/* datasheet says to divide this number by the fan reading to get fan rpm */
#define FAN_PERIOD_TO_RPM(x) ((90000 * 60) / (x))
#define FAN_RPM_TO_PERIOD FAN_PERIOD_TO_RPM
/* datasheet says to divide this number by the fan reading to get fan rpm */
#define FAN_PERIOD_TO_RPM(x) ((90000 * 60) / (x))
#define FAN_RPM_TO_PERIOD FAN_PERIOD_TO_RPM