linux-kernel - Re: [PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC

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Message-ID: <46BA7224-B229-4594-B039-8801A806657E@global.cadence.com>
Date:   Thu, 17 Jan 2019 10:46:50 +0000
From:   Jan Kotas <jank@...ence.com>
To:     Rob Herring <robh@...nel.org>
CC:     Jan Kotas <jank@...ence.com>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Mark Rutland <mark.rutland@....com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC


> On 16 Jan 2019, at 22:08, Rob Herring <robh@...nel.org> wrote:
> 
> 
> On Fri, Jan 11, 2019 at 03:14:00PM +0000, Jan Kotas wrote:
>> This patch adds a DT binding documentation for
>> Cadence RTC controller.
>> +Required properties:
>> +- compatible: Should be "cdns,rtc-r109v3"
>> +- reg: Specifies base physical address and size of the register area.
>> +- interrupts: A single interrupt specifier.
>> +- clocks: Must contain two entries:
>> +	- pclk: APB registers clock
>> +	- ref_clk: reference 1Hz of 100Hz clock, depending on IP configuration
> 
> 1Hz OR 100Hz?

Hi,

The IP has a configuration parameter at build time,
which selects the reference clock frequency.

It cannot be changed later, and there’s no register which
tells the software which option was selected.

In this version of the patch, both values are accepted.
If it makes sense I can add a bool property, like
refclock-100hz, which can be used to check the clock frequency.

Regards,
Jan