AM335x(TQ335x)學習筆記——u-boot-2014.10移植
阿新 • • 發佈：2019-01-30
最近移植了下u-boot-2014.10到TQ335x，如果基於am335x evm進行移植，需要修改的地方並不多。
由於TI的am335x evm開發使用了一個eeprom儲存了板載配置資訊，用來區分不同板子的型號的，而TQ335x沒有這個eeprom，因此，需要修改eeprom相關的部分，使u-boot適應TQ335x開發板。
使用source insight檢視程式碼，很容易發現，所有獲取板載配置的部分都是通過讀取eeprom獲得的，因此，首選修改read_eeprom（board/ti/am335x/board.c）函式，具體的修改如下：
通過上述修改，u-boot不去讀取eeprom，而是直接將header的name賦值為"TQ335x"，後面可以根據這一配置區分是否為TQ335x開發板。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; }
然後是修改get_dpll_ddr_params（board/ti/am335x/board.c）函式，具體的修改內容如下：
然後是修改sdram_init（board/ti/am335x/board.c）函式，具體的修改內容如下：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; }
然後新增board_is_tq335x函式的具體實現，參考其它類似函式實現即可，由於我們的read_eeprom僅讀到了name，其內容是"TQ335x"，故可如下實現，在board/ti/am335x/board.h中新增如下內容：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); }
static inline int board_is_tq335x(struct am335x_baseboard_id *header)
{
return !strncmp(header->name, "TQ335x", HDR_NAME_LEN);
}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，這個版本的u-boot有個bug，需要修改fat_register_device（fs/fat/fat.c）函式：
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);
}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);
}#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，編譯方法如下：
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- am335x_evm_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j8其中，arm-linux-gnueabi-需要根據自己的交叉編譯工具鏈字首進行修改。完成u-boot的移植工作後我們來研究如何啟動核心。
原始碼下載地址：
本文作者：girlkoo