Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932482AbcCKPEx (ORCPT ); Fri, 11 Mar 2016 10:04:53 -0500 Received: from bear.ext.ti.com ([192.94.94.41]:54435 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752628AbcCKPEq (ORCPT ); Fri, 11 Mar 2016 10:04:46 -0500 Subject: Re: [PATCH-vs-togreg 1/2] iio: ina2xx-adc: update the CALIB. register when RShunt changes To: Marc Titinger , , , , References: <1457707950-17593-1-git-send-email-marc.titinger@baylibre.com> CC: , From: "Andrew F. Davis" Message-ID: <56E2DE7E.5090905@ti.com> Date: Fri, 11 Mar 2016 09:04:30 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1457707950-17593-1-git-send-email-marc.titinger@baylibre.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2834 Lines: 84 On 03/11/2016 08:52 AM, 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 > --- > tested with BeagleBone-black and BayLibre-acme. > --- > drivers/iio/adc/ina2xx-adc.c | 36 +++++++++++++++++++++++++----------- > 1 file changed, 25 insertions(+), 11 deletions(-) > > diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c > index 65909d5..e5ac120 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; > } > > @@ -599,6 +621,8 @@ static const struct iio_info ina2xx_info = { > .debugfs_reg_access = ina2xx_debug_reg, > }; > > + > + ? > /* Initialize the configuration and calibration registers. */ > static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config) > { > @@ -609,17 +633,7 @@ static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int 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, >