diff --git a/arch/sh/boards/mach-dreamcast/irq.c b/arch/sh/boards/mach-dreamcast/irq.c
index cc06e4cdb4cdf9..0eec82fb85e7c6 100644
--- a/arch/sh/boards/mach-dreamcast/irq.c
+++ b/arch/sh/boards/mach-dreamcast/irq.c
@@ -108,13 +108,13 @@ int systemasic_irq_demux(int irq)
 	__u32 j, bit;
 
 	switch (irq) {
-	case 13:
+	case 13 + 16:
 		level = 0;
 		break;
-	case 11:
+	case 11 + 16:
 		level = 1;
 		break;
-	case  9:
+	case 9 + 16:
 		level = 2;
 		break;
 	default:
diff --git a/arch/sh/boards/mach-highlander/setup.c b/arch/sh/boards/mach-highlander/setup.c
index 533393d779c2b9..01565660a66950 100644
--- a/arch/sh/boards/mach-highlander/setup.c
+++ b/arch/sh/boards/mach-highlander/setup.c
@@ -389,10 +389,10 @@ static unsigned char irl2irq[HL_NR_IRL];
 
 static int highlander_irq_demux(int irq)
 {
-	if (irq >= HL_NR_IRL || irq < 0 || !irl2irq[irq])
+	if (irq >= HL_NR_IRL + 16 || irq < 16 || !irl2irq[irq - 16])
 		return irq;
 
-	return irl2irq[irq];
+	return irl2irq[irq - 16];
 }
 
 static void __init highlander_init_irq(void)
diff --git a/arch/sh/boards/mach-r2d/irq.c b/arch/sh/boards/mach-r2d/irq.c
index e34f81e9ae813b..d0a54a9adbce20 100644
--- a/arch/sh/boards/mach-r2d/irq.c
+++ b/arch/sh/boards/mach-r2d/irq.c
@@ -117,10 +117,10 @@ static unsigned char irl2irq[R2D_NR_IRL];
 
 int rts7751r2d_irq_demux(int irq)
 {
-	if (irq >= R2D_NR_IRL || irq < 0 || !irl2irq[irq])
+	if (irq >= R2D_NR_IRL + 16 || irq < 16 || !irl2irq[irq - 16])
 		return irq;
 
-	return irl2irq[irq];
+	return irl2irq[irq - 16];
 }
 
 /*
diff --git a/arch/sh/cchips/Kconfig b/arch/sh/cchips/Kconfig
index efde2edb562780..9659a0bc58dec4 100644
--- a/arch/sh/cchips/Kconfig
+++ b/arch/sh/cchips/Kconfig
@@ -29,9 +29,9 @@ endchoice
 config HD64461_IRQ
 	int "HD64461 IRQ"
 	depends on HD64461
-	default "36"
+	default "52"
 	help
-	  The default setting of the HD64461 IRQ is 36.
+	  The default setting of the HD64461 IRQ is 52.
 
 	  Do not change this unless you know what you are doing.
 
diff --git a/arch/sh/include/asm/hd64461.h b/arch/sh/include/asm/hd64461.h
index afb24cb034b114..d2c485fa333b51 100644
--- a/arch/sh/include/asm/hd64461.h
+++ b/arch/sh/include/asm/hd64461.h
@@ -229,7 +229,7 @@
 #define	HD64461_NIMR		HD64461_IO_OFFSET(0x5002)
 
 #define	HD64461_IRQBASE		OFFCHIP_IRQ_BASE
-#define	OFFCHIP_IRQ_BASE	64
+#define	OFFCHIP_IRQ_BASE	(64 + 16)
 #define	HD64461_IRQ_NUM		16
 
 #define	HD64461_IRQ_UART	(HD64461_IRQBASE+5)