[mirror_ubuntu-bionic-kernel.git] / drivers / net / wireless / rt2x00 / rt2x00queue.c

/*
        Copyright (C) 2010 Willow Garage <http://www.willowgarage.com>
        Copyright (C) 2004 - 2010 Ivo van Doorn <IvDoorn@gmail.com>
        Copyright (C) 2004 - 2009 Gertjan van Wingerde <gwingerde@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, write to the
        Free Software Foundation, Inc.,
        59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*
        Module: rt2x00lib
        Abstract: rt2x00 queue specific routines.
 */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>

#include "rt2x00.h"
#include "rt2x00lib.h"

struct sk_buff *rt2x00queue_alloc_rxskb(struct queue_entry *entry)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct sk_buff *skb;
        struct skb_frame_desc *skbdesc;
        unsigned int frame_size;
        unsigned int head_size = 0;
        unsigned int tail_size = 0;

        /*
         * The frame size includes descriptor size, because the
         * hardware directly receive the frame into the skbuffer.
         */
        frame_size = entry->queue->data_size + entry->queue->desc_size;

        /*
         * The payload should be aligned to a 4-byte boundary,
         * this means we need at least 3 bytes for moving the frame
         * into the correct offset.
         */
        head_size = 4;

        /*
         * For IV/EIV/ICV assembly we must make sure there is
         * at least 8 bytes bytes available in headroom for IV/EIV
         * and 8 bytes for ICV data as tailroon.
         */
        if (test_bit(CONFIG_SUPPORT_HW_CRYPTO, &rt2x00dev->flags)) {
                head_size += 8;
                tail_size += 8;
        }

        /*
         * Allocate skbuffer.
         */
        skb = dev_alloc_skb(frame_size + head_size + tail_size);
        if (!skb)
                return NULL;

        /*
         * Make sure we not have a frame with the requested bytes
         * available in the head and tail.
         */
        skb_reserve(skb, head_size);
        skb_put(skb, frame_size);

        /*
         * Populate skbdesc.
         */
        skbdesc = get_skb_frame_desc(skb);
        memset(skbdesc, 0, sizeof(*skbdesc));
        skbdesc->entry = entry;

        if (test_bit(DRIVER_REQUIRE_DMA, &rt2x00dev->flags)) {
                skbdesc->skb_dma = dma_map_single(rt2x00dev->dev,
                                                  skb->data,
                                                  skb->len,
                                                  DMA_FROM_DEVICE);
                skbdesc->flags |= SKBDESC_DMA_MAPPED_RX;
        }

        return skb;
}

void rt2x00queue_map_txskb(struct queue_entry *entry)
{
        struct device *dev = entry->queue->rt2x00dev->dev;
        struct skb_frame_desc *skbdesc = get_skb_frame_desc(entry->skb);

        skbdesc->skb_dma =
            dma_map_single(dev, entry->skb->data, entry->skb->len, DMA_TO_DEVICE);
        skbdesc->flags |= SKBDESC_DMA_MAPPED_TX;
}
EXPORT_SYMBOL_GPL(rt2x00queue_map_txskb);

void rt2x00queue_unmap_skb(struct queue_entry *entry)
{
        struct device *dev = entry->queue->rt2x00dev->dev;
        struct skb_frame_desc *skbdesc = get_skb_frame_desc(entry->skb);

        if (skbdesc->flags & SKBDESC_DMA_MAPPED_RX) {
                dma_unmap_single(dev, skbdesc->skb_dma, entry->skb->len,
                                 DMA_FROM_DEVICE);
                skbdesc->flags &= ~SKBDESC_DMA_MAPPED_RX;
        } else if (skbdesc->flags & SKBDESC_DMA_MAPPED_TX) {
                dma_unmap_single(dev, skbdesc->skb_dma, entry->skb->len,
                                 DMA_TO_DEVICE);
                skbdesc->flags &= ~SKBDESC_DMA_MAPPED_TX;
        }
}
EXPORT_SYMBOL_GPL(rt2x00queue_unmap_skb);

void rt2x00queue_free_skb(struct queue_entry *entry)
{
        if (!entry->skb)
                return;

        rt2x00queue_unmap_skb(entry);
        dev_kfree_skb_any(entry->skb);
        entry->skb = NULL;
}

void rt2x00queue_align_frame(struct sk_buff *skb)
{
        unsigned int frame_length = skb->len;
        unsigned int align = ALIGN_SIZE(skb, 0);

        if (!align)
                return;

        skb_push(skb, align);
        memmove(skb->data, skb->data + align, frame_length);
        skb_trim(skb, frame_length);
}

void rt2x00queue_align_payload(struct sk_buff *skb, unsigned int header_length)
{
        unsigned int frame_length = skb->len;
        unsigned int align = ALIGN_SIZE(skb, header_length);

        if (!align)
                return;

        skb_push(skb, align);
        memmove(skb->data, skb->data + align, frame_length);
        skb_trim(skb, frame_length);
}

void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
{
        unsigned int payload_length = skb->len - header_length;
        unsigned int header_align = ALIGN_SIZE(skb, 0);
        unsigned int payload_align = ALIGN_SIZE(skb, header_length);
        unsigned int l2pad = payload_length ? L2PAD_SIZE(header_length) : 0;

        /*
         * Adjust the header alignment if the payload needs to be moved more
         * than the header.
         */
        if (payload_align > header_align)
                header_align += 4;

        /* There is nothing to do if no alignment is needed */
        if (!header_align)
                return;

        /* Reserve the amount of space needed in front of the frame */
        skb_push(skb, header_align);

        /*
         * Move the header.
         */
        memmove(skb->data, skb->data + header_align, header_length);

        /* Move the payload, if present and if required */
        if (payload_length && payload_align)
                memmove(skb->data + header_length + l2pad,
                        skb->data + header_length + l2pad + payload_align,
                        payload_length);

        /* Trim the skb to the correct size */
        skb_trim(skb, header_length + l2pad + payload_length);
}

void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int header_length)
{
        /*
         * L2 padding is only present if the skb contains more than just the
         * IEEE 802.11 header.
         */
        unsigned int l2pad = (skb->len > header_length) ?
                                L2PAD_SIZE(header_length) : 0;

        if (!l2pad)
                return;

        memmove(skb->data + l2pad, skb->data, header_length);
        skb_pull(skb, l2pad);
}

static void rt2x00queue_create_tx_descriptor_seq(struct queue_entry *entry,
                                                 struct txentry_desc *txdesc)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)entry->skb->data;
        struct rt2x00_intf *intf = vif_to_intf(tx_info->control.vif);
        unsigned long irqflags;

        if (!(tx_info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ) ||
            unlikely(!tx_info->control.vif))
                return;

        /*
         * Hardware should insert sequence counter.
         * FIXME: We insert a software sequence counter first for
         * hardware that doesn't support hardware sequence counting.
         *
         * This is wrong because beacons are not getting sequence
         * numbers assigned properly.
         *
         * A secondary problem exists for drivers that cannot toggle
         * sequence counting per-frame, since those will override the
         * sequence counter given by mac80211.
         */
        spin_lock_irqsave(&intf->seqlock, irqflags);

        if (test_bit(ENTRY_TXD_FIRST_FRAGMENT, &txdesc->flags))
                intf->seqno += 0x10;
        hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG);
        hdr->seq_ctrl |= cpu_to_le16(intf->seqno);

        spin_unlock_irqrestore(&intf->seqlock, irqflags);

        __set_bit(ENTRY_TXD_GENERATE_SEQ, &txdesc->flags);
}

static void rt2x00queue_create_tx_descriptor_plcp(struct queue_entry *entry,
                                                  struct txentry_desc *txdesc,
                                                  const struct rt2x00_rate *hwrate)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
        struct ieee80211_tx_rate *txrate = &tx_info->control.rates[0];
        unsigned int data_length;
        unsigned int duration;
        unsigned int residual;

        /* Data length + CRC + Crypto overhead (IV/EIV/ICV/MIC) */
        data_length = entry->skb->len + 4;
        data_length += rt2x00crypto_tx_overhead(rt2x00dev, entry->skb);

        /*
         * PLCP setup
         * Length calculation depends on OFDM/CCK rate.
         */
        txdesc->signal = hwrate->plcp;
        txdesc->service = 0x04;

        if (hwrate->flags & DEV_RATE_OFDM) {
                txdesc->length_high = (data_length >> 6) & 0x3f;
                txdesc->length_low = data_length & 0x3f;
        } else {
                /*
                 * Convert length to microseconds.
                 */
                residual = GET_DURATION_RES(data_length, hwrate->bitrate);
                duration = GET_DURATION(data_length, hwrate->bitrate);

                if (residual != 0) {
                        duration++;

                        /*
                         * Check if we need to set the Length Extension
                         */
                        if (hwrate->bitrate == 110 && residual <= 30)
                                txdesc->service |= 0x80;
                }

                txdesc->length_high = (duration >> 8) & 0xff;
                txdesc->length_low = duration & 0xff;

                /*
                 * When preamble is enabled we should set the
                 * preamble bit for the signal.
                 */
                if (txrate->flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
                        txdesc->signal |= 0x08;
        }
}

static void rt2x00queue_create_tx_descriptor(struct queue_entry *entry,
                                             struct txentry_desc *txdesc)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)entry->skb->data;
        struct ieee80211_rate *rate =
            ieee80211_get_tx_rate(rt2x00dev->hw, tx_info);
        const struct rt2x00_rate *hwrate;

        memset(txdesc, 0, sizeof(*txdesc));

        /*
         * Header and frame information.
         */
        txdesc->length = entry->skb->len;
        txdesc->header_length = ieee80211_get_hdrlen_from_skb(entry->skb);

        /*
         * Check whether this frame is to be acked.
         */
        if (!(tx_info->flags & IEEE80211_TX_CTL_NO_ACK))
                __set_bit(ENTRY_TXD_ACK, &txdesc->flags);

        /*
         * Check if this is a RTS/CTS frame
         */
        if (ieee80211_is_rts(hdr->frame_control) ||
            ieee80211_is_cts(hdr->frame_control)) {
                __set_bit(ENTRY_TXD_BURST, &txdesc->flags);
                if (ieee80211_is_rts(hdr->frame_control))
                        __set_bit(ENTRY_TXD_RTS_FRAME, &txdesc->flags);
                else
                        __set_bit(ENTRY_TXD_CTS_FRAME, &txdesc->flags);
                if (tx_info->control.rts_cts_rate_idx >= 0)
                        rate =
                            ieee80211_get_rts_cts_rate(rt2x00dev->hw, tx_info);
        }

        /*
         * Determine retry information.
         */
        txdesc->retry_limit = tx_info->control.rates[0].count - 1;
        if (txdesc->retry_limit >= rt2x00dev->long_retry)
                __set_bit(ENTRY_TXD_RETRY_MODE, &txdesc->flags);

        /*
         * Check if more fragments are pending
         */
        if (ieee80211_has_morefrags(hdr->frame_control)) {
                __set_bit(ENTRY_TXD_BURST, &txdesc->flags);
                __set_bit(ENTRY_TXD_MORE_FRAG, &txdesc->flags);
        }

        /*
         * Check if more frames (!= fragments) are pending
         */
        if (tx_info->flags & IEEE80211_TX_CTL_MORE_FRAMES)
                __set_bit(ENTRY_TXD_BURST, &txdesc->flags);

        /*
         * Beacons and probe responses require the tsf timestamp
         * to be inserted into the frame, except for a frame that has been injected
         * through a monitor interface. This latter is needed for testing a
         * monitor interface.
         */
        if ((ieee80211_is_beacon(hdr->frame_control) ||
            ieee80211_is_probe_resp(hdr->frame_control)) &&
            (!(tx_info->flags & IEEE80211_TX_CTL_INJECTED)))
                __set_bit(ENTRY_TXD_REQ_TIMESTAMP, &txdesc->flags);

        /*
         * Determine with what IFS priority this frame should be send.
         * Set ifs to IFS_SIFS when the this is not the first fragment,
         * or this fragment came after RTS/CTS.
         */
        if ((tx_info->flags & IEEE80211_TX_CTL_FIRST_FRAGMENT) &&
            !test_bit(ENTRY_TXD_RTS_FRAME, &txdesc->flags)) {
                __set_bit(ENTRY_TXD_FIRST_FRAGMENT, &txdesc->flags);
                txdesc->ifs = IFS_BACKOFF;
        } else
                txdesc->ifs = IFS_SIFS;

        /*
         * Determine rate modulation.
         */
        hwrate = rt2x00_get_rate(rate->hw_value);
        txdesc->rate_mode = RATE_MODE_CCK;
        if (hwrate->flags & DEV_RATE_OFDM)
                txdesc->rate_mode = RATE_MODE_OFDM;

        /*
         * Apply TX descriptor handling by components
         */
        rt2x00crypto_create_tx_descriptor(entry, txdesc);
        rt2x00ht_create_tx_descriptor(entry, txdesc, hwrate);
        rt2x00queue_create_tx_descriptor_seq(entry, txdesc);
        rt2x00queue_create_tx_descriptor_plcp(entry, txdesc, hwrate);
}

static int rt2x00queue_write_tx_data(struct queue_entry *entry,
                                     struct txentry_desc *txdesc)
{
        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;

        /*
         * This should not happen, we already checked the entry
         * was ours. When the hardware disagrees there has been
         * a queue corruption!
         */
        if (unlikely(rt2x00dev->ops->lib->get_entry_state &&
                     rt2x00dev->ops->lib->get_entry_state(entry))) {
                ERROR(rt2x00dev,
                      "Corrupt queue %d, accessing entry which is not ours.\n"
                      "Please file bug report to %s.\n",
                      entry->queue->qid, DRV_PROJECT);
                return -EINVAL;
        }

        /*
         * Add the requested extra tx headroom in front of the skb.
         */
        skb_push(entry->skb, rt2x00dev->ops->extra_tx_headroom);
        memset(entry->skb->data, 0, rt2x00dev->ops->extra_tx_headroom);

        /*
         * Call the driver's write_tx_data function, if it exists.
         */
        if (rt2x00dev->ops->lib->write_tx_data)
                rt2x00dev->ops->lib->write_tx_data(entry, txdesc);

        /*
         * Map the skb to DMA.
         */
        if (test_bit(DRIVER_REQUIRE_DMA, &rt2x00dev->flags))
                rt2x00queue_map_txskb(entry);

        return 0;
}

static void rt2x00queue_write_tx_descriptor(struct queue_entry *entry,
                                            struct txentry_desc *txdesc)
{
        struct data_queue *queue = entry->queue;

        queue->rt2x00dev->ops->lib->write_tx_desc(entry, txdesc);

        /*
         * All processing on the frame has been completed, this means
         * it is now ready to be dumped to userspace through debugfs.
         */
        rt2x00debug_dump_frame(queue->rt2x00dev, DUMP_FRAME_TX, entry->skb);
}

static void rt2x00queue_kick_tx_queue(struct data_queue *queue,
                                      struct txentry_desc *txdesc)
{
        /*
         * Check if we need to kick the queue, there are however a few rules
         *      1) Don't kick unless this is the last in frame in a burst.
         *         When the burst flag is set, this frame is always followed
         *         by another frame which in some way are related to eachother.
         *         This is true for fragments, RTS or CTS-to-self frames.
         *      2) Rule 1 can be broken when the available entries
         *         in the queue are less then a certain threshold.
         */
        if (rt2x00queue_threshold(queue) ||
            !test_bit(ENTRY_TXD_BURST, &txdesc->flags))
                queue->rt2x00dev->ops->lib->kick_queue(queue);
}

int rt2x00queue_write_tx_frame(struct data_queue *queue, struct sk_buff *skb,
                               bool local)
{
        struct ieee80211_tx_info *tx_info;
        struct queue_entry *entry = rt2x00queue_get_entry(queue, Q_INDEX);
        struct txentry_desc txdesc;
        struct skb_frame_desc *skbdesc;
        u8 rate_idx, rate_flags;

        if (unlikely(rt2x00queue_full(queue)))
                return -ENOBUFS;

        if (unlikely(test_and_set_bit(ENTRY_OWNER_DEVICE_DATA,
                                      &entry->flags))) {
                ERROR(queue->rt2x00dev,
                      "Arrived at non-free entry in the non-full queue %d.\n"
                      "Please file bug report to %s.\n",
                      queue->qid, DRV_PROJECT);
                return -EINVAL;
        }

        /*
         * Copy all TX descriptor information into txdesc,
         * after that we are free to use the skb->cb array
         * for our information.
         */
        entry->skb = skb;
        rt2x00queue_create_tx_descriptor(entry, &txdesc);

        /*
         * All information is retrieved from the skb->cb array,
         * now we should claim ownership of the driver part of that
         * array, preserving the bitrate index and flags.
         */
        tx_info = IEEE80211_SKB_CB(skb);
        rate_idx = tx_info->control.rates[0].idx;
        rate_flags = tx_info->control.rates[0].flags;
        skbdesc = get_skb_frame_desc(skb);
        memset(skbdesc, 0, sizeof(*skbdesc));
        skbdesc->entry = entry;
        skbdesc->tx_rate_idx = rate_idx;
        skbdesc->tx_rate_flags = rate_flags;

        if (local)
                skbdesc->flags |= SKBDESC_NOT_MAC80211;

        /*
         * When hardware encryption is supported, and this frame
         * is to be encrypted, we should strip the IV/EIV data from
         * the frame so we can provide it to the driver separately.
         */
        if (test_bit(ENTRY_TXD_ENCRYPT, &txdesc.flags) &&
            !test_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc.flags)) {
                if (test_bit(DRIVER_REQUIRE_COPY_IV, &queue->rt2x00dev->flags))
                        rt2x00crypto_tx_copy_iv(skb, &txdesc);
                else
                        rt2x00crypto_tx_remove_iv(skb, &txdesc);
        }

        /*
         * When DMA allocation is required we should guarentee to the
         * driver that the DMA is aligned to a 4-byte boundary.
         * However some drivers require L2 padding to pad the payload
         * rather then the header. This could be a requirement for
         * PCI and USB devices, while header alignment only is valid
         * for PCI devices.
         */
        if (test_bit(DRIVER_REQUIRE_L2PAD, &queue->rt2x00dev->flags))
                rt2x00queue_insert_l2pad(entry->skb, txdesc.header_length);
        else if (test_bit(DRIVER_REQUIRE_DMA, &queue->rt2x00dev->flags))
                rt2x00queue_align_frame(entry->skb);

        /*
         * It could be possible that the queue was corrupted and this
         * call failed. Since we always return NETDEV_TX_OK to mac80211,
         * this frame will simply be dropped.
         */
        if (unlikely(rt2x00queue_write_tx_data(entry, &txdesc))) {
                clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags);
                entry->skb = NULL;
                return -EIO;
        }

        set_bit(ENTRY_DATA_PENDING, &entry->flags);

        rt2x00queue_index_inc(queue, Q_INDEX);
        rt2x00queue_write_tx_descriptor(entry, &txdesc);
        rt2x00queue_kick_tx_queue(queue, &txdesc);

        return 0;
}

int rt2x00queue_update_beacon(struct rt2x00_dev *rt2x00dev,
                              struct ieee80211_vif *vif,
                              const bool enable_beacon)
{
        struct rt2x00_intf *intf = vif_to_intf(vif);
        struct skb_frame_desc *skbdesc;
        struct txentry_desc txdesc;

        if (unlikely(!intf->beacon))
                return -ENOBUFS;

        mutex_lock(&intf->beacon_skb_mutex);

        /*
         * Clean up the beacon skb.
         */
        rt2x00queue_free_skb(intf->beacon);

        if (!enable_beacon) {
                rt2x00queue_stop_queue(intf->beacon->queue);
                mutex_unlock(&intf->beacon_skb_mutex);
                return 0;
        }

        intf->beacon->skb = ieee80211_beacon_get(rt2x00dev->hw, vif);
        if (!intf->beacon->skb) {
                mutex_unlock(&intf->beacon_skb_mutex);
                return -ENOMEM;
        }

        /*
         * Copy all TX descriptor information into txdesc,
         * after that we are free to use the skb->cb array
         * for our information.
         */
        rt2x00queue_create_tx_descriptor(intf->beacon, &txdesc);

        /*
         * Fill in skb descriptor
         */
        skbdesc = get_skb_frame_desc(intf->beacon->skb);
        memset(skbdesc, 0, sizeof(*skbdesc));
        skbdesc->entry = intf->beacon;

        /*
         * Send beacon to hardware and enable beacon genaration..
         */
        rt2x00dev->ops->lib->write_beacon(intf->beacon, &txdesc);

        mutex_unlock(&intf->beacon_skb_mutex);

        return 0;
}

void rt2x00queue_for_each_entry(struct data_queue *queue,
                                enum queue_index start,
                                enum queue_index end,
                                void (*fn)(struct queue_entry *entry))
{
        unsigned long irqflags;
        unsigned int index_start;
        unsigned int index_end;
        unsigned int i;

        if (unlikely(start >= Q_INDEX_MAX || end >= Q_INDEX_MAX)) {
                ERROR(queue->rt2x00dev,
                      "Entry requested from invalid index range (%d - %d)\n",
                      start, end);
                return;
        }

        /*
         * Only protect the range we are going to loop over,
         * if during our loop a extra entry is set to pending
         * it should not be kicked during this run, since it
         * is part of another TX operation.
         */
        spin_lock_irqsave(&queue->index_lock, irqflags);
        index_start = queue->index[start];
        index_end = queue->index[end];
        spin_unlock_irqrestore(&queue->index_lock, irqflags);

        /*
         * Start from the TX done pointer, this guarentees that we will
         * send out all frames in the correct order.
         */
        if (index_start < index_end) {
                for (i = index_start; i < index_end; i++)
                        fn(&queue->entries[i]);
        } else {
                for (i = index_start; i < queue->limit; i++)
                        fn(&queue->entries[i]);

                for (i = 0; i < index_end; i++)
                        fn(&queue->entries[i]);
        }
}
EXPORT_SYMBOL_GPL(rt2x00queue_for_each_entry);

struct data_queue *rt2x00queue_get_queue(struct rt2x00_dev *rt2x00dev,
                                         const enum data_queue_qid queue)
{
        int atim = test_bit(DRIVER_REQUIRE_ATIM_QUEUE, &rt2x00dev->flags);

        if (queue == QID_RX)
                return rt2x00dev->rx;

        if (queue < rt2x00dev->ops->tx_queues && rt2x00dev->tx)
                return &rt2x00dev->tx[queue];

        if (!rt2x00dev->bcn)
                return NULL;

        if (queue == QID_BEACON)
                return &rt2x00dev->bcn[0];
        else if (queue == QID_ATIM && atim)
                return &rt2x00dev->bcn[1];

        return NULL;
}
EXPORT_SYMBOL_GPL(rt2x00queue_get_queue);

struct queue_entry *rt2x00queue_get_entry(struct data_queue *queue,
                                          enum queue_index index)
{
        struct queue_entry *entry;
        unsigned long irqflags;

        if (unlikely(index >= Q_INDEX_MAX)) {
                ERROR(queue->rt2x00dev,
                      "Entry requested from invalid index type (%d)\n", index);
                return NULL;
        }

        spin_lock_irqsave(&queue->index_lock, irqflags);

        entry = &queue->entries[queue->index[index]];

        spin_unlock_irqrestore(&queue->index_lock, irqflags);

        return entry;
}
EXPORT_SYMBOL_GPL(rt2x00queue_get_entry);

void rt2x00queue_index_inc(struct data_queue *queue, enum queue_index index)
{
        unsigned long irqflags;

        if (unlikely(index >= Q_INDEX_MAX)) {
                ERROR(queue->rt2x00dev,
                      "Index change on invalid index type (%d)\n", index);
                return;
        }

        spin_lock_irqsave(&queue->index_lock, irqflags);

        queue->index[index]++;
        if (queue->index[index] >= queue->limit)
                queue->index[index] = 0;

        queue->last_action[index] = jiffies;

        if (index == Q_INDEX) {
                queue->length++;
        } else if (index == Q_INDEX_DONE) {
                queue->length--;
                queue->count++;
        }

        spin_unlock_irqrestore(&queue->index_lock, irqflags);
}

void rt2x00queue_pause_queue(struct data_queue *queue)
{
        if (!test_bit(DEVICE_STATE_PRESENT, &queue->rt2x00dev->flags) ||
            !test_bit(QUEUE_STARTED, &queue->flags) ||
            test_and_set_bit(QUEUE_PAUSED, &queue->flags))
                return;

        switch (queue->qid) {
        case QID_AC_BE:
        case QID_AC_BK:
        case QID_AC_VI:
        case QID_AC_VO:
                /*
                 * For TX queues, we have to disable the queue
                 * inside mac80211.
                 */
                ieee80211_stop_queue(queue->rt2x00dev->hw, queue->qid);
                break;
        default:
                break;
        }
}
EXPORT_SYMBOL_GPL(rt2x00queue_pause_queue);

void rt2x00queue_unpause_queue(struct data_queue *queue)
{
        if (!test_bit(DEVICE_STATE_PRESENT, &queue->rt2x00dev->flags) ||
            !test_bit(QUEUE_STARTED, &queue->flags) ||
            !test_and_clear_bit(QUEUE_PAUSED, &queue->flags))
                return;

        switch (queue->qid) {
        case QID_AC_BE:
        case QID_AC_BK:
        case QID_AC_VI:
        case QID_AC_VO:
                /*
                 * For TX queues, we have to enable the queue
                 * inside mac80211.
                 */
                ieee80211_wake_queue(queue->rt2x00dev->hw, queue->qid);
                break;
        case QID_RX:
                /*
                 * For RX we need to kick the queue now in order to
                 * receive frames.
                 */
                queue->rt2x00dev->ops->lib->kick_queue(queue);
        default:
                break;
        }
}
EXPORT_SYMBOL_GPL(rt2x00queue_unpause_queue);

void rt2x00queue_start_queue(struct data_queue *queue)
{
        mutex_lock(&queue->status_lock);

        if (!test_bit(DEVICE_STATE_PRESENT, &queue->rt2x00dev->flags) ||
            test_and_set_bit(QUEUE_STARTED, &queue->flags)) {
                mutex_unlock(&queue->status_lock);
                return;
        }

        set_bit(QUEUE_PAUSED, &queue->flags);

        queue->rt2x00dev->ops->lib->start_queue(queue);

        rt2x00queue_unpause_queue(queue);

        mutex_unlock(&queue->status_lock);
}
EXPORT_SYMBOL_GPL(rt2x00queue_start_queue);

void rt2x00queue_stop_queue(struct data_queue *queue)
{
        mutex_lock(&queue->status_lock);

        if (!test_and_clear_bit(QUEUE_STARTED, &queue->flags)) {
                mutex_unlock(&queue->status_lock);
                return;
        }

        rt2x00queue_pause_queue(queue);

        queue->rt2x00dev->ops->lib->stop_queue(queue);

        mutex_unlock(&queue->status_lock);
}
EXPORT_SYMBOL_GPL(rt2x00queue_stop_queue);

void rt2x00queue_flush_queue(struct data_queue *queue, bool drop)
{
        unsigned int i;
        bool started;
        bool tx_queue =
                (queue->qid == QID_AC_BE) ||
                (queue->qid == QID_AC_BK) ||
                (queue->qid == QID_AC_VI) ||
                (queue->qid == QID_AC_VO);

        mutex_lock(&queue->status_lock);

        /*
         * If the queue has been started, we must stop it temporarily
         * to prevent any new frames to be queued on the device. If
         * we are not dropping the pending frames, the queue must
         * only be stopped in the software and not the hardware,
         * otherwise the queue will never become empty on its own.
         */
        started = test_bit(QUEUE_STARTED, &queue->flags);
        if (started) {
                /*
                 * Pause the queue
                 */
                rt2x00queue_pause_queue(queue);

                /*
                 * If we are not supposed to drop any pending
                 * frames, this means we must force a start (=kick)
                 * to the queue to make sure the hardware will
                 * start transmitting.
                 */
                if (!drop && tx_queue)
                        queue->rt2x00dev->ops->lib->kick_queue(queue);
        }

        /*
         * Check if driver supports flushing, we can only guarentee
         * full support for flushing if the driver is able
         * to cancel all pending frames (drop = true).
         */
        if (drop && queue->rt2x00dev->ops->lib->flush_queue)
                queue->rt2x00dev->ops->lib->flush_queue(queue);

        /*
         * When we don't want to drop any frames, or when
         * the driver doesn't fully flush the queue correcly,
         * we must wait for the queue to become empty.
         */
        for (i = 0; !rt2x00queue_empty(queue) && i < 100; i++)
                msleep(10);

        /*
         * The queue flush has failed...
         */
        if (unlikely(!rt2x00queue_empty(queue)))
                WARNING(queue->rt2x00dev, "Queue %d failed to flush", queue->qid);

        /*
         * Restore the queue to the previous status
         */
        if (started)
                rt2x00queue_unpause_queue(queue);

        mutex_unlock(&queue->status_lock);
}
EXPORT_SYMBOL_GPL(rt2x00queue_flush_queue);

void rt2x00queue_start_queues(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;

        /*
         * rt2x00queue_start_queue will call ieee80211_wake_queue
         * for each queue after is has been properly initialized.
         */
        tx_queue_for_each(rt2x00dev, queue)
                rt2x00queue_start_queue(queue);

        rt2x00queue_start_queue(rt2x00dev->rx);
}
EXPORT_SYMBOL_GPL(rt2x00queue_start_queues);

void rt2x00queue_stop_queues(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;

        /*
         * rt2x00queue_stop_queue will call ieee80211_stop_queue
         * as well, but we are completely shutting doing everything
         * now, so it is much safer to stop all TX queues at once,
         * and use rt2x00queue_stop_queue for cleaning up.
         */
        ieee80211_stop_queues(rt2x00dev->hw);

        tx_queue_for_each(rt2x00dev, queue)
                rt2x00queue_stop_queue(queue);

        rt2x00queue_stop_queue(rt2x00dev->rx);
}
EXPORT_SYMBOL_GPL(rt2x00queue_stop_queues);

void rt2x00queue_flush_queues(struct rt2x00_dev *rt2x00dev, bool drop)
{
        struct data_queue *queue;

        tx_queue_for_each(rt2x00dev, queue)
                rt2x00queue_flush_queue(queue, drop);

        rt2x00queue_flush_queue(rt2x00dev->rx, drop);
}
EXPORT_SYMBOL_GPL(rt2x00queue_flush_queues);

static void rt2x00queue_reset(struct data_queue *queue)
{
        unsigned long irqflags;
        unsigned int i;

        spin_lock_irqsave(&queue->index_lock, irqflags);

        queue->count = 0;
        queue->length = 0;

        for (i = 0; i < Q_INDEX_MAX; i++) {
                queue->index[i] = 0;
                queue->last_action[i] = jiffies;
        }

        spin_unlock_irqrestore(&queue->index_lock, irqflags);
}

void rt2x00queue_init_queues(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;
        unsigned int i;

        queue_for_each(rt2x00dev, queue) {
                rt2x00queue_reset(queue);

                for (i = 0; i < queue->limit; i++) {
                        rt2x00dev->ops->lib->clear_entry(&queue->entries[i]);
                        if (queue->qid == QID_RX)
                                rt2x00queue_index_inc(queue, Q_INDEX);
                }
        }
}

static int rt2x00queue_alloc_entries(struct data_queue *queue,
                                     const struct data_queue_desc *qdesc)
{
        struct queue_entry *entries;
        unsigned int entry_size;
        unsigned int i;

        rt2x00queue_reset(queue);

        queue->limit = qdesc->entry_num;
        queue->threshold = DIV_ROUND_UP(qdesc->entry_num, 10);
        queue->data_size = qdesc->data_size;
        queue->desc_size = qdesc->desc_size;

        /*
         * Allocate all queue entries.
         */
        entry_size = sizeof(*entries) + qdesc->priv_size;
        entries = kcalloc(queue->limit, entry_size, GFP_KERNEL);
        if (!entries)
                return -ENOMEM;

#define QUEUE_ENTRY_PRIV_OFFSET(__base, __index, __limit, __esize, __psize) \
        (((char *)(__base)) + ((__limit) * (__esize)) + \
            ((__index) * (__psize)))

        for (i = 0; i < queue->limit; i++) {
                entries[i].flags = 0;
                entries[i].queue = queue;
                entries[i].skb = NULL;
                entries[i].entry_idx = i;
                entries[i].priv_data =
                    QUEUE_ENTRY_PRIV_OFFSET(entries, i, queue->limit,
                                            sizeof(*entries), qdesc->priv_size);
        }

#undef QUEUE_ENTRY_PRIV_OFFSET

        queue->entries = entries;

        return 0;
}

static void rt2x00queue_free_skbs(struct data_queue *queue)
{
        unsigned int i;

        if (!queue->entries)
                return;

        for (i = 0; i < queue->limit; i++) {
                rt2x00queue_free_skb(&queue->entries[i]);
        }
}

static int rt2x00queue_alloc_rxskbs(struct data_queue *queue)
{
        unsigned int i;
        struct sk_buff *skb;

        for (i = 0; i < queue->limit; i++) {
                skb = rt2x00queue_alloc_rxskb(&queue->entries[i]);
                if (!skb)
                        return -ENOMEM;
                queue->entries[i].skb = skb;
        }

        return 0;
}

int rt2x00queue_initialize(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;
        int status;

        status = rt2x00queue_alloc_entries(rt2x00dev->rx, rt2x00dev->ops->rx);
        if (status)
                goto exit;

        tx_queue_for_each(rt2x00dev, queue) {
                status = rt2x00queue_alloc_entries(queue, rt2x00dev->ops->tx);
                if (status)
                        goto exit;
        }

        status = rt2x00queue_alloc_entries(rt2x00dev->bcn, rt2x00dev->ops->bcn);
        if (status)
                goto exit;

        if (test_bit(DRIVER_REQUIRE_ATIM_QUEUE, &rt2x00dev->flags)) {
                status = rt2x00queue_alloc_entries(&rt2x00dev->bcn[1],
                                                   rt2x00dev->ops->atim);
                if (status)
                        goto exit;
        }

        status = rt2x00queue_alloc_rxskbs(rt2x00dev->rx);
        if (status)
                goto exit;

        return 0;

exit:
        ERROR(rt2x00dev, "Queue entries allocation failed.\n");

        rt2x00queue_uninitialize(rt2x00dev);

        return status;
}

void rt2x00queue_uninitialize(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;

        rt2x00queue_free_skbs(rt2x00dev->rx);

        queue_for_each(rt2x00dev, queue) {
                kfree(queue->entries);
                queue->entries = NULL;
        }
}

static void rt2x00queue_init(struct rt2x00_dev *rt2x00dev,
                             struct data_queue *queue, enum data_queue_qid qid)
{
        mutex_init(&queue->status_lock);
        spin_lock_init(&queue->index_lock);

        queue->rt2x00dev = rt2x00dev;
        queue->qid = qid;
        queue->txop = 0;
        queue->aifs = 2;
        queue->cw_min = 5;
        queue->cw_max = 10;
}

int rt2x00queue_allocate(struct rt2x00_dev *rt2x00dev)
{
        struct data_queue *queue;
        enum data_queue_qid qid;
        unsigned int req_atim =
            !!test_bit(DRIVER_REQUIRE_ATIM_QUEUE, &rt2x00dev->flags);

        /*
         * We need the following queues:
         * RX: 1
         * TX: ops->tx_queues
         * Beacon: 1
         * Atim: 1 (if required)
         */
        rt2x00dev->data_queues = 2 + rt2x00dev->ops->tx_queues + req_atim;

        queue = kcalloc(rt2x00dev->data_queues, sizeof(*queue), GFP_KERNEL);
        if (!queue) {
                ERROR(rt2x00dev, "Queue allocation failed.\n");
                return -ENOMEM;
        }

        /*
         * Initialize pointers
         */
        rt2x00dev->rx = queue;
        rt2x00dev->tx = &queue[1];
        rt2x00dev->bcn = &queue[1 + rt2x00dev->ops->tx_queues];

        /*
         * Initialize queue parameters.
         * RX: qid = QID_RX
         * TX: qid = QID_AC_BE + index
         * TX: cw_min: 2^5 = 32.
         * TX: cw_max: 2^10 = 1024.
         * BCN: qid = QID_BEACON
         * ATIM: qid = QID_ATIM
         */
        rt2x00queue_init(rt2x00dev, rt2x00dev->rx, QID_RX);

        qid = QID_AC_BE;
        tx_queue_for_each(rt2x00dev, queue)
                rt2x00queue_init(rt2x00dev, queue, qid++);

        rt2x00queue_init(rt2x00dev, &rt2x00dev->bcn[0], QID_BEACON);
        if (req_atim)
                rt2x00queue_init(rt2x00dev, &rt2x00dev->bcn[1], QID_ATIM);

        return 0;
}

void rt2x00queue_free(struct rt2x00_dev *rt2x00dev)
{
        kfree(rt2x00dev->rx);
        rt2x00dev->rx = NULL;
        rt2x00dev->tx = NULL;
        rt2x00dev->bcn = NULL;
}