U-Boot学习：[0]global_data 和 bd_info
基于U-Boot 2017.03-rc2-gc7a25b3-dirty 源码分析
global_data
global_data 数据结构
global_data 数据结构的定义位于源码目录：
include/asm-generic/global_data.h
typedef struct global_data {
bd_t *bd; //struct board_info指针，保存板子信息
unsigned long flags; //指示标志，如设备已经初始化标志等
unsigned int baudrate; //串口波特率
unsigned long cpu_clk; /* CPU clock in Hz! */
unsigned long bus_clk;
/* We cannot bracket this with CONFIG_PCI due to mpc5xxx */
unsigned long pci_clk;
unsigned long mem_clk;
#if defined(CONFIG_LCD) || defined(CONFIG_VIDEO)
unsigned long fb_base; /* Base address of framebuffer mem frame buffer的基址 */
#endif
#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
#ifdef CONFIG_BOARD_TYPES
unsigned long board_type;
#endif
unsigned long have_console; /* serial_init() was called 串口初始化标志 */
#if CONFIG_IS_ENABLED(PRE_CONSOLE_BUFFER)
unsigned long precon_buf_idx; /* Pre-Console buffer index */
#endif
unsigned long env_addr; /* Address of Environment struct 环境参数地址 */
unsigned long env_valid; /* Checksum of Environment valid? 环境参数CRC检验有效标志 */
unsigned long ram_top; /* Top address of RAM used by U-Boot */
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;
struct global_data *new_gd; /* relocated global data */
#ifdef CONFIG_DM
struct udevice *dm_root; /* Root instance for Driver Model */
struct udevice *dm_root_f; /* Pre-relocation root instance */
struct list_head uclass_root; /* Head of core tree */
#endif
#ifdef CONFIG_TIMER
struct udevice *timer; /* Timer instance for Driver Model */
#endif
const void *fdt_blob; /* Our device tree, NULL if none */
void *new_fdt; /* Relocated FDT */
unsigned long fdt_size; /* Space reserved for relocated FDT */
struct jt_funcs *jt; /* jump table 跳转表，用来"函数调用地址登记" */
char env_buf[32]; /* buffer for getenv() before reloc. */
#ifdef CONFIG_TRACE
void *trace_buff; /* The trace buffer */
#endif
#if defined(CONFIG_SYS_I2C)
int cur_i2c_bus; /* current used i2c bus */
#endif
#ifdef CONFIG_SYS_I2C_MXC
void *srdata[10];
#endif
unsigned long timebase_h;
unsigned long timebase_l;
#ifdef CONFIG_SYS_MALLOC_F_LEN
unsigned long malloc_base; /* base address of early malloc() */
unsigned long malloc_limit; /* limit address */
unsigned long malloc_ptr; /* current address */
#endif
#ifdef CONFIG_PCI
struct pci_controller *hose; /* PCI hose for early use */
phys_addr_t pci_ram_top; /* top of region accessible to PCI */
#endif
#ifdef CONFIG_PCI_BOOTDELAY
int pcidelay_done;
#endif
struct udevice *cur_serial_dev; /* current serial device */
struct arch_global_data arch; /* architecture-specific data */
#ifdef CONFIG_CONSOLE_RECORD
struct membuff console_out; /* console output */
struct membuff console_in; /* console input */
#endif
#ifdef CONFIG_DM_VIDEO
ulong video_top; /* Top of video frame buffer area */
ulong video_bottom; /* Bottom of video frame buffer area */
#endif
} gd_t;
global_data 声明
对于ARM架构，其 struct arch_global_data 定义位于源码目录：
arch/arm/include/asm/global_data.h:
/* Architecture-specific global data */
struct arch_global_data {
#if defined(CONFIG_FSL_ESDHC)
u32 sdhc_clk;
#endif
#if defined(CONFIG_U_QE)
u32 qe_clk;
u32 brg_clk;
uint mp_alloc_base;
uint mp_alloc_top;
#endif /* CONFIG_U_QE */
#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
/* "static data" needed by most of timer.c on ARM platforms */
unsigned long timer_rate_hz;
unsigned long tbu;
unsigned long tbl;
unsigned long lastinc;
unsigned long long timer_reset_value;
#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
unsigned long tlb_addr;
unsigned long tlb_size;
#if defined(CONFIG_ARM64)
unsigned long tlb_fillptr;
unsigned long tlb_emerg;
#endif
#endif
#ifdef CONFIG_SYS_MEM_RESERVE_SECURE
#define MEM_RESERVE_SECURE_SECURED 0x1
#define MEM_RESERVE_SECURE_MAINTAINED 0x2
#define MEM_RESERVE_SECURE_ADDR_MASK (~0x3)
/*
* Secure memory addr
* This variable needs maintenance if the RAM base is not zero,
* or if RAM splits into non-consecutive banks. It also has a
* flag indicating the secure memory is marked as secure by MMU.
* Flags used: 0x1 secured
* 0x2 maintained
*/
phys_addr_t secure_ram;
unsigned long tlb_allocated;
#endif
#ifdef CONFIG_ARCH_OMAP2
u32 omap_boot_device;
u32 omap_boot_mode;
u8 omap_ch_flags;
#endif
#if defined(CONFIG_FSL_LSCH3) && defined(CONFIG_SYS_FSL_HAS_DP_DDR)
unsigned long mem2_clk;
#endif
};
当使用gd_t时需用宏定义进行声明：DECLARE_GLOBAL_DATA_PTR。
对于ARM架构指定占用寄存器r9；对于ARM64架构制定占用寄存器x18。
#ifdef CONFIG_ARM64
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("x18")
#else
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r9")
#endif
#endif
bd_info
bd_info 数据结构
bd_info 数据结构的定义位于源码目录：
include/asm-generic/u-boot.h
typedef struct bd_info {
unsigned long bi_memstart; /* start of DRAM memory */
phys_size_t bi_memsize; /* size of DRAM memory in bytes */
unsigned long bi_flashstart; /* start of FLASH memory */
unsigned long bi_flashsize; /* size of FLASH memory */
unsigned long bi_flashoffset; /* reserved area for startup monitor */
unsigned long bi_sramstart; /* start of SRAM memory */
unsigned long bi_sramsize; /* size of SRAM memory */
#ifdef CONFIG_AVR32
unsigned char bi_phy_id[4]; /* PHY address for ATAG_ETHERNET */
unsigned long bi_board_number;/* ATAG_BOARDINFO */
#endif
#ifdef CONFIG_ARM
unsigned long bi_arm_freq; /* arm frequency */
unsigned long bi_dsp_freq; /* dsp core frequency */
unsigned long bi_ddr_freq; /* ddr frequency */
#endif
#if defined(CONFIG_5xx) || defined(CONFIG_8xx) || defined(CONFIG_MPC8260) \
|| defined(CONFIG_E500) || defined(CONFIG_MPC86xx)
unsigned long bi_immr_base; /* base of IMMR register */
#endif
#if defined(CONFIG_MPC5xxx) || defined(CONFIG_M68K)
unsigned long bi_mbar_base; /* base of internal registers */
#endif
#if defined(CONFIG_MPC83xx)
unsigned long bi_immrbar;
#endif
unsigned long bi_bootflags; /* boot / reboot flag (Unused) */
unsigned long bi_ip_addr; /* IP Address */
unsigned char bi_enetaddr[6]; /* OLD: see README.enetaddr */
unsigned short bi_ethspeed; /* Ethernet speed in Mbps */
unsigned long bi_intfreq; /* Internal Freq, in MHz */
unsigned long bi_busfreq; /* Bus Freq, in MHz */
#if defined(CONFIG_CPM2)
unsigned long bi_cpmfreq; /* CPM_CLK Freq, in MHz */
unsigned long bi_brgfreq; /* BRG_CLK Freq, in MHz */
unsigned long bi_sccfreq; /* SCC_CLK Freq, in MHz */
unsigned long bi_vco; /* VCO Out from PLL, in MHz */
#endif
#if defined(CONFIG_MPC512X)
unsigned long bi_ipsfreq; /* IPS Bus Freq, in MHz */
#endif /* CONFIG_MPC512X */
#if defined(CONFIG_MPC5xxx) || defined(CONFIG_M68K)
unsigned long bi_ipbfreq; /* IPB Bus Freq, in MHz */
unsigned long bi_pcifreq; /* PCI Bus Freq, in MHz */
#endif
#if defined(CONFIG_EXTRA_CLOCK)
unsigned long bi_inpfreq; /* input Freq in MHz */
unsigned long bi_vcofreq; /* vco Freq in MHz */
unsigned long bi_flbfreq; /* Flexbus Freq in MHz */
#endif
#if defined(CONFIG_405) || \
defined(CONFIG_405GP) || \
defined(CONFIG_405EP) || \
defined(CONFIG_405EZ) || \
defined(CONFIG_405EX) || \
defined(CONFIG_440)
unsigned char bi_s_version[4]; /* Version of this structure */
unsigned char bi_r_version[32]; /* Version of the ROM (AMCC) */
unsigned int bi_procfreq; /* CPU (Internal) Freq, in Hz */
unsigned int bi_plb_busfreq; /* PLB Bus speed, in Hz */
unsigned int bi_pci_busfreq; /* PCI Bus speed, in Hz */
unsigned char bi_pci_enetaddr[6]; /* PCI Ethernet MAC address */
#endif
#ifdef CONFIG_HAS_ETH1
unsigned char bi_enet1addr[6]; /* OLD: see README.enetaddr */
#endif
#ifdef CONFIG_HAS_ETH2
unsigned char bi_enet2addr[6]; /* OLD: see README.enetaddr */
#endif
#ifdef CONFIG_HAS_ETH3
unsigned char bi_enet3addr[6]; /* OLD: see README.enetaddr */
#endif
#ifdef CONFIG_HAS_ETH4
unsigned char bi_enet4addr[6]; /* OLD: see README.enetaddr */
#endif
#ifdef CONFIG_HAS_ETH5
unsigned char bi_enet5addr[6]; /* OLD: see README.enetaddr */
#endif
#if defined(CONFIG_405GP) || defined(CONFIG_405EP) || \
defined(CONFIG_405EZ) || defined(CONFIG_440GX) || \
defined(CONFIG_440EP) || defined(CONFIG_440GR) || \
defined(CONFIG_440EPX) || defined(CONFIG_440GRX) || \
defined(CONFIG_460EX) || defined(CONFIG_460GT)
unsigned int bi_opbfreq; /* OPB clock in Hz */
int bi_iic_fast[2]; /* Use fast i2c mode */
#endif
#if defined(CONFIG_4xx)
#if defined(CONFIG_440GX) || \
defined(CONFIG_460EX) || defined(CONFIG_460GT)
int bi_phynum[4]; /* Determines phy mapping */
int bi_phymode[4]; /* Determines phy mode */
#elif defined(CONFIG_405EP) || defined(CONFIG_405EX) || defined(CONFIG_440)
int bi_phynum[2]; /* Determines phy mapping */
int bi_phymode[2]; /* Determines phy mode */
#else
int bi_phynum[1]; /* Determines phy mapping */
int bi_phymode[1]; /* Determines phy mode */
#endif
#endif /* defined(CONFIG_4xx) */
ulong bi_arch_number; /* unique id for this board */
ulong bi_boot_params; /* where this board expects params */
#ifdef CONFIG_NR_DRAM_BANKS
struct { /* RAM configuration */
phys_addr_t start;
phys_size_t size;
} bi_dram[CONFIG_NR_DRAM_BANKS];
#endif /* CONFIG_NR_DRAM_BANKS */
} bd_t;
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