smol-gilbraltar/kernel/timer.c

#include <bcm.h>    /* for ARM_SYSTIMER_CLO */
#include <mem.h>    /* for read32() */
#include <stdint.h> /* for uint32_t */
#include <timer.h>  /* for CLOCKHZ */

void gilbraltar_delay_hot_loop(uint32_t cycle) {
  volatile uint32_t v;
  for (v = 0; v < cycle; v++)
    ;
}

void gilbraltar_delay_us(uint32_t us) {
  if (us > 0) {
    uint32_t ticks = us * (CLOCKHZ / 1000000) + 1;
    uint32_t s = read32(ARM_SYSTIMER_CLO);

    while (read32(ARM_SYSTIMER_CLO) - s < ticks)
      ;
  }
}

void gilbraltar_delay_ms(uint32_t ms) {
  if (ms > 0)
    gilbraltar_delay_us(ms * 1000);
}

uint32_t gilbraltar_system_clock(void) {
  return (read32(ARM_SYSTIMER_CLO)); // TODO(dinosaure): CLOCKHZ?
}