On Wed, Jul 18, 2018 at 12:40 PM, Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx> 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. > +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); > + bool freq_test_en = 0; First of all, initialization of boolean using int is not very best style. Second, this is not needed. > + int ret; > + > + ret = kstrtobool(buf, &freq_test_en); > + if (ret == -EINVAL) { What kind of other error code you may expect and why they are not considered as no error? > + dev_err(dev, "Failed to store RTC Frequency Test attribute\n"); > + return ret; > + } > + > + regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT, > + freq_test_en ? M41TXX_BIT_FT : 0); > + > + return count; > +} > + > +static ssize_t frequency_test_enable_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct ds1307 *ds1307 = dev_get_drvdata(dev); > + unsigned int ctrl_reg; > + > + regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg); > + > + if (ctrl_reg & M41TXX_BIT_FT) > + return scnprintf(buf, PAGE_SIZE, "on\n"); > + else > + return scnprintf(buf, PAGE_SIZE, "off\n"); Entire condition might be one line. > +} > + > +static int ds1307_add_frequency_test(struct ds1307 *ds1307) > +{ > + int err = 0; Redundant assignment. See below. > + > + switch (ds1307->type) { > + case m41t0: > + case m41t00: > + case m41t11: > + /* Export sysfs entries */ > + err = sysfs_create_group(&(ds1307->dev)->kobj, > + &rtc_freq_test_attr_group); > + if (err) { > + dev_err(ds1307->dev, > + "Failed to create sysfs group: %d\n", > + err); > + return err; > + } > + > + err = devm_add_action_or_reset(ds1307->dev, > + rtc_calib_remove_sysfs_group, > + ds1307->dev); > + if (err) { > + dev_err(ds1307->dev, > + "Failed to add sysfs cleanup action: %d\n", > + err); > + sysfs_remove_group(&(ds1307->dev)->kobj, > + &rtc_freq_test_attr_group); > + return err; > + } > + break; > + default: > + break; > + } > + > + return err; return 0; -- With Best Regards, Andy Shevchenko