drivers/net/wireless/mwifiex/uap_txrx.c - kernel/msm-4.9 - Gitiles

 /*
  * Marvell Wireless LAN device driver: AP TX and RX data handling
  *
  * Copyright (C) 2012, Marvell International Ltd.
  *
  * This software file (the "File") is distributed by Marvell International
  * Ltd. under the terms of the GNU General Public License Version 2, June 1991
  * (the "License").  You may use, redistribute and/or modify this File in
  * accordance with the terms and conditions of the License, a copy of which
  * is available by writing to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or on the
  * worldwide web at http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
  *
  * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
  * ARE EXPRESSLY DISCLAIMED.  The License provides additional details about
  * this warranty disclaimer.
  */

 #include "decl.h"
 #include "ioctl.h"
 #include "main.h"
 #include "wmm.h"
 #include "11n_aggr.h"
 #include "11n_rxreorder.h"

 static void mwifiex_uap_queue_bridged_pkt(struct mwifiex_private *priv,
 					 struct sk_buff *skb)
 {
 	struct mwifiex_adapter *adapter = priv->adapter;
 	struct uap_rxpd *uap_rx_pd;
 	struct rx_packet_hdr *rx_pkt_hdr;
 	struct sk_buff *new_skb;
 	struct mwifiex_txinfo *tx_info;
 	int hdr_chop;
 	struct timeval tv;
 	u8 rfc1042_eth_hdr[ETH_ALEN] = { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };

 	uap_rx_pd = (struct uap_rxpd *)(skb->data);
 	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

 	if ((atomic_read(&adapter->pending_bridged_pkts) >=
 					     MWIFIEX_BRIDGED_PKTS_THRESHOLD)) {
 		dev_err(priv->adapter->dev,
 			"Tx: Bridge packet limit reached. Drop packet!\n");
 		kfree_skb(skb);
 		return;
 	}

 	if (!memcmp(&rx_pkt_hdr->rfc1042_hdr,
 		    rfc1042_eth_hdr, sizeof(rfc1042_eth_hdr)))
 		/* Chop off the rxpd + the excess memory from
 		 * 802.2/llc/snap header that was removed.
 		 */
 		hdr_chop = (u8 *)eth_hdr - (u8 *)uap_rx_pd;
 	else
 		/* Chop off the rxpd */
 		hdr_chop = (u8 *)&rx_pkt_hdr->eth803_hdr - (u8 *)uap_rx_pd;

 	/* Chop off the leading header bytes so the it points
 	 * to the start of either the reconstructed EthII frame
 	 * or the 802.2/llc/snap frame.
 	 */
 	skb_pull(skb, hdr_chop);

 	if (skb_headroom(skb) < MWIFIEX_MIN_DATA_HEADER_LEN) {
 		dev_dbg(priv->adapter->dev,
 			"data: Tx: insufficient skb headroom %d\n",
 			skb_headroom(skb));
 		/* Insufficient skb headroom - allocate a new skb */
 		new_skb =
 			skb_realloc_headroom(skb, MWIFIEX_MIN_DATA_HEADER_LEN);
 		if (unlikely(!new_skb)) {
 			dev_err(priv->adapter->dev,
 				"Tx: cannot allocate new_skb\n");
 			kfree_skb(skb);
 			priv->stats.tx_dropped++;
 			return;
 		}

 		kfree_skb(skb);
 		skb = new_skb;
 		dev_dbg(priv->adapter->dev, "info: new skb headroom %d\n",
 			skb_headroom(skb));
 	}

 	tx_info = MWIFIEX_SKB_TXCB(skb);
 	tx_info->bss_num = priv->bss_num;
 	tx_info->bss_type = priv->bss_type;
 	tx_info->flags |= MWIFIEX_BUF_FLAG_BRIDGED_PKT;

 	do_gettimeofday(&tv);
 	skb->tstamp = timeval_to_ktime(tv);
 	mwifiex_wmm_add_buf_txqueue(priv, skb);
 	atomic_inc(&adapter->tx_pending);
 	atomic_inc(&adapter->pending_bridged_pkts);

 	if ((atomic_read(&adapter->tx_pending) >= MAX_TX_PENDING)) {
 		mwifiex_set_trans_start(priv->netdev);
 		mwifiex_stop_net_dev_queue(priv->netdev, priv->adapter);
 	}
 	return;
 }

 /*
  * This function contains logic for AP packet forwarding.
  *
  * If a packet is multicast/broadcast, it is sent to kernel/upper layer
  * as well as queued back to AP TX queue so that it can be sent to other
  * associated stations.
  * If a packet is unicast and RA is present in associated station list,
  * it is again requeued into AP TX queue.
  * If a packet is unicast and RA is not in associated station list,
  * packet is forwarded to kernel to handle routing logic.
  */
 int mwifiex_handle_uap_rx_forward(struct mwifiex_private *priv,
 				  struct sk_buff *skb)
 {
 	struct mwifiex_adapter *adapter = priv->adapter;
 	struct uap_rxpd *uap_rx_pd;
 	struct rx_packet_hdr *rx_pkt_hdr;
 	u8 ra[ETH_ALEN];
 	struct sk_buff *skb_uap;

 	uap_rx_pd = (struct uap_rxpd *)(skb->data);
 	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

 	/* don't do packet forwarding in disconnected state */
 	if (!priv->media_connected) {
 		dev_err(adapter->dev, "drop packet in disconnected state.\n");
 		dev_kfree_skb_any(skb);
 		return 0;
 	}

 	memcpy(ra, rx_pkt_hdr->eth803_hdr.h_dest, ETH_ALEN);

 	if (is_multicast_ether_addr(ra)) {
 		skb_uap = skb_copy(skb, GFP_ATOMIC);
 		mwifiex_uap_queue_bridged_pkt(priv, skb_uap);
 	} else {
 		if (mwifiex_get_sta_entry(priv, ra)) {
 			/* Requeue Intra-BSS packet */
 			mwifiex_uap_queue_bridged_pkt(priv, skb);
 			return 0;
 		}
 	}

 	/* Forward unicat/Inter-BSS packets to kernel. */
 	return mwifiex_process_rx_packet(priv, skb);
 }

 /*
  * This function processes the packet received on AP interface.
  *
  * The function looks into the RxPD and performs sanity tests on the
  * received buffer to ensure its a valid packet before processing it
  * further. If the packet is determined to be aggregated, it is
  * de-aggregated accordingly. Then skb is passed to AP packet forwarding logic.
  *
  * The completion callback is called after processing is complete.
  */
 int mwifiex_process_uap_rx_packet(struct mwifiex_private *priv,
 				  struct sk_buff *skb)
 {
 	struct mwifiex_adapter *adapter = priv->adapter;
 	int ret;
 	struct uap_rxpd *uap_rx_pd;
 	struct rx_packet_hdr *rx_pkt_hdr;
 	u16 rx_pkt_type;
 	u8 ta[ETH_ALEN], pkt_type;
 	struct mwifiex_sta_node *node;

 	uap_rx_pd = (struct uap_rxpd *)(skb->data);
 	rx_pkt_type = le16_to_cpu(uap_rx_pd->rx_pkt_type);
 	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

 	if ((le16_to_cpu(uap_rx_pd->rx_pkt_offset) +
 	     le16_to_cpu(uap_rx_pd->rx_pkt_length)) > (u16) skb->len) {
 		dev_err(adapter->dev,
 			"wrong rx packet: len=%d, offset=%d, length=%d\n",
 			skb->len, le16_to_cpu(uap_rx_pd->rx_pkt_offset),
 			le16_to_cpu(uap_rx_pd->rx_pkt_length));
 		priv->stats.rx_dropped++;

 		if (adapter->if_ops.data_complete)
 			adapter->if_ops.data_complete(adapter, skb);
 		else
 			dev_kfree_skb_any(skb);

 		return 0;
 	}

 	if (le16_to_cpu(uap_rx_pd->rx_pkt_type) == PKT_TYPE_AMSDU) {
 		struct sk_buff_head list;
 		struct sk_buff *rx_skb;

 		__skb_queue_head_init(&list);
 		skb_pull(skb, le16_to_cpu(uap_rx_pd->rx_pkt_offset));
 		skb_trim(skb, le16_to_cpu(uap_rx_pd->rx_pkt_length));

 		ieee80211_amsdu_to_8023s(skb, &list, priv->curr_addr,
 					 priv->wdev->iftype, 0, false);

 		while (!skb_queue_empty(&list)) {
 			rx_skb = __skb_dequeue(&list);
 			ret = mwifiex_recv_packet(priv, rx_skb);
 			if (ret)
 				dev_err(adapter->dev,
 					"AP:Rx A-MSDU failed");
 		}

 		return 0;
 	} else if (rx_pkt_type == PKT_TYPE_MGMT) {
 		ret = mwifiex_process_mgmt_packet(priv, skb);
 		if (ret)
 			dev_err(adapter->dev, "Rx of mgmt packet failed");
 		dev_kfree_skb_any(skb);
 		return ret;
 	}

 	memcpy(ta, rx_pkt_hdr->eth803_hdr.h_source, ETH_ALEN);

 	if (rx_pkt_type != PKT_TYPE_BAR && uap_rx_pd->priority < MAX_NUM_TID) {
 		node = mwifiex_get_sta_entry(priv, ta);
 		if (node)
 			node->rx_seq[uap_rx_pd->priority] =
 						le16_to_cpu(uap_rx_pd->seq_num);
 	}

 	if (!priv->ap_11n_enabled ||
 	    (!mwifiex_11n_get_rx_reorder_tbl(priv, uap_rx_pd->priority, ta) &&
 	    (le16_to_cpu(uap_rx_pd->rx_pkt_type) != PKT_TYPE_AMSDU))) {
 		ret = mwifiex_handle_uap_rx_forward(priv, skb);
 		return ret;
 	}

 	/* Reorder and send to kernel */
 	pkt_type = (u8)le16_to_cpu(uap_rx_pd->rx_pkt_type);
 	ret = mwifiex_11n_rx_reorder_pkt(priv, le16_to_cpu(uap_rx_pd->seq_num),
 					 uap_rx_pd->priority, ta, pkt_type,
 					 skb);

 	if (ret || (rx_pkt_type == PKT_TYPE_BAR)) {
 		if (adapter->if_ops.data_complete)
 			adapter->if_ops.data_complete(adapter, skb);
 		else
 			dev_kfree_skb_any(skb);
 	}

 	if (ret)
 		priv->stats.rx_dropped++;

 	return ret;
 }

 /*
  * This function fills the TxPD for AP tx packets.
  *
  * The Tx buffer received by this function should already have the
  * header space allocated for TxPD.
  *
  * This function inserts the TxPD in between interface header and actual
  * data and adjusts the buffer pointers accordingly.
  *
  * The following TxPD fields are set by this function, as required -
  *      - BSS number
  *      - Tx packet length and offset
  *      - Priority
  *      - Packet delay
  *      - Priority specific Tx control
  *      - Flags
  */
 void *mwifiex_process_uap_txpd(struct mwifiex_private *priv,
 			       struct sk_buff *skb)
 {
 	struct mwifiex_adapter *adapter = priv->adapter;
 	struct uap_txpd *txpd;
 	struct mwifiex_txinfo *tx_info = MWIFIEX_SKB_TXCB(skb);
 	int pad, len;
 	u16 pkt_type;

 	if (!skb->len) {
 		dev_err(adapter->dev, "Tx: bad packet length: %d\n", skb->len);
 		tx_info->status_code = -1;
 		return skb->data;
 	}

 	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;

 	/* If skb->data is not aligned, add padding */
 	pad = (4 - (((void *)skb->data - NULL) & 0x3)) % 4;

 	len = sizeof(*txpd) + pad;

 	BUG_ON(skb_headroom(skb) < len + INTF_HEADER_LEN);

 	skb_push(skb, len);

 	txpd = (struct uap_txpd *)skb->data;
 	memset(txpd, 0, sizeof(*txpd));
 	txpd->bss_num = priv->bss_num;
 	txpd->bss_type = priv->bss_type;
 	txpd->tx_pkt_length = cpu_to_le16((u16)(skb->len - len));

 	txpd->priority = (u8)skb->priority;
 	txpd->pkt_delay_2ms = mwifiex_wmm_compute_drv_pkt_delay(priv, skb);

 	if (txpd->priority < ARRAY_SIZE(priv->wmm.user_pri_pkt_tx_ctrl))
 		/*
 		 * Set the priority specific tx_control field, setting of 0 will
 		 * cause the default value to be used later in this function.
 		 */
 		txpd->tx_control =
 		    cpu_to_le32(priv->wmm.user_pri_pkt_tx_ctrl[txpd->priority]);

 	/* Offset of actual data */
 	if (pkt_type == PKT_TYPE_MGMT) {
 		/* Set the packet type and add header for management frame */
 		txpd->tx_pkt_type = cpu_to_le16(pkt_type);
 		len += MWIFIEX_MGMT_FRAME_HEADER_SIZE;
 	}

 	txpd->tx_pkt_offset = cpu_to_le16(len);

 	/* make space for INTF_HEADER_LEN */
 	skb_push(skb, INTF_HEADER_LEN);

 	if (!txpd->tx_control)
 		/* TxCtrl set by user or default */
 		txpd->tx_control = cpu_to_le32(priv->pkt_tx_ctrl);

 	return skb->data;
 }
	/*
	* Marvell Wireless LAN device driver: AP TX and RX data handling
	*
	* Copyright (C) 2012, Marvell International Ltd.
	*
	* This software file (the "File") is distributed by Marvell International
	* Ltd. under the terms of the GNU General Public License Version 2, June 1991
	* (the "License"). You may use, redistribute and/or modify this File in
	* accordance with the terms and conditions of the License, a copy of which
	* is available by writing to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or on the
	* worldwide web at http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
	*
	* THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
	* ARE EXPRESSLY DISCLAIMED. The License provides additional details about
	* this warranty disclaimer.
	*/

	#include "decl.h"
	#include "ioctl.h"
	#include "main.h"
	#include "wmm.h"
	#include "11n_aggr.h"
	#include "11n_rxreorder.h"

	static void mwifiex_uap_queue_bridged_pkt(struct mwifiex_private *priv,
	struct sk_buff *skb)
	{
	struct mwifiex_adapter *adapter = priv->adapter;
	struct uap_rxpd *uap_rx_pd;
	struct rx_packet_hdr *rx_pkt_hdr;
	struct sk_buff *new_skb;
	struct mwifiex_txinfo *tx_info;
	int hdr_chop;
	struct timeval tv;
	u8 rfc1042_eth_hdr[ETH_ALEN] = { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };

	uap_rx_pd = (struct uap_rxpd *)(skb->data);
	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

	if ((atomic_read(&adapter->pending_bridged_pkts) >=
	MWIFIEX_BRIDGED_PKTS_THRESHOLD)) {
	dev_err(priv->adapter->dev,
	"Tx: Bridge packet limit reached. Drop packet!\n");
	kfree_skb(skb);
	return;
	}

	if (!memcmp(&rx_pkt_hdr->rfc1042_hdr,
	rfc1042_eth_hdr, sizeof(rfc1042_eth_hdr)))
	/* Chop off the rxpd + the excess memory from
	* 802.2/llc/snap header that was removed.
	*/
	hdr_chop = (u8 )eth_hdr - (u8 )uap_rx_pd;
	else
	/* Chop off the rxpd */
	hdr_chop = (u8 )&rx_pkt_hdr->eth803_hdr - (u8 )uap_rx_pd;

	/* Chop off the leading header bytes so the it points
	* to the start of either the reconstructed EthII frame
	* or the 802.2/llc/snap frame.
	*/
	skb_pull(skb, hdr_chop);

	if (skb_headroom(skb) < MWIFIEX_MIN_DATA_HEADER_LEN) {
	dev_dbg(priv->adapter->dev,
	"data: Tx: insufficient skb headroom %d\n",
	skb_headroom(skb));
	/* Insufficient skb headroom - allocate a new skb */
	new_skb =
	skb_realloc_headroom(skb, MWIFIEX_MIN_DATA_HEADER_LEN);
	if (unlikely(!new_skb)) {
	dev_err(priv->adapter->dev,
	"Tx: cannot allocate new_skb\n");
	kfree_skb(skb);
	priv->stats.tx_dropped++;
	return;
	}

	kfree_skb(skb);
	skb = new_skb;
	dev_dbg(priv->adapter->dev, "info: new skb headroom %d\n",
	skb_headroom(skb));
	}

	tx_info = MWIFIEX_SKB_TXCB(skb);
	tx_info->bss_num = priv->bss_num;
	tx_info->bss_type = priv->bss_type;
	tx_info->flags \|= MWIFIEX_BUF_FLAG_BRIDGED_PKT;

	do_gettimeofday(&tv);
	skb->tstamp = timeval_to_ktime(tv);
	mwifiex_wmm_add_buf_txqueue(priv, skb);
	atomic_inc(&adapter->tx_pending);
	atomic_inc(&adapter->pending_bridged_pkts);

	if ((atomic_read(&adapter->tx_pending) >= MAX_TX_PENDING)) {
	mwifiex_set_trans_start(priv->netdev);
	mwifiex_stop_net_dev_queue(priv->netdev, priv->adapter);
	}
	return;
	}

	/*
	* This function contains logic for AP packet forwarding.
	*
	* If a packet is multicast/broadcast, it is sent to kernel/upper layer
	* as well as queued back to AP TX queue so that it can be sent to other
	* associated stations.
	* If a packet is unicast and RA is present in associated station list,
	* it is again requeued into AP TX queue.
	* If a packet is unicast and RA is not in associated station list,
	* packet is forwarded to kernel to handle routing logic.
	*/
	int mwifiex_handle_uap_rx_forward(struct mwifiex_private *priv,
	struct sk_buff *skb)
	{
	struct mwifiex_adapter *adapter = priv->adapter;
	struct uap_rxpd *uap_rx_pd;
	struct rx_packet_hdr *rx_pkt_hdr;
	u8 ra[ETH_ALEN];
	struct sk_buff *skb_uap;

	uap_rx_pd = (struct uap_rxpd *)(skb->data);
	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

	/* don't do packet forwarding in disconnected state */
	if (!priv->media_connected) {
	dev_err(adapter->dev, "drop packet in disconnected state.\n");
	dev_kfree_skb_any(skb);
	return 0;
	}

	memcpy(ra, rx_pkt_hdr->eth803_hdr.h_dest, ETH_ALEN);

	if (is_multicast_ether_addr(ra)) {
	skb_uap = skb_copy(skb, GFP_ATOMIC);
	mwifiex_uap_queue_bridged_pkt(priv, skb_uap);
	} else {
	if (mwifiex_get_sta_entry(priv, ra)) {
	/* Requeue Intra-BSS packet */
	mwifiex_uap_queue_bridged_pkt(priv, skb);
	return 0;
	}
	}

	/* Forward unicat/Inter-BSS packets to kernel. */
	return mwifiex_process_rx_packet(priv, skb);
	}

	/*
	* This function processes the packet received on AP interface.
	*
	* The function looks into the RxPD and performs sanity tests on the
	* received buffer to ensure its a valid packet before processing it
	* further. If the packet is determined to be aggregated, it is
	* de-aggregated accordingly. Then skb is passed to AP packet forwarding logic.
	*
	* The completion callback is called after processing is complete.
	*/
	int mwifiex_process_uap_rx_packet(struct mwifiex_private *priv,
	struct sk_buff *skb)
	{
	struct mwifiex_adapter *adapter = priv->adapter;
	int ret;
	struct uap_rxpd *uap_rx_pd;
	struct rx_packet_hdr *rx_pkt_hdr;
	u16 rx_pkt_type;
	u8 ta[ETH_ALEN], pkt_type;
	struct mwifiex_sta_node *node;

	uap_rx_pd = (struct uap_rxpd *)(skb->data);
	rx_pkt_type = le16_to_cpu(uap_rx_pd->rx_pkt_type);
	rx_pkt_hdr = (void *)uap_rx_pd + le16_to_cpu(uap_rx_pd->rx_pkt_offset);

	if ((le16_to_cpu(uap_rx_pd->rx_pkt_offset) +
	le16_to_cpu(uap_rx_pd->rx_pkt_length)) > (u16) skb->len) {
	dev_err(adapter->dev,
	"wrong rx packet: len=%d, offset=%d, length=%d\n",
	skb->len, le16_to_cpu(uap_rx_pd->rx_pkt_offset),
	le16_to_cpu(uap_rx_pd->rx_pkt_length));
	priv->stats.rx_dropped++;

	if (adapter->if_ops.data_complete)
	adapter->if_ops.data_complete(adapter, skb);
	else
	dev_kfree_skb_any(skb);

	return 0;
	}

	if (le16_to_cpu(uap_rx_pd->rx_pkt_type) == PKT_TYPE_AMSDU) {
	struct sk_buff_head list;
	struct sk_buff *rx_skb;

	__skb_queue_head_init(&list);
	skb_pull(skb, le16_to_cpu(uap_rx_pd->rx_pkt_offset));
	skb_trim(skb, le16_to_cpu(uap_rx_pd->rx_pkt_length));

	ieee80211_amsdu_to_8023s(skb, &list, priv->curr_addr,
	priv->wdev->iftype, 0, false);

	while (!skb_queue_empty(&list)) {
	rx_skb = __skb_dequeue(&list);
	ret = mwifiex_recv_packet(priv, rx_skb);
	if (ret)
	dev_err(adapter->dev,
	"AP:Rx A-MSDU failed");
	}

	return 0;
	} else if (rx_pkt_type == PKT_TYPE_MGMT) {
	ret = mwifiex_process_mgmt_packet(priv, skb);
	if (ret)
	dev_err(adapter->dev, "Rx of mgmt packet failed");
	dev_kfree_skb_any(skb);
	return ret;
	}

	memcpy(ta, rx_pkt_hdr->eth803_hdr.h_source, ETH_ALEN);

	if (rx_pkt_type != PKT_TYPE_BAR && uap_rx_pd->priority < MAX_NUM_TID) {
	node = mwifiex_get_sta_entry(priv, ta);
	if (node)
	node->rx_seq[uap_rx_pd->priority] =
	le16_to_cpu(uap_rx_pd->seq_num);
	}

	if (!priv->ap_11n_enabled \|\|
	(!mwifiex_11n_get_rx_reorder_tbl(priv, uap_rx_pd->priority, ta) &&
	(le16_to_cpu(uap_rx_pd->rx_pkt_type) != PKT_TYPE_AMSDU))) {
	ret = mwifiex_handle_uap_rx_forward(priv, skb);
	return ret;
	}

	/* Reorder and send to kernel */
	pkt_type = (u8)le16_to_cpu(uap_rx_pd->rx_pkt_type);
	ret = mwifiex_11n_rx_reorder_pkt(priv, le16_to_cpu(uap_rx_pd->seq_num),
	uap_rx_pd->priority, ta, pkt_type,
	skb);

	if (ret \|\| (rx_pkt_type == PKT_TYPE_BAR)) {
	if (adapter->if_ops.data_complete)
	adapter->if_ops.data_complete(adapter, skb);
	else
	dev_kfree_skb_any(skb);
	}

	if (ret)
	priv->stats.rx_dropped++;

	return ret;
	}

	/*
	* This function fills the TxPD for AP tx packets.
	*
	* The Tx buffer received by this function should already have the
	* header space allocated for TxPD.
	*
	* This function inserts the TxPD in between interface header and actual
	* data and adjusts the buffer pointers accordingly.
	*
	* The following TxPD fields are set by this function, as required -
	* - BSS number
	* - Tx packet length and offset
	* - Priority
	* - Packet delay
	* - Priority specific Tx control
	* - Flags
	*/
	void mwifiex_process_uap_txpd(struct mwifiex_private priv,
	struct sk_buff *skb)
	{
	struct mwifiex_adapter *adapter = priv->adapter;
	struct uap_txpd *txpd;
	struct mwifiex_txinfo *tx_info = MWIFIEX_SKB_TXCB(skb);
	int pad, len;
	u16 pkt_type;

	if (!skb->len) {
	dev_err(adapter->dev, "Tx: bad packet length: %d\n", skb->len);
	tx_info->status_code = -1;
	return skb->data;
	}

	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;

	/* If skb->data is not aligned, add padding */
	pad = (4 - (((void *)skb->data - NULL) & 0x3)) % 4;

	len = sizeof(*txpd) + pad;

	BUG_ON(skb_headroom(skb) < len + INTF_HEADER_LEN);

	skb_push(skb, len);

	txpd = (struct uap_txpd *)skb->data;
	memset(txpd, 0, sizeof(*txpd));
	txpd->bss_num = priv->bss_num;
	txpd->bss_type = priv->bss_type;
	txpd->tx_pkt_length = cpu_to_le16((u16)(skb->len - len));

	txpd->priority = (u8)skb->priority;
	txpd->pkt_delay_2ms = mwifiex_wmm_compute_drv_pkt_delay(priv, skb);

	if (txpd->priority < ARRAY_SIZE(priv->wmm.user_pri_pkt_tx_ctrl))
	/*
	* Set the priority specific tx_control field, setting of 0 will
	* cause the default value to be used later in this function.
	*/
	txpd->tx_control =
	cpu_to_le32(priv->wmm.user_pri_pkt_tx_ctrl[txpd->priority]);

	/* Offset of actual data */
	if (pkt_type == PKT_TYPE_MGMT) {
	/* Set the packet type and add header for management frame */
	txpd->tx_pkt_type = cpu_to_le16(pkt_type);
	len += MWIFIEX_MGMT_FRAME_HEADER_SIZE;
	}

	txpd->tx_pkt_offset = cpu_to_le16(len);

	/* make space for INTF_HEADER_LEN */
	skb_push(skb, INTF_HEADER_LEN);

	if (!txpd->tx_control)
	/* TxCtrl set by user or default */
	txpd->tx_control = cpu_to_le32(priv->pkt_tx_ctrl);

	return skb->data;
	}