linux-kernel - Re: [PATCH] rtc: add Abracon ABx80x driver

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Message-ID: <20150228205243.GF4094@piout.net>
Date:	Sat, 28 Feb 2015 21:52:43 +0100
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com
Subject: Re: [PATCH] rtc: add Abracon ABx80x driver

On 28/02/2015 at 11:32:15 -0800, Joe Perches wrote :
> On Sat, 2015-02-28 at 20:14 +0100, Alexandre Belloni wrote:
> > Add support for the i2c RTC from Abracon.
> 
> Perhaps you can run this through
> $ ./scripts/checkpatch.pl --strict --fix-inplace
> 

Right, I'll fix those

> Is there going to be a MAINTAINERS entry for this driver?
> 

If necessary, I can maintain it however, I'm not sure I'll have access
to the hardware indefinitely.

> > diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> []
> > @@ -22,6 +22,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
> >  
> >  obj-$(CONFIG_RTC_DRV_88PM860X)  += rtc-88pm860x.o
> >  obj-$(CONFIG_RTC_DRV_88PM80X)	+= rtc-88pm80x.o
> > +obj-$(CONFIG_RTC_DRV_ABX80X)	+= rtc-abx80x.o
> 
> alphabetic order?
> 

I renamed the driver from rtc-ab080x and forgot to move it. I will do.
I'll also rename the functions in the driver.

> >  obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
> >  obj-$(CONFIG_RTC_DRV_AB8500)	+= rtc-ab8500.o
> >  obj-$(CONFIG_RTC_DRV_ABB5ZES3)	+= rtc-ab-b5ze-s3.o
> 
> []
> 
> > diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
> []
> > +static int ab08xx_get_datetime(struct i2c_client *client, struct rtc_time *tm)
> > +{
> > +	unsigned char date[8];
> > +	int err;
> > +
> > +	/* Now read time and date */
> > +	err = i2c_smbus_read_i2c_block_data(client, AB08XX_REG_HTH,
> > +		8, date);
> > +	if (err < 0) {
> > +		dev_err(&client->dev, "Unable to read date\n");
> > +		return -EIO;
> > +	}
> > +
> > +	tm->tm_sec = bcd2bin(date[AB08XX_REG_SC] & 0x7F);
> > +	tm->tm_min = bcd2bin(date[AB08XX_REG_MN] & 0x7F);
> > +	tm->tm_hour = bcd2bin(date[AB08XX_REG_HR] & 0x3F);
> > +	tm->tm_wday = date[AB08XX_REG_WD] & 0x7;
> > +	tm->tm_mday = bcd2bin(date[AB08XX_REG_DA] & 0x3F);
> > +	tm->tm_mon = bcd2bin(date[AB08XX_REG_MO] & 0x1F) - 1;
> > +	tm->tm_year = bcd2bin(date[AB08XX_REG_YR]);
> > +	if (tm->tm_year < 70)
> > +		tm->tm_year += 100;
> > +
> > +	err = rtc_valid_tm(tm);
> > +	if (err < 0)
> > +		dev_err(&client->dev, "retrieved date/time is not valid.\n");
> 
> Is setting the date to a known bad value really the desired thing?

I'm not sure what you mean here, isn't that what is done in almost all
the rtc drivers? A lot of those are simply using return
rtc_valid_tm(tm); My guess is that a userspace program must not try to
use tm when errno is not 0.

> 
> > +static int ab08xx_probe(struct i2c_client *client,
> > +			const struct i2c_device_id *id)
> > +{
> > +	struct rtc_device *rtc;
> > +	int data, err, part0, part1;
> > +
> > +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> > +		return -ENODEV;
> > +
> > +
> > +	part0 = i2c_smbus_read_byte_data(client, AB08XX_REG_PART0);
> > +	part1 = i2c_smbus_read_byte_data(client, AB08XX_REG_PART1);
> > +	if ((part0 < 0) || (part1 < 0)) {
> > +		dev_err(&client->dev, "Unable to read part number\n");
> > +		return -EIO;
> > +	}
> > +	dev_info(&client->dev, "chip found %2x%2x\n", part0, part1);
> 
> 	"%02x%02x" ?
> 

Indeed, I'm not sure how but I believe I saw it zero padded at some
point.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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