[U-Boot] [PATCH v2 12/12] tegra: Set CNTFRQ for secondary CPUs

Jan Kiszka
2015-02-16T13:44:36Z

On 2015-02-16 14:37, Mark Rutland wrote:
> On Mon, Feb 16, 2015 at 12:54:49PM +0000, Jan Kiszka wrote:
>> We only set CNTFRQ in arch_timer_init for the boot CPU. But this has to
>> happen for all cores.
>>
>> Fixing this resolves problems of KVM with emulating the generic
>> timer/counter.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>> arch/arm/cpu/armv7/tegra-common/psci.S | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/arch/arm/cpu/armv7/tegra-common/psci.S b/arch/arm/cpu/armv7/tegra-common/psci.S
>> index b7501fb..119c246 100644
>> --- a/arch/arm/cpu/armv7/tegra-common/psci.S
>> +++ b/arch/arm/cpu/armv7/tegra-common/psci.S
>> @@ -51,12 +51,25 @@ ENTRY(psci_arch_init)
>>
>> mrc p15, 0, r4, c0, c0, 5 @ MPIDR
>> and r4, r4, #7 @ number of CPUs in cluster
>> +
>> + adr r5, _sys_clock_freq
>> + cmp r4, #0
>> +
>> + mrceq p15, 0, r7, c14, c0, 0 @ read CNTFRQ from CPU0
>> + streq r7, [r5]
>> +
>> + ldrne r7, [r5]
>> + mcrne p15, 0, r7, c14, c0, 0 @ write CNTFRQ to CPU1..3
>
> Is it not possible to have a hook that uses the same variable as
> arch_timer_init rather than doing a here copy? It seems a shame to
> duplicate the effort.

The problem is related to the different address spaces. Here we run in
the secure monitor, arch_timer_init - to my understanding - in
non-secure mode. Didn't find a pattern so far how to transfer data (and
that shouldn't be more complex than the above code).

Jan

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