rtc(7) rtc(7)
NAME
rtc - real time clock interface
DESCRIPTION
The rtc driver supports the real time clock chip, allowing it
to be set with the correct local time and allowing the time to
be read from the chip.
Ioctl Calls
RTCRTIME
This call is used to read the local time from the real
time clock chip. The argument to the ioctl is the
address of a buffer of RTCNREG unsigned characters
(RTCNREG is defined in sys/rtc.h ). The ioctl will fill
in the buffer with the contents of the chip registers.
Currently, RTCNREG is 14, and the meanings of the byte
registers are as follows:
Register| Contents
________|___________________
0 | Seconds
1 | Second alarm
2 | Minutes
3 | Minute alarm
4 | Hours
5 | Hour alarm
6 | Day of week
7 | Date of month
8 | Month
9 | Year
A | Status register A
B | Status register B
C | Status register C
D | Status register D
For further information on the functions of these
registers, see your hardware technical reference manual.
RTCSTIME
This call is used to set the time into the real time
clock chip. The argument to ioctl is the address of a
buffer of RTCNREGP unsigned characters (RTCNREGP is
defined in sys/rtc.h). These bytes should be the
desired chip register contents. Currently, RTCNREGP is
10, representing registers 0-9 as shown above. Note
Copyright 1994 Novell, Inc. Page 1
rtc(7) rtc(7)
that only the super-user may open the real time clock
device for writing and that the RTCSTIME ioctl will fail
for any other than the super-user.
FILES
/dev/rtc
Copyright 1994 Novell, Inc. Page 2