Re: [Xen-devel] [PATCH v1 3/3] xen/arm: Introduce support for Renesas R-Car Gen2 platform

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 16/01/2015 19:34, Julien Grall wrote:
> On 16/01/15 19:11, Iurii Konovalenko wrote:
> > On Fri, Jan 16, 2015 at 6:31 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> > > On 16/01/15 16:17, Iurii Konovalenko wrote:
> > > > I tried to add instruction: asm volatile("mcr p15, 0, %0, c14, c0, 0" :
> > > > : "r" (freq));
> > > > Also I tried to write it via Xen API: WRITE_SYSREG32(freq, CNTFRQ_EL0);
> > > >
> > > > But unfortunately Xen fails on both this instructions with "Undefined
> > > > instruction" exception.
> > > > You can see log in attachment.
> > > > Could you please suggest reason, why it happens?
> > > CNTFRQ can only be written in Secure PL1 mode.
> > >
> > > I have the feeling CNTFRQ is not update automatically when Xen is
> > > writing in CNTFID0. So the frequency may mismatch.
> > >
> > > Assuming this, I'm wondering if we hit the second part of the if
> > > sentence [1] and therefore this code useful?
> > Now I understand it.
> > So I will set up frequency and enable timer in u-boot.
> > As there is no way to change frequency in Hypervisor mode, I will
> > remove from board file mode checking and frequency related staff.
> > So time init function is like:
> >
> > static int __init shmobile_init_time(void)
> > {
> >      void __iomem *tmu;
> >
> >      /* Remap "armgcnt address map" space */
> >      tmu = ioremap_nocache(SHMOBILE_ARCH_TIMER_BASE, PAGE_SIZE);
> >      if ( !tmu )
> >      {
> >          dprintk(XENLOG_ERR, "Unable to map TMU\n");
> >          return -ENOMEM;
> >      }
> >      /* Enable the timer if it is not running */
> >      if ( (readl_relaxed(tmu + SHMOBILE_ARCH_TIMER_CNTCR) & 1) == 0 )
> >          writel_relaxed(1, tmu + SHMOBILE_ARCH_TIMER_CNTCR);
> >
> >      iounmap(tmu);
> >
> >      return 0;
> > }
> >
> > Am I right?
> While you are modifying U-boot, can you also enable the timer? It would
> avoid to do specific timer initialization for this board.
BTW, can you document somewhere (wiki page, commit message...) which 
U-boot will be required to use Xen on this platform?
In general, it would be nice if those patch reach upstream U-boot.

Regards,

--
Julien Grall

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