EMBRON Hatteland E Series, Руководство пользователя, Страница: 120 / 136

120
RTC Timer (Apollolake) - User Guide
Appendix
IND100077-195
DOC207017- rev 01 – 2018-09-24 - Created by: 6644
Page 12 of 12
Hatteland Display AS, Stokkastrandvegen 87B, N-5578 Nedre Vats, Norway
Tel: (+47) 4814 2200 - mail@hatteland-display.com - www.hatteland-display.com
User Guide RTC Timer - ApolloLake
All intellectual properties belongs to Hatteland Display AS
ioperm() sets the port access permission bits for the calling thread for num bits starting from port
addressfrom. If turn_on is nonzero, then permission for the specified bits is enabled; otherwise it is
disabled. Ifturn_on is nonzero, the calling thread must be privileged. [2]
int ioperm
(
unsigned long from
,
unsigned long num
,
int turn_on
);
3.2.2 RTC Driver
RTC Chip RV8803 is generically supported by Linux Kernel 4.4 and above.
The user can use standard RTC system calls to read, write date/time in external RTC timer.
4 Note
1. It is not recommended to operate read/write too frequently, because heavy load on this bus
may affect internal system devices working improperly.
2. It is always suggested to change RTC time at the same time when changing OS time/PCH
time.
Windows 10 refuses all the backwards date change in RTC. So when the date in RTC is
changed to earlier date and different from Windows date, Windows will ignore the date/time
change by RTC.
For example,
If user is changing RTC time from 01/10/2017 to 03/03/2015, by accessing RTC date in OS.
But the OS date is not updated accordingly. Then power input is cut off by accident.
This causes a mismatch between PCH date and RTC date. In next boot, the PCH date is
updated to 03/03/2015, but OS reject this earlier date and keep using 01/10/2017.
In this case the date must be changed manually before Windows will do automatic changes.
5 Reference
[1] InpOut32 and InpOutx64, http://www.highrez.co.uk/downloads/inpout32/default.htm
[2] ioperm(2) - Linux man page http://linux.die.net/man/2/ioperm