linux-kernel - Re: [PATCH v1 1/2] clocksource: loongson2

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Date:   Sat, 8 Oct 2022 10:59:56 +0800
From:   Yinbo Zhu <zhuyinbo@...ngson.cn>
To:     WANG Xuerui <kernel@...0n.name>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Jianmin Lv <lvjianmin@...ngson.cn>,
        Yun Liu <liuyun@...ngson.cn>,
        Yang Li <yang.lee@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        loongarch@...ts.linux.dev, zhuyinbo@...ngson.cn
Subject: Re: [PATCH v1 1/2] clocksource: loongson2_hpet: add hpet driver
 support



在 2022/9/30 下午10:43, WANG Xuerui 写道:
> Hi,
> 
> On 9/30/22 17:35, Yinbo Zhu wrote:
>> HPET (High Precision Event Timer) defines a new set of timers, which
>> are used by the operating system to schedule threads, interrupt the
>> kernel and interrupt the multimedia timer server. The operating
>> system can assign different timers to different applications. By
>> configuration, each timer can generate interrupt independently.
>>
>> The loongson2 HPET module includes a main count and three comparators
>> , all of which are 32 bits wide. Among the three comparators, only
>> one comparator supports periodic interrupt, all three comparators
>> support non periodic interrupts.
>>
>> Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
>> ---
>>   MAINTAINERS                          |   6 +
>>   arch/loongarch/kernel/time.c         |   3 +
>>   drivers/clocksource/Kconfig          |   9 +
>>   drivers/clocksource/Makefile         |   1 +
>>   drivers/clocksource/loongson2_hpet.c | 332 +++++++++++++++++++++++++++
>>   5 files changed, 351 insertions(+)
>>   create mode 100644 drivers/clocksource/loongson2_hpet.c
> 
> Thanks for the contribution, but as HPET is a fairly common peripheral 
> that have well standardized behavior, why not simply add DT support to 
> the drivers/char/hpet.c and be done with it?
At present, the drivers/char/hpet.c doesn't support DT(dts parse) and
loongson2 soc wasn't belong to X86 or IA64 architecture, Although it is
an option to add DT support for this driver, I consider that the hpet
design of loongson2 series socs may not be universal. In addition, I
notice that mips and x86 have their own hpet drivers. In order to reduce
the impact on the public driver and make more flexible modifications to
the loongson2 hpet driver under its own architecture, a separate
loongson2 hpet driver was submitted.

config HPET
         bool "HPET - High Precision Event Timer" if (X86 || IA64)
         default n
         depends on ACPI
         help
           If you say Y here, you will have a miscdevice named 
"/dev/hpet/".  Each
           open selects one of the timers supported by the HPET.  The 
timers are
           non-periodic and/or periodic.


BRs
Yinbo Zhu.

>