linux-kernel - Re: [PATCH-vs-togreg v2 1/2] iio: ina2xx-adc: update the CALIB. register when RShunt changes

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Date:	Mon, 21 Mar 2016 17:35:33 +0100
From:	Marc Titinger <mtitinger@...libre.com>
To:	Jonathan Cameron <jic23@...nel.org>, knaack.h@....de,
	lars@...afoo.de, pmeerw@...erw.net
Cc:	afd@...com, linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH-vs-togreg v2 1/2] iio: ina2xx-adc: update the CALIB.
 register when RShunt changes



On 20/03/2016 12:24, Jonathan Cameron wrote:
> On 14/03/16 10:20, Marc Titinger wrote:
>> The user (or an init script) may setup RShunt via sysfs after the
>> driver was initialized, for instance based on the EEPROM contents
>> of a modular probe. The calibration register must be set accordingly.
>>
>> Signed-off-by: Marc Titinger <marc.titinger@...libre.com>
>> ---
>>   v2 of http://www.spinics.net/lists/linux-iio/msg23402.html:
>>
>> 	- remove unnecessary line insertions
>> 	- cleanup leftover unused variable (build warning)
>> 	- patch 2/2 is unchanged (see v1)
> Err, can't find it for some reason.

sorry, it's here http://www.spinics.net/lists/linux-iio/msg23401.html
or here: pwclient get 8565821

BR,
Marc.

>
> Anyhow, applied this one to the togreg branch of iio.git - pushed
> out as testing for the autobuilders to play with it.
>
> Thanks,
>
> Jonathan
>> ---
>>   drivers/iio/adc/ina2xx-adc.c | 39 ++++++++++++++++++++++++---------------
>>   1 file changed, 24 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
>> index 65909d5..4e56fe3 100644
>> --- a/drivers/iio/adc/ina2xx-adc.c
>> +++ b/drivers/iio/adc/ina2xx-adc.c
>> @@ -350,6 +350,23 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
>>   	return len;
>>   }
>>
>> +/*
>> + * Set current LSB to 1mA, shunt is in uOhms
>> + * (equation 13 in datasheet). We hardcode a Current_LSB
>> + * of 1.0 x10-6. The only remaining parameter is RShunt.
>> + * There is no need to expose the CALIBRATION register
>> + * to the user for now. But we need to reset this register
>> + * if the user updates RShunt after driver init, e.g upon
>> + * reading an EEPROM/Probe-type value.
>> + */
>> +static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
>> +{
>> +	u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
>> +				   chip->shunt_resistor);
>> +
>> +	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
>> +}
>> +
>>   static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
>>   {
>>   	if (val <= 0 || val > chip->config->calibration_factor)
>> @@ -385,6 +402,11 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
>>   	if (ret)
>>   		return ret;
>>
>> +	/* Update the Calibration register */
>> +	ret = ina2xx_set_calibration(chip);
>> +	if (ret)
>> +		return ret;
>> +
>>   	return len;
>>   }
>>
>> @@ -602,24 +624,11 @@ static const struct iio_info ina2xx_info = {
>>   /* Initialize the configuration and calibration registers. */
>>   static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
>>   {
>> -	u16 regval;
>> -	int ret;
>> -
>> -	ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
>> +	int ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
>>   	if (ret)
>>   		return ret;
>>
>> -	/*
>> -	 * Set current LSB to 1mA, shunt is in uOhms
>> -	 * (equation 13 in datasheet). We hardcode a Current_LSB
>> -	 * of 1.0 x10-6. The only remaining parameter is RShunt.
>> -	 * There is no need to expose the CALIBRATION register
>> -	 * to the user for now.
>> -	 */
>> -	regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
>> -				   chip->shunt_resistor);
>> -
>> -	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
>> +	return ina2xx_set_calibration(chip);
>>   }
>>
>>   static int ina2xx_probe(struct i2c_client *client,
>>
>