linux-kernel - Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

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Date:   Tue, 4 Apr 2023 09:10:04 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Ibrahim Tilki <Ibrahim.Tilki@...log.com>, a.zummo@...ertech.it,
        jdelvare@...e.com, linux@...ck-us.net, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        devicetree@...r.kernel.org,
        Zeynep Arslanbenzer <Zeynep.Arslanbenzer@...log.com>
Subject: Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

On 04/04/2023 08:17:40+0200, Krzysztof Kozlowski wrote:
> On 03/04/2023 17:43, Ibrahim Tilki wrote:
> > Devicetree binding documentation for Analog Devices MAX313XX RTCs
> > 
> > Signed-off-by: Ibrahim Tilki <Ibrahim.Tilki@...log.com>
> > Signed-off-by: Zeynep Arslanbenzer <Zeynep.Arslanbenzer@...log.com>
> > ---
> >  .../devicetree/bindings/rtc/adi,max313xx.yaml | 144 ++++++++++++++++++
> >  1 file changed, 144 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/rtc/adi,max313xx.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/rtc/adi,max313xx.yaml b/Documentation/devicetree/bindings/rtc/adi,max313xx.yaml
> > new file mode 100644
> > index 000000000..0c17a395e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/adi,max313xx.yaml
> > @@ -0,0 +1,144 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright 2022 Analog Devices Inc.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/rtc/adi,max313xx.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices MAX313XX series I2C RTCs
> > +
> > +maintainers:
> > +  - Ibrahim Tilki <Ibrahim.Tilki@...log.com>
> > +  - Zeynep Arslanbenzer <Zeynep.Arslanbenzer@...log.com>
> > +
> > +description: Analog Devices MAX313XX series I2C RTCs.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - adi,max31328
> > +      - adi,max31329
> > +      - adi,max31331
> > +      - adi,max31334
> > +      - adi,max31341
> > +      - adi,max31342
> > +      - adi,max31343
> > +
> > +  reg:
> > +    description: I2C address of the RTC
> > +    items:
> > +      - enum: [0x68, 0x69]
> > +
> > +  interrupts:
> > +    description: |
> 
> Do not need '|'.
> 
> > +      Alarm1 interrupt line of the RTC. Some of the RTCs have two interrupt
> > +      lines and alarm1 interrupt muxing depends on the clockin/clockout
> > +      configuration.
> > +    maxItems: 1
> > +
> > +  "#clock-cells":
> > +    description: |
> 
> Do not need '|'.
> 
> > +      RTC can be used as a clock source through its clock output pin when
> > +      supplied.
> > +    const: 0
> > +
> > +  clocks:
> > +    description: |
> 
> Do not need '|'.
> 
> > +      RTC uses this clock for clock input when supplied. Clock has to provide
> > +      one of these four frequencies: 1Hz, 50Hz, 60Hz or 32.768kHz.
> > +    maxItems: 1
> > +
> > +  aux-voltage-chargeable:
> > +    enum: [0, 1, 2]
> > +    description: |
> > +      Enables trickle charger.
> > +      0: Charger is disabled (default)
> > +      1: Charger is enabled
> > +      2: Charger is enabled with a diode
> 
> 2 is not an allowed value. I asked to drop this property. It is coming
> from rtc.yaml. I also do not understand "with a diode". So otherwise it
> is charging with, I don't know, FET?

No, what is not explained here (and maybe not unsterstood by the
submitter) is that the RTC has an extra diode so, charging will always
enable a diode, select a resistor and then have or not an extra diode.
Figure2 of the MAX31329 datasheet is great.

> 
> > +
> > +  trickle-resistor-ohms:
> > +    description: Selected resistor for trickle charger.
> > +    enum: [3000, 6000, 11000]
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> Best regards,
> Krzysztof
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com