genirq: Add state field to irq_data

Some chip implementations need to access certain status flags. With
sparse irqs that requires a lookup of the irq descriptor. Add a state
field which contains such flags.

Name it in a way which will make coders happy to access it with the
proper accessor functions. And it's easy to grep for.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irq.h

@@ -102,6 +102,8 @@ struct msi_desc;
  * struct irq_data - per irq and irq chip data passed down to chip functions
  * @irq:		interrupt number
  * @node:		node index useful for balancing
+ * @state_use_accessor: status information for irq chip functions.
+ *			Use accessor functions to deal with it
  * @chip:		low level interrupt hardware access
  * @handler_data:	per-IRQ data for the irq_chip methods
  * @chip_data:		platform-specific per-chip private data for the chip
@@ -116,6 +118,7 @@ struct msi_desc;
 struct irq_data {
 	unsigned int		irq;
 	unsigned int		node;
+	unsigned int		state_use_accessors;
 	struct irq_chip		*chip;
 	void			*handler_data;
 	void			*chip_data;

include/linux/irqdesc.h

@@ -48,6 +48,7 @@ struct irq_desc {
 		struct {
 			unsigned int		irq;
 			unsigned int		node;
+			unsigned int		pad_do_not_even_think_about_it;
 			struct irq_chip		*chip;
 			void			*handler_data;
 			void			*chip_data;