mwl8k: Add timestamp information for tx packets

Timestamp tx packets using a HW micro-second timer.
This timestamp will be compared to the current timestamp
in the hardware and if the difference is greater than 500ms,
the packet will be dropped.
Signed-off-by: Pradeep Nemavat <pnemavat@marvell.com>
Signed-off-by: Nishant Sarmukadam <nishants@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwl8k.c

@@ -74,6 +74,14 @@ MODULE_PARM_DESC(ap_mode_default,
 #define  MWL8K_A2H_INT_RX_READY			 (1 << 1)
 #define  MWL8K_A2H_INT_TX_DONE			 (1 << 0)
 
+/* HW micro second timer register
+ * located at offset 0xA600. This
+ * will be used to timestamp tx
+ * packets.
+ */
+
+#define	MWL8K_HW_TIMER_REGISTER			0x0000a600
+
 #define MWL8K_A2H_EVENTS	(MWL8K_A2H_INT_DUMMY | \
 				 MWL8K_A2H_INT_CHNL_SWITCHED | \
 				 MWL8K_A2H_INT_QUEUE_EMPTY | \
@@ -1972,6 +1980,11 @@ mwl8k_txq_xmit(struct ieee80211_hw *hw, int index, struct sk_buff *skb)
 		tx->peer_id = MWL8K_STA(tx_info->control.sta)->peer_id;
 	else
 		tx->peer_id = 0;
+
+	if (priv->ap_fw)
+		tx->timestamp = cpu_to_le32(ioread32(priv->regs +
+						MWL8K_HW_TIMER_REGISTER));
+
 	wmb();
 	tx->status = cpu_to_le32(MWL8K_TXD_STATUS_FW_OWNED | txstatus);