/*
        Copyright (C) 2010 Willow Garage <http://www.willowgarage.com>
        Copyright (C) 2004 - 2010 Ivo van Doorn <IvDoorn@gmail.com>
        <http://rt2x00.serialmonkey.com>

        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, see <http://www.gnu.org/licenses/>.
 */

/*
        Module: rt2x00usb
        Abstract: rt2x00 generic usb device routines.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/bug.h>

#include "rt2x00.h"
#include "rt2x00usb.h"

/*
 * Interfacing with the HW.
 */
int rt2x00usb_vendor_request(struct rt2x00_dev *rt2x00dev,
                             const u8 request, const u8 requesttype,
                             const u16 offset, const u16 value,
                             void *buffer, const u16 buffer_length,
                             const int timeout)
{
        struct usb_device *usb_dev = to_usb_device_intf(rt2x00dev->dev);
        int status;
        unsigned int i;
        unsigned int pipe =
            (requesttype == USB_VENDOR_REQUEST_IN) ?
            usb_rcvctrlpipe(usb_dev, 0) : usb_sndctrlpipe(usb_dev, 0);

        if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
                return -ENODEV;

        for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
                status = usb_control_msg(usb_dev, pipe, request, requesttype,
                                         value, offset, buffer, buffer_length,
                                         timeout);
                if (status >= 0)
                        return 0;

                /*
                 * Check for errors
                 * -ENODEV: Device has disappeared, no point continuing.
                 * All other errors: Try again.
                 */
                else if (status == -ENODEV) {
                        clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
                        break;
                }
        }

        /* If the port is powered down, we get a -EPROTO error, and this
         * leads to a endless loop. So just say that the device is gone.
         */
        if (status == -EPROTO)
                clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);

        rt2x00_err(rt2x00dev,
                   "Vendor Request 0x%02x failed for offset 0x%04x with error %d\n",
                   request, offset, status);

        return status;
}
EXPORT_SYMBOL_GPL(rt2x00usb_vendor_request);

int rt2x00usb_vendor_req_buff_lock(struct rt2x00_dev *rt2x00dev,
                                   const u8 request, const u8 requesttype,
                                   const u16 offset, void *buffer,
                                   const u16 buffer_length, const int timeout)
{
        int status;

        BUG_ON(!mutex_is_locked(&rt2x00dev->csr_mutex));

        /*
         * Check for Cache availability.
         */
        if (unlikely(!rt2x00dev->csr.cache || buffer_length > CSR_CACHE_SIZE)) {
                rt2x00_err(rt2x00dev, "CSR cache not available\n");
                return -ENOMEM;
        }

        if (requesttype == USB_VENDOR_REQUEST_OUT)
                memcpy(rt2x00dev->csr.cache, buffer, buffer_length);

        status = rt2x00usb_vendor_request(rt2x00dev, request, requesttype,
                                          offset, 0, rt2x00dev->csr.cache,
                                          buffer_length, timeout);

        if (!status && requesttype == USB_VENDOR_REQUEST_IN)
                memcpy(buffer, rt2x00dev->csr.cache, buffer_length);

        return status;
}
EXPORT_SYMBOL_GPL(rt2x00usb_vendor_req_buff_lock);

int rt2x00usb_vendor_request_buff(struct rt2x00_dev *rt2x00dev,
                                  const u8 request, const u8 requesttype,
                                  const u16 offset, void *buffer,
                                  const u16 buffer_length, const int timeout)
{
        int status = 0;
        unsigned char *tb;
        u16 off, len, bsize;

        mutex_lock(&rt2x00dev->csr_mutex);

        tb  = (char *)buffer;
        off = offset;
        len = buffer_length;
        while (len && !status) {
                bsize = min_t(u16, CSR_CACHE_SIZE, len);
                status = rt2x00usb_vendor_req_buff_lock(rt2x00dev, request,
                                                        requesttype, off, tb,
                                                        bsize, timeout);

                tb  += bsize;
                len -= bsize;
                off += bsize;
        }

        mutex_unlock(&rt2x00dev->csr_mutex);

        return status;
}
EXPORT_SYMBOL_GPL(rt2x00usb_vendor_request_buff);

int rt2x00usb_regbusy_read(struct rt2x00_dev *rt2x00dev,
                           const unsigned int offset,
                           const struct rt2x00_field32 field,
                           u32 *reg)
{
        unsigned int i;

        if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
                return -ENODEV;

        for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
                rt2x00usb_register_read_lock(rt2x00dev, offset, reg);
                if (!rt2x00_get_field32(*reg, field))
                        return 1;
                udelay(REGISTER_BUSY_DELAY);
        }

        rt2x00_err(rt2x00dev, "Indirect register access failed: offset=0x%.08x, value=0x%.08x\n",
                   offset, *reg);
        *reg = ~0;

        return 0;
}
EXPORT_SYMBOL_GPL(rt2x00usb_regbusy_read);


struct rt2x00_async_read_data {
        __le32 reg;
        struct usb_ctrlrequest cr;
        struct rt2x00_dev *rt2x00dev;
        bool (*callback)(struct rt2x00_dev *, int, u32);
};

static void rt2x00usb_register_read_async_cb(struct urb *urb)
{
        struct rt2x00_async_read_data *rd = urb->context;
        if (rd->callback(rd->rt2x00dev, urb->status, le32_to_cpu(rd->reg))) {
                if (usb_submit_urb(urb, GFP_ATOMIC) < 0)
                        kfree(rd);
        } else
                kfree(rd);
}

void rt2x00usb_register_read_async(struct rt2x00_dev *rt2x00dev,
                                   const unsigned int offset,
                                   bool (*callback)(struct rt2x00_dev*, int, u32))
{
        struct usb_device *usb_dev = to_usb_device_intf(rt2x00dev->dev);
        struct urb *urb;
        struct rt2x00_async_read_data *rd;

        rd = kmalloc(sizeof(*rd), GFP_ATOMIC);
        if (!rd)
                return;

        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb) {
                kfree(rd);
                return;
        }

        rd->rt2x00dev = rt2x00dev;
        rd->callback = callback;
        rd->cr.bRequestType = USB_VENDOR_REQUEST_IN;
        rd->cr.bRequest = USB_MULTI_READ;
        rd->cr.wValue = 0;
        rd->cr.wIndex = cpu_to_le16(offset);
        rd->cr.wLength = cpu_to_le16(sizeof(u32));

        usb_fill_control_urb(urb, usb_dev, usb_rcvctrlpipe(usb_dev, 0),
                             (unsigned char *)(&rd->cr), &rd->reg, sizeof(rd->reg),
                             rt2x00usb_register_read_async_cb, rd);
        if (usb_submit_urb(urb, GFP_ATOMIC) < 0)
                kfree(rd);
        usb_free_urb(urb);
}
EXPORT_SYMBOL_GPL(rt2x00usb_register_read_async);

/*
 * TX data handlers.
 */
static void rt2x00usb_work_txdone_entry(struct queue_entry *entry)
{
        /*
         * If the transfer to hardware succeeded, it does not mean the
         * frame was send out correctly. It only means the frame
         * was successfully pushed to the hardware, we have no
         * way to determine the transmission status right now.
         * (Only indirectly by looking at the failed TX counters
         * in the register).
         */
        if (test_bit(ENTRY_DATA_IO_FAILED, &entry->flags))
                rt2x00lib_txdone_noinfo(entry, TXDONE_FAILURE);
        else
                rt2x00lib_txdone_noinfo(entry, TXDONE_UNKNOWN);
}

static void rt2x00usb_work_txdone(struct work_struct *work)
{
        struct rt2x00_dev *rt2x00dev =
            container_of(work, struct rt2x00_dev, txdone_work);
        struct data_queue *queue;
        struct queue_entry *entry;

        tx_queue_for_each(rt2x00dev, queue) {
                while (!rt2x00queue_empty(queue)) {
                        entry = rt2x00queue_get_entry(queue, Q_INDEX_DONE);

                        if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
                            !test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
                                break;

                        rt2x00usb_work_txdone_entry(entry);
                }
        }
}

static void rt2x00usb_interrupt_txdone(struct urb *urb)
{
        struct queue_entry *entry = (struct queue_entry *)urb->context;
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;

        if (!test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
                return;
        /*
         * Check if the frame was correctly uploaded
         */
        if (urb->status)
                set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
        /*
         * Report the frame as DMA done
         */
        rt2x00lib_dmadone(entry);

        if (rt2x00dev->ops->lib->tx_dma_done)
                rt2x00dev->ops->lib->tx_dma_done(entry);
        /*
         * Schedule the delayed work for reading the TX status
         * from the device.
         */
        if (!test_bit(REQUIRE_TXSTATUS_FIFO, &rt2x00dev->cap_flags) ||
            !kfifo_is_empty(&rt2x00dev->txstatus_fifo))
                queue_work(rt2x00dev->workqueue, &rt2x00dev->txdone_work);
}

static bool rt2x00usb_kick_tx_entry(struct queue_entry *entry, void *data)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct usb_device *usb_dev = to_usb_device_intf(rt2x00dev->dev);
        struct queue_entry_priv_usb *entry_priv = entry->priv_data;
        u32 length;
        int status;

        if (!test_and_clear_bit(ENTRY_DATA_PENDING, &entry->flags) ||
            test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
                return false;

        /*
         * USB devices require certain padding at the end of each frame
         * and urb. Those paddings are not included in skbs. Pass entry
         * to the driver to determine what the overall length should be.
         */
        length = rt2x00dev->ops->lib->get_tx_data_len(entry);

        status = skb_padto(entry->skb, length);
        if (unlikely(status)) {
                /* TODO: report something more appropriate than IO_FAILED. */
                rt2x00_warn(rt2x00dev, "TX SKB padding error, out of memory\n");
                set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
                rt2x00lib_dmadone(entry);

                return false;
        }

        usb_fill_bulk_urb(entry_priv->urb, usb_dev,
                          usb_sndbulkpipe(usb_dev, entry->queue->usb_endpoint),
                          entry->skb->data, length,
                          rt2x00usb_interrupt_txdone, entry);

        status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
        if (status) {
                if (status == -ENODEV)
                        clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
                set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
                rt2x00lib_dmadone(entry);
        }

        return false;
}

/*
 * RX data handlers.
 */
static void rt2x00usb_work_rxdone(struct work_struct *work)
{
        struct rt2x00_dev *rt2x00dev =
            container_of(work, struct rt2x00_dev, rxdone_work);
        struct queue_entry *entry;
        struct skb_frame_desc *skbdesc;
        u8 rxd[32];

        while (!rt2x00queue_empty(rt2x00dev->rx)) {
                entry = rt2x00queue_get_entry(rt2x00dev->rx, Q_INDEX_DONE);

                if (test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
                    !test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
                        break;

                /*
                 * Fill in desc fields of the skb descriptor
                 */
                skbdesc = get_skb_frame_desc(entry->skb);
                skbdesc->desc = rxd;
                skbdesc->desc_len = entry->queue->desc_size;

                /*
                 * Send the frame to rt2x00lib for further processing.
                 */
                rt2x00lib_rxdone(entry, GFP_KERNEL);
        }
}

static void rt2x00usb_interrupt_rxdone(struct urb *urb)
{
        struct queue_entry *entry = (struct queue_entry *)urb->context;
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;

        if (!test_and_clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
                return;

        /*
         * Report the frame as DMA done
         */
        rt2x00lib_dmadone(entry);

        /*
         * Check if the received data is simply too small
         * to be actually valid, or if the urb is signaling
         * a problem.
         */
        if (urb->actual_length < entry->queue->desc_size || urb->status)
                set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);

        /*
         * Schedule the delayed work for reading the RX status
         * from the device.
         */
        queue_work(rt2x00dev->workqueue, &rt2x00dev->rxdone_work);
}

static bool rt2x00usb_kick_rx_entry(struct queue_entry *entry, void *data)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct usb_device *usb_dev = to_usb_device_intf(rt2x00dev->dev);
        struct queue_entry_priv_usb *entry_priv = entry->priv_data;
        int status;

        if (test_and_set_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags) ||
            test_bit(ENTRY_DATA_STATUS_PENDING, &entry->flags))
                return false;

        rt2x00lib_dmastart(entry);

        usb_fill_bulk_urb(entry_priv->urb, usb_dev,
                          usb_rcvbulkpipe(usb_dev, entry->queue->usb_endpoint),
                          entry->skb->data, entry->skb->len,
                          rt2x00usb_interrupt_rxdone, entry);

        status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
        if (status) {
                if (status == -ENODEV)
                        clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
                set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
                rt2x00lib_dmadone(entry);
        }

        return false;
}

void rt2x00usb_kick_queue(struct data_queue *queue)
{
        switch (queue->qid) {
        case QID_AC_VO:
        case QID_AC_VI:
        case QID_AC_BE:
        case QID_AC_BK:
                if (!rt2x00queue_empty(queue))
                        rt2x00queue_for_each_entry(queue,
                                                   Q_INDEX_DONE,
                                                   Q_INDEX,
                                                   NULL,
                                                   rt2x00usb_kick_tx_entry);
                break;
        case QID_RX:
                if (!rt2x00queue_full(queue))
                        rt2x00queue_for_each_entry(queue,
                                                   Q_INDEX,
                                                   Q_INDEX_DONE,
                                                   NULL,
                                                   rt2x00usb_kick_rx_entry);
                break;
        default:
                break;
        }
}
EXPORT_SYMBOL_GPL(rt2x00usb_kick_queue);

static bool rt2x00usb_flush_entry(struct queue_entry *entry, void *data)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct queue_entry_priv_usb *entry_priv = entry->priv_data;
        struct queue_entry_priv_usb_bcn *bcn_priv = entry->priv_data;

        if (!test_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
                return false;

        usb_kill_urb(entry_priv->urb);

        /*
         * Kill guardian urb (if required by driver).
         */
        if ((entry->queue->qid == QID_BEACON) &&
            (test_bit(REQUIRE_BEACON_GUARD, &rt2x00dev->cap_flags)))
                usb_kill_urb(bcn_priv->guardian_urb);

        return false;
}

void rt2x00usb_flush_queue(struct data_queue *queue, bool drop)
{
        struct work_struct *completion;
        unsigned int i;

        if (drop)
                rt2x00queue_for_each_entry(queue, Q_INDEX_DONE, Q_INDEX, NULL,
                                           rt2x00usb_flush_entry);

        /*
         * Obtain the queue completion handler
         */
        switch (queue->qid) {
        case QID_AC_VO:
        case QID_AC_VI:
        case QID_AC_BE:
        case QID_AC_BK:
                completion = &queue->rt2x00dev->txdone_work;
                break;
        case QID_RX:
                completion = &queue->rt2x00dev->rxdone_work;
                break;
        default:
                return;
        }

        for (i = 0; i < 10; i++) {
                /*
                 * Check if the driver is already done, otherwise we
                 * have to sleep a little while to give the driver/hw
                 * the oppurtunity to complete interrupt process itself.
                 */
                if (rt2x00queue_empty(queue))
                        break;

                /*
                 * Schedule the completion handler manually, when this
                 * worker function runs, it should cleanup the queue.
                 */
                queue_work(queue->rt2x00dev->workqueue, completion);

                /*
                 * Wait for a little while to give the driver
                 * the oppurtunity to recover itself.
                 */
                msleep(10);
        }
}
EXPORT_SYMBOL_GPL(rt2x00usb_flush_queue);

static void rt2x00usb_watchdog_tx_dma(struct data_queue *queue)
{
        rt2x00_warn(queue->rt2x00dev, "TX queue %d DMA timed out, invoke forced forced reset\n",
                    queue->qid);

        rt2x00queue_stop_queue(queue);
        rt2x00queue_flush_queue(queue, true);
        rt2x00queue_start_queue(queue);
}

static int rt2x00usb_dma_timeout(struct data_queue *queue)
{
        struct queue_entry *entry;

        entry = rt2x00queue_get_entry(queue, Q_INDEX_DMA_DONE);
        return rt2x00queue_dma_timeout(entry);
}

void rt2x00usb_watchdog(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;

        tx_queue_for_each(rt2x00dev, queue) {
                if (!rt2x00queue_empty(queue)) {
                        if (rt2x00usb_dma_timeout(queue))
                                rt2x00usb_watchdog_tx_dma(queue);
                }
        }
}
EXPORT_SYMBOL_GPL(rt2x00usb_watchdog);

/*
 * Radio handlers
 */
void rt2x00usb_disable_radio(struct rt2x00_dev *rt2x00dev)
{
        rt2x00usb_vendor_request_sw(rt2x00dev, USB_RX_CONTROL, 0, 0,
                                    REGISTER_TIMEOUT);
}
EXPORT_SYMBOL_GPL(rt2x00usb_disable_radio);

/*
 * Device initialization handlers.
 */
void rt2x00usb_clear_entry(struct queue_entry *entry)
{
        entry->flags = 0;

        if (entry->queue->qid == QID_RX)
                rt2x00usb_kick_rx_entry(entry, NULL);
}
EXPORT_SYMBOL_GPL(rt2x00usb_clear_entry);

static void rt2x00usb_assign_endpoint(struct data_queue *queue,
                                      struct usb_endpoint_descriptor *ep_desc)
{
        struct usb_device *usb_dev = to_usb_device_intf(queue->rt2x00dev->dev);
        int pipe;

        queue->usb_endpoint = usb_endpoint_num(ep_desc);

        if (queue->qid == QID_RX) {
                pipe = usb_rcvbulkpipe(usb_dev, queue->usb_endpoint);
                queue->usb_maxpacket = usb_maxpacket(usb_dev, pipe, 0);
        } else {
                pipe = usb_sndbulkpipe(usb_dev, queue->usb_endpoint);
                queue->usb_maxpacket = usb_maxpacket(usb_dev, pipe, 1);
        }

        if (!queue->usb_maxpacket)
                queue->usb_maxpacket = 1;
}

static int rt2x00usb_find_endpoints(struct rt2x00_dev *rt2x00dev)
{
        struct usb_interface *intf = to_usb_interface(rt2x00dev->dev);
        struct usb_host_interface *intf_desc = intf->cur_altsetting;
        struct usb_endpoint_descriptor *ep_desc;
        struct data_queue *queue = rt2x00dev->tx;
        struct usb_endpoint_descriptor *tx_ep_desc = NULL;
        unsigned int i;

        /*
         * Walk through all available endpoints to search for "bulk in"
         * and "bulk out" endpoints. When we find such endpoints collect
         * the information we need from the descriptor and assign it
         * to the queue.
         */
        for (i = 0; i < intf_desc->desc.bNumEndpoints; i++) {
                ep_desc = &intf_desc->endpoint[i].desc;

                if (usb_endpoint_is_bulk_in(ep_desc)) {
                        rt2x00usb_assign_endpoint(rt2x00dev->rx, ep_desc);
                } else if (usb_endpoint_is_bulk_out(ep_desc) &&
                           (queue != queue_end(rt2x00dev))) {
                        rt2x00usb_assign_endpoint(queue, ep_desc);
                        queue = queue_next(queue);

                        tx_ep_desc = ep_desc;
                }
        }

        /*
         * At least 1 endpoint for RX and 1 endpoint for TX must be available.
         */
        if (!rt2x00dev->rx->usb_endpoint || !rt2x00dev->tx->usb_endpoint) {
                rt2x00_err(rt2x00dev, "Bulk-in/Bulk-out endpoints not found\n");
                return -EPIPE;
        }

        /*
         * It might be possible not all queues have a dedicated endpoint.
         * Loop through all TX queues and copy the endpoint information
         * which we have gathered from already assigned endpoints.
         */
        txall_queue_for_each(rt2x00dev, queue) {
                if (!queue->usb_endpoint)
                        rt2x00usb_assign_endpoint(queue, tx_ep_desc);
        }

        return 0;
}

static int rt2x00usb_alloc_entries(struct data_queue *queue)
{
        struct rt2x00_dev *rt2x00dev = queue->rt2x00dev;
        struct queue_entry_priv_usb *entry_priv;
        struct queue_entry_priv_usb_bcn *bcn_priv;
        unsigned int i;

        for (i = 0; i < queue->limit; i++) {
                entry_priv = queue->entries[i].priv_data;
                entry_priv->urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!entry_priv->urb)
                        return -ENOMEM;
        }

        /*
         * If this is not the beacon queue or
         * no guardian byte was required for the beacon,
         * then we are done.
         */
        if (queue->qid != QID_BEACON ||
            !test_bit(REQUIRE_BEACON_GUARD, &rt2x00dev->cap_flags))
                return 0;

        for (i = 0; i < queue->limit; i++) {
                bcn_priv = queue->entries[i].priv_data;
                bcn_priv->guardian_urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!bcn_priv->guardian_urb)
                        return -ENOMEM;
        }

        return 0;
}

static void rt2x00usb_free_entries(struct data_queue *queue)
{
        struct rt2x00_dev *rt2x00dev = queue->rt2x00dev;
        struct queue_entry_priv_usb *entry_priv;
        struct queue_entry_priv_usb_bcn *bcn_priv;
        unsigned int i;

        if (!queue->entries)
                return;

        for (i = 0; i < queue->limit; i++) {
                entry_priv = queue->entries[i].priv_data;
                usb_kill_urb(entry_priv->urb);
                usb_free_urb(entry_priv->urb);
        }

        /*
         * If this is not the beacon queue or
         * no guardian byte was required for the beacon,
         * then we are done.
         */
        if (queue->qid != QID_BEACON ||
            !test_bit(REQUIRE_BEACON_GUARD, &rt2x00dev->cap_flags))
                return;

        for (i = 0; i < queue->limit; i++) {
                bcn_priv = queue->entries[i].priv_data;
                usb_kill_urb(bcn_priv->guardian_urb);
                usb_free_urb(bcn_priv->guardian_urb);
        }
}

int rt2x00usb_initialize(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;
        int status;

        /*
         * Find endpoints for each queue
         */
        status = rt2x00usb_find_endpoints(rt2x00dev);
        if (status)
                goto exit;

        /*
         * Allocate DMA
         */
        queue_for_each(rt2x00dev, queue) {
                status = rt2x00usb_alloc_entries(queue);
                if (status)
                        goto exit;
        }

        return 0;

exit:
        rt2x00usb_uninitialize(rt2x00dev);

        return status;
}
EXPORT_SYMBOL_GPL(rt2x00usb_initialize);

void rt2x00usb_uninitialize(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;

        queue_for_each(rt2x00dev, queue)
                rt2x00usb_free_entries(queue);
}
EXPORT_SYMBOL_GPL(rt2x00usb_uninitialize);

/*
 * USB driver handlers.
 */
static void rt2x00usb_free_reg(struct rt2x00_dev *rt2x00dev)
{
        kfree(rt2x00dev->rf);
        rt2x00dev->rf = NULL;

        kfree(rt2x00dev->eeprom);
        rt2x00dev->eeprom = NULL;

        kfree(rt2x00dev->csr.cache);
        rt2x00dev->csr.cache = NULL;
}

static int rt2x00usb_alloc_reg(struct rt2x00_dev *rt2x00dev)
{
        rt2x00dev->csr.cache = kzalloc(CSR_CACHE_SIZE, GFP_KERNEL);
        if (!rt2x00dev->csr.cache)
                goto exit;

        rt2x00dev->eeprom = kzalloc(rt2x00dev->ops->eeprom_size, GFP_KERNEL);
        if (!rt2x00dev->eeprom)
                goto exit;

        rt2x00dev->rf = kzalloc(rt2x00dev->ops->rf_size, GFP_KERNEL);
        if (!rt2x00dev->rf)
                goto exit;

        return 0;

exit:
        rt2x00_probe_err("Failed to allocate registers\n");

        rt2x00usb_free_reg(rt2x00dev);

        return -ENOMEM;
}

int rt2x00usb_probe(struct usb_interface *usb_intf,
                    const struct rt2x00_ops *ops)
{
        struct usb_device *usb_dev = interface_to_usbdev(usb_intf);
        struct ieee80211_hw *hw;
        struct rt2x00_dev *rt2x00dev;
        int retval;

        usb_dev = usb_get_dev(usb_dev);
        usb_reset_device(usb_dev);

        hw = ieee80211_alloc_hw(sizeof(struct rt2x00_dev), ops->hw);
        if (!hw) {
                rt2x00_probe_err("Failed to allocate hardware\n");
                retval = -ENOMEM;
                goto exit_put_device;
        }

        usb_set_intfdata(usb_intf, hw);

        rt2x00dev = hw->priv;
        rt2x00dev->dev = &usb_intf->dev;
        rt2x00dev->ops = ops;
        rt2x00dev->hw = hw;

        rt2x00_set_chip_intf(rt2x00dev, RT2X00_CHIP_INTF_USB);

        INIT_WORK(&rt2x00dev->rxdone_work, rt2x00usb_work_rxdone);
        INIT_WORK(&rt2x00dev->txdone_work, rt2x00usb_work_txdone);
        hrtimer_init(&rt2x00dev->txstatus_timer, CLOCK_MONOTONIC,
                     HRTIMER_MODE_REL);

        retval = rt2x00usb_alloc_reg(rt2x00dev);
        if (retval)
                goto exit_free_device;

        retval = rt2x00lib_probe_dev(rt2x00dev);
        if (retval)
                goto exit_free_reg;

        return 0;

exit_free_reg:
        rt2x00usb_free_reg(rt2x00dev);

exit_free_device:
        ieee80211_free_hw(hw);

exit_put_device:
        usb_put_dev(usb_dev);

        usb_set_intfdata(usb_intf, NULL);

        return retval;
}
EXPORT_SYMBOL_GPL(rt2x00usb_probe);

void rt2x00usb_disconnect(struct usb_interface *usb_intf)
{
        struct ieee80211_hw *hw = usb_get_intfdata(usb_intf);
        struct rt2x00_dev *rt2x00dev = hw->priv;

        /*
         * Free all allocated data.
         */
        rt2x00lib_remove_dev(rt2x00dev);
        rt2x00usb_free_reg(rt2x00dev);
        ieee80211_free_hw(hw);

        /*
         * Free the USB device data.
         */
        usb_set_intfdata(usb_intf, NULL);
        usb_put_dev(interface_to_usbdev(usb_intf));
}
EXPORT_SYMBOL_GPL(rt2x00usb_disconnect);

#ifdef CONFIG_PM
int rt2x00usb_suspend(struct usb_interface *usb_intf, pm_message_t state)
{
        struct ieee80211_hw *hw = usb_get_intfdata(usb_intf);
        struct rt2x00_dev *rt2x00dev = hw->priv;

        return rt2x00lib_suspend(rt2x00dev, state);
}
EXPORT_SYMBOL_GPL(rt2x00usb_suspend);

int rt2x00usb_resume(struct usb_interface *usb_intf)
{
        struct ieee80211_hw *hw = usb_get_intfdata(usb_intf);
        struct rt2x00_dev *rt2x00dev = hw->priv;

        return rt2x00lib_resume(rt2x00dev);
}
EXPORT_SYMBOL_GPL(rt2x00usb_resume);
#endif /* CONFIG_PM */

/*
 * rt2x00usb module information.
 */
MODULE_AUTHOR(DRV_PROJECT);
MODULE_VERSION(DRV_VERSION);
MODULE_DESCRIPTION("rt2x00 usb library");
MODULE_LICENSE("GPL");