microblaze: Add comment about NR_IRQS macro calculation

Improve readability of the code.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

diff --git a/arch/microblaze/include/asm/irq.h b/arch/microblaze/include/asm/irq.h
index d785defeeed58e0927c4d5de221c6e623b8590c8..c253239419810ba78e6f2af28c950a96d2988e47 100644 (file)
--- a/arch/microblaze/include/asm/irq.h
+++ b/arch/microblaze/include/asm/irq.h
@@ -9,7 +9,12 @@
 #ifndef _ASM_MICROBLAZE_IRQ_H
 #define _ASM_MICROBLAZE_IRQ_H
 
+/*
+ * Linux IRQ# is currently offset by one to map to the hardware
+ * irq number. So hardware IRQ0 maps to Linux irq 1.
+ */
 #define NR_IRQS                (32 + 1)
+
 #include <asm-generic/irq.h>
 
 struct pt_regs;