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

[Julien Grall <julien.grall@linaro.org>]

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@linaro.org> 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