genirq: add doc to struct irqaction

Impact: documentation

struct irqaction is not documented. Add kernel doc comments and add
interrupt.h to the genirq docbook.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Documentation/DocBook/genericirq.tmpl

@@ -440,6 +440,7 @@ desc->chip->end();
      used in the generic IRQ layer.
      </para>
 !Iinclude/linux/irq.h
+!Iinclude/linux/interrupt.h
   </chapter>
 
   <chapter id="pubfunctions">

include/linux/interrupt.h

@@ -61,6 +61,17 @@
 
 typedef irqreturn_t (*irq_handler_t)(int, void *);
 
+/**
+ * struct irqaction - per interrupt action descriptor
+ * @handler:	interrupt handler function
+ * @flags:	flags (see IRQF_* above)
+ * @mask:	no comment as it is useless and about to be removed
+ * @name:	name of the device
+ * @dev_id:	cookie to identify the device
+ * @next:	pointer to the next irqaction for shared interrupts
+ * @irq:	interrupt number
+ * @dir:	pointer to the proc/irq/NN/name entry
+ */
 struct irqaction {
 	irq_handler_t handler;
 	unsigned long flags;