linux-kernel - Re: [PATCH v4 04/14] dt-bindings: rtc: add bindings for microchip mpfs rtc

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Message-ID: <262b1a79-1119-4767-f3f4-7a77824d1bc9@microchip.com>
Date:   Wed, 19 Jan 2022 10:47:02 +0000
From:   <Conor.Dooley@...rochip.com>
To:     <robh@...nel.org>
CC:     <linus.walleij@...aro.org>, <bgolaszewski@...libre.com>,
        <jassisinghbrar@...il.com>, <paul.walmsley@...ive.com>,
        <palmer@...belt.com>, <aou@...s.berkeley.edu>,
        <a.zummo@...ertech.it>, <alexandre.belloni@...tlin.com>,
        <broonie@...nel.org>, <gregkh@...uxfoundation.org>,
        <thierry.reding@...il.com>, <u.kleine-koenig@...gutronix.de>,
        <lee.jones@...aro.org>, <linux-gpio@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
        <linux-riscv@...ts.infradead.org>, <linux-crypto@...r.kernel.org>,
        <linux-rtc@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <krzysztof.kozlowski@...onical.com>,
        <geert@...ux-m68k.org>, <bin.meng@...driver.com>,
        <heiko@...ech.de>, <Lewis.Hanly@...rochip.com>,
        <Daire.McNamara@...rochip.com>, <Ivan.Griffin@...rochip.com>,
        <atishp@...osinc.com>
Subject: Re: [PATCH v4 04/14] dt-bindings: rtc: add bindings for microchip
 mpfs rtc

On 19/01/2022 03:12, Rob Herring wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Mon, Jan 17, 2022 at 11:07:45AM +0000, conor.dooley@...rochip.com wrote:
>> From: Conor Dooley <conor.dooley@...rochip.com>
>>
>> Add device tree bindings for the real time clock on
>> the Microchip PolarFire SoC.
>>
>> Signed-off-by: Daire McNamara <daire.mcnamara@...rochip.com>
>> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
>> ---
>>   .../bindings/rtc/microchip,mfps-rtc.yaml      | 63 +++++++++++++++++++
>>   1 file changed, 63 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/rtc/microchip,mfps-rtc.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/rtc/microchip,mfps-rtc.yaml b/Documentation/devicetree/bindings/rtc/microchip,mfps-rtc.yaml
>> new file mode 100644
>> index 000000000000..d57460cbe5e3
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/rtc/microchip,mfps-rtc.yaml
>> @@ -0,0 +1,63 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/rtc/microchip,mfps-rtc.yaml#
>> +
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Microchip PolarFire Soc (MPFS) RTC Device Tree Bindings
>> +
>> +allOf:
>> +  - $ref: rtc.yaml#
>> +
>> +maintainers:
>> +  - Daire McNamara <daire.mcnamara@...rochip.com>
>> +  - Lewis Hanly <lewis.hanly@...rochip.com>
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - microchip,mpfs-rtc
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 2
> 
> Need to define what each one is.
Sure.
> 
>> +
>> +  microchip,prescaler:
>> +    description: |
>> +      The prescaler divides the input frequency to create a time-based strobe (typically 1 Hz) for
>> +      the calendar counter. The Alarm and Compare Registers, in conjunction with the calendar
>> +      counter, facilitate time-matched events. To properly operate in Calendar or Binary mode,
>> +      the 26-bit prescaler must be programmed to generate a strobe to the RTC.
>> +    maxItems: 1
>> +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> Can't you calculate this based on the clock input freq?

I mistakenly thought this was set when the bitstream was programmed to 
the FPGA but it is just an APB register & should be calculated. I'll 
drop the property.

> 
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    items:
>> +      - const: rtc
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +  - clocks
>> +  - clock-names
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/microchip,mpfs-clock.h>
>> +    rtc@...24000 {
>> +        compatible = "microchip,mpfs-rtc";
>> +        reg = <0x20124000 0x1000>;
>> +        clocks = <&clkcfg CLK_RTC>;
>> +        clock-names = "rtc";
>> +        interrupts = <80>, <81>;
>> +    };
>> +...
>> --
>> 2.32.0
>>
>>