get_duration
ops->get_duration = ar9002_hw_get_duration;
ops->get_duration = ar9003_hw_get_duration;
return ath9k_hw_ops(ah)->get_duration(ah, ds, index);
int (*get_duration)(struct ath_hw *ah, const void *ds, int index);
get_duration(tool->start_time, duration, sizeof(duration));
get_duration(top->start_time, duration, sizeof(duration));
get_duration(tool->start_time, duration, sizeof(duration));
get_duration(top->start_time, duration, sizeof(duration));
void get_duration(time_t start_time, char *output, int output_size);