mwl8k: Initiate BA sessions

Specifically, handle ampdu_action and attempt to start a BA
session on receiving the first qos packet from mac80211 for
transmission to a HT sta.  While the BA session is being created,
all the packets belonging to that stream will be dropped to
prevent sequence number mismatch at the recipient.

Contains contributions from:
Yogesh Powar <yogeshp@marvell.com>
Pradeep Nemavat <pnemavat@marvell.com>
Brian Cavagnolo <brian@cozybit.com>

Signed-off-by: Brian Cavagnolo <brian@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 187 insertions, 7 deletions

diff --git a/drivers/net/wireless/mwl8k.c b/drivers/net/wireless/mwl8k.c
index dcd4508b1fd..ec1190ab0f8 100644
--- a/drivers/net/wireless/mwl8k.c
+++ b/drivers/net/wireless/mwl8k.c
@@ -1577,7 +1577,8 @@ mwl8k_txq_reclaim(struct ieee80211_hw *hw, int index, int limit, int force)
                 processed++;
         }
 
-        if (processed && priv->radio_on && !mutex_is_locked(&priv->fw_mutex))
+        if (index < MWL8K_TX_WMM_QUEUES && processed && priv->radio_on &&
+            !mutex_is_locked(&priv->fw_mutex))
                 ieee80211_wake_queue(hw, index);
 
         return processed;
@@ -1677,6 +1678,7 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
         struct mwl8k_priv *priv = hw->priv;
         struct ieee80211_tx_info *tx_info;
         struct mwl8k_vif *mwl8k_vif;
+        struct ieee80211_sta *sta;
         struct ieee80211_hdr *wh;
         struct mwl8k_tx_queue *txq;
         struct mwl8k_tx_desc *tx;
@@ -1684,6 +1686,10 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
         u32 txstatus;
         u8 txdatarate;
         u16 qos;
+        int txpriority;
+        u8 tid = 0;
+        struct mwl8k_ampdu_stream *stream = NULL;
+        bool start_ba_session = false;
 
         wh = (struct ieee80211_hdr *)skb->data;
         if (ieee80211_is_data_qos(wh->frame_control))
@@ -1699,6 +1705,7 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
         wh = &((struct mwl8k_dma_data *)skb->data)->wh;
 
         tx_info = IEEE80211_SKB_CB(skb);
+        sta = tx_info->control.sta;
         mwl8k_vif = MWL8K_VIF(tx_info->control.vif);
 
         if (tx_info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ) {
@@ -1726,12 +1733,70 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
                         qos |= MWL8K_QOS_ACK_POLICY_NORMAL;
         }
 
+        txpriority = index;
+
+        if (ieee80211_is_data_qos(wh->frame_control) &&
+            skb->protocol != cpu_to_be16(ETH_P_PAE) &&
+            sta->ht_cap.ht_supported && priv->ap_fw) {
+                tid = qos & 0xf;
+                spin_lock(&priv->stream_lock);
+                stream = mwl8k_lookup_stream(hw, sta->addr, tid);
+                if (stream != NULL) {
+                        if (stream->state == AMPDU_STREAM_ACTIVE) {
+                                txpriority = stream->txq_idx;
+                                index = stream->txq_idx;
+                        } else if (stream->state == AMPDU_STREAM_NEW) {
+                                /* We get here if the driver sends us packets
+                                 * after we've initiated a stream, but before
+                                 * our ampdu_action routine has been called
+                                 * with IEEE80211_AMPDU_TX_START to get the SSN
+                                 * for the ADDBA request.  So this packet can
+                                 * go out with no risk of sequence number
+                                 * mismatch.  No special handling is required.
+                                 */
+                        } else {
+                                /* Drop packets that would go out after the
+                                 * ADDBA request was sent but before the ADDBA
+                                 * response is received.  If we don't do this,
+                                 * the recipient would probably receive it
+                                 * after the ADDBA request with SSN 0.  This
+                                 * will cause the recipient's BA receive window
+                                 * to shift, which would cause the subsequent
+                                 * packets in the BA stream to be discarded.
+                                 * mac80211 queues our packets for us in this
+                                 * case, so this is really just a safety check.
+                                 */
+                                wiphy_warn(hw->wiphy,
+                                           "Cannot send packet while ADDBA "
+                                           "dialog is underway.\n");
+                                spin_unlock(&priv->stream_lock);
+                                dev_kfree_skb(skb);
+                                return;
+                        }
+                } else {
+                        /* Defer calling mwl8k_start_stream so that the current
+                         * skb can go out before the ADDBA request.  This
+                         * prevents sequence number mismatch at the recepient
+                         * as described above.
+                         */
+                        stream = mwl8k_add_stream(hw, sta, tid);
+                        if (stream != NULL)
+                                start_ba_session = true;
+                }
+                spin_unlock(&priv->stream_lock);
+        }
+
         dma = pci_map_single(priv->pdev, skb->data,
                                 skb->len, PCI_DMA_TODEVICE);
 
         if (pci_dma_mapping_error(priv->pdev, dma)) {
                 wiphy_debug(hw->wiphy,
                             "failed to dma map skb, dropping TX frame.\n");
+                if (start_ba_session) {
+                        spin_lock(&priv->stream_lock);
+                        mwl8k_remove_stream(hw, stream);
+                        spin_unlock(&priv->stream_lock);
+                }
                 dev_kfree_skb(skb);
                 return;
         }
@@ -1740,12 +1805,22 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
 
         txq = priv->txq + index;
 
+        if (index >= MWL8K_TX_WMM_QUEUES && txq->len >= MWL8K_TX_DESCS) {
+                /* This is the case in which the tx packet is destined for an
+                 * AMPDU queue and that AMPDU queue is full.  Because we don't
+                 * start and stop the AMPDU queues, we must drop these packets.
+                 */
+                dev_kfree_skb(skb);
+                spin_unlock_bh(&priv->tx_lock);
+                return;
+        }
+
         BUG_ON(txq->skb[txq->tail] != NULL);
         txq->skb[txq->tail] = skb;
 
         tx = txq->txd + txq->tail;
         tx->data_rate = txdatarate;
-        tx->tx_priority = index;
+        tx->tx_priority = txpriority;
         tx->qos_control = cpu_to_le16(qos);
         tx->pkt_phys_addr = cpu_to_le32(dma);
         tx->pkt_len = cpu_to_le16(skb->len);
@@ -1764,12 +1839,20 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
         if (txq->tail == MWL8K_TX_DESCS)
                 txq->tail = 0;
 
-        if (txq->head == txq->tail)
+        if (txq->head == txq->tail && index < MWL8K_TX_WMM_QUEUES)
                 ieee80211_stop_queue(hw, index);
 
         mwl8k_tx_start(priv);
 
         spin_unlock_bh(&priv->tx_lock);
+
+        /* Initiate the ampdu session here */
+        if (start_ba_session) {
+                spin_lock(&priv->stream_lock);
+                if (mwl8k_start_stream(hw, stream))
+                        mwl8k_remove_stream(hw, stream);
+                spin_unlock(&priv->stream_lock);
+        }
 }
 
 
@@ -4632,21 +4715,118 @@ static int mwl8k_get_survey(struct ieee80211_hw *hw, int idx,
         return 0;
 }
 
+#define MAX_AMPDU_ATTEMPTS 5
+
 static int
 mwl8k_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
                    enum ieee80211_ampdu_mlme_action action,
                    struct ieee80211_sta *sta, u16 tid, u16 *ssn,
                    u8 buf_size)
 {
+
+        int i, rc = 0;
+        struct mwl8k_priv *priv = hw->priv;
+        struct mwl8k_ampdu_stream *stream;
+        u8 *addr = sta->addr;
+
+        if (!(hw->flags & IEEE80211_HW_AMPDU_AGGREGATION))
+                return -ENOTSUPP;
+
+        spin_lock(&priv->stream_lock);
+        stream = mwl8k_lookup_stream(hw, addr, tid);
+
         switch (action) {
         case IEEE80211_AMPDU_RX_START:
         case IEEE80211_AMPDU_RX_STOP:
-                if (!(hw->flags & IEEE80211_HW_AMPDU_AGGREGATION))
-                        return -ENOTSUPP;
-                return 0;
+                break;
+        case IEEE80211_AMPDU_TX_START:
+                /* By the time we get here the hw queues may contain outgoing
+                 * packets for this RA/TID that are not part of this BA
+                 * session.  The hw will assign sequence numbers to these
+                 * packets as they go out.  So if we query the hw for its next
+                 * sequence number and use that for the SSN here, it may end up
+                 * being wrong, which will lead to sequence number mismatch at
+                 * the recipient.  To avoid this, we reset the sequence number
+                 * to O for the first MPDU in this BA stream.
+                 */
+                *ssn = 0;
+                if (stream == NULL) {
+                        /* This means that somebody outside this driver called
+                         * ieee80211_start_tx_ba_session.  This is unexpected
+                         * because we do our own rate control.  Just warn and
+                         * move on.
+                         */
+                        wiphy_warn(hw->wiphy, "Unexpected call to %s.  "
+                                   "Proceeding anyway.\n", __func__);
+                        stream = mwl8k_add_stream(hw, sta, tid);
+                }
+                if (stream == NULL) {
+                        wiphy_debug(hw->wiphy, "no free AMPDU streams\n");
+                        rc = -EBUSY;
+                        break;
+                }
+                stream->state = AMPDU_STREAM_IN_PROGRESS;
+
+                /* Release the lock before we do the time consuming stuff */
+                spin_unlock(&priv->stream_lock);
+                for (i = 0; i < MAX_AMPDU_ATTEMPTS; i++) {
+                        rc = mwl8k_check_ba(hw, stream);
+
+                        if (!rc)
+                                break;
+                        /*
+                         * HW queues take time to be flushed, give them
+                         * sufficient time
+                         */
+
+                        msleep(1000);
+                }
+                spin_lock(&priv->stream_lock);
+                if (rc) {
+                        wiphy_err(hw->wiphy, "Stream for tid %d busy after %d"
+                                " attempts\n", tid, MAX_AMPDU_ATTEMPTS);
+                        mwl8k_remove_stream(hw, stream);
+                        rc = -EBUSY;
+                        break;
+                }
+                ieee80211_start_tx_ba_cb_irqsafe(vif, addr, tid);
+                break;
+        case IEEE80211_AMPDU_TX_STOP:
+                if (stream == NULL)
+                        break;
+                if (stream->state == AMPDU_STREAM_ACTIVE) {
+                        spin_unlock(&priv->stream_lock);
+                        mwl8k_destroy_ba(hw, stream);
+                        spin_lock(&priv->stream_lock);
+                }
+                mwl8k_remove_stream(hw, stream);
+                ieee80211_stop_tx_ba_cb_irqsafe(vif, addr, tid);
+                break;
+        case IEEE80211_AMPDU_TX_OPERATIONAL:
+                BUG_ON(stream == NULL);
+                BUG_ON(stream->state != AMPDU_STREAM_IN_PROGRESS);
+                spin_unlock(&priv->stream_lock);
+                rc = mwl8k_create_ba(hw, stream, buf_size);
+                spin_lock(&priv->stream_lock);
+                if (!rc)
+                        stream->state = AMPDU_STREAM_ACTIVE;
+                else {
+                        spin_unlock(&priv->stream_lock);
+                        mwl8k_destroy_ba(hw, stream);
+                        spin_lock(&priv->stream_lock);
+                        wiphy_debug(hw->wiphy,
+                                "Failed adding stream for sta %pM tid %d\n",
+                                addr, tid);
+                        mwl8k_remove_stream(hw, stream);
+                }
+                break;
+
         default:
-                return -ENOTSUPP;
+                rc = -ENOTSUPP;
         }
+
+        spin_unlock(&priv->stream_lock);
+        return rc;
 }
 
 static const struct ieee80211_ops mwl8k_ops = {