diff --git a/arch/arm/mach-kirkwood/include/mach/kw88f6281.h b/arch/arm/mach-kirkwood/include/mach/kw88f6281.h
index 87406081cf..f86cd0bb60 100644
--- a/arch/arm/mach-kirkwood/include/mach/kw88f6281.h
+++ b/arch/arm/mach-kirkwood/include/mach/kw88f6281.h
@@ -15,6 +15,7 @@
 #define KW_REGS_PHY_BASE		KW88F6281_REGS_PHYS_BASE
 
 /* TCLK Core Clock definition */
-#define CONFIG_SYS_TCLK	200000000 /* 200MHz */
+#define CONFIG_SYS_TCLK			((readl(CONFIG_SAR_REG) & BIT(21)) ? \
+					166666667 : 200000000)
 
 #endif /* _ASM_ARCH_KW88F6281_H */
diff --git a/arch/arm/mach-kirkwood/include/mach/soc.h b/arch/arm/mach-kirkwood/include/mach/soc.h
index 1d7f2828cd..5f545c6f43 100644
--- a/arch/arm/mach-kirkwood/include/mach/soc.h
+++ b/arch/arm/mach-kirkwood/include/mach/soc.h
@@ -62,6 +62,8 @@
 #define MVCPU_WIN_ENABLE	KWCPU_WIN_ENABLE
 #define MVCPU_WIN_DISABLE	KWCPU_WIN_DISABLE
 
+#define CONFIG_SAR_REG		(KW_MPP_BASE + 0x0030)
+
 #if defined (CONFIG_KW88F6281)
 #include <asm/arch/kw88f6281.h>
 #elif defined (CONFIG_KW88F6192)
diff --git a/board/Synology/ds109/ds109.c b/board/Synology/ds109/ds109.c
index 3914faaf37..9e7f6ac6c7 100644
--- a/board/Synology/ds109/ds109.c
+++ b/board/Synology/ds109/ds109.c
@@ -10,6 +10,7 @@
 #include <miiphy.h>
 #include <net.h>
 #include <asm/global_data.h>
+#include <asm/io.h>
 #include <asm/setup.h>
 #include <asm/arch/cpu.h>
 #include <asm/arch/soc.h>