由于NXP基于NAND的U-Boot使用了S1L的一些初始化工作，因此需要把S1L中的初始化工作放到U-Boot中。 修改u-boot.lds，将U-Bootd饿入口地址修改为NOR FLASH的物理地址0xE0000000. 24 OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm") 25 OUTPUT_ARCH(arm) 26 ENTRY(_start) 27 SECTIONS 28 { 29 . = 0xE0000000; #修改为NOR FLASH的物理地址 30 31 . = ALIGN(4); 32 .text : 33 { 34 cpu/arm926ejs/start.o (.text) 35 *(.text) 36 } 37 38 . = ALIGN(4); 39 .rodata : { *(.rodata) } 40 41 . = ALIGN(4); 42 .data : { *(.data) } 43 44 . = ALIGN(4); 45 .got : { *(.got) } 46 47 . = .; 48 __u_boot_cmd_start = .; 49 .u_boot_cmd : { *(.u_boot_cmd) } 50 __u_boot_cmd_end = .; 51 52 . = ALIGN(4); 53 __bss_start = .; 54 .bss (NOLOAD) : { *(.bss) } 55 _end = .; 56 } 特别注意，LPC3250芯片，如果要能够基于NOR FLASH启动，必须在NOR FLASH的第一个字写入一个特殊的值，加在异常向量表之前，修改cpu/arm926ejs/start.S文件 51 52 .globl _start 53 _start: 54 .word 0x13579BD1 /* NOR FLASH BOOT, 16-bit Bus-width */ 55 b reset 56 ldr pc, _undefined_instruction 57 ldr pc, _software_interrupt 58 ldr pc, _prefetch_abort 59 ldr pc, _data_abort 60 ldr pc, _not_used 61 ldr pc, _irq 62 ldr pc, _fiq 文件： include/configs/smartarm3250.h 直接从NOR FLASH启动，则不再需要S1L。可以在这个文件中配置，去掉CFG_BOOT_USES1L的宏定义。 34 /* 35 * There are 2 boot options for u-boot on the SmartARM3250 board. Option 1 36 * or option 2. In either cases, u-boot does not need to be relocated. 37 * 38 * Option 1 - define CFG_BOOT_USES1L 39 * With this option, the S1L loader present in the board initializes the 40 * system (including SDRAM, MMUs, some MUX states, etc.). U-boot is loaded 41 * into an already initialized system in SDRAM at address 0x83FC0000 (the 42 * end of SDRAM in a 64M system). Because most of the system is already 43 * initialized, system init is not performed again. 44 * 45 * Option 2 - undefine CFG_BOOT_USES1L 46 * With this option, u-boot is the primary boot loader that is loaded and 47 * started from the Phytec kickstart loader (see documentation with the 48 * Phytec board for the kickstart loader). In this configuration, u-boot 49 * loads and runs from RAM at address 0x00000000 and requires complete 50 * system initialization. The kickstart loader will copy the u-boot image 51 * from FLASH starting at block 1 into IRAM and start it at address 0x0. 52 */ 53 #define CFG_BOOT_USES1L 54 55 #ifdef CFG_BOOT_USES1L 56 /* 57 * Skip low level init of MMU, SDRAM, muxing, etc. if u-boot is loaded 58 * and executed from S1L 59 */ 60 #define CONFIG_SKIP_LOWLEVEL_INIT 61 #endif 文件： board/zhiyuan/smartarm3250/lowlevelsys_init.c212 /* 213 * Miscellaneous platform dependent initializations 214 */ 215 void phy3250_sys_init(void) 216 { 217 /* Get board information to determine DRAM size and MAC address */ 218 phy3250_get_board_info(); 219 220 #ifndef CFG_BOOT_USES1L 221 /* Initialize system including clocking, SDRAM, muxing, MMU, etc. */ //需要在这里进行时钟、SDRAM、MUXING、MMU等初始化。 222 /* TBD stubbed */ 223 #endif 224 } 增加NOR FLASH支持： 在board/zhiyuan/smartarm3250/目录下增加flash.c和flash_common.c两个文件（参考了EPC-8000的U-Boot）。 |