MIPS: ralink: add memory definition for MT7620

Populate struct soc_info with the data that describes our RAM window.
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5183/

arch/mips/include/asm/mach-ralink/mt7620.h

@@ -50,6 +50,14 @@
 #define SYSCFG0_DRAM_TYPE_DDR1		1
 #define SYSCFG0_DRAM_TYPE_DDR2		2
 
+#define MT7620_DRAM_BASE		0x0
+#define MT7620_SDRAM_SIZE_MIN		2
+#define MT7620_SDRAM_SIZE_MAX		64
+#define MT7620_DDR1_SIZE_MIN		32
+#define MT7620_DDR1_SIZE_MAX		128
+#define MT7620_DDR2_SIZE_MIN		32
+#define MT7620_DDR2_SIZE_MAX		256
+
 #define MT7620_GPIO_MODE_I2C		BIT(0)
 #define MT7620_GPIO_MODE_UART0_SHIFT	2
 #define MT7620_GPIO_MODE_UART0_MASK	0x7

arch/mips/ralink/mt7620.c

@@ -211,4 +211,24 @@ void prom_soc_init(struct ralink_soc_info *soc_info)
 
 	cfg0 = __raw_readl(sysc + SYSC_REG_SYSTEM_CONFIG0);
 	dram_type = (cfg0 >> SYSCFG0_DRAM_TYPE_SHIFT) & SYSCFG0_DRAM_TYPE_MASK;
+
+	switch (dram_type) {
+	case SYSCFG0_DRAM_TYPE_SDRAM:
+		soc_info->mem_size_min = MT7620_SDRAM_SIZE_MIN;
+		soc_info->mem_size_max = MT7620_SDRAM_SIZE_MAX;
+		break;
+
+	case SYSCFG0_DRAM_TYPE_DDR1:
+		soc_info->mem_size_min = MT7620_DDR1_SIZE_MIN;
+		soc_info->mem_size_max = MT7620_DDR1_SIZE_MAX;
+		break;
+
+	case SYSCFG0_DRAM_TYPE_DDR2:
+		soc_info->mem_size_min = MT7620_DDR2_SIZE_MIN;
+		soc_info->mem_size_max = MT7620_DDR2_SIZE_MAX;
+		break;
+	default:
+		BUG();
+	}
+	soc_info->mem_base = MT7620_DRAM_BASE;
 }