP Avail "
                        "Notification for filtering. Expected %zu, "
                        "received %zu.\n", (size_t)sizeof(*da), bytes_left);
                return -EINVAL;
        }
        bytes_left -= sizeof(*da);
        ielength = le16_to_cpu(da->wIELength);
        if (bytes_left < ielength) {
                dev_err(dev, "DRP Avail Notification filter: IE length "
                        "[%zu bytes] does not match actual length "
                        "[%zu bytes].\n", ielength, bytes_left);
                return -EINVAL;
        }
        if (ielength < sizeof(*ie_hdr)) {
                dev_err(dev, "DRP Avail Notification filter: Not enough "
                        "data to decode IE [%zu bytes, %zu needed]\n",
                        ielength, sizeof(*ie_hdr));
                return -EINVAL;
        }
        ie_hdr = (void *) da->IEData;
        if (ie_hdr->length > 32) {
                dev_err(dev, "DRP Availability Change event has unexpected "
                        "length for filtering. Expected < 32 bytes, "
                        "got %zu bytes.\n", (size_t)ie_hdr->length);
                return -EINVAL;
        }
        newda = kzalloc(sizeof(*newda), GFP_ATOMIC);
        if (newda == NULL)
                return -ENOMEM;
        newda->rceb = da->rceb;
        memcpy(newda->bmp, (u8 *) ie_hdr + sizeof(*ie_hdr), ie_hdr->length);
        *header = &newda->rceb;
        *new_size = sizeof(*newda);
        return 1; /* calling function will free memory */
}


/* DRP notification (WUSB 1.0 [8.6.3.9]) */
struct uwb_rc_evt_drp_WUSB_0100 {
        struct uwb_rceb rceb;
        struct uwb_dev_addr wSrcAddr;
        u8 bExplicit;
        __le16 wIELength;
        u8 IEData[];
} __attribute__((packed));

/**
 * Filter WUSB 1.0 DRP Notification to be WHCI 0.95
 *
 * @header: the incoming event
 * @buf_size: size of buffer containing incoming event
 * @new_size: size of event after filtering completed
 *
 * It is hard to manage DRP reservations without having a Reason code.
 * Unfortunately there is none in the WUSB spec. We just set the default to
 * DRP IE RECEIVED.
 * We do not currently use the bBeaconSlotNumber value, so we set this to
 * zero for now.
 */
static
int hwarc_filter_evt_drp_WUSB_0100(struct uwb_rc *rc,
                                   struct uwb_rceb **header,
                                   const size_t buf_size,
                                   size_t *new_size)
{
        struct uwb_rc_evt_drp_WUSB_0100 *drpev;
        struct uwb_rc_evt_drp *newdrpev;
        size_t bytes_left, ielength;
        struct device *dev = &rc->uwb_dev.dev;

        drpev = container_of(*header, struct uwb_rc_evt_drp_WUSB_0100, rceb);
        bytes_left = buf_size;
        if (bytes_left < sizeof(*drpev)) {
                dev_err(dev, "Not enough data to decode DRP Notification "
                        "for filtering. Expected %zu, received %zu.\n",
                        (size_t)sizeof(*drpev), bytes_left);
                return -EINVAL;
        }
        ielength = le16_to_cpu(drpev->wIELength);
        bytes_left -= sizeof(*drpev);
        if (bytes_left < ielength) {
                dev_err(dev, "DRP Notification filter: header length [%zu "
                        "bytes] does not match actual length [%zu "
                        "bytes].\n", ielength, bytes_left);
                return -EINVAL;
        }
        newdrpev = kzalloc(sizeof(*newdrpev) + ielength, GFP_ATOMIC);
        if (newdrpev == NULL)
                return -ENOMEM;
        newdrpev->rceb = drpev->rceb;
        newdrpev->src_addr = drpev->wSrcAddr;
        newdrpev->reason = UWB_DRP_NOTIF_DRP_IE_RCVD;
        newdrpev->beacon_slot_number = 0;
        newdrpev->ie_length = drpev->wIELength;
        memcpy(newdrpev->ie_data, drpev->IEData, ielength);
        *header = &newdrpev->rceb;
        *new_size = sizeof(*newdrpev) + ielength;
        return 1; /* calling function will free memory */
}


/* Scan Command (WUSB 1.0 [8.6.2.5]) */
struct uwb_rc_cmd_scan_WUSB_0100 {
        struct uwb_rccb rccb;
        u8 bChannelNumber;
        u8 bScanState;
} __attribute__((packed));

/**
 * Filter WHCI 0.95 SCAN command to be WUSB 1.0 SCAN command
 *
 * @header:   command sent to device (compliant to WHCI 0.95)
 * @size:     size of command sent to device
 *
 * We only reduce the size by two bytes because the WUSB 1.0 scan command
 * does not have the last field (wStarttime). Also, make sure we don't send
 * the device an unexpected scan type.
 */
static
int hwarc_filter_cmd_scan_WUSB_0100(struct uwb_rc *rc,
                                    struct uwb_rccb **header,
                                    size_t *size)
{
        struct uwb_rc_cmd_scan *sc;

        sc = container_of(*header, struct uwb_rc_cmd_scan, rccb);

        if (sc->bScanState == UWB_SCAN_ONLY_STARTTIME)
                sc->bScanState = UWB_SCAN_ONLY;
        /* Don't send the last two bytes. */
        *size -= 2;
        return 0;
}


/* SET DRP IE command (WUSB 1.0 [8.6.2.7]) */
struct uwb_rc_cmd_set_drp_ie_WUSB_0100 {
        struct uwb_rccb rccb;
        u8 bExplicit;
        __le16 wIELength;
        struct uwb_ie_drp IEData[];
} __attribute__((packed));

/**
 * Filter WHCI 0.95 SET DRP IE command to be WUSB 1.0 SET DRP IE command
 *
 * @header:   command sent to device (compliant to WHCI 0.95)
 * @size:     size of command sent to device
 *
 * WUSB has an extra bExplicit field - we assume always explicit
 * negotiation so this field is set. The command expected by the device is
 * thus larger than the one prepared by the driver so we need to
 * reallocate memory to accommodate this.
 * We trust the driver to send us the correct data so no checking is done
 * on incoming data - evn though it is variable length.
 */
static
int hwarc_filter_cmd_set_drp_ie_WUSB_0100(struct uwb_rc *rc,
                                          struct uwb_rccb **header,
                                          size_t *size)
{
        struct uwb_rc_cmd_set_drp_ie *orgcmd;
        struct uwb_rc_cmd_set_drp_ie_WUSB_0100 *cmd;
        size_t ielength;

        orgcmd = container_of(*header, struct uwb_rc_cmd_set_drp_ie, rccb);
        ielength = le16_to_cpu(orgcmd->wIELength);
        cmd = kzalloc(sizeof(*cmd) + ielength, GFP_KERNEL);
        if (cmd == NULL)
                return -ENOMEM;
        cmd->rccb = orgcmd->rccb;
        cmd->bExplicit = 0;
        cmd->wIELength = orgcmd->wIELength;
        memcpy(cmd->IEData, orgcmd->IEData, ielength);
        *header = &cmd->rccb;
        *size = sizeof(*cmd) + ielength;
        return 1; /* calling function will free memory */
}


/**
 * Filter data from WHCI driver to WUSB device
 *
 * @header: WHCI 0.95 compliant command from driver
 * @size:   length of command
 *
 * The routine managing commands to the device (uwb_rc_cmd()) will call the
 * filtering function pointer (if it exists) before it passes any data to
 * the device. At this time the command has been formatted according to
 * WHCI 0.95 and is ready to be sent to the device.
 *
 * The filter function will be provided with the current command and its
 * length. The function will manipulate the command if necessary and
 * potentially reallocate memory for a command that needed more memory that
 * the given command. If new memory was created the function will return 1
 * to indicate to the calling function that the memory need to be freed
 * when not needed any more. The size will contain the new length of the
 * command.
 * If memory has not been allocated we rely on the original mechanisms to
 * free the memory of the command - even when we reduce the value of size.
 */
static
int hwarc_filter_cmd_WUSB_0100(struct uwb_rc *rc, struct uwb_rccb **header,
                               size_t *size)
{
        int result;
        struct uwb_rccb *rccb = *header;
        int cmd = le16_to_cpu(rccb->wCommand);
        switch (cmd) {
        case UWB_RC_CMD_SCAN:
                result = hwarc_filter_cmd_scan_WUSB_0100(rc, header, size);
                break;
        case UWB_RC_CMD_SET_DRP_IE:
                result = hwarc_filter_cmd_set_drp_ie_WUSB_0100(rc, header, size);
                break;
        default:
                result = -ENOANO;
                break;
        }
        return result;
}


/**
 * Filter data from WHCI driver to WUSB device
 *
 * @header: WHCI 0.95 compliant command from driver
 * @size:   length of command
 *
 * Filter commands based on which protocol the device supports. The WUSB
 * errata should be the same as WHCI 0.95 so we do not filter that here -
 * only WUSB 1.0.
 */
static
int hwarc_filter_cmd(struct uwb_rc *rc, struct uwb_rccb **header,
                     size_t *size)
{
        int result = -ENOANO;
        if (rc->version == 0x0100)
                result = hwarc_filter_cmd_WUSB_0100(rc, header, size);
        return result;
}


/**
 * Compute return value as sum of incoming value and value at given offset
 *
 * @rceb:      event for which we compute the size, it contains a variable
 *             length field.
 * @core_size: size of the "non variable" part of the event
 * @offset:    place in event where the length of the variable part is stored
 * @buf_size: total length of buffer in which event arrived - we need to make
 *             sure we read the offset in memory that is still part of the event
 */
static
ssize_t hwarc_get_event_size(struct uwb_rc *rc, const struct uwb_rceb *rceb,
                             size_t core_size, size_t offset,
                             const size_t buf_size)
{
        ssize_t size = -ENOSPC;
        const void *ptr = rceb;
        size_t type_size = sizeof(__le16);
        struct device *dev = &rc->uwb_dev.dev;

        if (offset + type_size >= buf_size) {
                dev_err(dev, "Not enough data to read extra size of event "
                        "0x%02x/%04x/%02x, only got %zu bytes.\n",
                        rceb->bEventType, le16_to_cpu(rceb->wEvent),
                        rceb->bEventContext, buf_size);
                goto out;
        }
        ptr += offset;
        size = core_size + le16_to_cpu(*(__le16 *)ptr);
out:
        return size;
}


/* Beacon slot change notification (WUSB 1.0 [8.6.3.5]) */
struct uwb_rc_evt_bp_slot_change_WUSB_0100 {
        struct uwb_rceb rceb;
        u8 bSlotNumber;
} __attribute__((packed));


/**
 * Filter data from WUSB device to WHCI driver
 *
 * @header:      incoming event
 * @buf_size:    size of buffer in which event arrived
 * @_event_size: actual size of event in the buffer
 * @new_size:    size of event after filtered
 *
 * We don't know how the buffer is constructed - there may be more than one
 * event in it so buffer length does not determine event length. We first
 * determine the expected size of the incoming event. This value is passed
 * back only if the actual filtering succeeded (so we know the computed
 * expected size is correct). This value will be zero if
 * the event did not need any filtering.
 *
 * WHCI interprets the BP Slot Change event's data differently than
 * WUSB. The event sizes are exactly the same. The data field
 * indicates the new beacon slot in which a RC is transmitting its
 * beacon. The maximum value of this is 96 (wMacBPLength ECMA-368
 * 17.16 (Table 117)). We thus know that the WUSB value will not set
 * the bit bNoSlot, so we don't really do anything (placeholder).
 */
static
int hwarc_filter_event_WUSB_0100(struct uwb_rc *rc, struct uwb_rceb **header,
                                 const size_t buf_size, size_t *_real_size,
                                 size_t *_new_size)
{
        int result = -ENOANO;
        struct uwb_rceb *rceb = *header;
        int event = le16_to_cpu(rceb->wEvent);
        size_t event_size;
        size_t core_size, offset;

        if (rceb->bEventType != UWB_RC_CET_GENERAL)
                goto out;
        switch (event) {
        case UWB_RC_EVT_BEACON:
                core_size = sizeof(struct uwb_rc_evt_beacon_WUSB_0100);
                offset = offsetof(struct uwb_rc_evt_beacon_WUSB_0100,
                                  wBeaconInfoLength);
                event_size = hwarc_get_event_size(rc, rceb, core_size,
                                                  offset, buf_size);
                if (event_size < 0)
                        goto out;
                *_real_size = event_size;
                result = hwarc_filter_evt_beacon_WUSB_0100(rc, header,
                                                           buf_size, _new_size);
                break;
        case UWB_RC_EVT_BP_SLOT_CHANGE:
                *_new_size = *_real_size =
                        sizeof(struct uwb_rc_evt_bp_slot_change_WUSB_0100);
                result = 0;
                break;

        case UWB_RC_EVT_DRP_AVAIL:
                core_size = sizeof(struct uwb_rc_evt_drp_avail_WUSB_0100);
                offset = offsetof(struct uwb_rc_evt_drp_avail_WUSB_0100,
                                  wIELength);
                event_size = hwarc_get_event_size(rc, rceb, core_size,
                                                  offset, buf_size);
                if (event_size < 0)
                        goto out;
                *_real_size = event_size;
                result = hwarc_filter_evt_drp_avail_WUSB_0100(
                        rc, header, buf_size, _new_size);
                break;

        case UWB_RC_EVT_DRP:
                core_size = sizeof(struct uwb_rc_evt_drp_WUSB_0100);
                offset = offsetof(struct uwb_rc_evt_drp_WUSB_0100, wIELength);
                event_size = hwarc_get_event_size(rc, rceb, core_size,
                                                  offset, buf_size);
                if (event_size < 0)
                        goto out;
                *_real_size = event_size;
                result = hwarc_filter_evt_drp_WUSB_0100(rc, header,
                                                        buf_size, _new_size);
                break;

        default:
                break;
        }
out:
        return result;
}

/**
 * Filter data from WUSB device to WHCI driver
 *
 * @header:      incoming event
 * @buf_size:    size of buffer in which event arrived
 * @_event_size: actual size of event in the buffer
 * @_new_size:   size of event after filtered
 *
 * Filter events based on which protocol the device supports. The WUSB
 * errata should be the same as WHCI 0.95 so we do not filter that here -
 * only WUSB 1.0.
 *
 * If we don't handle it, we return -ENOANO (why the weird error code?
 * well, so if I get it, I can pinpoint in the code that raised
 * it...after all, not too many places use the higher error codes).
 */
static
int hwarc_filter_event(struct uwb_rc *rc, struct uwb_rceb **header,
                       const size_t buf_size, size_t *_real_size,
                       size_t *_new_size)
{
        int result = -ENOANO;
        if (rc->version == 0x0100)
                result =  hwarc_filter_event_WUSB_0100(
                        rc, header, buf_size, _real_size, _new_size);
        return result;
}


/**
 * Execute an UWB RC command on HWA
 *
 * @rc:       Instance of a Radio Controller that is a HWA
 * @cmd:      Buffer containing the RCCB and payload to execute
 * @cmd_size: Size of the command buffer.
 *
 * NOTE: rc's mutex has to be locked
 */
static
int hwarc_cmd(struct uwb_rc *uwb_rc, const struct uwb_rccb *cmd, size_t cmd_size)
{
        struct hwarc *hwarc = uwb_rc->priv;
        return usb_control_msg(
                hwarc->usb_dev, usb_sndctrlpipe(hwarc->usb_dev, 0),
                WA_EXEC_RC_CMD, USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                0, hwarc->usb_iface->cur_altsetting->desc.bInterfaceNumber,
                (void *) cmd, cmd_size, 100 /* FIXME: this is totally arbitrary */);
}

static
int hwarc_reset(struct uwb_rc *uwb_rc)
{
        struct hwarc *hwarc = uwb_rc->priv;
        return usb_reset_device(hwarc->usb_dev);
}

/**
 * Callback for the notification and event endpoint
 *
 * Check's that everything is fine and then passes the read data to
 * the notification/event handling mechanism (neh).
 */
static
void hwarc_neep_cb(struct urb *urb)
{
        struct hwarc *hwarc = urb->context;
        struct usb_interface *usb_iface = hwarc->usb_iface;
        struct device *dev = &usb_iface->dev;
        int result;

        switch (result = urb->status) {
        case 0:
                uwb_rc_neh_grok(hwarc->uwb_rc, urb->transfer_buffer,
                                urb->actual_length);
                break;
        case -ECONNRESET:       /* Not an error, but a controlled situation; */
        case -ENOENT:           /* (we killed the URB)...so, no broadcast */
                goto out;
        case -ESHUTDOWN:        /* going away! */
                goto out;
        default:                /* On general errors, retry unless it gets ugly */
                if (edc_inc(&hwarc->neep_edc, EDC_MAX_ERRORS,
                            EDC_ERROR_TIMEFRAME))
                        goto error_exceeded;
                dev_err(dev, "NEEP: URB error %d\n", urb->status);
        }
        result = usb_submit_urb(urb, GFP_ATOMIC);
        if (result < 0) {
                dev_err(dev, "NEEP: Can't resubmit URB (%d) resetting device\n",
                        result);
                goto error;
        }
out:
        return;

error_exceeded:
        dev_err(dev, "NEEP: URB max acceptable errors "
                "exceeded, resetting device\n");
error:
        uwb_rc_neh_error(hwarc->uwb_rc, result);
        uwb_rc_reset_all(hwarc->uwb_rc);
        return;
}

static void hwarc_init(struct hwarc *hwarc)
{
        edc_init(&hwarc->neep_edc);
}

/**
 * Initialize the notification/event endpoint stuff
 *
 * Note this is effectively a parallel thread; it knows that
 * hwarc->uwb_rc always exists because the existence of a 'hwarc'
 * means that there is a reverence on the hwarc->uwb_rc (see
 * _probe()), and thus _neep_cb() can execute safely.
 */
static int hwarc_neep_init(struct uwb_rc *rc)
{
        struct hwarc *hwarc = rc->priv;
        struct usb_interface *iface = hwarc->usb_iface;
        struct usb_device *usb_dev = interface_to_usbdev(iface);
        struct device *dev = &iface->dev;
        int result;
        struct usb_endpoint_descriptor *epd;

        epd = &iface->cur_altsetting->endpoint[0].desc;
        hwarc->rd_buffer = (void *) __get_free_page(GFP_KERNEL);
        if (hwarc->rd_buffer == NULL) {
                dev_err(dev, "Unable to allocate notification's read buffer\n");
                goto error_rd_buffer;
        }
        hwarc->neep_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (hwarc->neep_urb == NULL) {
                dev_err(dev, "Unable to allocate notification URB\n");
                goto error_urb_alloc;
        }
        usb_fill_int_urb(hwarc->neep_urb, usb_dev,
                         usb_rcvintpipe(usb_dev, epd->bEndpointAddress),
                         hwarc->rd_buffer, PAGE_SIZE,
                         hwarc_neep_cb, hwarc, epd->bInterval);
        result = usb_submit_urb(hwarc->neep_urb, GFP_ATOMIC);
        if (result < 0) {
                dev_err(dev, "Cannot submit notification URB: %d\n", result);
                goto error_neep_submit;
        }
        return 0;

error_neep_submit:
        usb_free_urb(hwarc->neep_urb);
error_urb_alloc:
        free_page((unsigned long)hwarc->rd_buffer);
error_rd_buffer:
        return -ENOMEM;
}


/** Clean up all the notification endpoint resources */
static void hwarc_neep_release(struct uwb_rc *rc)
{
        struct hwarc *hwarc = rc->priv;

        usb_kill_urb(hwarc->neep_urb);
        usb_free_urb(hwarc->neep_urb);
        free_page((unsigned long)hwarc->rd_buffer);
}

/**
 * Get the version from class-specific descriptor
 *
 * NOTE: this descriptor comes with the big bundled configuration
 *       descriptor that includes the interfaces' and endpoints', so
 *       we just look for it in the cached copy kept by the USB stack.
 *
 * NOTE2: We convert LE fields to CPU order.
 */
static int hwarc_get_version(struct uwb_rc *rc)
{
        int result;

        struct hwarc *hwarc = rc->priv;
        struct uwb_rc_control_intf_class_desc *descr;
        struct device *dev = &rc->uwb_dev.dev;
        struct usb_device *usb_dev = hwarc->usb_dev;
        char *itr;
        struct usb_descriptor_header *hdr;
        size_t itr_size, actconfig_idx;
        u16 version;

        actconfig_idx = (usb_dev->actconfig - usb_dev->config) /
                sizeof(usb_dev->config[0]);
        itr = usb_dev->rawdescriptors[actconfig_idx];
        itr_size = le16_to_cpu(usb_dev->actconfig->desc.wTotalLength);
        while (itr_size >= sizeof(*hdr)) {
                hdr = (struct usb_descriptor_header *) itr;
                dev_dbg(dev, "Extra device descriptor: "
                        "type %02x/%u bytes @ %zu (%zu left)\n",
                        hdr->bDescriptorType, hdr->bLength,
                        (itr - usb_dev->rawdescriptors[actconfig_idx]),
                        itr_size);
                if (hdr->bDescriptorType == USB_DT_CS_RADIO_CONTROL)
                        goto found;
                itr += hdr->bLength;
                itr_size -= hdr->bLength;
        }
        dev_err(dev, "cannot find Radio Control Interface Class descriptor\n");
        return -ENODEV;

found:
        result = -EINVAL;
        if (hdr->bLength > itr_size) {  /* is it available? */
                dev_err(dev, "incomplete Radio Control Interface Class "
                        "descriptor (%zu bytes left, %u needed)\n",
                        itr_size, hdr->bLength);
                goto error;
        }
        if (hdr->bLength < sizeof(*descr)) {
                dev_err(dev, "short Radio Control Interface Class "
                        "descriptor\n");
                goto error;
        }
        descr = (struct uwb_rc_control_intf_class_desc *) hdr;
        /* Make LE fields CPU order */
        version = __le16_to_cpu(descr->bcdRCIVersion);
        if (version != 0x0100) {
                dev_err(dev, "Device reports protocol version 0x%04x. We "
                        "do not support that. \n", version);
                result = -EINVAL;
                goto error;
        }
        rc->version = version;
        dev_dbg(dev, "Device supports WUSB protocol version 0x%04x \n", rc->version);
        result = 0;
error:
        return result;
}

/*
 * By creating a 'uwb_rc', we have a reference on it -- that reference
 * is the one we drop when we disconnect.
 *
 * No need to switch altsettings; according to WUSB1.0[8.6.1.1], there
 * is only one altsetting allowed.
 */
static int hwarc_probe(struct usb_interface *iface,
                       const struct usb_device_id *id)
{
        int result;
        struct uwb_rc *uwb_rc;
        struct hwarc *hwarc;
        struct device *dev = &iface->dev;

        result = -ENOMEM;
        uwb_rc = uwb_rc_alloc();
        if (uwb_rc == NULL) {
                dev_err(dev, "unable to allocate RC instance\n");
                goto error_rc_alloc;
        }
        hwarc = kzalloc(sizeof(*hwarc), GFP_KERNEL);
        if (hwarc == NULL) {
                dev_err(dev, "unable to allocate HWA RC instance\n");
                goto error_alloc;
        }
        hwarc_init(hwarc);
        hwarc->usb_dev = usb_get_dev(interface_to_usbdev(iface));
        hwarc->usb_iface = usb_get_intf(iface);
        hwarc->uwb_rc = uwb_rc;

        uwb_rc->owner = THIS_MODULE;
        uwb_rc->start = hwarc_neep_init;
        uwb_rc->stop  = hwarc_neep_release;
        uwb_rc->cmd   = hwarc_cmd;
        uwb_rc->reset = hwarc_reset;
        if (id->driver_info & WUSB_QUIRK_WHCI_CMD_EVT) {
                uwb_rc->filter_cmd   = NULL;
                uwb_rc->filter_event = NULL;
        } else {
                uwb_rc->filter_cmd   = hwarc_filter_cmd;
                uwb_rc->filter_event = hwarc_filter_event;
        }

        result = uwb_rc_add(uwb_rc, dev, hwarc);
        if (result < 0)
                goto error_rc_add;
        result = hwarc_get_version(uwb_rc);
        if (result < 0) {
                dev_err(dev, "cannot retrieve version of RC \n");
                goto error_get_version;
        }
        usb_set_intfdata(iface, hwarc);
        return 0;

error_get_version:
        uwb_rc_rm(uwb_rc);
error_rc_add:
        usb_put_intf(iface);
        usb_put_dev(hwarc->usb_dev);
error_alloc:
        uwb_rc_put(uwb_rc);
error_rc_alloc:
        return result;
}

static void hwarc_disconnect(struct usb_interface *iface)
{
        struct hwarc *hwarc = usb_get_intfdata(iface);
        struct uwb_rc *uwb_rc = hwarc->uwb_rc;

        usb_set_intfdata(hwarc->usb_iface, NULL);
        uwb_rc_rm(uwb_rc);
        usb_put_intf(hwarc->usb_iface);
        usb_put_dev(hwarc->usb_dev);
        kfree(hwarc);
        uwb_rc_put(uwb_rc);     /* when creating the device, refcount = 1 */
}

static int hwarc_pre_reset(struct usb_interface *iface)
{
        struct hwarc *hwarc = usb_get_intfdata(iface);
        struct uwb_rc *uwb_rc = hwarc->uwb_rc;

        uwb_rc_pre_reset(uwb_rc);
        return 0;
}

static int hwarc_post_reset(struct usb_interface *iface)
{
        struct hwarc *hwarc = usb_get_intfdata(iface);
        struct uwb_rc *uwb_rc = hwarc->uwb_rc;

        uwb_rc_post_reset(uwb_rc);
        return 0;
}

/** USB device ID's that we handle */
static struct usb_device_id hwarc_id_table[] = {
        /* D-Link DUB-1210 */
        { USB_DEVICE_AND_INTERFACE_INFO(0x07d1, 0x3d02, 0xe0, 0x01, 0x02),
          .driver_info = WUSB_QUIRK_WHCI_CMD_EVT },
        /* Intel i1480 (using firmware 1.3PA2-20070828) */
        { USB_DEVICE_AND_INTERFACE_INFO(0x8086, 0x0c3b, 0xe0, 0x01, 0x02),
          .driver_info = WUSB_QUIRK_WHCI_CMD_EVT },
        /* Generic match for the Radio Control interface */
        { USB_INTERFACE_INFO(0xe0, 0x01, 0x02), },
        { },
};
MODULE_DEVICE_TABLE(usb, hwarc_id_table);

static struct usb_driver hwarc_driver = {
        .name =         "hwa-rc",
        .id_table =     hwarc_id_table,
        .probe =        hwarc_probe,
        .disconnect =   hwarc_disconnect,
        .pre_reset =    hwarc_pre_reset,
        .post_reset =   hwarc_post_reset,
};

static int __init hwarc_driver_init(void)
{
        return usb_register(&hwarc_driver);
}
module_init(hwarc_driver_init);

static void __exit hwarc_driver_exit(void)
{
        usb_deregister(&hwarc_driver);
}
module_exit(hwarc_driver_exit);

MODULE_AUTHOR("Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>");
MODULE_DESCRIPTION("Host Wireless Adapter Radio Control Driver");
MODULE_LICENSE("GPL");