iwlagn: keep track of failure tx status

Tx command response sent to host by uCode after completed
the transmission attempt. The status parameter indicates
whether the transmission was successful, or else why if failed.

Here we keep the counters to help understand the different failure
cases.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-debugfs.c b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
index e0b31a2..265ad01 100644
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -1642,6 +1642,18 @@
 	return count;
 }
 
+static ssize_t iwl_dbgfs_reply_tx_error_read(struct file *file,
+					char __user *user_buf,
+					size_t count, loff_t *ppos)
+{
+	struct iwl_priv *priv = file->private_data;
+
+	if (priv->cfg->ops->lib->debugfs_ops.reply_tx_error)
+		return priv->cfg->ops->lib->debugfs_ops.reply_tx_error(
+			file, user_buf, count, ppos);
+	else
+		return -ENODATA;
+}
 DEBUGFS_READ_FILE_OPS(rx_statistics);
 DEBUGFS_READ_FILE_OPS(tx_statistics);
 DEBUGFS_READ_WRITE_FILE_OPS(traffic_log);
@@ -1668,6 +1680,7 @@
 DEBUGFS_WRITE_FILE_OPS(monitor_period);
 DEBUGFS_READ_FILE_OPS(bt_traffic);
 DEBUGFS_READ_WRITE_FILE_OPS(protection_mode);
+DEBUGFS_READ_FILE_OPS(reply_tx_error);
 
 /*
  * Create the debugfs files and directories
@@ -1738,6 +1751,7 @@
 		DEBUGFS_ADD_FILE(ucode_tracing, dir_debug, S_IWUSR | S_IRUSR);
 	if (priv->cfg->bt_statistics)
 		DEBUGFS_ADD_FILE(ucode_bt_stats, dir_debug, S_IRUSR);
+	DEBUGFS_ADD_FILE(reply_tx_error, dir_debug, S_IRUSR);
 	DEBUGFS_ADD_FILE(rxon_flags, dir_debug, S_IWUSR);
 	DEBUGFS_ADD_FILE(rxon_filter_flags, dir_debug, S_IWUSR);
 	DEBUGFS_ADD_FILE(monitor_period, dir_debug, S_IWUSR);