20 Apr
2018
20 Apr
'18
8 p.m.
On Fri, Apr 20, 2018 at 06:25:08AM -0600, Andy Shevchenko 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.
OK. Existing style does not correctly handle overflow, but for a 64-bit counter it's a very unlikely event.