comedi_get_timer man page
comedi_get_timer — timer information (deprecated)
int comedi_get_timer (comedi_t * device, unsigned int subdevice, double frequency, unsigned int * trigvar, double * actual_frequency);
The function comedi_get_timer converts the frequency frequency to a number suitable to send to the driver in a comedi_trig structure. This function remains for compatibility with very old versions of Comedi, that converted sampling rates to timer values in the libary. This conversion is now done in the kernel, and every device has the timer type nanosec_timer, indicating that timer values are simply a time specified in nanoseconds.