mirror of https://gitee.com/openkylin/linux.git
hwmon: driver for Sensirion SHT21 humidity and temperature sensor
Signed-off-by: Urs Fleisch <urs.fleisch@sensirion.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
This commit is contained in:
Urs Fleisch
Guenter Roeck
parent
c6c2c1636e
commit
430400b863
|
|
@ -0,0 +1,49 @@
|
|||
Kernel driver sht21
|
||||
===================
|
||||
|
||||
Supported chips:
|
||||
* Sensirion SHT21
|
||||
Prefix: 'sht21'
|
||||
Addresses scanned: none
|
||||
Datasheet: Publicly available at the Sensirion website
|
||||
http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf
|
||||
|
||||
* Sensirion SHT25
|
||||
Prefix: 'sht21'
|
||||
Addresses scanned: none
|
||||
Datasheet: Publicly available at the Sensirion website
|
||||
http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT25.pdf
|
||||
|
||||
Author:
|
||||
Urs Fleisch <urs.fleisch@sensirion.com>
|
||||
|
||||
Description
|
||||
-----------
|
||||
|
||||
The SHT21 and SHT25 are humidity and temperature sensors in a DFN package of
|
||||
only 3 x 3 mm footprint and 1.1 mm height. The difference between the two
|
||||
devices is the higher level of precision of the SHT25 (1.8% relative humidity,
|
||||
0.2 degree Celsius) compared with the SHT21 (2.0% relative humidity,
|
||||
0.3 degree Celsius).
|
||||
|
||||
The devices communicate with the I2C protocol. All sensors are set to the same
|
||||
I2C address 0x40, so an entry with I2C_BOARD_INFO("sht21", 0x40) can be used
|
||||
in the board setup code.
|
||||
|
||||
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 22 ms for
|
||||
humidity and 66 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.
|
||||
|
||||
Different resolutions, the on-chip heater, using the CRC checksum and reading
|
||||
the serial number are not supported yet.
|
||||
|
|
@ -734,6 +734,16 @@ 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 "Samsung built-in ADC"
|
||||
depends on S3C_ADC
|
||||
|
|
|
|||
|
|
@ -90,6 +90,7 @@ 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
|
||||
|
|
|
|||
|
|
@ -0,0 +1,307 @@
|
|||
/* 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");
|
||||
Loading…
Reference in New Issue