On Wed, Jan 24, 2024 at 11:40 AM Théo Lebrun <theo.lebrun@xxxxxxxxxxx> wrote: > > Hello, > > On Wed Jan 24, 2024 at 6:28 PM CET, Théo Lebrun wrote: > > Hello, > > > > On Wed Jan 24, 2024 at 4:14 PM CET, Rob Herring wrote: > > > On Tue, Jan 23, 2024 at 07:46:49PM +0100, Théo Lebrun wrote: > > > > Add documentation to describe the "Other Logic Block" syscon. > > > > > > > > Signed-off-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx> > > > > --- > > > > .../bindings/soc/mobileye/mobileye,eyeq5-olb.yaml | 77 ++++++++++++++++++++++ > > > > MAINTAINERS | 1 + > > > > 2 files changed, 78 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/soc/mobileye/mobileye,eyeq5-olb.yaml b/Documentation/devicetree/bindings/soc/mobileye/mobileye,eyeq5-olb.yaml > > > > new file mode 100644 > > > > index 000000000000..031ef6a532c1 > > > > --- /dev/null > > > > +++ b/Documentation/devicetree/bindings/soc/mobileye/mobileye,eyeq5-olb.yaml > > > > @@ -0,0 +1,77 @@ > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > > > +%YAML 1.2 > > > > +--- > > > > +$id: http://devicetree.org/schemas/soc/mobileye/mobileye,eyeq5-olb.yaml# > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > + > > > > +title: Mobileye EyeQ5 SoC system controller > > > > + > > > > +maintainers: > > > > + - Grégory Clement <gregory.clement@xxxxxxxxxxx> > > > > + - Théo Lebrun <theo.lebrun@xxxxxxxxxxx> > > > > + - Vladimir Kondratiev <vladimir.kondratiev@xxxxxxxxxxxx> > > > > + > > > > +description: > > > > + OLB ("Other Logic Block") is a hardware block grouping smaller blocks. Clocks, > > > > + resets, pinctrl are being handled from here. > > > > + > > > > +properties: > > > > + compatible: > > > > + items: > > > > + - const: mobileye,eyeq5-olb > > > > + - const: syscon > > > > + - const: simple-mfd > > > > + > > > > + reg: > > > > + maxItems: 1 > > > > + > > > > + clock-controller: > > > > + $ref: /schemas/clock/mobileye,eyeq5-clk.yaml# > > > > + type: object > > > > + > > > > + reset-controller: > > > > + $ref: /schemas/reset/mobileye,eyeq5-reset.yaml# > > > > + type: object > > > > + > > > > + pinctrl-a: > > > > + $ref: /schemas/pinctrl/mobileye,eyeq5-pinctrl.yaml# > > > > + type: object > > > > + > > > > + pinctrl-b: > > > > + $ref: /schemas/pinctrl/mobileye,eyeq5-pinctrl.yaml# > > > > + type: object > > > > + > > > > +required: > > > > + - compatible > > > > + - reg > > > > + > > > > +additionalProperties: false > > > > + > > > > +examples: > > > > + - | > > > > + system-controller@e00000 { > > > > + compatible = "mobileye,eyeq5-olb", "syscon", "simple-mfd"; > > > > + reg = <0xe00000 0x400>; > > > > + > > > > + clock-controller { > > > > + compatible = "mobileye,eyeq5-clk"; > > > > + #clock-cells = <1>; > > > > + clocks = <&xtal>; > > > > + clock-names = "ref"; > > > > + }; > > > > + > > > > + reset-controller { > > > > + compatible = "mobileye,eyeq5-reset"; > > > > + #reset-cells = <2>; > > > > + }; > > > > + > > > > + pinctrl-a { > > > > + compatible = "mobileye,eyeq5-a-pinctrl"; > > > > + #pinctrl-cells = <1>; > > > > > > Sure you need this? Generally only pinctrl-single uses this. > > > > You are completely right, it is useless. I naively expected it in the > > same vein as other subsystems. > > > > > > > > > + }; > > > > + > > > > + pinctrl-b { > > > > + compatible = "mobileye,eyeq5-b-pinctrl"; > > > > + #pinctrl-cells = <1>; > > > > + }; > > > > + }; > > > > > > This can all be simplified to: > > > > > > system-controller@e00000 { > > > compatible = "mobileye,eyeq5-olb", "syscon"; > > > reg = <0xe00000 0x400>; > > > #reset-cells = <2>; > > > #clock-cells = <1>; > > > clocks = <&xtal>; > > > clock-names = "ref"; > > > > > > pins { ... }; > > > }; > > > > > > There is no need for sub nodes unless you have reusable blocks or each > > > block has its own resources in DT. > > > > That is right, and it does simplify the devicetree as you have shown. > > However, the split nodes gives the following advantages: > > > > - Devicetree-wise, it allows for one alias per function. > > `clocks = <&clocks EQ5C_PLL_CPU>` is surely more intuitive > > than `clocks = <&olb EQ5C_PLL_CPU>;`. Same for reset. clocks: resets: pinctrl: system-controller@e00000 { > > > > - It means an MFD driver must be implemented, adding between 100 to 200 > > lines of boilerplate code to the kernel. >From a binding perspective, not my problem... That's Linux details defining the binding. What about u-boot, BSD, future versions of Linux with different structure? I don't think an MFD is required here. A driver should be able to be both clock and reset provider. That's pretty common. pinctrl less so. > > - It means one pinctrl device for the two banks. That addresses your > > comment on [PATCH v3 10/17]. This is often done and would be doable > > on this platform. However it means added logic to each individual > > function of pinctrl-eyeq5. If it makes things easier, 2 'pins' sub-nodes is fine. That's just container nodes. > > Overall it makes for less readable code, for code that already looks > > more complex than it really is. > > > > My initial non-public version of pinctrl-eyeq5 was using this method > > (a device handling both banks) and I've leaned away from it. > > I had forgotten one other reason: > > - Reusability does count for something. Other Mobileye platforms exist, > and the system controller stuff is more complex on those. Multiple > different OLB blocks, etc. But my understanding is that > per-peripheral logic is reused across versions. IME, this stuff never stays exactly the same from chip to chip. Rob
