+static void mwl8k_encapsulate_tx_frame(struct sk_buff *skb)
+{
+ struct ieee80211_hdr *wh;
+ struct ieee80211_tx_info *tx_info;
+ struct ieee80211_key_conf *key_conf;
+ int data_pad;
+
+ wh = (struct ieee80211_hdr *)skb->data;
+
+ tx_info = IEEE80211_SKB_CB(skb);
+
+ key_conf = NULL;
+ if (ieee80211_is_data(wh->frame_control))
+ key_conf = tx_info->control.hw_key;
+
+ /*
+ * Make sure the packet header is in the DMA header format (4-address
+ * without QoS), the necessary crypto padding between the header and the
+ * payload has already been provided by mac80211, but it doesn't add tail
+ * padding when HW crypto is enabled.
+ *
+ * We have the following trailer padding requirements:
+ * - WEP: 4 trailer bytes (ICV)
+ * - TKIP: 12 trailer bytes (8 MIC + 4 ICV)
+ * - CCMP: 8 trailer bytes (MIC)
+ */
+ data_pad = 0;
+ if (key_conf != NULL) {
+ switch (key_conf->cipher) {
+ case WLAN_CIPHER_SUITE_WEP40:
+ case WLAN_CIPHER_SUITE_WEP104:
+ data_pad = 4;
+ break;
+ case WLAN_CIPHER_SUITE_TKIP:
+ data_pad = 12;
+ break;
+ case WLAN_CIPHER_SUITE_CCMP:
+ data_pad = 8;
+ break;
+ }
+ }
+ mwl8k_add_dma_header(skb, data_pad);
+}