Messages in this thread | | | Date | Thu, 06 Jan 2011 10:58:23 +0000 | From | Jonathan Cameron <> | Subject | Re: [PATCH V4] hwmon: driver for Sensirion SHT21 humidity and temperature sensor |
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On 01/06/11 07:43, Urs Fleisch wrote: > Thanks for the review, Jonathan and Guenter. > > Changes: > - removed user register related sysfs attributes, keeping only temp1_input and > humidity1_input > - cleaned up code flow when returning errors for better readability Short and clean. I do wonder if you want some of those users register bits available via platform data though. Perhaps that can be added in a later patch as and when someone needs them. > > Regards, > Urs > > Signed-off-by: Urs Fleisch <urs.fleisch@sensirion.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> > --- > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 95ccbe3..4a96429 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -688,6 +688,16 @@ config SENSORS_SHT15 > This driver can also be built as a module. If so, the module > will be called sht15. > > +config SENSORS_SHT21 > + tristate "Sensiron humidity and temperature sensors. SHT21 and compat." > + depends on I2C > + help > + If you say yes here you get support for the Sensiron SHT21, SHT25 > + humidity and temperature sensors. > + > + This driver can also be built as a module. If so, the module > + will be called sht21. > + > config SENSORS_S3C > tristate "S3C24XX/S3C64XX Inbuilt ADC" > depends on ARCH_S3C2410 > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 33c2ee1..7439653 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -80,6 +80,7 @@ obj-$(CONFIG_SENSORS_PC87427) += pc87427.o > obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o > obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o > obj-$(CONFIG_SENSORS_SHT15) += sht15.o > +obj-$(CONFIG_SENSORS_SHT21) += sht21.o > obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o > obj-$(CONFIG_SENSORS_SMM665) += smm665.o > obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o > diff --git a/drivers/hwmon/sht21.c b/drivers/hwmon/sht21.c > new file mode 100644 > index 0000000..7d3ec82 > --- /dev/null > +++ b/drivers/hwmon/sht21.c > @@ -0,0 +1,300 @@ > +/* Sensirion SHT21 humidity and temperature sensor driver > + * > + * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.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., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA > + * > + * Data sheet available (5/2010) at > + * http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf > + */ > + > +#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> > + > +/* I2C command bytes */ > +#define SHT21_TRIG_T_MEASUREMENT_HM 0xe3 > +#define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5 > + > +/** > + * struct sht21 - SHT21 device specific data > + * @hwmon_dev: device registered with hwmon > + * @lock: mutex to protect measurement values > + * @valid: only 0 before first measurement is taken > + * @last_update: time of last update (jiffies) > + * @temperature: cached temperature measurement value > + * @humidity: cached humidity measurement value > + */ > +struct sht21 { > + struct device *hwmon_dev; > + struct mutex lock; > + char valid; > + unsigned long last_update; > + int temperature; > + int humidity; > +}; > + > +/** > + * sht21_temp_ticks_to_millicelsius() - convert raw temperature ticks to > + * milli celsius > + * @ticks: temperature ticks value received from sensor > + */ > +static inline int sht21_temp_ticks_to_millicelsius(int ticks) > +{ > + ticks &= ~0x0003; /* clear status bits */ > + /* Formula T = -46.85 + 175.72 * ST / 2^16 from data sheet 6.2, > + optimized for integer fixed point (3 digits) arithmetic */ > + return ((21965 * ticks) >> 13) - 46850; > +} > + > +/** > + * sht21_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to > + * one-thousandths of a percent relative humidity > + * @ticks: humidity ticks value received from sensor > + */ > +static inline int sht21_rh_ticks_to_per_cent_mille(int ticks) > +{ > + ticks &= ~0x0003; /* clear status bits */ > + /* Formula RH = -6 + 125 * SRH / 2^16 from data sheet 6.1, > + optimized for integer fixed point (3 digits) arithmetic */ > + return ((15625 * ticks) >> 13) - 6000; > +} > + > +/** > + * sht21_read_word_data() - read word from register > + * @client: I2C client device > + * @reg: I2C command byte > + * > + * Returns value, negative errno on error. > + */ > +static inline int sht21_read_word_data(struct i2c_client *client, u8 reg) > +{ > + int ret = i2c_smbus_read_word_data(client, reg); > + if (ret < 0) > + return ret; > + /* SMBus specifies low byte first, but the SHT21 returns MSB > + * first, so we have to swab16 the values */ > + return swab16(ret); > +} > + > +/** > + * sht21_update_measurements() - get updated measurements from device > + * @client: I2C client device > + * > + * Returns 0 on success, else negative errno. > + */ > +static int sht21_update_measurements(struct i2c_client *client) > +{ > + int ret = 0; > + struct sht21 *sht21 = i2c_get_clientdata(client); > + > + mutex_lock(&sht21->lock); > + /* Data sheet 2.4: > + * SHT2x should not be active for more than 10% of the time - e.g. > + * maximum two measurements per second at 12bit accuracy shall be made. > + */ > + if (time_after(jiffies, sht21->last_update + HZ / 2) || !sht21->valid) { > + ret = sht21_read_word_data(client, SHT21_TRIG_T_MEASUREMENT_HM); > + if (ret < 0) > + goto out; > + sht21->temperature = sht21_temp_ticks_to_millicelsius(ret); > + ret = sht21_read_word_data(client, > + SHT21_TRIG_RH_MEASUREMENT_HM); > + if (ret < 0) > + goto out; > + sht21->humidity = sht21_rh_ticks_to_per_cent_mille(ret); > + sht21->last_update = jiffies; > + sht21->valid = 1; > + } > +out: > + mutex_unlock(&sht21->lock); > + > + return ret >= 0 ? 0 : ret; > +} > + > +/** > + * sht21_show_temperature() - show temperature measurement value in sysfs > + * @dev: device > + * @attr: device attribute > + * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to > + * > + * Will be called on read access to temp1_input sysfs attribute. > + * Returns number of bytes written into buffer, negative errno on error. > + */ > +static ssize_t sht21_show_temperature(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct i2c_client *client = to_i2c_client(dev); > + struct sht21 *sht21 = i2c_get_clientdata(client); > + int ret = sht21_update_measurements(client); > + if (ret < 0) > + return ret; > + return sprintf(buf, "%d\n", sht21->temperature); > +} > + > +/** > + * sht21_show_humidity() - show humidity measurement value in sysfs > + * @dev: device > + * @attr: device attribute > + * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to > + * > + * Will be called on read access to humidity1_input sysfs attribute. > + * Returns number of bytes written into buffer, negative errno on error. > + */ > +static ssize_t sht21_show_humidity(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct i2c_client *client = to_i2c_client(dev); > + struct sht21 *sht21 = i2c_get_clientdata(client); > + int ret = sht21_update_measurements(client); > + if (ret < 0) > + return ret; > + return sprintf(buf, "%d\n", sht21->humidity); > +} > + > +/* sysfs attributes */ > +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, sht21_show_temperature, > + NULL, 0); > +static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, sht21_show_humidity, > + NULL, 0); > + > +static struct attribute *sht21_attributes[] = { > + &sensor_dev_attr_temp1_input.dev_attr.attr, > + &sensor_dev_attr_humidity1_input.dev_attr.attr, > + NULL > +}; > + > +static const struct attribute_group sht21_attr_group = { > + .attrs = sht21_attributes, > +}; > + > +/** > + * sht21_probe() - probe device > + * @client: I2C client device > + * @id: device ID > + * > + * Called by the I2C core when an entry in the ID table matches a > + * device's name. > + * Returns 0 on success. > + */ > +static int __devinit sht21_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct sht21 *sht21; > + int err; > + > + if (!i2c_check_functionality(client->adapter, > + I2C_FUNC_SMBUS_WORD_DATA)) { > + dev_err(&client->dev, > + "adapter does not support SMBus word transactions\n"); > + return -ENODEV; > + } > + > + sht21 = kzalloc(sizeof(*sht21), GFP_KERNEL); > + if (!sht21) { > + dev_dbg(&client->dev, "kzalloc failed\n"); > + return -ENOMEM; > + } > + i2c_set_clientdata(client, sht21); > + > + mutex_init(&sht21->lock); > + > + err = sysfs_create_group(&client->dev.kobj, &sht21_attr_group); > + if (err) { > + dev_dbg(&client->dev, "could not create sysfs files\n"); > + goto fail_free; > + } > + sht21->hwmon_dev = hwmon_device_register(&client->dev); > + if (IS_ERR(sht21->hwmon_dev)) { > + dev_dbg(&client->dev, "unable to register hwmon device\n"); > + err = PTR_ERR(sht21->hwmon_dev); > + goto fail_remove_sysfs; > + } > + > + dev_info(&client->dev, "initialized\n"); > + > + return 0; > + > +fail_remove_sysfs: > + sysfs_remove_group(&client->dev.kobj, &sht21_attr_group); > +fail_free: > + kfree(sht21); > + > + return err; > +} > + > +/** > + * sht21_remove() - remove device > + * @client: I2C client device > + */ > +static int __devexit sht21_remove(struct i2c_client *client) > +{ > + struct sht21 *sht21 = i2c_get_clientdata(client); > + > + hwmon_device_unregister(sht21->hwmon_dev); > + sysfs_remove_group(&client->dev.kobj, &sht21_attr_group); > + kfree(sht21); > + > + return 0; > +} > + > +/* Device ID table */ > +static const struct i2c_device_id sht21_id[] = { > + { "sht21", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, sht21_id); > + > +static struct i2c_driver sht21_driver = { > + .driver.name = "sht21", > + .probe = sht21_probe, > + .remove = __devexit_p(sht21_remove), > + .id_table = sht21_id, > +}; > + > +/** > + * sht21_init() - initialize driver > + * > + * Called when kernel is booted or module is inserted. > + * Returns 0 on success. > + */ > +static int __init sht21_init(void) > +{ > + return i2c_add_driver(&sht21_driver); > +} > +module_init(sht21_init); > + > +/** > + * sht21_init() - clean up driver > + * > + * Called when module is removed. > + */ > +static void __exit sht21_exit(void) > +{ > + i2c_del_driver(&sht21_driver); > +} > +module_exit(sht21_exit); > + > +MODULE_AUTHOR("Urs Fleisch <urs.fleisch@sensirion.com>"); > +MODULE_DESCRIPTION("Sensirion SHT21 humidity and temperature sensor driver"); > +MODULE_LICENSE("GPL"); >
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