Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932358AbcCKOwl (ORCPT ); Fri, 11 Mar 2016 09:52:41 -0500 Received: from mail-wm0-f42.google.com ([74.125.82.42]:33758 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932081AbcCKOwd (ORCPT ); Fri, 11 Mar 2016 09:52:33 -0500 From: Marc Titinger X-Google-Original-From: Marc Titinger To: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net Cc: afd@ti.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH-vs-togreg 1/2] iio: ina2xx-adc: update the CALIB. register when RShunt changes Date: Fri, 11 Mar 2016 15:52:29 +0100 Message-Id: <1457707950-17593-1-git-send-email-marc.titinger@baylibre.com> X-Mailer: git-send-email 2.5.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2634 Lines: 81 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, -- 2.5.0