linux-kernel - Re: [PATCH v2 1/2] gpio: dt-bindings: add parsing of loongson gpio offset

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Message-ID: <20230803-tartar-tainted-968687047460@wendy>
Date:   Thu, 3 Aug 2023 07:30:53 +0100
From:   Conor Dooley <conor.dooley@...rochip.com>
To:     Yinbo Zhu <zhuyinbo@...ngson.cn>
CC:     Conor Dooley <conor@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        <linux-gpio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Jianmin Lv <lvjianmin@...ngson.cn>,
        <wanghongliang@...ngson.cn>, Liu Peibao <liupeibao@...ngson.cn>,
        <loongson-kernel@...ts.loongnix.cn>
Subject: Re: [PATCH v2 1/2] gpio: dt-bindings: add parsing of loongson gpio
 offset

On Thu, Aug 03, 2023 at 09:56:02AM +0800, Yinbo Zhu wrote:
> 
> 
> 在 2023/8/2 下午11:36, Conor Dooley 写道:
> > On Wed, Aug 02, 2023 at 04:37:50PM +0800, Yinbo Zhu wrote:
> > > 
> > > 
> > > 在 2023/8/2 下午3:50, Conor Dooley 写道:
> > > > On Wed, Aug 02, 2023 at 03:44:17PM +0800, Yinbo Zhu wrote:
> > > > > 在 2023/8/2 下午3:22, Conor Dooley 写道:
> > > > > > On Wed, Aug 02, 2023 at 09:38:34AM +0800, Yinbo Zhu wrote:
> > > > > > > 在 2023/8/1 下午11:54, Conor Dooley 写道:
> > > > > > > > On Tue, Aug 01, 2023 at 04:34:30PM +0800, Yinbo Zhu wrote:
> > > > 
> > > > > > > > > Sorry, I may not have described it clearly before, the ls2k500 was only
> > > > > > > > > as a example, actually, Loongson GPIO controllers (2k500,2k1000,eg)come
> > > > > > > > > in multiple variants that are compatible except for certain register
> > > > > > > > > offset values.  So above all offset device property was used to in all
> > > > > > > > > loongson gpio controller.
> > > > > > > > 
> > > > > > > > But it would be good to know why they are different. Do they each
> > > > > > > > support some different features, or was there some other reason for
> > > > > > > > making controllers like this?
> > > > > > > 
> > > > > > > 
> > > > > > > There are no other reasons, just differences in these offset addresses.
> > > > > > 
> > > > > > Huh. Do you have a link to a devicetree for the ls2k500?
> > > > > 
> > > > > 
> > > > > Yes,  there was a link about ls2k500 dts,  but that ls2k500 dts has not
> > > > > yet added a gpio node.  this gpio node will be added later.
> > > > 
> > > > You must have something that you used to test with, no? I don't mind if
> > > > it is not a patch, but rather is some WIP - I'd just like to see user of
> > > > the binding :)
> > > 
> > > 
> > > yes, I have a test, for 2k0500, that gpio dts as follows:
> > > 
> > >                  gpio0:gpio@...fe10430 {
> > >                          compatible = "loongson,ls2k-gpio";
> > >                          reg = <0 0x1fe10430 0 0x20>;
> > >                          gpio-controller;
> > >                          #gpio-cells = <2>;
> > > 			interrupt-parent = <&liointc1>;
> > >                          ngpios = <64>;
> > >                          loongson,gpio-conf-offset = <0>;
> > >                          loongson,gpio-out-offset = <0x10>;
> > >                          loongson,gpio-in-offset = <0x8>;
> > >                          loongson,gpio-inten-offset = <0xb0>;
> > > 			loongson,gpio-ctrl-mode = <0x0>;
> > >                          ...
> > > 		  }
> > > 
> > >                  gpio1:gpio@...fe10450 {
> > >                          compatible = "loongson,ls2k-gpio";
> > >                          reg = <0 0x1fe10450 0 0x20>;
> > >                          gpio-controller;
> > >                          #gpio-cells = <2>;
> > > 			interrupt-parent = <&liointc1>;
> > >                          ngpios = <64>;
> > >                          loongson,gpio-conf-offset = <0>;
> > >                          loongson,gpio-out-offset = <0x10>;
> > >                          loongson,gpio-in-offset = <0x8>;
> > 
> > These 3 are the same for both controllers, no?
> > Is only the inten-offset a variable?
> > 
> > >                          loongson,gpio-inten-offset = <0x98>;
> > 
> > These offsets exceed the region that you've got in the reg property for
> > this controller, do they not?
> > 
> > Is there some sort of "miscellaneous register area" at 0x1FE104E0, or
> > just those two interrupt registers and nothing else?
> 
> 
> 2k500 gpio dts is just an example, like 3a5000, or more other platform,
> above offset was different but the gpio controller was compatible.
> 
>                 gpio: gpio@...00500 {
>                         compatible = "loongson,ls2k-gpio";
>                         reg = <0 0x1fe00500 0xc00>;
>                         gpio-controller;
>                         #gpio-cells = <2>;
>                         ngpios = <16>;
>                         loongson,gpio-conf-offset = <0x0>;
>                         loongson,gpio-out-offset = <0x8>;
>                         loongson,gpio-in-offset = <0xc>;
> 			...
> 			}

That is a different SoC and needs to have a different compatible string.
"loongson,ls2k-foo" compatible strings were a mistake that only got past
us because we were not aware it was a family, rather than a specific
SoC. They certainly should not be used in isolation on a 3a5000!

Are there more than one GPIO controllers on the 3a5000? If so, what do
those nodes look like.

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)