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

From: Conor Dooley
Date: Thu Aug 03 2023 - 02:31:46 EST


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@0x1fe10430 {
> > > 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@0x1fe10450 {
> > > 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@1fe00500 {
> 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.

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