[U-Boot] [PATCH 1/3] ARM: rmobile: Switch CPU to non-secure HYP mode for r8a7790 based boards

[Marek Vasut <marek.vasut@gmail.com>]

On 2/7/19 6:19 PM, Oleksandr wrote:

[...]

>>>>> +        /* Update registers with correct frequency */
>>>>> +        writel(freq, TIMER_BASE + TIMER_CNTFID0);
>>>>> +        asm volatile("mcr p15, 0, %0, c14, c0, 0" : : "r" (freq));
>>>>> +
>>>>> +        /* Make sure arch timer is started by setting bit 0 of
>>>>> CNTCR */
>>>>> +        writel(1, TIMER_BASE + TIMER_CNTCR);
>>>> Shouldn't this be in the timer driver instead ?
>>> Which timer driver? Probably, I missed something, but I didn't find any
>>> arch timer driver being used for Gen2.
>>>
>>> I see that TMU timer (arch/sh/lib/time.c) is used as a system timer, but
>>> it is yet another IP.
>>>
>>> Would it be correct, if I move arch timer updating code to
>>> arch/arm/mach-rmobile directory?
>>>
>>> Actually, at the same location the corresponding code lives in Linux:
>>>
>>> https://elixir.bootlin.com/linux/v5.0-rc5/source/arch/arm/mach-shmobile/setup-rcar-gen2.c#L61
>>>
>> Presumably if this is something else than TMU, it needs proper driver
>> that goes into drivers/ .
> 
> Did I get your point correctly that new driver (specially for Gen2 arch
> timer) should be introduced in U-Boot and
> 
> the only one thing it is intended to do is to configure that timer for
> the future use by Linux/Hypervisor?
> 
> If yes, the only question I have is how that new driver is going to be
> populated? There is no corresponding node for arch timer in the device
> tree.
> 
> https://elixir.bootlin.com/linux/v5.0-rc5/source/arch/arm/boot/dts/r8a7790.dtsi
> 
> 
> So, do I need specially for this case add arch timer node with reg and
> compatible properties?
> 
> Sorry if I ask obvious questions, not familiar enough with U-Boot.

You would need a DT entry and a bit of code to start the timer in case
the PSCI is enabled, yes. This would then fit into the DM/DT paradigm.

>>>>> +    }
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * In order not to break compilation if someone decides to build
>>>>> with PSCI
>>>>> + * support disabled, keep these dummy functions.
>>>>> + */
>>>> That's currently the only use-case.
>>> Shall I drop this comment and dummy functions below?
>> Since there is no PSCI support, yes.
> 
> Understand.
> 
>>
>> [...]
>>
>> I'd like to have a cover letter go with V2, which describes what you're
>> trying to achieve here.
> 
> Yes, sure. Cover letter is present for the current V1 as well.
> 
> I thought that I had CC-ed all.
> 
> This is a link to it:
> 
> http://u-boot.10912.n7.nabble.com/PATCH-0-3-PSCI-support-for-r8a7790-SoC-Lager-Stout-boards-td357352.html

Thanks

-- 
Best regards,
Marek Vasut