/*
  	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 pipe =
  	    (requesttype == USB_VENDOR_REQUEST_IN) ?
  	    usb_rcvctrlpipe(usb_dev, 0) : usb_sndctrlpipe(usb_dev, 0);
  	unsigned long expire = jiffies + msecs_to_jiffies(timeout);
  
  	if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
  		return -ENODEV;
  
  	do {
  		status = usb_control_msg(usb_dev, pipe, request, requesttype,
  					 value, offset, buffer, buffer_length,
  					 timeout / 2);
  		if (status >= 0)
  			return 0;
  
  		if (status == -ENODEV) {
  			/* Device has disappeared. */
  			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
  			break;
  		}
  	} while (time_before(jiffies, expire));
  
  	rt2x00_err(rt2x00dev,
  		   "Vendor Request 0x%02x failed for offset 0x%04x with error %d
  ",
  		   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
  ");
  		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)
  {
  	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, REGISTER_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_USB_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
  ",
  		   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 (!rt2x00_has_cap_flag(rt2x00dev, REQUIRE_TXSTATUS_FIFO) ||
  	    !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
  ");
  		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) &&
  	    (rt2x00_has_cap_flag(rt2x00dev, REQUIRE_BEACON_GUARD)))
  		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
  ",
  		    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
  ");
  		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 ||
  	    !rt2x00_has_cap_flag(rt2x00dev, REQUIRE_BEACON_GUARD))
  		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 ||
  	    !rt2x00_has_cap_flag(rt2x00dev, REQUIRE_BEACON_GUARD))
  		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
  ");
  
  	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
  ");
  		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");