diff --git a/cpu/mpc83xx/serdes.c b/cpu/mpc83xx/serdes.c
index 630b111..3936796 100644
--- a/cpu/mpc83xx/serdes.c
+++ b/cpu/mpc83xx/serdes.c
@@ -42,7 +42,7 @@
 #define FSL_SRDSRSTCTL_RST		0x80000000
 #define FSL_SRDSRSTCTL_SATA_RESET	0xf
 
-void fsl_setup_serdes(u32 offset, char proto, char rfcks, char vdd)
+void fsl_setup_serdes(u32 offset, char proto, u32 rfcks, char vdd)
 {
 	void *regs = (void *)CONFIG_SYS_IMMR + offset;
 	u32 tmp;
diff --git a/include/asm-ppc/fsl_serdes.h b/include/asm-ppc/fsl_serdes.h
index 733f919..6da4b6f 100644
--- a/include/asm-ppc/fsl_serdes.h
+++ b/include/asm-ppc/fsl_serdes.h
@@ -3,9 +3,9 @@
 
 #include <config.h>
 
-#define FSL_SERDES_CLK_100		0
-#define FSL_SERDES_CLK_125		1
-#define FSL_SERDES_CLK_150		3
+#define FSL_SERDES_CLK_100		(0 << 28)
+#define FSL_SERDES_CLK_125		(1 << 28)
+#define FSL_SERDES_CLK_150		(3 << 28)
 #define FSL_SERDES_PROTO_SATA		0
 #define FSL_SERDES_PROTO_PEX		1
 #define FSL_SERDES_PROTO_PEX_X2		2
@@ -13,9 +13,9 @@
 #define FSL_SERDES_VDD_1V		1
 
 #ifdef CONFIG_FSL_SERDES
-extern void fsl_setup_serdes(u32 offset, char proto, char rfcks, char vdd);
+extern void fsl_setup_serdes(u32 offset, char proto, u32 rfcks, char vdd);
 #else
-static void fsl_setup_serdes(u32 offset, char proto, char rfcks, char vdd) {}
+static void fsl_setup_serdes(u32 offset, char proto, u32 rfcks, char vdd) {}
 #endif /* CONFIG_FSL_SERDES */
 
 #endif /* __FSL_SERDES_H */