On Wed, 9 May 2012, burnsmicro wrote:
> Darn!
>
> I am using the TS7553 Cavium based board which only appears to have a
> watchdog timer.
>
> --- In Jim Jackson <> wrote:
> >
> > It is one of the hardware timers in the chip - assuming you are talking
> > about one of the EP9301/2 based boards (72xx). The details for programming
> > the timers are in the EP9301/2 user's guide.
>
> I understand the kernel uses an interval called a Jiffy. Would there be a
> simple way of getting a signal every n jiffies without messing with the
> kernel or creating a new driver?
It's an FAQ...
"Linux maintains a system clock with a resolution (in the 2.4 kernel
supplied with TS-Linux) of 10millisec. Any user space program can use
standard Unix/Linux timer functions alarm(2), getitimer(2), setitimer(2)
e.g. see
http://www.quepublishing.com/articles/article.asp?p=23618&seqNum=14&rl=1
All this is standard stuff and not in any way specific to ts-linux or this
board etc. If you have access to a standard linux desktop, try
man alarm
etc to read the manual pages for the functions. They can be found also on
the web.
If you need resolution better than 10ms then you need to write a kernel
driver to control one of the free timers not used by the kernel, and
provide an interface for calls from userspace. An example of such a driver
is the adc driver by Phillip McCarley that is on the files section of the
group. It uses a free hardware timer to generate an interrupt to time the
reading of the ADC. You can use modify it to suite your needs."
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