Re: [U-Boot] [PATCH v6 1/2] x86: Add TSC-specific timer functions

On Thu, 2018-04-12 at 15:12 -0700, Ivan Gorinov wrote:

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Add tsc_rate_mhz() function and use it in the code that specifically needs to get TSC rate regardless of currently selected early timer.

void delay_n(uint32_t ns) { /* 1000 MHz clock has 1ns period --> no conversion required */

• uint64_t final_tsc = rdtsc();

• uint64_t start_tsc = rdtsc();
• uint64_t ticks;

• final_tsc += ((get_tbclk_mhz() * ns) / 1000);
• while (rdtsc() < final_tsc)

• ;
  

• ticks = (tsc_rate_mhz() * ns) / 1000;

• while (rdtsc() - start_tsc < ticks);

I would rather preserve existing style.

}

/* Delay number of microseconds */ -void delay_u(uint32_t ms) +void delay_u(uint32_t us) { /* 64-bit math is not an option, just use loops */

• while (ms--)

• while (us--) delay_n(1000);

}

This is a separate change.