在uboot 下初始化nand，一般需要做如下工作：
第一： 配置默认从NAND boot
Index: include/configs/am335x_evm.h
===================================================================
--- include/configs/am335x_evm.h (revision 8)
+++ include/configs/am335x_evm.h (revision 9)
@@ -17,9 +17,11 @@
#define __CONFIG_AM335X_EVM_H
#include <configs/ti_am335x_common.h>
-#define CONFIG_SD_BOOT
+/*#define CONFIG_SD_BOOT*/
+#define CONFIG_NAND_BOOT
#define CONFIG_PHY_MICREL
#define CONFIG_PHY_MICREL_KSZ8XXX
#ifndef CONFIG_SPL_BUILD
# define CONFIG_TIMESTAMP
第二，nand 相应的引脚做初始化
===================================================================
--- board/ti/am335x/mux.c (revision 8)
+++ board/ti/am335x/mux.c (revision 9)
@@ -422,4 +422,5 @@
configure_module_pin_mux(gpio0_7_pin_mux);
configure_module_pin_mux(rmii1_pin_mux);
configure_module_pin_mux(mmc0_pin_mux_sk_evm);
+ configure_module_pin_mux(nand_pin_mux);
}
第三：指定uboot变量何存至uboot-env分区
Index: Kconfig
===================================================================
--- Kconfig (revision 13)
+++ Kconfig (revision 14)
@@ -22,7 +22,7 @@
default ENV_IS_IN_SPI_FLASH if INTEL_QUARK
default ENV_IS_IN_SPI_FLASH if INTEL_QUEENSBAY
default ENV_IS_IN_FAT if ARCH_BCM283X
- default ENV_IS_IN_FAT if MMC_OMAP_HS && TI_COMMON_CMD_OPTIONS
+ default ENV_IS_IN_NAND if TI_COMMON_CMD_OPTIONS
default ENV_IS_NOWHERE
help
At present the environment can be stored in only one place. Use this
第四：指nand env的大小
Index: am335x_evm.h
===================================================================
--- am335x_evm.h (revision 15)
+++ am335x_evm.h (revision 16)
@@ -301,6 +301,7 @@
#define CONFIG_ENV_OFFSET_REDUND (768 << 10) /* 768 KiB */
#elif defined(CONFIG_ENV_IS_IN_NAND)
#define CONFIG_ENV_OFFSET 0x001c0000
+#define CONFIG_ENV_SIZE (128 << 10) /* 128 KiB */
/*#define CONFIG_ENV_OFFSET_REDUND 0x001e0000*/
#define CONFIG_SYS_ENV_SECT_SIZE CONFIG_SYS_NAND_BLOCK_SIZE
#endif
第五： 需要修改默认的bootcmd从nand启动
Index: am335x_evm_defconfig
===================================================================
--- am335x_evm_defconfig (revision 15)
+++ am335x_evm_defconfig (revision 16)
@@ -6,7 +6,7 @@
CONFIG_DISTRO_DEFAULTS=y
CONFIG_SPL_SYS_MALLOC_F_LEN=0x1000
CONFIG_SPL_LOAD_FIT=y
-CONFIG_BOOTCOMMAND="if test ${boot_fit} -eq 1; then run update_to_fit; fi; run findfdt; run init_console; run envboot; run distro_bootcmd"
+CONFIG_BOOTCOMMAND="run nandboot"
CONFIG_LOGLEVEL=3
CONFIG_SYS_CONSOLE_INFO_QUIET=y
CONFIG_VERSION_VARIABLE=y
经过上述修改之后，便可以默认从NAND引导，uboot环境变量保存至uboot-env分区
boot log:
U-Boot SPL 2018.01-svn16 (Nov 22 2018 - 15:56:43)
Trying to boot from NAND
U-Boot 2018.01-svn16 (Nov 22 2018 - 15:56:43 +0800)
CPU : AM335X-GP rev 2.1
Model: TI AM335x EVM
DRAM: 256 MiB
NAND: 256 MiB
MMC: OMAP SD/MMC: 0
Net: cpsw
Hit any key to stop autoboot: 0