RE: [PATCH 1/4] dt-bindings: mfd: nxp,bbnsm: Add binding for nxp bbnsm

[Jacky Bai <ping.bai@xxxxxxx>]

> Subject: Re: [PATCH 1/4] dt-bindings: mfd: nxp,bbnsm: Add binding for nxp
> bbnsm
> 
> On 21/11/2022 10:09:40+0100, Krzysztof Kozlowski wrote:
> > On 21/11/2022 07:51, Jacky Bai wrote:
> > > Add binding for NXP BBNSM(Battery-Backed Non-Secure Module).
> > >
> > > Signed-off-by: Jacky Bai <ping.bai@xxxxxxx>
> > > ---
> > >  .../devicetree/bindings/mfd/nxp,bbnsm.yaml    | 103
> ++++++++++++++++++
> > >  1 file changed, 103 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/mfd/nxp,bbnsm.yaml

...

> > > +
> > > +title: NXP Battery-Backed Non-Secure Module bindings
> > > +
> > > +maintainers:
> > > +  - Jacky Bai <ping.bai@xxxxxxx>
> > > +
> > > +description: |
> > > +  NXP BBNSM serves as non-volatile logic and storage for the system.
> > > +  it Intergrates RTC & ON/OFF control.
> > > +  The RTC can retain its state and continues counting even when the
> > > +  main chip is power down. A time alarm is generated once the most
> > > +  significant 32 bits of the real-time counter match the value in
> > > +the
> > > +  Time Alarm register.
> > > +  The ON/OFF logic inside the BBNSM allows for connecting directly
> > > +to
> > > +  a PMIC or other voltage regulator device. both smart PMIC mode
> > > +and
> > > +  Dumb PMIC mode supported.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - enum:
> > > +          - nxp,bbnsm
> > > +      - const: syscon
> > > +      - const: simple-mfd
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  rtc:
> > > +    type: object
> > > +
> > > +    properties:
> > > +      compatible:
> > > +        const: nxp,bbnsm-rtc
> >
> >
> > Missing ref to rtc.yaml.
> >
> 
> This is also missing start-year

The RTC counter will be reset to 0 after PoR reset, do we still need to add
this property?

BR
> 
> > > +
> > > +      regmap:
> >
> > Use vendor prefix, descriptive name and description. Where is the type
> > of 'regmap' defined?
> >
> > > +        maxItems: 1
> >
> > I don't think this is correct. Rob explained the simple-mfd means
> > children do not depend on anything from the parent, but taking a
> > regmap from its parent contradicts it.
> >
> > > +
> > > +      interrupts:
> > > +        maxItems: 1
> >
> > You have same interrupt and same address space used by two devices.
> >
> > Both arguments (depending on parent regmap, sharing interrupt)
> > suggests that this is one device block, so describing it with
> > simple-mfd is quite unflexible.
> >
> > > +
> > > +    required:
> > > +      - compatible
> > > +      - regmap
> > > +      - interrupts
> > > +
> > > +    additionalProperties: false
> > > +
> > > +  pwrkey:
> > > +    type: object
> > > +    $ref: /schemas/input/input.yaml#
> > > +
> > > +    properties:
> > > +      compatible:
> > > +        const: nxp,bbnsm-pwrkey
> > > +
> > > +      regmap:
> > > +        maxItems: 1
> > > +
> > > +      interrupts:
> > > +        maxItems: 1
> > > +
> > > +      linux,code: true
> > > +
> > > +    required:
> > > +      - compatible
> > > +      - regmap
> > > +      - interrupts
> > > +
> > > +    additionalProperties: false
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - rtc
> > > +  - pwrkey
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    bbnsm: bbnsm@44440000 {
> > > +      compatible = "nxp,bbnsm", "syscon", "simple-mfd";
> > > +      reg = <0x44440000 0x10000>;
> > > +
> > > +      bbnsm_rtc: rtc {
> > > +        compatible = "nxp,bbnsm-rtc";
> >
> > Use 4 spaces for example indentation.
> >
> > > +        regmap = <&bbnsm>;
> > > +        interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>;
> > > +      };
> > > +
> > > +      bbnsm_pwrkey: pwrkey {
> > > +         compatible = "nxp,bbnsm-pwrkey";
> > > +         regmap = <&bbnsm>;
> > > +         interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>;
> > > +         linux,code = <KEY_POWER>;
> > > +       };
> > > +    };
> >
> > Best regards,
> > Krzysztof
> >
> 
> --
> Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel
> engineering
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