Definition and use of Gd in uboot

Recently, I am working on NAND boot in uboot and have been struggling with a problem. Now I have clarified this issue. I think there are still many brothers struggling in a dark corner or in front of a computer, so I should write it down for reference.

Uboot version 2014.4

/* Architecture-specific global data */
Struct arch_global_data {
# If defined (config_fsl_esdhc)
U32 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
/* "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 timer_reset_value;
# If! (Defined (config_sys_icache_off) & defined (config_sys_dcache_off ))
Unsigned long tlb_addr;
Unsigned long tlb_size;
# Endif


# Ifdef config_omap
Struct omap_boot_parameters omap_boot_params;
# Endif
};


# Include <ASM-generic/global_data.h>


# Ifdef config_arm64
# Define declare_global_data_ptr register volatile gd_t * gd asm ("X18 ")
# Else
# Define declare_global_data_ptrregister volatile gd_t * gd asm ("R9 ")
# Endif

We can see the definition of GD from here, and we can know that the structure definition of temperament is in the: # include <ASM-generic/global_data.h> folder.

Add a private variable to this folder to make it easier to use it !!!!!!!!!!!

Typedef struct global_data {
Bd_t * BD;
Unsigned long flags;
Unsigned int baudrate;
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 */
# 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 */
# Ifdef config_pre_lele_buffer
Unsigned long precon_buf_idx;/* pre-Console Buffer Index */
# Endif
# Ifdef config_modem_support
Unsigned long do_mdm_init;
Unsigned long be_quiet;
# Endif
Unsigned long env_addr;/* address of Environment struct */
Unsigned long env_valid;/* checksum of Environment valid? */


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 device * dm_root;/* root instance for Driver Model */
Struct list_head uclass_root;/* Head of core tree */
# 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 */
Void ** JT;/* Jump table */
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
Unsigned long timebase_h;
Unsigned long timebase_l;
Struct arch_global_data arch;/* architecture-specific data */


# Ifdef config_xxxxx // random x
Void * priv;/* point to the private data */
# Endif
} Gd_t;

You can use the header file in the Process of use.