ath9k_htc: Use SKB's private area for TX parameters

For all packets sent through the USB_WLAN_TX_PIPE endpoint,
the private area of the SKB's tx_info can be used to store
driver-specific information. For packets sent through USB_REG_OUT_PIPE,
this will not make a difference since they are routed through a
separate routine that doesn't access the private region.

This would help in situations where TX information is required
in the URB callback.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 0e48fa0..2eabfe4 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -67,8 +67,11 @@
 };
 
 #define ATH9K_HTC_HDRSPACE sizeof(struct htc_frame_hdr)
-#define ATH9K_HTC_AMPDU	1
+
+#define ATH9K_HTC_AMPDU  1
 #define ATH9K_HTC_NORMAL 2
+#define ATH9K_HTC_BEACON 3
+#define ATH9K_HTC_MGMT   4
 
 #define ATH9K_HTC_TX_CTSONLY      0x1
 #define ATH9K_HTC_TX_RTSCTS       0x2
@@ -288,6 +291,15 @@
 	u8 type; /* ATH9K_HTC_* */
 };
 
+static inline struct ath9k_htc_tx_ctl *HTC_SKB_CB(struct sk_buff *skb)
+{
+	struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
+
+	BUILD_BUG_ON(sizeof(struct ath9k_htc_tx_ctl) >
+		     IEEE80211_TX_INFO_DRIVER_DATA_SIZE);
+	return (struct ath9k_htc_tx_ctl *) &tx_info->driver_data;
+}
+
 #ifdef CONFIG_ATH9K_HTC_DEBUGFS
 
 #define TX_STAT_INC(c) (hif_dev->htc_handle->drv_priv->debug.tx_stats.c++)