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Subject: Re: [PATCH v4 4/4] rtc: ds1307: add freq_test sysfs attribute to
 check tick on m41txx
To:     a.zummo@towertech.it, alexandre.belloni@bootlin.com
Cc:     robh+dt@kernel.org, mark.rutland@arm.com,
        linux-rtc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20180516100526.73549-1-giulio.benetti@micronovasrl.com>
 <20180516100526.73549-4-giulio.benetti@micronovasrl.com>
From:   Giulio Benetti <giulio.benetti@micronovasrl.com>
Message-ID: <72e1b582-d9c5-523b-9a21-5ad2c6fb1d98@micronovasrl.com>
Date:   Wed, 16 May 2018 12:27:12 +0200
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Oh, sorry, I've forgotten to reword commit log.
I follow with v5 patchset.
Sorry again.

Giulio

Il 16/05/2018 12:05, Giulio Benetti ha scritto:
> On m41txx you can enable open-drain OUT pin to check if offset is ok.
> Enabling OUT pin with freq_test 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@micronovasrl.com>
> ---
> V3 => V4:
> * change attribute from freq_test to frequency_test_enable
> * use regmap_update_bits instead of regmap_write
> 
>   drivers/rtc/rtc-ds1307.c | 99 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 99 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index 2797d01bfa1d..de98ddc39515 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -1053,6 +1053,99 @@ static int m41txx_rtc_set_offset(struct device *dev, long offset)
>   				  ctrl_reg);
>   }
>   
> +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)) {
> +		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
> +		return -EINVAL;
> +	}
> +
> +	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
> +			   freq_test ? M41TXX_BIT_FT : 0);
> +
> +	return retval ? retval : count;
> +}
> +
> +static ssize_t frequency_test_enable_show(struct device *dev,
> +					  struct device_attribute *attr,
> +					  char *buf)
> +{
> +	struct ds1307 *ds1307 = dev_get_drvdata(dev);
> +	int freq_test_en = 0;
> +	unsigned int ctrl_reg;
> +
> +	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
> +
> +	if (ctrl_reg & M41TXX_BIT_FT)
> +		freq_test_en = true;
> +	else
> +		freq_test_en = false;
> +
> +	return sprintf(buf, "%d\n", freq_test_en);
> +}
> +
> +static DEVICE_ATTR_RW(frequency_test_enable);
> +
> +static struct attribute *rtc_freq_test_attrs[] = {
> +	&dev_attr_frequency_test_enable.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group rtc_freq_test_attr_group = {
> +	.attrs		= rtc_freq_test_attrs,
> +};
> +
> +static void rtc_calib_remove_sysfs_group(void *_dev)
> +{
> +	struct device *dev = _dev;
> +
> +	sysfs_remove_group(&dev->kobj, &rtc_freq_test_attr_group);
> +}
> +
> +static int ds1307_add_frequency_test(struct ds1307 *ds1307)
> +{
> +	int err = 0;
> +
> +	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;
> +}
> +
>   /*----------------------------------------------------------------------*/
>   
>   static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
> @@ -1794,6 +1887,12 @@ static int ds1307_probe(struct i2c_client *client,
>   	if (err)
>   		return err;
>   
> +	err = ds1307_add_frequency_test(ds1307);
> +	if (err) {
> +		rtc_device_unregister(ds1307->rtc);
> +		return err;
> +	}
> +
>   	if (chip->nvram_size) {
>   		struct nvmem_config nvmem_cfg = {
>   			.name = "ds1307_nvram",
>