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Subject: Re: [PATCH v2 1/2] gpio: loongson: add dts/acpi gpio support
To:     WANG Xuerui <kernel@xen0n.name>,
        Bartosz Golaszewski <brgl@bgdev.pl>
Cc:     Linus Walleij <linus.walleij@linaro.org>, zhuyinbo@loongson.cn,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Juxin Gao <gaojuxin@loongson.cn>,
        Bibo Mao <maobibo@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>, linux-gpio@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        loongarch@lists.linux.dev, linux-mips@vger.kernel.org,
        Arnaud Patard <apatard@mandriva.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        lvjianmin <lvjianmin@loongson.cn>,
        zhanghongchen <zhanghongchen@loongson.cn>,
        Liu Peibao <liupeibao@loongson.cn>
References: <20221114095332.21079-1-zhuyinbo@loongson.cn>
 <CAMRc=McnEiSj1Q51pG3Lc8e+HcXE_uU7dm=1VoOa__xOgyoZPg@mail.gmail.com>
 <8b24e3df-8c22-bd09-cfc1-b27e39a05c25@loongson.cn>
 <fd5cc541-dfc6-d1cf-0865-669b11ce2e7a@xen0n.name>
From:   Yinbo Zhu <zhuyinbo@loongson.cn>
Message-ID: <9a448680-0bb6-c4f0-93d2-29a86fede2d4@loongson.cn>
Date:   Tue, 15 Nov 2022 21:07:05 +0800
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在 2022/11/15 下午6:17, WANG Xuerui 写道:
> Sorry for jumping in, but...
> 
> On 2022/11/15 17:53, Yinbo Zhu wrote:
>>
>>
>> 在 2022/11/15 下午5:05, Bartosz Golaszewski 写道:
>>> On Mon, Nov 14, 2022 at 10:53 AM Yinbo Zhu <zhuyinbo@loongson.cn> wrote:
>>>>
>>>> The latest Loongson series platform use dts or acpi framework to
>>>> register gpio device resources, such as the Loongson-2 series
>>>> SoC of LOONGARCH architecture. In order to support dts, acpi and
>>>> compatibility with previous platform device resources in driver,
>>>> this patch was added.
>>>>
>>>> Signed-off-by: lvjianmin <lvjianmin@loongson.cn>
>>>> Signed-off-by: zhanghongchen <zhanghongchen@loongson.cn>
>>>> Signed-off-by: Liu Peibao <liupeibao@loongson.cn>
>>>> Signed-off-by: Juxin Gao <gaojuxin@loongson.cn>
>>>> Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
>>>> ---
>>>> Change in v2:
>>>>                  1. Fixup of_loongson_gpio_get_props and remove the 
>>>> parse logic about
>>>>                     "loongson,conf_offset", "loongson,out_offset", 
>>>> "loongson,in_offset",
>>>>                     "loongson,gpio_base", "loongson,support_irq" 
>>>> then kernel driver will
>>>>                     initial them that depend compatible except 
>>>> "loongson,gpio_base".
>>>>
>>>>   arch/loongarch/include/asm/loongson.h         |  13 +
>>>>   .../include/asm/mach-loongson2ef/loongson.h   |  12 +
>>>>   .../include/asm/mach-loongson64/loongson.h    |  13 +
>>>>   drivers/gpio/Kconfig                          |   6 +-
>>>>   drivers/gpio/gpio-loongson.c                  | 422 
>>>> +++++++++++++++---
>>>>   5 files changed, 391 insertions(+), 75 deletions(-)
>>>>
>>>> diff --git a/arch/loongarch/include/asm/loongson.h 
>>>> b/arch/loongarch/include/asm/loongson.h
>>>> index 00db93edae1b..383fdda155f0 100644
>>>> --- a/arch/loongarch/include/asm/loongson.h
>>>> +++ b/arch/loongarch/include/asm/loongson.h
>>>> @@ -60,6 +60,19 @@ static inline void xconf_writeq(u64 val64, 
>>>> volatile void __iomem *addr)
>>>>          );
>>>>   }
>>>>
>>>> +/* ============== Data structrues =============== */
>>>> +
>>>> +/* gpio data */
>>>> +struct platform_gpio_data {
>>>> +       u32 gpio_conf;
>>>> +       u32 gpio_out;
>>>> +       u32 gpio_in;
>>>> +       u32 support_irq;
>>>> +       char *label;
>>>> +       int gpio_base;
>>>> +       int ngpio;
>>>> +};
>>>
>>> This is a terrible name for an exported structure. You would at least
>>> need some kind of a namespace prefix. But even then the need to add a
>>> platform data structure is very questionable. We've moved past the
>>> need for platform data in the kernel. I don't see anyone setting it up
>>> in this series either. Could you provide more explanation on why you
>>> would need it and who would use it?
>> okay, I will add a namespace prefix, about this platform data was added
>> that was to compatible with legacy platforms that do not support dts or
>> acpi, then, the mips loongson platform or loongarch loongson platform
> 
> Why are you trying to support "legacy" LoongArch platforms when the 
> architecture was just upstreamed *this year*?
the leagacy gpio driver had support LoongArch, and you can find some
gpio register defined in arch/loongarch/include
/asm/loongson.h in legacy gpio driver, such as LOONGSON_GPIODATA,
The legacy gpio driver is the driver that doesn't include my gpio patch.
> 
>> can implement the gpio device driver to initialize the
>> platform_gpio_data structure as needed after exporting the structure.
>>>
>>>> +
>>>>   /* ============== LS7A registers =============== */
>>>>   #define LS7A_PCH_REG_BASE              0x10000000UL
>>>>   /* LPC regs */
>>>> diff --git a/arch/mips/include/asm/mach-loongson2ef/loongson.h 
>>>> b/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>>> index ca039b8dcde3..b261cea4fee1 100644
>>>> --- a/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>>> +++ b/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>>> @@ -315,4 +315,16 @@ extern unsigned long _loongson_addrwincfg_base;
>>>>
>>>>   #endif /* ! CONFIG_CPU_SUPPORTS_ADDRWINCFG */
>>>>
>>>> +/* ============== Data structrues =============== */
>>>> +
>>>> +/* gpio data */
>>>> +struct platform_gpio_data {
>>>> +       u32 gpio_conf;
>>>> +       u32 gpio_out;
>>>> +       u32 gpio_in;
>>>> +       u32 support_irq;
>>>> +       char *label;
>>>> +       int gpio_base;
>>>> +       int ngpio;
>>>> +};
>>>
>>> No idea why you would need to duplicate it like this either. And why
>>> put it in arch/.
>> because loongson platform include mips and loongarch, and the gpio 
>> device data was defined in arch/ in leagcy loongson gpio driver.  so the
>> latest loongson gpio drvier add platform_gpio_data in same dir.
> 
> I think at this point it's hopefully clear, that the way forward to 
> supporting Loongson IP blocks shared between MIPS/LoongArch SoCs is to 
> start over and do things properly, making the code as platform-agnostic 
> as possible. Just make sure the drivers can get initialized via DT and 
> ACPI then you're all set -- the upstream kernel is guaranteed to use one 
> of the two well-established boot flows for every Loongson chip it 
> supports. Be it hard-coded DT in arch/mips/boot/dts/loongson, or the 
> LoongArch ACPI/upcoming DT, no need for hard-coding things in arch/ in 
> either case.
Our old platforms are used by customers, but we will not maintain those
platforms. Adding dts/acpi support to those old platforms not only makes
no sense, but also affects their use. Because the configuration of
dts/acpi requires the support of the firmware team, but in fact, we have
no one to maintain those old platforms.

in a words, My patch to upstream was supposed to consider dts/acpi in
LoongArch platform  But I have to consider the original legacy gpio
driver and to compatible with it.
> 
>>>
>>> [snip]
>>>
>>> I will hold off reviewing the rest of the patch until we get that 
>>> clarified.
>>>
>>> Bartosz
>>>
>>
>