rtc(HW)

Description

The following ioctl calls are supported.

RTCRTIME

This call is used to read the local time from the real-time clock chip. The argument to the ioctl(S) is the address of a buffer of RTC_NREG unsigned characters (RTC_NREG is defined as <sys/rtc.h>). The ioctl will fill in the buffer with the contents of the chip registers. Currently, RTC_NREG is 14, and the meanings of the byte registers are as follows:

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 within century. Values in the range 69-99 refer to years in the twentieth century (1969 to 1999 inclusive); values in the range 00-68 refer to years in the twenty-first century (2000 to 2068 inclusive).

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 the ioctl is the address of a buffer of RTC_NREGP unsigned characters (RTC_NREGP as defined in <sys/rtc.h>). These bytes should be the desired chip register contents. Currently, RTC_NREGP is 10, representing registers 0-9 as shown above. Note that only the superuser may open the real-time clock device for writing and that the RTCSTIME ioctl will fail for any other than the superuser.

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