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AM335x(TQ335x)学习笔记——u-boot-2014.10移植
最近移植了下u-boot-2014.10到TQ335x,如果基于am335x evm进行移植,需要修改的地方并不多。
由于TI的am335x evm开发使用了一个eeprom保存了板载配置信息,用来区分不同板子的型号的,而TQ335x没有这个eeprom,因此,需要修改eeprom相关的部分,使u-boot适应TQ335x开发板。
使用source insight查看代码,很容易发现,所有获取板载配置的部分都是通过读取eeprom获得的,因此,首选修改read_eeprom(board/ti/am335x/board.c)函数,具体的修改如下:
static int read_eeprom(struct am335x_baseboard_id *header) { #if 1 strcpy(header->name, "TQ335x"); #else /* Check if baseboard eeprom is available */ if (i2c_probe(CONFIG_SYS_I2C_EEPROM_ADDR)) { puts("Could not probe the EEPROM; something fundamentally " "wrong on the I2C bus.\n"); return -ENODEV; } /* read the eeprom using i2c */ if (i2c_read(CONFIG_SYS_I2C_EEPROM_ADDR, 0, 2, (uchar *)header, sizeof(struct am335x_baseboard_id))) { puts("Could not read the EEPROM; something fundamentally" " wrong on the I2C bus.\n"); return -EIO; } if (header->magic != 0xEE3355AA) { /* * read the eeprom using i2c again, * but use only a 1 byte address */ if (i2c_read(CONFIG_SYS_I2C_EEPROM_ADDR, 0, 1, (uchar *)header, sizeof(struct am335x_baseboard_id))) { puts("Could not read the EEPROM; something " "fundamentally wrong on the I2C bus.\n"); return -EIO; } if (header->magic != 0xEE3355AA) { printf("Incorrect magic number (0x%x) in EEPROM\n", header->magic); return -EINVAL; } } #endif return 0; }通过上述修改,u-boot不去读取eeprom,而是直接将header的name赋值为"TQ335x",后面可以根据这一配置区分是否为TQ335x开发板。
然后是修改get_dpll_ddr_params(board/ti/am335x/board.c)函数,具体的修改内容如下:
const struct dpll_params *get_dpll_ddr_params(void) { struct am335x_baseboard_id header; enable_i2c0_pin_mux(); i2c_init(CONFIG_SYS_OMAP24_I2C_SPEED, CONFIG_SYS_OMAP24_I2C_SLAVE); if (read_eeprom(&header) < 0) puts("Could not get board ID.\n"); if (board_is_tq335x(&header) || board_is_evm_sk(&header)) return &dpll_ddr_evm_sk; else if (board_is_bone_lt(&header)) return &dpll_ddr_bone_black; else if (board_is_evm_15_or_later(&header)) return &dpll_ddr_evm_sk; else return &dpll_ddr; }然后是修改sdram_init(board/ti/am335x/board.c)函数,具体的修改内容如下:
void sdram_init(void) { __maybe_unused struct am335x_baseboard_id header; if (read_eeprom(&header) < 0) puts("Could not get board ID.\n"); if (board_is_evm_sk(&header)) { /* * EVM SK 1.2A and later use gpio0_7 to enable DDR3. * This is safe enough to do on older revs. */ gpio_request(GPIO_DDR_VTT_EN, "ddr_vtt_en"); gpio_direction_output(GPIO_DDR_VTT_EN, 1); } if (board_is_evm_sk(&header) || board_is_tq335x(&header)) config_ddr(303, &ioregs_evmsk, &ddr3_data, &ddr3_cmd_ctrl_data, &ddr3_emif_reg_data, 0); else if (board_is_bone_lt(&header)) config_ddr(400, &ioregs_bonelt, &ddr3_beagleblack_data, &ddr3_beagleblack_cmd_ctrl_data, &ddr3_beagleblack_emif_reg_data, 0); else if (board_is_evm_15_or_later(&header)) config_ddr(303, &ioregs_evm15, &ddr3_evm_data, &ddr3_evm_cmd_ctrl_data, &ddr3_evm_emif_reg_data, 0); else config_ddr(266, &ioregs, &ddr2_data, &ddr2_cmd_ctrl_data, &ddr2_emif_reg_data, 0); }然后添加board_is_tq335x函数的具体实现,参考其它类似函数实现即可,由于我们的read_eeprom仅读到了name,其内容是"TQ335x",故可如下实现,在board/ti/am335x/board.h中添加如下内容:
static inline int board_is_tq335x(struct am335x_baseboard_id *header) { return !strncmp(header->name, "TQ335x", HDR_NAME_LEN); }最后是修改enable_board_pin_mux(board/ti/am335x/mux.c)函数,具体的修改内容如下:
void enable_board_pin_mux(struct am335x_baseboard_id *header) { /* Do board-specific muxes. */ if (board_is_bone(header) || board_is_tq335x(header)) { /* Beaglebone pinmux */ configure_module_pin_mux(i2c1_pin_mux); configure_module_pin_mux(mii1_pin_mux); configure_module_pin_mux(mmc0_pin_mux); #if defined(CONFIG_NAND) configure_module_pin_mux(nand_pin_mux); #elif defined(CONFIG_NOR) configure_module_pin_mux(bone_norcape_pin_mux); #else configure_module_pin_mux(mmc1_pin_mux); #endif } else if (board_is_gp_evm(header)) { /* General Purpose EVM */ unsigned short profile = detect_daughter_board_profile(); configure_module_pin_mux(rgmii1_pin_mux); configure_module_pin_mux(mmc0_pin_mux); /* In profile #2 i2c1 and spi0 conflict. */ if (profile & ~PROFILE_2) configure_module_pin_mux(i2c1_pin_mux); /* Profiles 2 & 3 don't have NAND */ #ifdef CONFIG_NAND if (profile & ~(PROFILE_2 | PROFILE_3)) configure_module_pin_mux(nand_pin_mux); #endif else if (profile == PROFILE_2) { configure_module_pin_mux(mmc1_pin_mux); configure_module_pin_mux(spi0_pin_mux); } } else if (board_is_idk(header)) { /* Industrial Motor Control (IDK) */ configure_module_pin_mux(mii1_pin_mux); configure_module_pin_mux(mmc0_no_cd_pin_mux); } else if (board_is_evm_sk(header)) { /* Starter Kit EVM */ configure_module_pin_mux(i2c1_pin_mux); configure_module_pin_mux(gpio0_7_pin_mux); configure_module_pin_mux(rgmii1_pin_mux); configure_module_pin_mux(mmc0_pin_mux_sk_evm); } else if (board_is_bone_lt(header)) { /* Beaglebone LT pinmux */ configure_module_pin_mux(i2c1_pin_mux); configure_module_pin_mux(mii1_pin_mux); configure_module_pin_mux(mmc0_pin_mux); #if defined(CONFIG_NAND) configure_module_pin_mux(nand_pin_mux); #elif defined(CONFIG_NOR) configure_module_pin_mux(bone_norcape_pin_mux); #else configure_module_pin_mux(mmc1_pin_mux); #endif } else { puts("Unknown board, cannot configure pinmux."); hang(); } }
另外,这个版本的u-boot有个bug,需要修改fat_register_device(fs/fat/fat.c)函数:
int fat_register_device(block_dev_desc_t *dev_desc, int part_no) { disk_partition_t info; /* First close any currently found FAT filesystem */ cur_dev = NULL; /* Read the partition table, if present */ if (get_partition_info(dev_desc, part_no, &info)) { /*if (part_no != 0) { printf("** Partition %d not valid on device %d **\n", part_no, dev_desc->dev); return -1; }*/ info.start = 0; info.size = dev_desc->lba; info.blksz = dev_desc->blksz; info.name[0] = 0; info.type[0] = 0; info.bootable = 0; #ifdef CONFIG_PARTITION_UUIDS info.uuid[0] = 0; #endif } return fat_set_blk_dev(dev_desc, &info); }至此,u-boot就已经可以启动了,但是有多余的步骤和log,不过可以去掉,修改file_fat_read_at(fs/fat/fat.c)函数:
long file_fat_read_at(const char *filename, unsigned long pos, void *buffer, unsigned long maxsize) { debug("reading %s\n", filename); return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0); }最后,TQ335x是MLO启动u-boot,然后u-boot去启动内核,故可以去掉配置项CONFIG_SPL_OS_BOOT,具体的修改文件include/configs/ti_armv7_common.h:
#if defined CONFIG_SPL_OS_BOOT_ENABLE #define CONFIG_SPL_OS_BOOT #endif
至此,u-boot的移植工作就完成了,下一步来研究如何启动内核。
本文作者:girlkoo
本文链接:http://blog.csdn.net/girlkoo/article/details/41183217
AM335x(TQ335x)学习笔记——u-boot-2014.10移植
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