Uboot版本：u-boot-2013.01

一、gd結構體的定義與使用

gd_t 和 bd_t 是u-boot中兩個重要的數據結構，在初始化操作很多都要靠這兩個數據結構來保存或傳遞。

gd_t 定義在/u-boot-2013.01/arch/arm/include/asm/global_data.h

bd_t 定義在 ./include/asm-arm/u-boot.h

1、gd_t : global data數據結構定義

位于文件/u-boot-2013.01/arch/arm/include/asm/global_data.h 中。其成員主要是一些全局的系統初始化參數。

當使用gd_t 時需用宏定義進行聲明DECLARE_GLOBAL_DATA_PTR

從這個宏的定義可以看出，gd是一個保存在ARM的r8寄存器中的gd_t結構體的指針。指定占用寄存器R8。

[cpp]?view plaincopy

typedef?struct??global_data?{??

????bd_t????????*bd;//struct?board_info指針，保存開發板信息??

????unsigned?long???flags;//指示標志，如設備已經初始化標志等??

????unsigned?int????baudrate;//串口波特率??

????unsigned?long???have_console;???//串口初始化標志??

#ifdef?CONFIG_PRE_CONSOLE_BUFFER??

????unsigned?long???precon_buf_idx;?/*?Pre-Console?buffer?index?*/??

#endif??

????unsigned?long???env_addr;???/*?Address??of?Environment?struct?*/??

????unsigned?long???env_valid;??/*?Checksum?of?Environment?valid??*/??

????unsigned?long???fb_base;????/*?base?address?of?frame?buffer?*/??

#ifdef?CONFIG_FSL_ESDHC??

????unsigned?long???sdhc_clk;??

#endif??

#ifdef?CONFIG_AT91FAMILY??

????/*?"static?data"?needed?by?at91's?clock.c?*/??

????unsigned?long???cpu_clk_rate_hz;??

????unsigned?long???main_clk_rate_hz;??

????unsigned?long???mck_rate_hz;??

????unsigned?long???plla_rate_hz;??

????unsigned?long???pllb_rate_hz;??

????unsigned?long???at91_pllb_usb_init;??

#endif??

#ifdef?CONFIG_ARM??

????/*?"static?data"?needed?by?most?of?timer.c?on?ARM?platforms?*/??

????unsigned?long???timer_rate_hz;??

????unsigned?long???tbl;??

????unsigned?long???tbu;??

????unsigned?long?long??timer_reset_value;??

????unsigned?long???lastinc;??

#endif??

#ifdef?CONFIG_IXP425??

????unsigned?long???timestamp;??

#endif??

????unsigned?long???relocaddr;??/*?Start?address?of?U-Boot?in?RAM?*/??

????phys_size_t?ram_size;???/*?RAM?size?*/??

????unsigned?long???mon_len;????/*?monitor?len?*/??

????unsigned?long???irq_sp;?????/*?irq?stack?pointer?*/??

????unsigned?long???start_addr_sp;??/*?start_addr_stackpointer?*/??

????unsigned?long???reloc_off;??

#if?!(defined(CONFIG_SYS_ICACHE_OFF)?&&?defined(CONFIG_SYS_DCACHE_OFF))??

????unsigned?long???tlb_addr;??

????unsigned?long???tlb_size;??

#endif??

????const?void??*fdt_blob;??/*?Our?device?tree,?NULL?if?none?*/??

????void????????**jt;???????/*?jump?table?*/??

????char????????env_buf[32];????/*?buffer?for?getenv()?before?reloc.?*/??

#if?defined(CONFIG_POST)?||?defined(CONFIG_LOGBUFFER)??

????unsigned?long???post_log_word;?/*?Record?POST?activities?*/??

????unsigned?long???post_log_res;?/*?success?of?POST?test?*/??

????unsigned?long???post_init_f_time;?/*?When?post_init_f?started?*/??

#endif??

}?gd_t;??

2.、bd_t :board info數據結構定義

位于文件u-boot-2013.01/arch/arm/include/asm/u-boot.h。保存板子參數。

[cpp]?view plaincopy

typedef?struct?bd_info?{??

????unsigned?int????bi_baudrate;????/*?串口波特率?*/??

????ulong???????????bi_arch_number;?/*?開發板機器ID?*/??

????ulong???????????bi_boot_params;?/*?啟動參數?*/??

????unsigned?long???bi_arm_freq;?/*?arm?frequency?*/??

????unsigned?long???bi_dsp_freq;?/*?dsp?core?frequency?*/??

????unsigned?long???bi_ddr_freq;?/*?ddr?frequency?*/??

????struct??????????????/*?RAM?configuration?*/??

????{??

????ulong?start;??

????ulong?size;??

????}???????????bi_dram[CONFIG_NR_DRAM_BANKS];??

}?bd_t; ?

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