Index: linux-2.6/include/linux/irq.h
===================================================================
--- linux-2.6.orig/include/linux/irq.h
+++ linux-2.6/include/linux/irq.h
@@ -119,6 +119,7 @@ struct irq_domain;
 
 /**
  * struct irq_data - per irq and irq chip data passed down to chip functions
+ * @mask:		precomputed bitmask for accessing the chip registers
  * @irq:		interrupt number
  * @hwirq:		hardware interrupt number, local to the interrupt domain
  * @node:		node index useful for balancing
@@ -138,6 +139,7 @@ struct irq_domain;
  * irq_data.
  */
 struct irq_data {
+	u32			mask;
 	unsigned int		irq;
 	unsigned long		hwirq;
 	unsigned int		node;
@@ -705,11 +707,13 @@ struct irq_chip_generic {
  *				irq chips which need to call irq_set_wake() on
  *				the parent irq. Usually GPIO implementations
  * @IRQ_GC_MASK_CACHE_PER_TYPE:	Mask cache is chip type private
+ * @IRQ_GC_NO_MASK:		Do not calculate irq_data->mask
  */
 enum irq_gc_flags {
 	IRQ_GC_INIT_MASK_CACHE		= 1 << 0,
 	IRQ_GC_INIT_NESTED_LOCK		= 1 << 1,
 	IRQ_GC_MASK_CACHE_PER_TYPE	= 1 << 2,
+	IRQ_GC_NO_MASK			= 1 << 3,
 };
 
 /* Generic chip callback functions */
Index: linux-2.6/kernel/irq/generic-chip.c
===================================================================
--- linux-2.6.orig/kernel/irq/generic-chip.c
+++ linux-2.6/kernel/irq/generic-chip.c
@@ -35,7 +35,7 @@ void irq_gc_mask_disable_reg(struct irq_
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.disable);
@@ -54,7 +54,7 @@ void irq_gc_mask_set_bit(struct irq_data
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	*ct->mask_cache |= mask;
@@ -73,7 +73,7 @@ void irq_gc_mask_clr_bit(struct irq_data
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	*ct->mask_cache &= ~mask;
@@ -92,7 +92,7 @@ void irq_gc_unmask_enable_reg(struct irq
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.enable);
@@ -108,7 +108,7 @@ void irq_gc_ack_set_bit(struct irq_data 
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.ack);
@@ -123,7 +123,7 @@ void irq_gc_ack_clr_bit(struct irq_data 
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = ~(1 << (d->irq - gc->irq_base));
+	u32 mask = ~(d->mask);
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.ack);
@@ -138,7 +138,7 @@ void irq_gc_mask_disable_reg_and_ack(str
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.mask);
@@ -154,7 +154,7 @@ void irq_gc_eoi(struct irq_data *d)
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	struct irq_chip_type *ct = irq_data_get_chip_type(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	irq_gc_lock(gc);
 	irq_reg_writel(mask, gc->reg_base + ct->regs.eoi);
@@ -172,7 +172,7 @@ void irq_gc_eoi(struct irq_data *d)
 int irq_gc_set_wake(struct irq_data *d, unsigned int on)
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
-	u32 mask = 1 << (d->irq - gc->irq_base);
+	u32 mask = d->mask;
 
 	if (!(mask & gc->wake_enabled))
 		return -EINVAL;
@@ -264,6 +264,11 @@ void irq_setup_generic_chip(struct irq_c
 		if (flags & IRQ_GC_INIT_NESTED_LOCK)
 			irq_set_lockdep_class(i, &irq_nested_lock_class);
 
+		if (!(flags & IRQ_GC_NO_MASK)) {
+			struct irq_data *d = irq_get_irq_data(i);
+
+			d->mask = 1 << (i - gc->irq_base);
+		}
 		irq_set_chip_and_handler(i, &ct->chip, ct->handler);
 		irq_set_chip_data(i, gc);
 		irq_modify_status(i, clr, set);
