mfd: ab8500-core: Ignore masked out interrupts

AB8500 asserts LATCH bits for masked out interrupts.  This patch
explicitly masks those out using the cached mask value to prevent
handle_nested_irq() being called for masked IRQ on the same register as
unmasked ones.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/ab8500-core.c

@@ -458,11 +458,7 @@ static void update_latch_offset(u8 *offset, int i)
 static int ab8500_handle_hierarchical_line(struct ab8500 *ab8500,
 					int latch_offset, u8 latch_val)
 {
-	int int_bit = __ffs(latch_val);
-	int line, i;
-
-	do {
-		int_bit = __ffs(latch_val);
+	int int_bit, line, i;
 
 	for (i = 0; i < ab8500->mask_size; i++)
 		if (ab8500->irq_reg_offset[i] == latch_offset)
@@ -474,6 +470,11 @@ static int ab8500_handle_hierarchical_line(struct ab8500 *ab8500,
 		return -ENXIO;
 	}
 
+	/* ignore masked out interrupts */
+	latch_val &= ~ab8500->mask[i];
+
+	while (latch_val) {
+		int_bit = __ffs(latch_val);
 		line = (i << 3) + int_bit;
 		latch_val &= ~(1 << int_bit);
 
@@ -491,7 +492,7 @@ static int ab8500_handle_hierarchical_line(struct ab8500 *ab8500,
 			line += 1;
 
 		handle_nested_irq(ab8500->irq_base + line);
-	} while (latch_val);
+	}
 
 	return 0;
 }