From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Flavio Suligoi <f.suligoi@asem.it>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
"linux-rtc@vger.kernel.org" <linux-rtc@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] rtc: pcf2127: add battery-low INTn generation
Date: Wed, 3 Apr 2019 17:31:43 +0200 [thread overview]
Message-ID: <20190403153143.GQ22216@piout.net> (raw)
In-Reply-To: <452a4cf1410a41c8b6f767ac6258482e@asem.it>
On 03/04/2019 15:14:24+0000, Flavio Suligoi wrote:
> Hi Alexandre,
>
> > On 03/04/2019 16:52:45+0200, Flavio Suligoi wrote:
> > > The pcf2127 has an automatic battery-low detection function.
> > >
> > > In case of battery-low event, an interrupt generation through
> > > the pin INTn (active low) can be enabled, setting the flag BLIE
> > > in the register Control_3.
> > >
> > > This function is activated by the "battery-low-hw-alarm" DT property.
> > >
> > > Example of use for an NXP i.MX7D board:
> > >
> > > &i2c3 {
> > > clock-frequency = <100000>;
> > > pinctrl-names = "default";
> > > pinctrl-0 = <&pinctrl_i2c3>;
> > > status = "okay";
> > >
> > > pcf2127@51 {
> > > compatible = "nxp,pcf2127";
> > > reg = <0x51>;
> > > battery-low-hw-alarm;
> > > status = "okay";
> > > };
> > > };
> > >
> >
> > So I'm curious, how do you then use that signal? I have a (not yet sent)
> > series adding alarm support for the pcf2127. The issue having BLIE is
> > that then this will prevent the alarm to work properly.
> >
> > So my guess is that you have nINT connected to an LED or something that
> > the user can see?
> >
>
> I'm working on our custom embedded board with an NXP i.MX7D,
> developed here, in Asem (www.asem.it).
> The nINT pin is connected to a GPIO of the MX7 and then
> used by an applicative sw, to generate an alarm for the user.
>
Then, you should probably not enable BLIE because this will cause issues
with the alarm functionnality.. It is certainly enough to use
RTC_VL_READ periodically.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2019-04-03 15:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 14:52 [PATCH 1/2] dt-bindings: rtc: add battery-low-hw-alarm property Flavio Suligoi
2019-04-03 14:52 ` [PATCH 2/2] rtc: pcf2127: add battery-low INTn generation Flavio Suligoi
2019-04-03 15:08 ` Alexandre Belloni
2019-04-03 15:14 ` Flavio Suligoi
2019-04-03 15:31 ` Alexandre Belloni [this message]
2019-04-03 15:49 ` Flavio Suligoi
2019-04-03 15:56 ` Alexandre Belloni
2019-04-03 16:09 ` Flavio Suligoi
2019-04-03 16:15 ` Alexandre Belloni
2019-04-03 16:20 ` Flavio Suligoi
2019-04-03 14:57 ` [PATCH 1/2] dt-bindings: rtc: add battery-low-hw-alarm property Alexandre Belloni
2019-04-03 15:06 ` Flavio Suligoi
2019-04-03 15:28 ` Alexandre Belloni
2019-04-03 15:32 ` Flavio Suligoi
2019-04-06 6:07 ` Rob Herring
2019-04-06 12:55 ` Alexandre Belloni
2019-04-08 7:22 ` Flavio Suligoi
2019-04-09 1:18 ` Rob Herring
2019-04-10 8:04 ` Flavio Suligoi
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