Re: [PATCH v6 2/2] clocksource: Ingenic: Add support for the Ingenic X1000 OST.

[Daniel Lezcano]

On 17/07/2020 08:13, Zhou Yanjie wrote:
> Hi Daniel,
> 
> å 2020/7/17 äå12:20, Daniel Lezcano åé:
>> On 10/07/2020 19:02, åçæ (Zhou Yanjie) wrote:
>>> X1000 and SoCs after X1000 (such as X1500 and X1830) had a separate
>>> OST, it no longer belongs to TCU. This driver will register both a
>>> clocksource and a sched_clock to the system.
>>>
>>> Tested-by: åæ (Zhou Zheng) <sernia.zhou@xxxxxxxxxxx>
>>> Co-developed-by: æéæ (Qi Pengzhen) <aric.pzqi@xxxxxxxxxxx>
>>> Signed-off-by: æéæ (Qi Pengzhen) <aric.pzqi@xxxxxxxxxxx>
>>> Signed-off-by: åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>
>>> Reviewed-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
>>> ---
>>>
>>> Notes:
>>> ÂÂÂÂ v1->v2:
>>> ÂÂÂÂ Fix compile warnings.
>>> ÂÂÂÂ Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>> ÂÂÂÂ ÂÂÂÂ v2->v3:
>>> ÂÂÂÂ No change.
>>> ÂÂÂÂ ÂÂÂÂ v3->v4:
>>> ÂÂÂÂ 1.Rename "ost" to "sysost"
>>> ÂÂÂÂ 1.Remove unrelated changes.
>>> ÂÂÂÂ 2.Remove ost_clock_parent enum.
>>> ÂÂÂÂ 3.Remove ost->percpu_timer_channel/ost->global_timer_channel.
>>> ÂÂÂÂ 4.Set up independent .recalc_rate/.set_rate for percpu/global
>>> timer.
>>> ÂÂÂÂ 5.No longer call functions in variable declarations.
>>> ÂÂÂÂ ÂÂÂÂ v4->v5:
>>> ÂÂÂÂ Use "of_io_request_and_map()" instead "of_iomap()".
>>> ÂÂÂÂ Suggested-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
>>> ÂÂÂÂ ÂÂÂÂ v5->v6:
>>> ÂÂÂÂ No change.
>>>
>>> Â drivers/clocksource/KconfigÂÂÂÂÂÂÂÂÂ |Â 11 +
>>> Â drivers/clocksource/MakefileÂÂÂÂÂÂÂÂ |ÂÂ 1 +
>>> Â drivers/clocksource/ingenic-sysost.c | 539
>>> +++++++++++++++++++++++++++++++++++
>>> Â 3 files changed, 551 insertions(+)
>>> Â create mode 100644 drivers/clocksource/ingenic-sysost.c
>>>
>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>> index 91418381fcd4..1bca8b8fb30f 100644
>>> --- a/drivers/clocksource/Kconfig
>>> +++ b/drivers/clocksource/Kconfig
>>> @@ -696,6 +696,17 @@ config INGENIC_TIMER
>>> ÂÂÂÂÂ help
>>> ÂÂÂÂÂÂÂ Support for the timer/counter unit of the Ingenic JZ SoCs.
>>> Â +config INGENIC_SYSOST
>>> +ÂÂÂ bool "Clocksource/timer using the SYSOST in Ingenic X SoCs"
>> We usually use silent options and let the platform's Kconfig enable it.
>> We show up the option only when COMPILE_TEST is enabled.
>>
>> Is there a reason to do it differently?
> 
> 
> Do you mean
> 
> bool "Clocksource/timer using the SYSOST in Ingenic X SoCs"
> 
> or
> 
> default MACH_INGENIC ?

Both, no default here.

eg.

bool "Clocksource/timer using the SYSOST in Ingenic X SoCs" if COMPILE_TEST

and

in arch/mips/Kconfig in the config MACH_INGENIC section :

...
select INGENIC_SYSOST
...

> This driver has some origins from "INGENIC_TIMER" driver and
> "INGENIC_OST" driver.
> Early Ingenic processors used TCU (timer/counter unit, has 6 or 8
> generic timer channels) to provide clocksource and clockevent (both with
> only 16bit precision). This part of the processor can only use
> "INGENIC_TIMER" driver.
> 
> Later processors provide an independent 32bit or 64bit timer channel
> (still under TCU, known as ost channel, this channel can not generate
> interrupt) to provid higher precision clocksource. The "INGENIC_OST"
> driver is for this channel. These processors can use "INGENIC_TIMER"
> driver, but using "INGENIC_OST" driver to provide higher precision
> clocksource would be a better choice (clockevent still needs to be
> provided by generic timer channel of TCU, and still 16bit precision).
> 
> And the recent processors provide a SYSOST components, it is independent
> from TCU, including a 64bit timer channel for clocksource and a 32bit
> timer channel for clockevent. Although these processors can also use
> "INGENIC_TIMER" driver, but the better choice is completely independent
> use of "INGENIC_SYSOST" driver to provide higher precision clocksource
> and clockevent.

Ok, the rating should do the job then.

Thanks for the explanation.

> You may have already noticed that this independent SYSOST component is
> like an upgraded and streamlined TCU, which only retains one generic
> timer channel that can generate interrupts, upgrade it from 16bit to
> 32bit, and then retain the 64bit ost channel. so the driver code and
> Kconfig code of this patch is largely referenced
> "INGENIC_TIMER" driver and "INGENIC_OST" driver.
> 
> Thanks and best regards!
> 
>>> +ÂÂÂ default MACH_INGENIC
>>> +ÂÂÂ depends on MIPS || COMPILE_TEST
>>> +ÂÂÂ depends on COMMON_CLK
>>> +ÂÂÂ select MFD_SYSCON
>>> +ÂÂÂ select TIMER_OF
>>> +ÂÂÂ select IRQ_DOMAIN
>>> +ÂÂÂ help
>>> +ÂÂÂÂÂ Support for the SYSOST of the Ingenic X Series SoCs.
>>> +
>> [ ... ]
>>
>>


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