linux-kernel - Re: [PATCH v2 2/5] rtc: gamecube: Report low battery as invalid data

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Message-ID: <20211215175214.qweez756f4azvbqf@luna>
Date:   Wed, 15 Dec 2021 18:52:14 +0100
From:   Emmanuel Gil Peyrot <linkmauve@...kmauve.fr>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Emmanuel Gil Peyrot <linkmauve@...kmauve.fr>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        rw-r-r-0644 <r.r.qwertyuiop.r.r@...il.com>,
        Ash Logan <ash@...quark.com>,
        Jonathan Neuschäfer <j.ne@...teo.net>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linux-kernel@...r.kernel.org, linux-rtc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/5] rtc: gamecube: Report low battery as invalid data

On Tue, Nov 30, 2021 at 11:45:18PM +0100, Alexandre Belloni wrote:
> Hello,

Hi,

> 
> On 28/10/2021 00:35:12+0200, Emmanuel Gil Peyrot wrote:
> > I haven’t been able to test this patch as all of my consoles have a
> > working RTC battery, but according to the documentation it should work
> > like that.
> > 
> > Signed-off-by: Emmanuel Gil Peyrot <linkmauve@...kmauve.fr>
> > ---
> >  drivers/rtc/rtc-gamecube.c | 30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> > 
> > diff --git a/drivers/rtc/rtc-gamecube.c b/drivers/rtc/rtc-gamecube.c
> > index e8260c82c07d..1932c6fe1301 100644
> > --- a/drivers/rtc/rtc-gamecube.c
> > +++ b/drivers/rtc/rtc-gamecube.c
> > @@ -83,6 +83,10 @@
> >  #define RTC_CONTROL0	0x21000c
> >  #define RTC_CONTROL1	0x21000d
> >  
> > +/* RTC flags */
> > +#define RTC_CONTROL0_UNSTABLE_POWER	0x00000800
> > +#define RTC_CONTROL0_LOW_BATTERY	0x00000200
> > +
> >  struct priv {
> >  	struct regmap *regmap;
> >  	void __iomem *iob;
> > @@ -182,9 +186,35 @@ static int gamecube_rtc_set_time(struct device *dev, struct rtc_time *t)
> >  	return regmap_write(d->regmap, RTC_COUNTER, timestamp - d->rtc_bias);
> >  }
> >  
> > +static int gamecube_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
> > +{
> > +	struct priv *d = dev_get_drvdata(dev);
> > +	int value;
> > +	int control0;
> > +	int ret;
> > +
> > +	switch (cmd) {
> > +	case RTC_VL_READ:
> > +		ret = regmap_read(d->regmap, RTC_CONTROL0, &control0);
> > +		if (ret)
> > +			return ret;
> > +
> > +		value = 0;
> > +		if (control0 & RTC_CONTROL0_UNSTABLE_POWER)
> > +			value |= RTC_VL_DATA_INVALID;
> > +		if (control0 & RTC_CONTROL0_LOW_BATTERY)
> > +			value |= RTC_VL_DATA_INVALID;
> 
> Shouldn't that one be RTC_VL_BACKUP_LOW?

Oops indeed, that seems like a better report, I’ll send a v3 with this
change only.

> 
> Else, the driver is great, I'm ready to apply it.

Perfect!

> 
> > +		return put_user(value, (unsigned int __user *)arg);
> > +
> > +	default:
> > +		return -ENOIOCTLCMD;
> > +	}
> > +}
> > +
> >  static const struct rtc_class_ops gamecube_rtc_ops = {
> >  	.read_time	= gamecube_rtc_read_time,
> >  	.set_time	= gamecube_rtc_set_time,
> > +	.ioctl		= gamecube_rtc_ioctl,
> >  };
> >  
> >  static int gamecube_rtc_read_offset_from_sram(struct priv *d)
> > -- 
> > 2.33.1
> > 
> 
> -- 
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

-- 
Emmanuel Gil Peyrot

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