It is to set a hot point to compare to the value gets from thermal sensor, to decide in the uboot stage if the temperature if it is fine for boot to the next stage here is linux.
void check_cpu_temperature(void)
{
int cpu_tmp = 0;
cpu_tmp = read_cpu_temperature();
while (cpu_tmp > TEMPERATURE_MIN && cpu_tmp < TEMPERATURE_MAX) {
if (cpu_tmp >= TEMPERATURE_HOT) {
printf("CPU is %d C, too hot to boot, waiting...\n",
cpu_tmp);
udelay(5000000);
cpu_tmp = read_cpu_temperature();
} else
break;
}
if (cpu_tmp > TEMPERATURE_MIN && cpu_tmp < TEMPERATURE_MAX)
printf("CPU: Temperature %d C, calibration data: 0x%x\n",
cpu_tmp, fuse);
else
printf("CPU: Temperature: can't get valid data!\n");
}