From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [Adeos-main] Porting to Intel IXP425
From: Philippe Gerum <rpm@xenomai.org>
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Date: Fri, 30 Mar 2007 16:55:19 +0200
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: adeos-main@gna.org, Richard Cochran <richard.cochran@domain.hid>

On Fri, 2007-03-30 at 16:05 +0200, Gilles Chanteperdrix wrote:
> Richard Cochran wrote:
> >>Right. And I think the IXP425 has no cascaded IRQ, so you can define
> >>__ipipe_mach_irq_mux_p to 0, and do not have to implement
> >>__ipipe_mach_demux_irq.
> > 
> > 
> > That was easy.
> > 
> > (The IXP425 has no cascaded interrupts.)
> > 
> > Now, about the rest, by reading the other arm ports, I learned the
> > following:
> > 
> > __ipipe_mach_get_dec()
> > 
> > Returns the periodic timer interval in HW ticks.
> > 
> > __ipipe_mach_set_dec()
> > 
> > Sets the periodic timer interval.
> 
> The timer is aperiodic (most of the time) when running Xenomai,

Moreover, Xenomai 2.4 (i.e. our current development trunk/) will always
drive the timer chip in oneshot mode. Periodic mode is emulated over
aperiodic ticks there.

>  so
> __ipipe_mach_set_dec is called for each timer tick and programs the
> timer hardware for the next tick.
> 
> > 
> > __ipipe_mach_get_tsc()
> > 
> > Returns the free flowing time stamp register as a 64 bit integer.
> > 
> > __ipipe_mach_acktimer()
> > 
> > Called by the timer ISR, clears the timer interrupt.
> > 
> > __ipipe_mach_release_timer()
> > 
> > Restores the timer interval to the value expected by Linux.
> 
> __ipipe_mach_release_timer is called when Xenomai stops handling the
> timer and let Linux handle it.
> 
> 
-- 
Philippe.