> From: Rob Herring <robh+dt@xxxxxxxxxx> > Date: Thu, 1 Sep 2022 17:26:18 -0500 > > On Thu, Sep 1, 2022 at 10:56 AM Russell King (Oracle) > <linux@xxxxxxxxxxxxxxx> wrote: > > > > On Thu, Sep 01, 2022 at 06:45:52PM +0300, Krzysztof Kozlowski wrote: > > > On 01/09/2022 18:24, Russell King (Oracle) wrote: > > > > On Thu, Sep 01, 2022 at 06:15:46PM +0300, Krzysztof Kozlowski wrote: > > > >> On 01/09/2022 18:12, Russell King (Oracle) wrote: > > > >>>>> + compatible: > > > >>>>> + items: > > > >>>>> + - enum: > > > >>>>> + - apple,t8103-smc > > > >>>> > > > >>>> You miss two spaces of indentation on this level. > > > >>> > > > >>> Should that be picked up by the dt checker? > > I have a problem that Krzysztof is quicker. ;) Maybe I should stop > screening the emails (for the times I break things mostly). > > > > >> > > > >> I think yamllint complains about it. It is not a hard-dependency, so > > > >> maybe you don't have it installed. > > > >> > > > >>> > > > >>>>> + - apple,t8112-smc > > > >>>>> + - apple,t6000-smc > > > >>>> > > > >>>> Bring some order here - either alphabetical or by date of release (as in > > > >>>> other Apple schemas). I think t6000 was before t8112, so it's none of > > > >>>> that orders. > > > >>> > > > >>> Ok. > > > >>> > > > >>>>> + - const: apple,smc > > > >>>>> + > > > >>>>> + reg: > > > >>>>> + description: Two regions, one for the SMC area and one for the SRAM area. > > > >>>> > > > >>>> You need constraints for size/order, so in this context list with > > > >>>> described items. > > > >>> > > > >>> How do I do that? I tried maxItems/minItems set to 2, but the dt checker > > > >>> objected to it. > > > >> > > > >> One way: > > > >> reg: > > > >> items: > > > >> - description: SMC area > > > >> - description: SRAM area > > > >> > > > >> but actually this is very similar what you wrote for reg-names - kind of > > > >> obvious, so easier way: > > > >> > > > >> reg: > > > >> maxItems: 2 > > > > > > > > Doesn't work. With maxItems: 2, the example fails, yet it correctly lists > > > > two regs which are 64-bit address and 64-bit size - so in total 8 32-bit > > > > ints. > > > > > > > > Documentation/devicetree/bindings/mfd/apple,smc.example.dtb: smc@23e400000: reg: [[2, 1044381696], [0, 16384], [2, 1071644672], [0, 1048576]] is too long > > > > From schema: /home/rmk/git/linux-rmk/Documentation/devicetree/bindings/mfd/apple,smc.yaml > > > > > > > > Hence, I originally had maxItems: 2, and ended up deleting it because of > > > > the dt checker. > > > > > > > > With the two descriptions, it's the same failure. > > > > > > Yeah, they should create same result. > > > > > > > > > > > I think the problem is that the checker has no knowledge in the example > > > > of how big each address and size element of the reg property is. So, > > > > it's interpreting it as four entries of 32-bit address,size pairs > > > > instead of two entries of 64-bit address,size pairs. Yep, that's it, > > > > if I increase the number of "- description" entries to four then it's > > > > happy. > > > > > > > > So, what's the solution? > > > > > > > > > > If you open generated DTS examples (in your > > > kbuild-output/Documentation/devicetree/bindings/mfd/) you will see which > > > address/size cells are expected. By default it is I think address/size > > > cells=1, so you need a bus node setting it to 2. > > > > Thanks, that works. The patch with all those points addressed now looks > > like: > > > > 8<=== > > From: "Russell King (Oracle)" <rmk+kernel@xxxxxxxxxxxxxxx> > > Subject: [PATCH] dt-bindings: mfd: add binding for Apple Mac System Management > > Controller > > > > Add a DT binding for the Apple Mac System Management Controller. > > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> > > --- > > .../devicetree/bindings/mfd/apple,smc.yaml | 61 +++++++++++++++++++ > > 1 file changed, 61 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/mfd/apple,smc.yaml > > > > diff --git a/Documentation/devicetree/bindings/mfd/apple,smc.yaml b/Documentation/devicetree/bindings/mfd/apple,smc.yaml > > new file mode 100644 > > index 000000000000..168f237c2962 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/mfd/apple,smc.yaml > > @@ -0,0 +1,61 @@ > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/mfd/apple,smc.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Apple Mac System Management Controller > > + > > +maintainers: > > + - Hector Martin <marcan@xxxxxxxxx> > > + > > +description: > > + Apple Mac System Management Controller implements various functions > > + such as GPIO, RTC, power, reboot. > > + > > +properties: > > + compatible: > > + items: > > + - enum: > > + - apple,t6000-smc > > + - apple,t8103-smc > > + - apple,t8112-smc > > + - const: apple,smc > > + > > + reg: > > + items: > > + - description: SMC area > > + - description: SRAM area > > Based on the disjoint addresses, is this really one device? Perhaps > the SRAM area should use mmio-sram binding? That already supports > sub-dividing the sram for different uses. I'll comment more on the > full example. To me it does look as if the SRAM is part of the SMC coprocessor block. It is probably part of a larger SRAM on the side of the SMC coprocessor. There is a gap, but the addresses are close. The only thing in between is the SMC mailbox, which is represented by a separate node. The address of the SRAM can be discovered by sending SMC commands. I believe Hector added it in order to verify the address that the SMC firmware provides. My OpenBSD driver doesn't use it, so in that sense changing the binding to use a separate node with a "mmio-sram" compatible (and presumably an "apple,sram" property to reference that node using a phandle) would work fine. The extra level of indirection obviously would mean more code in the Linux SMC driver though.
