iwlwifi: re-introduce per device debugging

Commit "iwlwifi: make debug level more user friendly" cleaned up the
debug level handling. In doing so it created a single global debug
level for all devices. Some setups do consits of more that one iwlwifi
device and in these setups there is a requirement that debug levels
should be unique per device.

We now re-introduce the per device debugging while maintaining the
cleanup effort of the previous patch.

The maintain the global debug level and now introduce a per-device debug
level that will be used if it (the per-device debug level) is set. The
per-device debug level can be controlled via the debug_level sysfs file
while the global debug level is controlled by the debug module parameter.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index cab6255..1bf3e4c 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -1175,6 +1175,8 @@
 
 #ifdef CONFIG_IWLWIFI_DEBUG
 	/* debugging info */
+	u32 debug_level; /* per device debugging will override global
+			    iwl_debug_level if set */
 	u32 framecnt_to_us;
 	atomic_t restrict_refcnt;
 	bool disable_ht40;
@@ -1211,8 +1213,27 @@
 
 #ifdef CONFIG_IWLWIFI_DEBUG
 const char *iwl_get_tx_fail_reason(u32 status);
+/*
+ * iwl_get_debug_level: Return active debug level for device
+ *
+ * Using sysfs it is possible to set per device debug level. This debug
+ * level will be used if set, otherwise the global debug level which can be
+ * set via module parameter is used.
+ */
+static inline u32 iwl_get_debug_level(struct iwl_priv *priv)
+{
+	if (priv->debug_level)
+		return priv->debug_level;
+	else
+		return iwl_debug_level;
+}
 #else
 static inline const char *iwl_get_tx_fail_reason(u32 status) { return ""; }
+
+static inline u32 iwl_get_debug_level(struct iwl_priv *priv)
+{
+	return iwl_debug_level;
+}
 #endif