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[ts-7000] Re: RTC daughterboard on TS-7200 - how to use?

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Subject: [ts-7000] Re: RTC daughterboard on TS-7200 - how to use?
From: "charliem_1216" <>
Date: Wed, 23 Jan 2008 05:48:27 -0000
--- In  Jeff Cunningham <> wrote:
>
> charliem_1216 wrote:
> >
> >
> >  Both the ep93xx and the DS12887 have worked OK for me 
(TS-7250), from
> >  about 2.6.19. You're right, now multiple RTCs can be used, but 
most
> >  userspace code seemed to look for /dev/rtc and crap out if it 
was
> >  missing. Try symlinking /dev/rtc0 (or rtc1) to /dev/rtc in a 
startup
> >  script.
> >
> >  I don't have a TS7800 to play with yet. AFAIK there are no 
general
> >  problems with RTCs on ARM as long as you have a chipset driver 
and do
> >  the platform device registration for the RTC. There's a lot of 
Orion
> >  code waiting for 2.6.25 to open up ... but no TS-7800 platform 
code
> >  (hint hint :)
> >
> >  Regards, ...... Charlie
> >
> 
> I have the opposite problem: /dev/rtc exists, but hwclock doesn't 
> recognize it.
> 
> I believe I have the right chipset driver. The chip says: 
M48T86PC1 on 
> it, with the trademark "ST" in the corner. And when I modprobe 
> rtc_m48t86 into the system it shows up in dmesg this way:
> 
>   rtc-m48t86 rtc-m48t86: rtc core: registered m48t86 as rtc0
>   rtc-m48t86 rtc-m48t86: battery ok
> 
> So, it thinks it's the right chipset and the module seems to be 
talking 
> to it alright. But hwclock still can't see it.
> 
> :dev# hwclock --debug
> hwclock from util-linux-2.12p
> hwclock: Open of /dev/rtc failed, errno=19: No such device.
> No usable clock interface found.
> Cannot access the Hardware Clock via any known method.
> 
> I also tried building the rtc_cmos module but it won't work:
> 
>   :dev# modprobe rtc-cmos
>   FATAL: Error inserting rtc_cmos 
> (/lib/modules/2.6.23-rc1ide_2/kernel/drivers/rtc/rtc-cmos.ko): No 
such 
> device
> 
> --Jeff
>

Hi Jeff --

What do the following commands give?

ls -l /dev/rtc*
dmesg | grep rtc
ln -s /dev/rtc0 /dev/rtc
hwclock

Looks like you have /dev/rtc0, but not /dev/rtc.  hwclock doesn't 
know how to look for anything but /dev/rtc, so we just create a link 
named /dev/rtc and point it to the real device /dev/rtc0.

This works for me (hwclock of util-linux-2.12r, but it shouldn't 
matter).

Regards, ........ Charlie




 
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