iwlwifi: document the operational mode

Also add a might_sleep to enforce the context requirements.
Signed-off-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/iwl-op-mode.h

@@ -69,17 +69,47 @@ struct sk_buff;
 struct iwl_device_cmd;
 struct iwl_rx_mem_buffer;
 
+/**
+ * DOC: Operational mode - what is it ?
+ *
+ * The operational mode (a.k.a. op_mode) is the layer that implements
+ * mac80211's handlers. It knows two APIs: mac80211's and the fw's. It uses
+ * the transport API to access the HW. The op_mode doesn't need to know how the
+ * underlying HW works, since the transport layer takes care of that.
+ *
+ * There can be several op_mode: i.e. different fw APIs will require two
+ * different op_modes. This is why the op_mode is virtualized.
+ */
+
+/**
+ * DOC: Life cycle of the Operational mode
+ *
+ * The operational mode has a very simple life cycle.
+ *
+ *	1) The driver layer (iwl-drv.c) chooses the op_mode based on the
+ *	   capabilities advertized by the fw file (in TLV format).
+ *	2) The driver layer starts the op_mode (ops->start)
+ *	3) The op_mode registers registers mac80211
+ *	4) The op_mode is governed by mac80211
+ *	5) The driver layer stops the op_mode
+ */
+
 /**
  * struct iwl_op_mode_ops - op_mode specific operations
  *
+ * The op_mode exports its ops so that external components can start it and
+ * interact with it. The driver layer typically calls the start and stop
+ * handlers, the transport layer calls the others.
+ *
  * All the handlers MUST be implemented
  *
- * @start: start the op_mode
+ * @start: start the op_mode. The transport layer is already allocated.
  *	May sleep
- * @stop: stop the op_mode
+ * @stop: stop the op_mode. Must free all the memory allocated.
  *	May sleep
  * @rx: Rx notification to the op_mode. rxb is the Rx buffer itself. Cmd is the
  *	HCMD the this Rx responds to.
+ *	Must be atomic.
  * @queue_full: notifies that a HW queue is full. Ac is the ac of the queue
  *	Must be atomic
  * @queue_not_full: notifies that a HW queue is not full any more.
@@ -120,6 +150,8 @@ struct iwl_op_mode {
 
 static inline void iwl_op_mode_stop(struct iwl_op_mode *op_mode)
 {
+	might_sleep();
+
 	op_mode->ops->stop(op_mode);
 }
 

drivers/net/wireless/iwlwifi/iwl-trans.h

@@ -106,12 +106,6 @@
  *	6) Eventually, the free function will be called.
  */
 
-/**
- * DOC: API needed by the transport layer from the op_mode
- *
- * TODO
- */
-
 struct iwl_priv;
 struct iwl_shared;
 struct iwl_op_mode;