linux-kernel - Re: [PATCH v5 4/4] rtc: ds1307: add frequency_test_enable sysfs attribute to check tick on m41txx

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Date:   Wed, 16 May 2018 23:02:16 +0200
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        alexandre.belloni@...tlin.com, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-rtc@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 4/4] rtc: ds1307: add frequency_test_enable sysfs
 attribute to check tick on m41txx

Hi,

Il 16/05/2018 22:22, Andy Shevchenko ha scritto:
> On Wed, May 16, 2018 at 1:32 PM, Giulio Benetti
> <giulio.benetti@...ronovasrl.com> wrote:
>> On m41txx you can enable open-drain OUT pin to check if offset is ok.
>> Enabling OUT pin with frequency_test_enable attribute, OUT pin will tick
>> 512 times faster than 1s tick base.
>>
>> Enable or Disable FT bit on CONTROL register if freq_test is 1 or 0.
>>
>> Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>
> 
>> +static ssize_t frequency_test_enable_store(struct device *dev,
>> +                                          struct device_attribute *attr,
>> +                                          const char *buf, size_t count)
>> +{
>> +       struct ds1307 *ds1307 = dev_get_drvdata(dev);
>> +       unsigned long freq_test = 0;
>> +       int retval;
>> +
>> +       retval = kstrtoul(buf, 10, &freq_test);
>> +       if ((retval < 0) || (retval > 1)) {
> 
> kstrtobool() then?

Yes, you're right.

> 
>> +               dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
> 
>> +               return -EINVAL;
> 
> ...and do not shadow actual error code.

Ok

> 
>> +       }
>> +
>> +       regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
>> +                          freq_test ? M41TXX_BIT_FT : 0);
>> +
> 
>> +       return retval ? retval : count;
> 
> Does the condition make any sense?

You're right, not at all.
I changed it into:
"return count;"

> 
>> +}
> 
>> +static ssize_t frequency_test_enable_show(struct device *dev,
>> +                                         struct device_attribute *attr,
>> +                                         char *buf)
>> +{
> 
>> +       int freq_test_en = 0;
> 
>> +       if (ctrl_reg & M41TXX_BIT_FT)
>> +               freq_test_en = true;
>> +       else
>> +               freq_test_en = false;
>> +
>> +       return sprintf(buf, "%d\n", freq_test_en);
> 
> So, is it boolean or integer? This code makes it confusing a lot.

It is a boolean, so now I've updated with this:

if (ctrl_reg & M41TXX_BIT_FT)
	return scnprintf(buf, PAGE_SIZE, "on\n");
else
	return scnprintf(buf, PAGE_SIZE, "off\n");

> 
>> +}
> 

Thank you very much for review

Giulio Benetti