From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755478AbaLJKjv (ORCPT ); Wed, 10 Dec 2014 05:39:51 -0500 Received: from mail-wg0-f42.google.com ([74.125.82.42]:35918 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753222AbaLJKjK (ORCPT ); Wed, 10 Dec 2014 05:39:10 -0500 From: Bartosz Golaszewski To: Guenter Roeck Cc: LKML , Benoit Cousson , Patrick Titiano , LM Sensors , Bartosz Golaszewski Subject: [PATCH v5 1/3] hwmon: ina2xx: make shunt resistance configurable at run-time Date: Wed, 10 Dec 2014 11:38:55 +0100 Message-Id: <1418207937-11648-2-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.3 In-Reply-To: <1418207937-11648-1-git-send-email-bgolaszewski@baylibre.com> References: <1418207937-11648-1-git-send-email-bgolaszewski@baylibre.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The shunt resistance can only be set via platform_data or device tree. This isn't suitable for devices in which the shunt resistance can change/isn't known at boot-time. Add a sysfs attribute that allows to read and set the shunt resistance. Signed-off-by: Bartosz Golaszewski --- drivers/hwmon/ina2xx.c | 74 ++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 65 insertions(+), 9 deletions(-) diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c index e01feba..6e73add 100644 --- a/drivers/hwmon/ina2xx.c +++ b/drivers/hwmon/ina2xx.c @@ -51,7 +51,6 @@ #define INA226_ALERT_LIMIT 0x07 #define INA226_DIE_ID 0xFF - /* register count */ #define INA219_REGISTERS 6 #define INA226_REGISTERS 8 @@ -65,6 +64,9 @@ /* worst case is 68.10 ms (~14.6Hz, ina219) */ #define INA2XX_CONVERSION_RATE 15 +/* default shunt resistance */ +#define INA2XX_RSHUNT_DEFAULT 10000 + enum ina2xx_ids { ina219, ina226 }; struct ina2xx_config { @@ -87,6 +89,8 @@ struct ina2xx_data { int kind; u16 regs[INA2XX_MAX_REGISTERS]; + + long rshunt; }; static const struct ina2xx_config ina2xx_config[] = { @@ -110,6 +114,11 @@ static const struct ina2xx_config ina2xx_config[] = { }, }; +static u16 ina2xx_calibration_val(const struct ina2xx_data *data) +{ + return data->config->calibration_factor / data->rshunt; +} + static struct ina2xx_data *ina2xx_update_device(struct device *dev) { struct ina2xx_data *data = dev_get_drvdata(dev); @@ -164,6 +173,13 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg) /* signed register, LSB=1mA (selected), in mA */ val = (s16)data->regs[reg]; break; + case INA2XX_CALIBRATION: + if (data->regs[reg] == 0) + val = 0; + else + val = data->config->calibration_factor + / data->regs[reg]; + break; default: /* programmer goofed */ WARN_ON_ONCE(1); @@ -187,6 +203,38 @@ static ssize_t ina2xx_show_value(struct device *dev, ina2xx_get_value(data, attr->index)); } +static ssize_t ina2xx_set_shunt(struct device *dev, + struct device_attribute *da, + const char *buf, size_t count) +{ + struct ina2xx_data *data = ina2xx_update_device(dev); + unsigned long val; + int status; + + if (IS_ERR(data)) + return PTR_ERR(data); + + status = kstrtoul(buf, 10, &val); + if (status < 0) + return status; + + if (val == 0 || + /* Values greater than the calibration factor make no sense. */ + val > data->config->calibration_factor || + val > LONG_MAX) + return -EINVAL; + + mutex_lock(&data->update_lock); + data->rshunt = val; + status = i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION, + ina2xx_calibration_val(data)); + mutex_unlock(&data->update_lock); + if (status < 0) + return status; + + return count; +} + /* shunt voltage */ static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL, INA2XX_SHUNT_VOLTAGE); @@ -203,12 +251,18 @@ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_value, NULL, static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL, INA2XX_POWER); +/* shunt resistance */ +static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR, + ina2xx_show_value, ina2xx_set_shunt, + INA2XX_CALIBRATION); + /* pointers to created device attributes */ static struct attribute *ina2xx_attrs[] = { &sensor_dev_attr_in0_input.dev_attr.attr, &sensor_dev_attr_in1_input.dev_attr.attr, &sensor_dev_attr_curr1_input.dev_attr.attr, &sensor_dev_attr_power1_input.dev_attr.attr, + &sensor_dev_attr_shunt_resistor.dev_attr.attr, NULL, }; ATTRIBUTE_GROUPS(ina2xx); @@ -221,7 +275,6 @@ static int ina2xx_probe(struct i2c_client *client, struct device *dev = &client->dev; struct ina2xx_data *data; struct device *hwmon_dev; - long shunt = 10000; /* default shunt value 10mOhms */ u32 val; int ret; @@ -234,19 +287,22 @@ static int ina2xx_probe(struct i2c_client *client, if (dev_get_platdata(dev)) { pdata = dev_get_platdata(dev); - shunt = pdata->shunt_uohms; + data->rshunt = pdata->shunt_uohms; } else if (!of_property_read_u32(dev->of_node, "shunt-resistor", &val)) { - shunt = val; + data->rshunt = val; + } else { + data->rshunt = INA2XX_RSHUNT_DEFAULT; } - if (shunt <= 0) - return -ENODEV; - /* set the device type */ data->kind = id->driver_data; data->config = &ina2xx_config[data->kind]; + if (data->rshunt <= 0 || + data->rshunt > data->config->calibration_factor) + return -ENODEV; + /* device configuration */ ret = i2c_smbus_write_word_swapped(client, INA2XX_CONFIG, data->config->config_default); @@ -261,7 +317,7 @@ static int ina2xx_probe(struct i2c_client *client, * (equation 13 in datasheet). */ ret = i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION, - data->config->calibration_factor / shunt); + ina2xx_calibration_val(data)); if (ret < 0) { dev_err(dev, "error writing to the calibration register: %d", ret); @@ -277,7 +333,7 @@ static int ina2xx_probe(struct i2c_client *client, return PTR_ERR(hwmon_dev); dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n", - id->name, shunt); + id->name, data->rshunt); return 0; } -- 2.1.3