Re: [lm-sensors] RE : [PATCH] hwmon: (htu

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Aug 29, 2013 at 10:06:00AM +0200, Markezana, William wrote:

Please see Documentation/SubmittingPatches, section 15, "The canonical patch
format". Also, please run your patch through scripts/checkpatch.pl; we won't
accept it with checkpatch warnings or errors unless you provide a good reason
why the problem should be acceptable. It is also customary to include a list
of changes made compared to the previous version, as explained in section 15
of SubmittingPatches.

Thanks,
Guenter

> diff --git a/Documentation/hwmon/htu21 b/Documentation/hwmon/htu21
> new file mode 100644
> index 0000000..ddcef55
> --- /dev/null
> +++ b/Documentation/hwmon/htu21
> @@ -0,0 +1,46 @@
> +Kernel driver htu21
> +===================
> +
> +Supported chips:
> +  * Measurement Specialties HTU21D
> +    Prefix: 'htu21'
> +    Addresses scanned: none
> +    Datasheet: Publicly available at the Measurement Specialties website
> +    http://www.meas-spec.com/downloads/HTU21D.pdf
> +
> +
> +Author:
> +  William Markezana <william.markezana@meas-spec.com>
> +
> +Description
> +-----------
> +
> +The HTU21D is a humidity and temperature sensor in a DFN package of
> +only 3 x 3 mm footprint and 0.9 mm height.
> +
> +The devices communicate with the I2C protocol. All sensors are set to the same
> +I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can be used
> +in the board setup code.
> +
> +This driver does not auto-detect devices. You will have to instantiate the 
> +devices explicitly. Please see Documentation/i2c/instantiating-devices 
> +for details."
> +
> +sysfs-Interface
> +---------------
> +
> +temp1_input - temperature input
> +humidity1_input - humidity input
> +
> +Notes
> +-----
> +
> +The driver uses the default resolution settings of 12 bit for humidity and 14
> +bit for temperature, which results in typical measurement times of 11 ms for
> +humidity and 44 ms for temperature. To keep self heating below 0.1 degree
> +Celsius, the device should not be active for more than 10% of the time. For 
> +this reason, the driver performs no more than two measurements per second and 
> +reports cached information if polled more frequently.
> +
> +Different resolutions, the on-chip heater, using the CRC checksum and reading
> +the serial number are not supported yet.
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index e989f7f..eb46eb8 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -511,6 +511,16 @@ config SENSORS_HIH6130
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called hih6130.
>  
> +config SENSORS_HTU21
> +	tristate "Measurement Specialties HTU21D humidity and temperature sensors"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for the Measurement Specialties
> +	  HTU21D humidity and temperature sensors.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called htu21.
> +
>  config SENSORS_CORETEMP
>  	tristate "Intel Core/Core2/Atom temperature sensor"
>  	depends on X86
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 4f0fb52..ec7cde0 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
>  obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
>  obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
>  obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
> +obj-$(CONFIG_SENSORS_HTU21)	+= htu21.o
>  obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
>  obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
>  obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
> diff --git a/drivers/hwmon/htu21.c b/drivers/hwmon/htu21.c
> new file mode 100644
> index 0000000..d9470fb
> --- /dev/null
> +++ b/drivers/hwmon/htu21.c
> @@ -0,0 +1,198 @@
> +/*
> + * Measurement Specialties HTU21D humidity and temperature sensor driver
> + *
> + * Copyright (C) 2013 William Markezana <william.markezana@meas-spec.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/device.h>
> +#include <linux/jiffies.h>
> +
> +/* HTU21 Commands */
> +#define HTU21_T_MEASUREMENT_HM	0xE3
> +#define HTU21_RH_MEASUREMENT_HM	0xE5
> +
> +struct htu21 {
> +	struct device *hwmon_dev;
> +	struct mutex lock;
> +	bool valid;
> +	unsigned long last_update;
> +	int temperature;
> +	int humidity;
> +};
> +
> +static inline int htu21_temp_ticks_to_millicelsius(int ticks)
> +{
> +	ticks &= ~0x0003; /* clear status bits */
> +	/*
> +	 * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
> +	 * optimized for integer fixed point (3 digits) arithmetic
> +	 */
> +	return ((21965 * ticks) >> 13) - 46850;
> +}
> +
> +static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
> +{
> +	ticks &= ~0x0003; /* clear status bits */
> +	/*
> +	 * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
> +	 * optimized for integer fixed point (3 digits) arithmetic
> +	 */
> +	return ((15625 * ticks) >> 13) - 6000;
> +}
> +
> +static int htu21_update_measurements(struct i2c_client *client)
> +{
> +	int ret = 0;
> +	struct htu21 *htu21 = i2c_get_clientdata(client);
> +
> +	mutex_lock(&htu21->lock);
> +
> +	if (time_after(jiffies, htu21->last_update + HZ / 2) || !htu21->valid) {
> +		ret = i2c_smbus_read_word_swapped(client, HTU21_T_MEASUREMENT_HM);
> +		if (ret < 0)
> +			goto out;
> +		htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
> +		ret = i2c_smbus_read_word_swapped(client, HTU21_RH_MEASUREMENT_HM);
> +		if (ret < 0)
> +			goto out;
> +		htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
> +		htu21->last_update = jiffies;
> +		htu21->valid = true;
> +	}
> +out:
> +	mutex_unlock(&htu21->lock);
> +
> +	return ret >= 0 ? 0 : ret;
> +}
> +
> +static ssize_t htu21_show_temperature(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct htu21 *htu21 = i2c_get_clientdata(client);
> +	int ret = htu21_update_measurements(client);
> +	if (ret < 0)
> +		return ret;
> +	return sprintf(buf, "%d\n", htu21->temperature);
> +}
> +
> +static ssize_t htu21_show_humidity(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct htu21 *htu21 = i2c_get_clientdata(client);
> +	int ret = htu21_update_measurements(client);
> +	if (ret < 0)
> +		return ret;
> +	return sprintf(buf, "%d\n", htu21->humidity);
> +}
> +
> +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, 
> +	htu21_show_temperature, NULL, 0);
> +static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, 
> +	htu21_show_humidity, NULL, 0);
> +
> +static struct attribute *htu21_attributes[] = {
> +	&sensor_dev_attr_temp1_input.dev_attr.attr,
> +	&sensor_dev_attr_humidity1_input.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group htu21_group = {
> +	.attrs = htu21_attributes,
> +};
> +
> +static int htu21_probe(struct i2c_client *client,
> +	const struct i2c_device_id *id)
> +{
> +	struct htu21 *htu21;
> +	int err;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
> +		dev_err(&client->dev,
> +			"adapter does not support SMBus word transactions\n");
> +		return -ENODEV;
> +	}
> +
> +	htu21 = devm_kzalloc(&client->dev, sizeof(*htu21), GFP_KERNEL);
> +	if (!htu21)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, htu21);
> +
> +	mutex_init(&htu21->lock);
> +
> +	err = sysfs_create_group(&client->dev.kobj, &htu21_group);
> +	if (err) {
> +		dev_dbg(&client->dev, "could not create sysfs files\n");
> +		return err;
> +	}
> +	htu21->hwmon_dev = hwmon_device_register(&client->dev);
> +	if (IS_ERR(htu21->hwmon_dev)) {
> +		dev_dbg(&client->dev, "unable to register hwmon device\n");
> +		err = PTR_ERR(htu21->hwmon_dev);
> +		goto error;
> +	}
> +
> +	dev_info(&client->dev, "initialized\n");
> +
> +	return 0;
> +
> +error:
> +	sysfs_remove_group(&client->dev.kobj, &htu21_group);
> +	return err;
> +}
> +
> +static int htu21_remove(struct i2c_client *client)
> +{
> +	struct htu21 *htu21 = i2c_get_clientdata(client);
> +
> +	hwmon_device_unregister(htu21->hwmon_dev);
> +	sysfs_remove_group(&client->dev.kobj, &htu21_group);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id htu21_id[] = {
> +	{ "htu21", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, htu21_id);
> +
> +static struct i2c_driver htu21_driver = {
> +	.class = I2C_CLASS_HWMON,
> +	.driver = {
> +		.name	= "htu21",
> +	},
> +	.probe       = htu21_probe,
> +	.remove      = htu21_remove,
> +	.id_table    = htu21_id,
> +};
> +
> +module_i2c_driver(htu21_driver);
> +
> +MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
> +MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
> +MODULE_LICENSE("GPL");
> 
> 
> 
> -------- Message d'origine--------
> De: Guenter Roeck de la part de Guenter Roeck
> Date: mer. 28/08/2013 18:18
> À: Markezana, William
> Cc: khali@linux-fr.org; lm-sensors@lm-sensors.org; linux-kernel@vger.kernel.org
> Objet : Re: [PATCH] hwmon: (htu21) Add Measurement Specialties HTU21D support
>  
> On Wed, Aug 28, 2013 at 08:49:36AM +0200, Markezana, William wrote:
> > From 55fc390d0079841405d5345b55a6e158ca5f3749 Mon Sep 17 00:00:00 2001
> > From: William Markezana <william.markezana@meas-spec.com>
> > Date: Wed, 28 Aug 2013 08:33:49 +0200
> > Subject: [PATCH] hwmon: (htu21) Add Measurement Specialties HTU21D support
> > 
> 
> Your patch got corrupted and produces lots of checkpatch errors as result
> (and can not be aplied). YOu might want to use a diffeent mailer for the next
> version.
> 
> In addition to that, there are several other checkpatch errors and warnings.
> 
> ERROR: trailing statements should be on next line
> WARNING: line over 80 characters
> ERROR: Missing Signed-off-by: line(s)
> 
> Some more comments below.
> 
> Thanks,
> Guenter
> 
> > ---
> >  Documentation/hwmon/htu21 |   43 ++++++++++
> >  drivers/hwmon/Kconfig     |   10 +++
> >  drivers/hwmon/Makefile    |    1 +
> >  drivers/hwmon/htu21.c     |  201 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 255 insertions(+)
> >  create mode 100644 Documentation/hwmon/htu21
> >  create mode 100644 drivers/hwmon/htu21.c
> > 
> > diff --git a/Documentation/hwmon/htu21 b/Documentation/hwmon/htu21
> > new file mode 100644
> > index 0000000..ab756bc
> > --- /dev/null
> > +++ b/Documentation/hwmon/htu21
> > @@ -0,0 +1,43 @@
> > +Kernel driver htu21
> > +===================
> > +
> > +Supported chips:
> > +  * Measurement Specialties HTU21D
> > +    Prefix: 'htu21'
> > +    Addresses scanned: none
> > +    Datasheet: Publicly available at the Measurement Specialties website
> > +    http://www.meas-spec.com/downloads/HTU21D.pdf
> > +
> > +
> > +Author:
> > +  William Markezana <william.markezana@meas-spec.com>
> > +
> > +Description
> > +-----------
> > +
> > +HTU21D(F), the new digital humidity sensor with temperature output of MEAS is about 
> > +to set new standards in terms of size and intelligence: Embedded in a reflow 
> > +solderable Dual Flat No leads (DFN) package of 3 x 3 mm foot print and 0.9 mm height 
> > +it provides calibrated, linearized signals in digital, I²C format.
> > +
> Please drop the marketing pitch. Just describe what the chip is doing.
> 
> > +The devices communicate with the I2C protocol. All sensors are set to the same
> > +I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can be used
> > +in the board setup code.
> > +
> 
> I would suggest to add something like
> 
> "This driver does not auto-detect devices. You will have to instantiate the
> devices explicitly. Please see Documentation/i2c/instantiating-devices for
> details."
> 
> to the notes instead. After all, there are other means to instantiate the
> driver.
> 
> > +sysfs-Interface
> > +---------------
> > +
> > +temp1_input - temperature input
> > +humidity1_input - humidity input
> > +
> > +Notes
> > +-----
> > +
> > +The driver uses the default resolution settings of 12 bit for humidity and 14
> > +bit for temperature, which results in typical measurement times of 11 ms for
> > +humidity and 44 ms for temperature. To keep self heating below 0.1 degree
> > +Celsius, the device should not be active for more than 10% of the time,
> > +e.g. maximum two measurements per second at the given resolution.
> > +
> You might want to add that the driver is doing this, or phrase it differently,
> such as
> 
> "To keep self heating below 0.1 degree Celsius, the device should not be
> active for more than 10% of the time. For this reason, the driver performs no
> more than two measurements per second and reports cached information if polled
> more frequently."
> 
> > +Different resolutions, the on-chip heater, using the CRC checksum and reading
> > +the serial number are not supported yet.
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index e989f7f..eb46eb8 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -511,6 +511,16 @@ config SENSORS_HIH6130
> >  	  This driver can also be built as a module.  If so, the module
> >  	  will be called hih6130.
> >  
> > +config SENSORS_HTU21
> > +	tristate "Measurement Specialties HTU21D humidity and temperature sensors"
> > +	depends on I2C
> > +	help
> > +	  If you say yes here you get support for the Measurement Specialties
> > +	  HTU21D humidity and temperature sensors.
> > +
> > +	  This driver can also be built as a module.  If so, the module
> > +	  will be called htu21.
> > +
> >  config SENSORS_CORETEMP
> >  	tristate "Intel Core/Core2/Atom temperature sensor"
> >  	depends on X86
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> > index 4f0fb52..ec7cde0 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -65,6 +65,7 @@ obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
> >  obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
> >  obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
> >  obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
> > +obj-$(CONFIG_SENSORS_HTU21)	+= htu21.o
> >  obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
> >  obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
> >  obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
> > diff --git a/drivers/hwmon/htu21.c b/drivers/hwmon/htu21.c
> > new file mode 100644
> > index 0000000..8b8d132
> > --- /dev/null
> > +++ b/drivers/hwmon/htu21.c
> > @@ -0,0 +1,201 @@
> > +/* Measurement Specialties HTU21D humidity and temperature sensor driver
> > + *
> > + * Copyright (C) 2013 William Markezana <william.markezana@meas-spec.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > + *
> 
> Please drop the "You should have..." note and the FSF address. The license
> is in the "COPYING" file, and the address may change.
> 
> > + * Data sheet available (7/2013) at
> > + * http://www.meas-spec.com/downloads/HTU21D.pdf
> 
> The datasheet location is already mentioned in the Documentation. Please drop
> it from here, so we don't have to update it at two places is the link changes.
> 
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/slab.h>
> > +#include <linux/i2c.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/hwmon-sysfs.h>
> > +#include <linux/err.h>
> > +#include <linux/mutex.h>
> > +#include <linux/device.h>
> > +#include <linux/jiffies.h>
> > +
> > +/* HTU21 Commands */
> > +#define HTU21_T_MEASUREMENT_HM  0xE3
> > +#define HTU21_RH_MEASUREMENT_HM 0xE5
> > +
> Please use tabs before the 0x
> 
> > +struct htu21 {
> > +	struct device *hwmon_dev;
> > +	struct mutex lock;
> > +	char valid;
> 
> The above should be bool (and use '= true' for assignments).
> 
> > +	unsigned long last_update;
> > +	int temperature;
> > +	int humidity;
> > +};
> > +
> > +static inline int htu21_temp_ticks_to_millicelsius(int ticks)
> > +{
> > +	ticks &= ~0x0003; /* clear status bits */
> > +	/*
> > +	 * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
> > +	 * optimized for integer fixed point (3 digits) arithmetic
> > +	 */
> > +	return ((21965 * ticks) >> 13) - 46850;
> > +}
> > +
> > +static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
> > +{
> > +	ticks &= ~0x0003; /* clear status bits */
> > +	/*
> > +	 * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
> > +	 * optimized for integer fixed point (3 digits) arithmetic
> > +	 */
> > +	return ((15625 * ticks) >> 13) - 6000;
> > +}
> > +
> > +static int htu21_update_measurements(struct i2c_client *client)
> > +{
> > +	int ret = 0;
> > +	struct htu21 *htu21 = i2c_get_clientdata(client);
> > +
> > +	mutex_lock(&htu21->lock);
> > +
> > +	if (time_after(jiffies, htu21->last_update + HZ / 2) || !htu21->valid) {
> > +		ret = i2c_smbus_read_word_swapped(client, HTU21_T_MEASUREMENT_HM);
> > +		if (ret < 0)
> > +			goto out;
> > +		htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
> > +		ret = i2c_smbus_read_word_swapped(client, HTU21_RH_MEASUREMENT_HM);
> > +		if (ret < 0)
> > +			goto out;
> > +		htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
> > +		htu21->last_update = jiffies;
> > +		htu21->valid = 1;
> > +	}
> > +out:
> > +	mutex_unlock(&htu21->lock);
> > +
> > +	return ret >= 0 ? 0 : ret;
> > +}
> > +
> > +static ssize_t htu21_show_temperature(struct device *dev,
> > +	struct device_attribute *attr,
> > +	char *buf)
> > +{
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct htu21 *htu21 = i2c_get_clientdata(client);
> > +	int ret = htu21_update_measurements(client);
> > +	if (ret < 0)
> > +		return ret;
> > +	return sprintf(buf, "%d\n", htu21->temperature);
> > +}
> > +
> > +static ssize_t htu21_show_humidity(struct device *dev,
> > +	struct device_attribute *attr,
> > +	char *buf)
> > +{
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct htu21 *htu21 = i2c_get_clientdata(client);
> > +	int ret = htu21_update_measurements(client);
> > +	if (ret < 0)
> > +		return ret;
> > +	return sprintf(buf, "%d\n", htu21->humidity);
> > +}
> > +
> > +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, htu21_show_temperature,	NULL, 0);
> 
> space instead of tab before the NULL
> 
> > +static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, htu21_show_humidity, NULL, 0);
> > +
> > +static struct attribute *htu21_attributes[] = {
> > +	&sensor_dev_attr_temp1_input.dev_attr.attr,
> > +	&sensor_dev_attr_humidity1_input.dev_attr.attr,
> > +	NULL
> > +};
> > +
> > +static const struct attribute_group htu21_group = {
> > +	.attrs = htu21_attributes,
> > +};
> > +
> > +static int htu21_probe(struct i2c_client *client,
> > +	const struct i2c_device_id *id)
> > +{
> > +	struct htu21 *htu21;
> > +	int err;
> > +
> > +	if (!i2c_check_functionality(client->adapter,
> > +				     I2C_FUNC_SMBUS_WORD_DATA)) {
> 
> Strictly speaking, you only need I2C_FUNC_SMBUS_READ_WORD_DATA.
> 
> > +		dev_err(&client->dev,
> > +			"adapter does not support SMBus word transactions\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	htu21 = devm_kzalloc(&client->dev, sizeof(*htu21), GFP_KERNEL);
> > +	if (!htu21)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, htu21);
> > +
> > +	mutex_init(&htu21->lock);
> > +
> > +	err = sysfs_create_group(&client->dev.kobj, &htu21_group);
> > +	if (err) {
> > +		dev_dbg(&client->dev, "could not create sysfs files\n");
> > +		return err;
> > +	}
> > +	htu21->hwmon_dev = hwmon_device_register(&client->dev);
> > +	if (IS_ERR(htu21->hwmon_dev)) {
> > +		dev_dbg(&client->dev, "unable to register hwmon device\n");
> > +		err = PTR_ERR(htu21->hwmon_dev);
> > +		goto error;
> > +	}
> > +
> > +	dev_info(&client->dev, "initialized\n");
> > +
> > +	return 0;
> > +
> > +error:
> > +	sysfs_remove_group(&client->dev.kobj, &htu21_group);
> > +	return err;
> > +}
> > +
> > +static int htu21_remove(struct i2c_client *client)
> > +{
> > +	struct htu21 *htu21 = i2c_get_clientdata(client);
> > +
> > +	hwmon_device_unregister(htu21->hwmon_dev);
> > +	sysfs_remove_group(&client->dev.kobj, &htu21_group);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct i2c_device_id htu21_id[] = {
> > +	{ "htu21", 0 },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, htu21_id);
> > +
> > +static struct i2c_driver htu21_driver = {
> > +	.class = I2C_CLASS_HWMON,
> > +	.driver = {
> > +		.name	= "htu21",
> > +	},
> > +	.probe       = htu21_probe,
> > +	.remove      = htu21_remove,
> > +	.id_table    = htu21_id,
> > +};
> > +
> > +module_i2c_driver(htu21_driver);
> > +
> > +MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
> > +MODULE_DESCRIPTION("Measurement Specialties HTU21D humidity and temperature sensor driver");
> > +MODULE_LICENSE("GPL");
> > -- 
> > 1.7.10.4
> > 
> > 
> 

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