u-boot debugging and positioning means

Enable debugging information reference
https://blog.csdn.net/zwjzwj108108/article/details/126147584
Debugging shows the following information

initcall: 040152e4
initcall: 04068584
initcall: 0401e9a8
initcall: 04015344
initcall: 04001510
initcall: 04015304
initcall: 0401552c
malloc_simple: size=18, ptr=18, limit=400: ffff0b30
malloc_simple: size=54, ptr=6c, limit=400: ffff0b48
malloc_simple: size=4, ptr=70, limit=400: ffff0b9c
uclass_find_device_by_seq: 0 -1
uclass_find_device_by_seq: 0 0
   - -1 -1
   - not found
malloc_simple: size=18, ptr=88, limit=400: ffff0ba0
malloc_simple: size=54, ptr=dc, limit=400: ffff0bb8
Bound device mod_exp_sw to root_driver
initcall: 04015354
initcall: 04015518
initcall: 04001478
initcall: 040177ec
initcall: 040154ec
initcall: 040445c0  //The value is a symbolic address,通过u-boot.mapSpecific symbols can be viewed
malloc_simple: size=18, ptr=f4, limit=400: ffff0c0c
bind node [email protected]
   - attempt to match compatible string 'xlnx,xuartps'
   - found match at 'serial_zynq'
malloc_simple: size=54, ptr=148, limit=400: ffff0c24
Looking for 'serial' at 2876, name [email protected]
   - serial0, /amba/[email protected]
Found seq 0
Bound device [email protected] to root_driver
malloc_simple: size=4, ptr=14c, limit=400: ffff0c78
malloc_simple: size=4, ptr=150, limit=400: ffff0c7c
uclass_find_device_by_seq: 0 0
   - 0 -1
   - not found
OF: ** translation for device [email protected] **
OF: bus is default (na=1, ns=1) on amba
OF: translating address: 001000e0
OF: parent bus is default (na=1, ns=1) on 
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 3758100480
OF: one level translation: 001000e0
OF: reached root nodeclk_get_by_index(dev=ffff0c24, index=0, clk=ffff0990)
fdtdec_get_int: #clock-cells: 0x1 (1)
malloc_simple: size=18, ptr=168, limit=400: ffff0c80
clk_get_by_index: uclass_get_device_by_of_offset failed: err=-19
failed to get clock 
uclass_find_device_by_seq: 0 0
   - 0 -1
   - not found
uclass_find_device_by_seq: 1 0
   - 0 -1
   - found
malloc_simple: size=4, ptr=16c, limit=400: ffff0c98
malloc_simple: size=4, ptr=170, limit=400: ffff0c9c
uclass_find_device_by_seq: 0 0
   - 0 -1
   - not found
OF: ** translation for device [email protected] **
OF: bus is default (na=1, ns=1) on amba
OF: translating address: 001000e0
OF: parent bus is default (na=1, ns=1) on 
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 3758100480
OF: one level translation: 001000e0
OF: reached root nodeclk_get_by_index(dev=ffff0c24, index=0, clk=ffff0968)
fdtdec_get_int: #clock-cells: 0x1 (1)
clk_get_by_index: uclass_get_device_by_of_offset failed: err=-19
failed to get clock
malloc_simple: size=4, ptr=174, limit=400: ffff0ca0
malloc_simple: size=4, ptr=178, limit=400: ffff0ca4
uclass_find_device_by_seq: 0 0
   - 0 -1
   - not found
OF: ** translation for device [email protected] **
OF: bus is default (na=1, ns=1) on amba
OF: translating address: 001000e0
OF: parent bus is default (na=1, ns=1) on 
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 3758100480
OF: one level translation: 001000e0
OF: reached root nodeclk_get_by_index(dev=ffff0c24, index=0, clk=ffff0970)
fdtdec_get_int: #clock-cells: 0x1 (1)
clk_get_by_index: uclass_get_device_by_of_offset failed: err=-19
failed to get clock
malloc_simple: size=4, ptr=17c, limit=400: ffff0ca8
malloc_simple: size=4, ptr=180, limit=400: ffff0cac
uclass_find_device_by_seq: 0 0
   - 0 -1
   - not found
OF: ** translation for device [email protected] **
OF: bus is default (na=1, ns=1) on amba
OF: translating address: 001000e0
OF: parent bus is default (na=1, ns=1) on 
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 3758100480
OF: one level translation: 001000e0
OF: reached root nodeclk_get_by_index(dev=ffff0c24, index=0, clk=ffff0970)
fdtdec_get_int: #clock-cells: 0x1 (1)
clk_get_by_index: uclass_get_device_by_of_offset failed: err=-19
failed to get clock
No serial driver found
resetting ...
Error, wrong i2c adapter 0 max 0 possible
Error, wrong i2c adapter 0 max 0 possible

itcall: 040445c0 //The value is a symbolic address,通过u-boot.mapSpecific symbols can be viewed.So it can be located that there is a problem in the function.

显示的错误信息：查看serial_init函数,It can be seen that it is related to the serial port.

OF: ** translation for device [email protected] **
OF: bus is default (na=1, ns=1) on amba
OF: translating address: 001000e0
OF: parent bus is default (na=1, ns=1) on 
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 3758100480
OF: one level translation: 001000e0
OF: reached root nodeclk_get_by_index(dev=ffff0c24, index=0, clk=ffff0990)
fdtdec_get_int: #clock-cells: 0x1 (1)
malloc_simple: size=18, ptr=168, limit=400: ffff0c80
clk_get_by_index: uclass_get_device_by_of_offset failed: err=-19
failed to get clock 

最后定位到serial_zynq.c文件中的打印.There was a problem getting the clock.

int zynq_serial_setbrg(struct udevice *dev, int baudrate)
{
    
	struct zynq_uart_priv *priv = dev_get_priv(dev);
	unsigned long clock;

#if defined(CONFIG_CLK) || defined(CONFIG_SPL_CLK)
	int ret;
	struct clk clk;

	ret = clk_get_by_index(dev, 0, &clk);
	if (ret < 0) {
    
		dev_err(dev, "failed to get clock\n");
		return ret;
	}

	clock = clk_get_rate(&clk);
	if (IS_ERR_VALUE(clock)) {
    
		dev_err(dev, "failed to get rate\n");
		return clock;
	}
	debug("%s: CLK %ld\n", __func__, clock);

	ret = clk_enable(&clk);
	if (ret && ret != -ENOSYS) {
    
		dev_err(dev, "failed to enable clock\n");
		return ret;
	}
#else
	clock = get_uart_clk(0);
#endif
	_uart_zynq_serial_setbrg(priv->regs, clock, baudrate);

	return 0;
}