/*
   * This file contains the handling of RX in wlan driver.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/etherdevice.h>
  #include <linux/hardirq.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/export.h>
  #include <net/cfg80211.h>
  
  #include "defs.h"
  #include "host.h"
  #include "radiotap.h"
  #include "decl.h"
  #include "dev.h"
  #include "mesh.h"
  
  struct eth803hdr {
  	u8 dest_addr[6];
  	u8 src_addr[6];
  	u16 h803_len;
  } __packed;
  
  struct rfc1042hdr {
  	u8 llc_dsap;
  	u8 llc_ssap;
  	u8 llc_ctrl;
  	u8 snap_oui[3];
  	u16 snap_type;
  } __packed;
  
  struct rxpackethdr {
  	struct eth803hdr eth803_hdr;
  	struct rfc1042hdr rfc1042_hdr;
  } __packed;
  
  struct rx80211packethdr {
  	struct rxpd rx_pd;
  	void *eth80211_hdr;
  } __packed;
  
  static int process_rxed_802_11_packet(struct lbs_private *priv,
  	struct sk_buff *skb);
  
  /**
   * lbs_process_rxed_packet - processes received packet and forwards it
   * to kernel/upper layer
   *
   * @priv:	A pointer to &struct lbs_private
   * @skb:	A pointer to skb which includes the received packet
   * returns:	0 or -1
   */
  int lbs_process_rxed_packet(struct lbs_private *priv, struct sk_buff *skb)
  {
  	int ret = 0;
  	struct net_device *dev = priv->dev;
  	struct rxpackethdr *p_rx_pkt;
  	struct rxpd *p_rx_pd;
  	int hdrchop;
  	struct ethhdr *p_ethhdr;
  	static const u8 rfc1042_eth_hdr[] = {
  		0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00
  	};
  
  	lbs_deb_enter(LBS_DEB_RX);
  
  	BUG_ON(!skb);
  
  	skb->ip_summed = CHECKSUM_NONE;
  
  	if (priv->wdev->iftype == NL80211_IFTYPE_MONITOR) {
  		ret = process_rxed_802_11_packet(priv, skb);
  		goto done;
  	}
  
  	p_rx_pd = (struct rxpd *) skb->data;
  	p_rx_pkt = (struct rxpackethdr *) ((u8 *)p_rx_pd +
  		le32_to_cpu(p_rx_pd->pkt_ptr));
  
  	dev = lbs_mesh_set_dev(priv, dev, p_rx_pd);
  
  	lbs_deb_hex(LBS_DEB_RX, "RX Data: Before chop rxpd", skb->data,
  		 min_t(unsigned int, skb->len, 100));
  
  	if (skb->len < (ETH_HLEN + 8 + sizeof(struct rxpd))) {
  		lbs_deb_rx("rx err: frame received with bad length
  ");
  		dev->stats.rx_length_errors++;
  		ret = -EINVAL;
  		dev_kfree_skb(skb);
  		goto done;
  	}
  
  	lbs_deb_rx("rx data: skb->len - pkt_ptr = %d-%zd = %zd
  ",
  		skb->len, (size_t)le32_to_cpu(p_rx_pd->pkt_ptr),
  		skb->len - (size_t)le32_to_cpu(p_rx_pd->pkt_ptr));
  
  	lbs_deb_hex(LBS_DEB_RX, "RX Data: Dest", p_rx_pkt->eth803_hdr.dest_addr,
  		sizeof(p_rx_pkt->eth803_hdr.dest_addr));
  	lbs_deb_hex(LBS_DEB_RX, "RX Data: Src", p_rx_pkt->eth803_hdr.src_addr,
  		sizeof(p_rx_pkt->eth803_hdr.src_addr));
  
  	if (memcmp(&p_rx_pkt->rfc1042_hdr,
  		   rfc1042_eth_hdr, sizeof(rfc1042_eth_hdr)) == 0) {
  		/*
  		 *  Replace the 803 header and rfc1042 header (llc/snap) with an
  		 *    EthernetII header, keep the src/dst and snap_type (ethertype)
  		 *
  		 *  The firmware only passes up SNAP frames converting
  		 *    all RX Data from 802.11 to 802.2/LLC/SNAP frames.
  		 *
  		 *  To create the Ethernet II, just move the src, dst address right
  		 *    before the snap_type.
  		 */
  		p_ethhdr = (struct ethhdr *)
  		    ((u8 *) &p_rx_pkt->eth803_hdr
  		     + sizeof(p_rx_pkt->eth803_hdr) + sizeof(p_rx_pkt->rfc1042_hdr)
  		     - sizeof(p_rx_pkt->eth803_hdr.dest_addr)
  		     - sizeof(p_rx_pkt->eth803_hdr.src_addr)
  		     - sizeof(p_rx_pkt->rfc1042_hdr.snap_type));
  
  		memcpy(p_ethhdr->h_source, p_rx_pkt->eth803_hdr.src_addr,
  		       sizeof(p_ethhdr->h_source));
  		memcpy(p_ethhdr->h_dest, p_rx_pkt->eth803_hdr.dest_addr,
  		       sizeof(p_ethhdr->h_dest));
  
  		/* Chop off the rxpd + the excess memory from the 802.2/llc/snap header
  		 *   that was removed
  		 */
  		hdrchop = (u8 *)p_ethhdr - (u8 *)p_rx_pd;
  	} else {
  		lbs_deb_hex(LBS_DEB_RX, "RX Data: LLC/SNAP",
  			(u8 *) &p_rx_pkt->rfc1042_hdr,
  			sizeof(p_rx_pkt->rfc1042_hdr));
  
  		/* Chop off the rxpd */
  		hdrchop = (u8 *)&p_rx_pkt->eth803_hdr - (u8 *)p_rx_pd;
  	}
  
  	/* Chop off the leading header bytes so the skb points to the start of
  	 *   either the reconstructed EthII frame or the 802.2/llc/snap frame
  	 */
  	skb_pull(skb, hdrchop);
  
  	priv->cur_rate = lbs_fw_index_to_data_rate(p_rx_pd->rx_rate);
  
  	lbs_deb_rx("rx data: size of actual packet %d
  ", skb->len);
  	dev->stats.rx_bytes += skb->len;
  	dev->stats.rx_packets++;
  
  	skb->protocol = eth_type_trans(skb, dev);
  	if (in_interrupt())
  		netif_rx(skb);
  	else
  		netif_rx_ni(skb);
  
  	ret = 0;
  done:
  	lbs_deb_leave_args(LBS_DEB_RX, "ret %d", ret);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(lbs_process_rxed_packet);
  
  /**
   * convert_mv_rate_to_radiotap - converts Tx/Rx rates from Marvell WLAN format
   * (see Table 2 in Section 3.1) to IEEE80211_RADIOTAP_RATE units (500 Kb/s)
   *
   * @rate:	Input rate
   * returns:	Output Rate (0 if invalid)
   */
  static u8 convert_mv_rate_to_radiotap(u8 rate)
  {
  	switch (rate) {
  	case 0:		/*   1 Mbps */
  		return 2;
  	case 1:		/*   2 Mbps */
  		return 4;
  	case 2:		/* 5.5 Mbps */
  		return 11;
  	case 3:		/*  11 Mbps */
  		return 22;
  	/* case 4: reserved */
  	case 5:		/*   6 Mbps */
  		return 12;
  	case 6:		/*   9 Mbps */
  		return 18;
  	case 7:		/*  12 Mbps */
  		return 24;
  	case 8:		/*  18 Mbps */
  		return 36;
  	case 9:		/*  24 Mbps */
  		return 48;
  	case 10:		/*  36 Mbps */
  		return 72;
  	case 11:		/*  48 Mbps */
  		return 96;
  	case 12:		/*  54 Mbps */
  		return 108;
  	}
  	pr_alert("Invalid Marvell WLAN rate %i
  ", rate);
  	return 0;
  }
  
  /**
   * process_rxed_802_11_packet - processes a received 802.11 packet and forwards
   * it to kernel/upper layer
   *
   * @priv:	A pointer to &struct lbs_private
   * @skb:	A pointer to skb which includes the received packet
   * returns:	0 or -1
   */
  static int process_rxed_802_11_packet(struct lbs_private *priv,
  	struct sk_buff *skb)
  {
  	int ret = 0;
  	struct net_device *dev = priv->dev;
  	struct rx80211packethdr *p_rx_pkt;
  	struct rxpd *prxpd;
  	struct rx_radiotap_hdr radiotap_hdr;
  	struct rx_radiotap_hdr *pradiotap_hdr;
  
  	lbs_deb_enter(LBS_DEB_RX);
  
  	p_rx_pkt = (struct rx80211packethdr *) skb->data;
  	prxpd = &p_rx_pkt->rx_pd;
  
  	/* lbs_deb_hex(LBS_DEB_RX, "RX Data: Before chop rxpd", skb->data, min(skb->len, 100)); */
  
  	if (skb->len < (ETH_HLEN + 8 + sizeof(struct rxpd))) {
  		lbs_deb_rx("rx err: frame received with bad length
  ");
  		dev->stats.rx_length_errors++;
  		ret = -EINVAL;
  		kfree_skb(skb);
  		goto done;
  	}
  
  	lbs_deb_rx("rx data: skb->len-sizeof(RxPd) = %d-%zd = %zd
  ",
  	       skb->len, sizeof(struct rxpd), skb->len - sizeof(struct rxpd));
  
  	/* create the exported radio header */
  
  	/* radiotap header */
  	memset(&radiotap_hdr, 0, sizeof(radiotap_hdr));
  	/* XXX must check radiotap_hdr.hdr.it_pad for pad */
  	radiotap_hdr.hdr.it_len = cpu_to_le16 (sizeof(struct rx_radiotap_hdr));
  	radiotap_hdr.hdr.it_present = cpu_to_le32 (RX_RADIOTAP_PRESENT);
  	radiotap_hdr.rate = convert_mv_rate_to_radiotap(prxpd->rx_rate);
  	/* XXX must check no carryout */
  	radiotap_hdr.antsignal = prxpd->snr + prxpd->nf;
  
  	/* chop the rxpd */
  	skb_pull(skb, sizeof(struct rxpd));
  
  	/* add space for the new radio header */
  	if ((skb_headroom(skb) < sizeof(struct rx_radiotap_hdr)) &&
  	    pskb_expand_head(skb, sizeof(struct rx_radiotap_hdr), 0, GFP_ATOMIC)) {
  		netdev_alert(dev, "%s: couldn't pskb_expand_head
  ", __func__);
  		ret = -ENOMEM;
  		kfree_skb(skb);
  		goto done;
  	}
  
  	pradiotap_hdr = (void *)skb_push(skb, sizeof(struct rx_radiotap_hdr));
  	memcpy(pradiotap_hdr, &radiotap_hdr, sizeof(struct rx_radiotap_hdr));
  
  	priv->cur_rate = lbs_fw_index_to_data_rate(prxpd->rx_rate);
  
  	lbs_deb_rx("rx data: size of actual packet %d
  ", skb->len);
  	dev->stats.rx_bytes += skb->len;
  	dev->stats.rx_packets++;
  
  	skb->protocol = eth_type_trans(skb, priv->dev);
  
  	if (in_interrupt())
  		netif_rx(skb);
  	else
  		netif_rx_ni(skb);
  
  	ret = 0;
  
  done:
  	lbs_deb_leave_args(LBS_DEB_RX, "ret %d", ret);
  	return ret;
  }