rockchip: add sdram_common for common functions
There are some functions like sdram_size_mb can be re-used for
different rockchip SoCs, just put them into common file.
Add board_get_usable_ram_top() for ram_top init base on
SDRAM_MAX_SIZE.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Added SDRAM_MAX_SIZE definition for RK3036:
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
fixup: 3036 fix for sdram_common
diff --git a/include/configs/rk3188_common.h b/include/configs/rk3188_common.h
index a1e0eb7..7f57dd3 100644
--- a/include/configs/rk3188_common.h
+++ b/include/configs/rk3188_common.h
@@ -64,6 +64,7 @@
#define CONFIG_SYS_SDRAM_BASE 0x60000000
#define CONFIG_NR_DRAM_BANKS 1
#define SDRAM_BANK_SIZE (2UL << 30)
+#define SDRAM_MAX_SIZE 0x80000000
#define CONFIG_SPI_FLASH
#define CONFIG_SPI