ath10k: cleanup RX decap handling

Simplify decapping code and make it easier to
understand.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/htt_rx.c

@@ -669,11 +669,16 @@ static void ath10k_htt_rx_amsdu(struct ath10k_htt *htt,
 
 		switch (fmt) {
 		case RX_MSDU_DECAP_RAW:
+			/* remove trailing FCS */
 			skb_trim(skb, skb->len - FCS_LEN);
 			break;
 		case RX_MSDU_DECAP_NATIVE_WIFI:
+			/* nothing to do */
 			break;
 		case RX_MSDU_DECAP_ETHERNET2_DIX:
+			/* strip ethernet header and insert decapped 802.11
+			 * header, amsdu subframe header and rfc1042 header */
+
 			len = 0;
 			len += sizeof(struct rfc1042_hdr);
 			len += sizeof(struct amsdu_subframe_hdr);
@@ -683,6 +688,8 @@ static void ath10k_htt_rx_amsdu(struct ath10k_htt *htt,
 			memcpy(skb_push(skb, hdr_len), hdr, hdr_len);
 			break;
 		case RX_MSDU_DECAP_8023_SNAP_LLC:
+			/* insert decapped 802.11 header making a singly
+			 * A-MSDU */
 			memcpy(skb_push(skb, hdr_len), hdr, hdr_len);
 			break;
 		}
@@ -706,6 +713,8 @@ static void ath10k_htt_rx_msdu(struct ath10k_htt *htt, struct htt_rx_info *info)
 	struct ieee80211_hdr *hdr;
 	enum rx_msdu_decap_format fmt;
 	enum htt_rx_mpdu_encrypt_type enctype;
+	int hdr_len;
+	void *rfc1042;
 
 	/* This shouldn't happen. If it does than it may be a FW bug. */
 	if (skb->next) {
@@ -719,46 +728,39 @@ static void ath10k_htt_rx_msdu(struct ath10k_htt *htt, struct htt_rx_info *info)
 			RX_MSDU_START_INFO1_DECAP_FORMAT);
 	enctype = MS(__le32_to_cpu(rxd->mpdu_start.info0),
 			RX_MPDU_START_INFO0_ENCRYPT_TYPE);
-	hdr = (void *)skb->data - RX_HTT_HDR_STATUS_LEN;
+	hdr = (struct ieee80211_hdr *)rxd->rx_hdr_status;
+	hdr_len = ieee80211_hdrlen(hdr->frame_control);
 
 	skb->ip_summed = ath10k_htt_rx_get_csum_state(skb);
 
 	switch (fmt) {
 	case RX_MSDU_DECAP_RAW:
 		/* remove trailing FCS */
-		skb_trim(skb, skb->len - 4);
+		skb_trim(skb, skb->len - FCS_LEN);
 		break;
 	case RX_MSDU_DECAP_NATIVE_WIFI:
 		/* nothing to do here */
 		break;
 	case RX_MSDU_DECAP_ETHERNET2_DIX:
-		/* macaddr[6] + macaddr[6] + ethertype[2] */
-		skb_pull(skb, 6 + 6 + 2);
-		break;
-	case RX_MSDU_DECAP_8023_SNAP_LLC:
-		/* macaddr[6] + macaddr[6] + len[2] */
-		/* we don't need this for non-A-MSDU */
-		skb_pull(skb, 6 + 6 + 2);
-		break;
-	}
+		/* strip ethernet header and insert decapped 802.11 header and
+		 * rfc1042 header */
 
-	if (fmt == RX_MSDU_DECAP_ETHERNET2_DIX) {
-		void *llc;
-		int llclen;
+		rfc1042 = hdr;
+		rfc1042 += roundup(hdr_len, 4);
+		rfc1042 += roundup(ath10k_htt_rx_crypto_param_len(enctype), 4);
 
-		llclen = 8;
-		llc  = hdr;
-		llc += roundup(ieee80211_hdrlen(hdr->frame_control), 4);
-		llc += roundup(ath10k_htt_rx_crypto_param_len(enctype), 4);
-
-		skb_push(skb, llclen);
-		memcpy(skb->data, llc, llclen);
-	}
+		skb_pull(skb, sizeof(struct ethhdr));
+		memcpy(skb_push(skb, sizeof(struct rfc1042_hdr)),
+		       rfc1042, sizeof(struct rfc1042_hdr));
+		memcpy(skb_push(skb, hdr_len), hdr, hdr_len);
+		break;
+	case RX_MSDU_DECAP_8023_SNAP_LLC:
+		/* remove A-MSDU subframe header and insert
+		 * decapped 802.11 header. rfc1042 header is already there */
 
-	if (fmt >= RX_MSDU_DECAP_ETHERNET2_DIX) {
-		int len = ieee80211_hdrlen(hdr->frame_control);
-		skb_push(skb, len);
-		memcpy(skb->data, hdr, len);
+		skb_pull(skb, sizeof(struct amsdu_subframe_hdr));
+		memcpy(skb_push(skb, hdr_len), hdr, hdr_len);
+		break;
 	}
 
 	info->skb = skb;