diff --git a/arch/arm/mach-iop13xx/iq81340mc.c b/arch/arm/mach-iop13xx/iq81340mc.c
index a519d707..1ae08cc 100644
--- a/arch/arm/mach-iop13xx/iq81340mc.c
+++ b/arch/arm/mach-iop13xx/iq81340mc.c
@@ -79,7 +79,9 @@
 
 static void __init iq81340mc_timer_init(void)
 {
-	iop_init_time(400000000);
+	unsigned long bus_freq = iop13xx_core_freq() / iop13xx_xsi_bus_ratio();
+	printk(KERN_DEBUG "%s: bus frequency: %lu\n", __FUNCTION__, bus_freq);
+	iop_init_time(bus_freq);
 }
 
 static struct sys_timer iq81340mc_timer = {
diff --git a/arch/arm/mach-iop13xx/iq81340sc.c b/arch/arm/mach-iop13xx/iq81340sc.c
index 0e71fbc..0f88014 100644
--- a/arch/arm/mach-iop13xx/iq81340sc.c
+++ b/arch/arm/mach-iop13xx/iq81340sc.c
@@ -81,7 +81,9 @@
 
 static void __init iq81340sc_timer_init(void)
 {
-	iop_init_time(400000000);
+	unsigned long bus_freq = iop13xx_core_freq() / iop13xx_xsi_bus_ratio();
+	printk(KERN_DEBUG "%s: bus frequency: %lu\n", __FUNCTION__, bus_freq);
+	iop_init_time(bus_freq);
 }
 
 static struct sys_timer iq81340sc_timer = {
diff --git a/include/asm-arm/arch-iop13xx/iop13xx.h b/include/asm-arm/arch-iop13xx/iop13xx.h
index 2d1e23b..c8762ae 100644
--- a/include/asm-arm/arch-iop13xx/iop13xx.h
+++ b/include/asm-arm/arch-iop13xx/iop13xx.h
@@ -455,4 +455,5 @@
 #define IOP13XX_PBI_BAR1      		IOP13XX_PBI_OFFSET(0x10)
 #define IOP13XX_PBI_LR1       		IOP13XX_PBI_OFFSET(0x14)
 
+#define IOP13XX_PROCESSOR_FREQ		IOP13XX_REG_ADDR32(0x2180)
 #endif /* _IOP13XX_HW_H_ */
diff --git a/include/asm-arm/arch-iop13xx/time.h b/include/asm-arm/arch-iop13xx/time.h
index 77a837a..49213d9 100644
--- a/include/asm-arm/arch-iop13xx/time.h
+++ b/include/asm-arm/arch-iop13xx/time.h
@@ -7,9 +7,65 @@
 #define IOP_TMR_PRIVILEGED 0x08
 #define IOP_TMR_RATIO_1_1  0x00
 
+#define IOP13XX_XSI_FREQ_RATIO_MASK	(3 << 19)
+#define IOP13XX_XSI_FREQ_RATIO_2   	(0 << 19)
+#define IOP13XX_XSI_FREQ_RATIO_3	(1 << 19)
+#define IOP13XX_XSI_FREQ_RATIO_4	(2 << 19)
+#define IOP13XX_CORE_FREQ_MASK		(7 << 16)
+#define IOP13XX_CORE_FREQ_600		(0 << 16)
+#define IOP13XX_CORE_FREQ_667		(1 << 16)
+#define IOP13XX_CORE_FREQ_800		(2 << 16)
+#define IOP13XX_CORE_FREQ_933		(3 << 16)
+#define IOP13XX_CORE_FREQ_1000		(4 << 16)
+#define IOP13XX_CORE_FREQ_1200		(5 << 16)
+
 void iop_init_time(unsigned long tickrate);
 unsigned long iop_gettimeoffset(void);
 
+static inline unsigned long iop13xx_core_freq(void)
+{
+	unsigned long freq = __raw_readl(IOP13XX_PROCESSOR_FREQ);
+	freq &= IOP13XX_CORE_FREQ_MASK;
+	switch (freq) {
+	case IOP13XX_CORE_FREQ_600:
+		return 600000000;
+	case IOP13XX_CORE_FREQ_667:
+		return 667000000;
+	case IOP13XX_CORE_FREQ_800:
+		return 800000000;
+	case IOP13XX_CORE_FREQ_933:
+		return 933000000;
+	case IOP13XX_CORE_FREQ_1000:
+		return 1000000000;
+	case IOP13XX_CORE_FREQ_1200:
+		return 1200000000;
+	default:
+		printk("%s: warning unknown frequency, defaulting to 800Mhz\n",
+			__FUNCTION__);
+	}
+
+	return 800000000;
+}
+
+static inline unsigned long iop13xx_xsi_bus_ratio(void)
+{
+	unsigned long  ratio = __raw_readl(IOP13XX_PROCESSOR_FREQ);
+	ratio &= IOP13XX_XSI_FREQ_RATIO_MASK;
+	switch (ratio) {
+	case IOP13XX_XSI_FREQ_RATIO_2:
+		return 2;
+	case IOP13XX_XSI_FREQ_RATIO_3:
+		return 3;
+	case IOP13XX_XSI_FREQ_RATIO_4:
+		return 4;
+	default:
+		printk("%s: warning unknown ratio, defaulting to 2\n",
+			__FUNCTION__);
+	}
+
+	return 2;
+}
+
 static inline void write_tmr0(u32 val)
 {
 	asm volatile("mcr p6, 0, %0, c0, c9, 0" : : "r" (val));