I'm running into an chicken and egg problem when modifying (fixing) some drivers for STMicroelectronics SoC's

The problem, I will implement a timeout, when accessing some registers. Unfortunately I cannot use the basic mdelay() or higher level functions, which use this function, because on these SoC's there isn't setup and enabled the timer before. Also the ARMv7-M SysTick timer will not be used.

I could write a simple delay loop which counts down at the frequency from the processor speed. But I think, this is not a good idea.

Any suggestion, what I can do? I'm still new in U-Boot, so I don't know if there a simple delay function exists.

UPDATE:
The reason why I currently cannot use the SysTick timer is, that it will be not linked in the current configuration. This is not a big problem. But the current implementation of the SysTick low-level source defines functions, which will be defined by another timer driver on these SoC series. So when I enable the SysTick in Kconfig I will be possible that I get a linker error with multiple definition of those functions.

Example driver with IMHO an fatal issue (missing timeout when polling a register value):
GitHub: U-Boot: driver/clk/clk_stm32h7.c

The driver currently requires a external working clock source (HSE). No issues in the circuit are accepted by the current implementation. Also a fixed (defined) frequency of the external clock source.

In the probe function stm32_clk_probe() from the driver there will be configure_clocks() called. Here are the issues.

A code snippet from configure_clocks():

/* Switch on HSE */
setbits_le32(&regs->cr, RCC_CR_HSEON);
while (!(readl(&regs->cr) & RCC_CR_HSERDY))
    ;

RCC_CR_HSERDY will here never set by hardware, when there is no external clock source or an issue in the circuit. These leads in an endless loop. The loop of dead.