diff --git a/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt288x/ralink_soc.h b/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt288x/ralink_soc.h
index c379f3919..60ca647d8 100644
--- a/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt288x/ralink_soc.h
+++ b/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt288x/ralink_soc.h
@@ -11,6 +11,10 @@
 #ifndef __RT288X_RALINK_SOC_H
 #define __RT288X_RALINK_SOC_H
 
+#define RALINK_SOC_SDRAM_BASE		0x08000000
+#define RALINK_SOC_MEM_SIZE_MIN		(2 * 1024 * 1024)
+#define RALINK_SOC_MEM_SIZE_MAX		(128 * 1024 * 1024)
+
 #define RALINK_SOC_GPIO_BASE	0x300600
 
 #define RALINK_SOC_GPIO0_COUNT	24
diff --git a/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt305x/ralink_soc.h b/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt305x/ralink_soc.h
index 144cc4ea4..fd0e8b304 100644
--- a/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt305x/ralink_soc.h
+++ b/target/linux/ramips/files/arch/mips/include/asm/mach-ralink/rt305x/ralink_soc.h
@@ -11,6 +11,10 @@
 #ifndef __RT288X_RALINK_SOC_H
 #define __RT288X_RALINK_SOC_H
 
+#define RALINK_SOC_SDRAM_BASE		0
+#define RALINK_SOC_MEM_SIZE_MIN		(2 * 1024 * 1024)
+#define RALINK_SOC_MEM_SIZE_MAX		(64 * 1024 * 1024)
+
 #define RALINK_SOC_GPIO_BASE	0x10000600
 
 #define RALINK_SOC_GPIO0_COUNT	24
diff --git a/target/linux/ramips/files/arch/mips/ralink/common/setup.c b/target/linux/ramips/files/arch/mips/ralink/common/setup.c
index 6440ccb01..86e951ca2 100644
--- a/target/linux/ramips/files/arch/mips/ralink/common/setup.c
+++ b/target/linux/ramips/files/arch/mips/ralink/common/setup.c
@@ -13,12 +13,30 @@
 #include <linux/init.h>
 #include <linux/io.h>
 
+#include <asm/bootinfo.h>
 #include <asm/addrspace.h>
+
 #include <asm/mach-ralink/common.h>
+#include <ralink_soc.h>
+
+static void __init detect_mem_size(void)
+{
+	unsigned long size;
+
+	for (size = RALINK_SOC_MEM_SIZE_MIN; size < RALINK_SOC_MEM_SIZE_MAX;
+	     size <<= 1 ) {
+		if (!memcmp(detect_mem_size,
+			    detect_mem_size + size, 1024))
+			break;
+	}
+
+	add_memory_region(RALINK_SOC_SDRAM_BASE, size, BOOT_MEM_RAM);
+}
 
 void __init plat_mem_setup(void)
 {
 	set_io_port_base(KSEG1);
 
+	detect_mem_size();
 	ramips_soc_setup();
 }
diff --git a/target/linux/ramips/files/arch/mips/ralink/rt288x/setup.c b/target/linux/ramips/files/arch/mips/ralink/rt288x/setup.c
index fe94126e5..920f44ae4 100644
--- a/target/linux/ramips/files/arch/mips/ralink/rt288x/setup.c
+++ b/target/linux/ramips/files/arch/mips/ralink/rt288x/setup.c
@@ -16,7 +16,6 @@
 #include <linux/io.h>
 #include <linux/serial_8250.h>
 
-#include <asm/bootinfo.h>
 #include <asm/mips_machine.h>
 #include <asm/reboot.h>
 #include <asm/time.h>
@@ -25,9 +24,6 @@
 #include <asm/mach-ralink/rt288x.h>
 #include <asm/mach-ralink/rt288x_regs.h>
 
-#define RT288X_MEM_SIZE_MIN (2 * 1024 * 1024)
-#define RT288X_MEM_SIZE_MAX (128 * 1024 * 1024)
-
 unsigned long rt288x_mach_type;
 
 static void rt288x_restart(char *command)
@@ -44,20 +40,6 @@ static void rt288x_halt(void)
 		cpu_wait();
 }
 
-static void __init rt288x_detect_mem_size(void)
-{
-	unsigned long size;
-
-	for (size = RT288X_MEM_SIZE_MIN; size < RT288X_MEM_SIZE_MAX;
-	     size <<= 1 ) {
-		if (!memcmp(rt288x_detect_mem_size,
-			    rt288x_detect_mem_size + size, 1024))
-			break;
-	}
-
-	add_memory_region(RT2880_SDRAM_BASE, size, BOOT_MEM_RAM);
-}
-
 static void __init rt288x_early_serial_setup(void)
 {
 	struct uart_port p;
@@ -106,7 +88,6 @@ void __init ramips_soc_setup(void)
 	rt288x_sysc_base = ioremap_nocache(RT2880_SYSC_BASE, RT2880_SYSC_SIZE);
 	rt288x_memc_base = ioremap_nocache(RT2880_MEMC_BASE, RT2880_MEMC_SIZE);
 
-	rt288x_detect_mem_size();
 	rt288x_detect_sys_type();
 	rt288x_detect_sys_freq();
 
diff --git a/target/linux/ramips/files/arch/mips/ralink/rt305x/setup.c b/target/linux/ramips/files/arch/mips/ralink/rt305x/setup.c
index 70eaae425..3aa6c9b9f 100644
--- a/target/linux/ramips/files/arch/mips/ralink/rt305x/setup.c
+++ b/target/linux/ramips/files/arch/mips/ralink/rt305x/setup.c
@@ -15,7 +15,6 @@
 #include <linux/io.h>
 #include <linux/serial_8250.h>
 
-#include <asm/bootinfo.h>
 #include <asm/mips_machine.h>
 #include <asm/reboot.h>
 #include <asm/time.h>
@@ -43,20 +42,6 @@ static void rt305x_halt(void)
 			cpu_wait();
 }
 
-static void __init rt305x_detect_mem_size(void)
-{
-	unsigned long size;
-
-	for (size = RT305X_MEM_SIZE_MIN; size < RT305X_MEM_SIZE_MAX;
-	     size <<= 1 ) {
-		if (!memcmp(rt305x_detect_mem_size,
-			    rt305x_detect_mem_size + size, 1024))
-			break;
-	}
-
-	add_memory_region(RT305X_SDRAM_BASE, size, BOOT_MEM_RAM);
-}
-
 static void __init rt305x_early_serial_setup(void)
 {
 	struct uart_port p;
@@ -105,7 +90,6 @@ void __init ramips_soc_setup(void)
 	rt305x_sysc_base = ioremap_nocache(RT305X_SYSC_BASE, PAGE_SIZE);
 	rt305x_memc_base = ioremap_nocache(RT305X_MEMC_BASE, PAGE_SIZE);
 
-	rt305x_detect_mem_size();
 	rt305x_detect_sys_type();
 	rt305x_detect_sys_freq();