iwlwifi: update reply_statistics_cmd with 'clear' parameter

When issue REPLY_STATISTICS_CMD to uCode, two possible flag
can be set in the configuration flags

bit 0: Clear statistics
       0: Do not clear Statistics counters
       1: Clear to zero Statistics counters

Allow "clear" parameter to be set from the caller.

Add debugfs file to clear the statistics counters to help monitor and
debug the uCode behavior.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-rx.c

@@ -635,6 +635,24 @@ void iwl_rx_statistics(struct iwl_priv *priv,
 }
 EXPORT_SYMBOL(iwl_rx_statistics);
 
+void iwl_reply_statistics(struct iwl_priv *priv,
+			      struct iwl_rx_mem_buffer *rxb)
+{
+	struct iwl_rx_packet *pkt = rxb_addr(rxb);
+
+	if (le32_to_cpu(pkt->u.stats.flag) & UCODE_STATISTICS_CLEAR_MSK) {
+		memset(&priv->statistics, 0,
+			sizeof(struct iwl_notif_statistics));
+#ifdef CONFIG_IWLWIFI_DEBUG
+		memset(&priv->accum_statistics, 0,
+			sizeof(struct iwl_notif_statistics));
+#endif
+		IWL_DEBUG_RX(priv, "Statistics have been cleared\n");
+	}
+	iwl_rx_statistics(priv, rxb);
+}
+EXPORT_SYMBOL(iwl_reply_statistics);
+
 #define PERFECT_RSSI (-20) /* dBm */
 #define WORST_RSSI (-95)   /* dBm */
 #define RSSI_RANGE (PERFECT_RSSI - WORST_RSSI)