linux-kernel - Re: [PATCH 1/3] iio: ina2xx: re-instate a sysfs show/store for the shunt resistor value

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Date:	Sat, 12 Dec 2015 15:57:35 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Marc Titinger <mtitinger@...libre.com>, knaack.h@....de,
	lars@...afoo.de, pmeerw@...erw.net
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] iio: ina2xx: re-instate a sysfs show/store for the
 shunt resistor value

On 11/12/15 16:49, Marc Titinger wrote:
> Different probe modules use different resistor values. The front-end
> application may read a probe ID (from eeprom) and set the shunt value
> accordingly.
> 
> Signed-off-by: Marc Titinger <mtitinger@...libre.com>
Fair enough.

Applied.
> ---
>  drivers/iio/adc/ina2xx-adc.c | 52 +++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> index 615c203..fe42872 100644
> --- a/drivers/iio/adc/ina2xx-adc.c
> +++ b/drivers/iio/adc/ina2xx-adc.c
> @@ -106,7 +106,7 @@ struct ina2xx_chip_info {
>  	struct task_struct *task;
>  	const struct ina2xx_config *config;
>  	struct mutex state_lock;
> -	long rshunt;
> +	unsigned int shunt_resistor;
>  	int avg;
>  	s64 prev_ns;	/* track buffer capture time, check for underruns*/
>  	int int_time_vbus; /* Bus voltage integration time uS */
> @@ -353,6 +353,42 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
>  	return len;
>  }
>  
> +static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
> +{
> +	if (val <= 0 || val > chip->config->calibration_factor)
> +		return -EINVAL;
> +
> +	chip->shunt_resistor = val;
> +	return 0;
> +}
> +
> +static ssize_t ina2xx_shunt_resistor_show(struct device *dev,
> +					  struct device_attribute *attr,
> +					  char *buf)
> +{
> +	struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
> +
> +	return sprintf(buf, "%d\n", chip->shunt_resistor);
> +}
> +
> +static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
> +					   struct device_attribute *attr,
> +					   const char *buf, size_t len)
> +{
> +	struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
> +	unsigned long val;
> +	int ret;
> +
> +	ret = kstrtoul((const char *) buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	ret = set_shunt_resistor(chip, val);
> +	if (ret)
> +		return ret;
> +
> +	return len;
> +}
>  
>  #define INA2XX_CHAN(_type, _index, _address) { \
>  	.type = (_type), \
> @@ -547,9 +583,14 @@ static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
>  		       ina2xx_allow_async_readout_show,
>  		       ina2xx_allow_async_readout_store, 0);
>  
> +static IIO_DEVICE_ATTR(in_shunt_resistor, S_IRUGO | S_IWUSR,
> +		       ina2xx_shunt_resistor_show,
> +		       ina2xx_shunt_resistor_store, 0);
> +
>  static struct attribute *ina2xx_attributes[] = {
>  	&iio_dev_attr_in_allow_async_readout.dev_attr.attr,
>  	&iio_const_attr_integration_time_available.dev_attr.attr,
> +	&iio_dev_attr_in_shunt_resistor.dev_attr.attr,
>  	NULL,
>  };
>  
> @@ -581,7 +622,7 @@ static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
>  	 * to the user for now.
>  	 */
>  	regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
> -			    chip->rshunt);
> +			    chip->shunt_resistor);
>  
>  	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
>  }
> @@ -614,10 +655,9 @@ static int ina2xx_probe(struct i2c_client *client,
>  			val = INA2XX_RSHUNT_DEFAULT;
>  	}
>  
> -	if (val <= 0 || val > chip->config->calibration_factor)
> -		return -ENODEV;
> -
> -	chip->rshunt = val;
> +	ret = set_shunt_resistor(chip, val);
> +	if (ret)
> +		return ret;
>  
>  	mutex_init(&chip->state_lock);
>  
> 

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