TODR(9)

NAME
todr_attach, todr_gettime, todr_settime, todr_getcal, todr_setcal, clock_ymdhms_to_secs, clock_secs_to_ymdhms - time-of-day clock support

SYNOPSIS
#include <dev/clock_subr.h>
void
todr_attach(todr_chip_handle_t);
int
todr_gettime(todr_chip_handle_t, struct timeval *);
int
todr_settime(todr_chip_handle_t, struct timeval *);
int
todr_getcal(todr_chip_handle_t, int *);
int
todr_setcal(todr_chip_handle_t, int);
void
clock_secs_to_ymdhms(int, struct clock_ymdhms *);
time_t
clock_ymdhms_to_secs(struct clock_ymdhms *);

DESCRIPTION
The todr_*() functions provide an interface to read, set and control ‘time-of-day’ devices. A driver for a ‘time-of-day’ device registers its todr_chip_handle_t with machine-dependent code using the todr_attach() function. Alternatively, a machine-dependent front-end to a ‘time-of-day’ device driver may obtain the todr_chip_handle_t directly.

The todr_gettime() retrieves the current data and time from the TODR device and returns it in the struct timeval storage provided by the caller. todr_settime() sets the date and time in the TODR device represented by todr_chip_handle_t according to the struct timeval argument.

todr_setcal() specifies a calibration value in PPM units to be programmed in the TODR device. Positive values shall speed up the TODR clock, negative values shall slow it down. If the device in not capable of handling calibration, this function shall return EOPNOTSUPP. The measurement and calculations necessary to use this method is expected to be provided by higher-level software modules. todr_getcal() returns the current calibration (in PPM units) in effect on the TODR device.

The utilities clock_secs_to_ymdhms() and clock_ymdhms_to_secs() are provided to convert a time value in seconds to and from a structure representing the date and time as a <year,month,day,weekday,hour,minute,seconds> tuple. This structure is defined as follows:

    struct clock_ymdhms {
    	u_short dt_year;	/* Year */
    	u_char dt_mon;		/* Month (1-12) */
    	u_char dt_day;		/* Day (0-365) */
    	u_char dt_wday;		/* Day of week (0-6) */
    	u_char dt_hour;		/* Hour (0-23) */
    	u_char dt_min;		/* Minute (0-59) */
    	u_char dt_sec;		/* Second (0-59) */
    };

Note: leap years are recognised by these conversion routines.

RETURN VALUES
The todr_*() functions return 0 if the requested operation was successful; otherwise an error code from <sys/errno.h> shall be returned. However, behaviour is undefined if an invalid todr_chip_handle_t is passed to any of these functions.

The clock_ymdhms_to_secs() function returns -1 if the time in seconds would be less that zero or too large to fit in a time_t. The clock_secs_to_ymdhms() function never fails.

SEE ALSO
intersil7170(4), mk48txx(4), inittodr(9), resettodr(9), time(9)