genirq: irqchip: Add a mask calculation function

Some chips have weird bit mask access patterns instead of the linear
you expect. Allow them to calculate the cached mask themself.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jean-Francois Moine <moinejf@free.fr>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Gerlando Falauto <gerlando.falauto@keymile.com>
Cc: Rob Landley <rob@landley.net>
Acked-by: Grant Likely <grant.likely@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Link: http://lkml.kernel.org/r/20130506142539.302898834@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irq.h

@@ -296,6 +296,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
  * @irq_suspend:	function called from core code on suspend once per chip
  * @irq_resume:		function called from core code on resume once per chip
  * @irq_pm_shutdown:	function called from core code on shutdown once per chip
+ * @irq_calc_mask:	Optional function to set irq_data.mask for special cases
  * @irq_print_chip:	optional to print special chip info in show_interrupts
  * @flags:		chip specific flags
  */
@@ -327,6 +328,8 @@ struct irq_chip {
 	void		(*irq_resume)(struct irq_data *data);
 	void		(*irq_pm_shutdown)(struct irq_data *data);
 
+	void		(*irq_calc_mask)(struct irq_data *data);
+
 	void		(*irq_print_chip)(struct irq_data *data, struct seq_file *p);
 
 	unsigned long	flags;

kernel/irq/generic-chip.c

@@ -240,6 +240,7 @@ void irq_setup_generic_chip(struct irq_chip_generic *gc, u32 msk,
 			    unsigned int set)
 {
 	struct irq_chip_type *ct = gc->chip_types;
+	struct irq_chip *chip = &ct->chip;
 	unsigned int i;
 	u32 *mskptr = &gc->mask_cache, mskreg = ct->regs.mask;
 
@@ -267,9 +268,12 @@ void irq_setup_generic_chip(struct irq_chip_generic *gc, u32 msk,
 		if (!(flags & IRQ_GC_NO_MASK)) {
 			struct irq_data *d = irq_get_irq_data(i);
 
-			d->mask = 1 << (i - gc->irq_base);
+			if (chip->irq_calc_mask)
+				chip->irq_calc_mask(d);
+			else
+				d->mask = 1 << (i - gc->irq_base);
 		}
-		irq_set_chip_and_handler(i, &ct->chip, ct->handler);
+		irq_set_chip_and_handler(i, chip, ct->handler);
 		irq_set_chip_data(i, gc);
 		irq_modify_status(i, clr, set);
 	}