linux/drivers/hwmon/hih6130.c
Thomas Gleixner fd534e9b5f treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 50 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190523091649.499889647@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:39:00 +02:00

262 lines
7.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
*
* Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
*
* heavily based on the sht21 driver
* Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
*
* Data sheets available (2012-06-22) at
* http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872
*/
#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/delay.h>
#include <linux/jiffies.h>
/**
* struct hih6130 - HIH-6130 device specific data
* @client: pointer to I2C client device
* @lock: mutex to protect measurement values
* @valid: only false before first measurement is taken
* @last_update: time of last update (jiffies)
* @temperature: cached temperature measurement value
* @humidity: cached humidity measurement value
* @write_length: length for I2C measurement request
*/
struct hih6130 {
struct i2c_client *client;
struct mutex lock;
bool valid;
unsigned long last_update;
int temperature;
int humidity;
size_t write_length;
};
/**
* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
* milli celsius
* @ticks: temperature ticks value received from sensor
*/
static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
{
ticks = ticks >> 2;
/*
* from data sheet section 5.0
* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
*/
return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
}
/**
* hih6130_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 hih6130_rh_ticks_to_per_cent_mille(int ticks)
{
ticks &= ~0xC000; /* clear status bits */
/*
* from data sheet section 4.0
* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
*/
return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
}
/**
* hih6130_update_measurements() - get updated measurements from device
* @dev: device
*
* Returns 0 on success, else negative errno.
*/
static int hih6130_update_measurements(struct device *dev)
{
struct hih6130 *hih6130 = dev_get_drvdata(dev);
struct i2c_client *client = hih6130->client;
int ret = 0;
int t;
unsigned char tmp[4];
struct i2c_msg msgs[1] = {
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = 4,
.buf = tmp,
}
};
mutex_lock(&hih6130->lock);
/*
* While the measurement can be completed in ~40ms the sensor takes
* much longer to react to a change in external conditions. How quickly
* it reacts depends on airflow and other factors outwith our control.
* The datasheet specifies maximum 'Response time' for humidity at 8s
* and temperature at 30s under specified conditions.
* We therefore choose to only read the sensor at most once per second.
* This trades off pointless activity polling the sensor much faster
* than it can react against better response times in conditions more
* favourable than specified in the datasheet.
*/
if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) {
/*
* Write to slave address to request a measurement.
* According with the datasheet it should be with no data, but
* for systems with I2C bus drivers that do not allow zero
* length packets we write one dummy byte to allow sensor
* measurements on them.
*/
tmp[0] = 0;
ret = i2c_master_send(client, tmp, hih6130->write_length);
if (ret < 0)
goto out;
/* measurement cycle time is ~36.65msec */
msleep(40);
ret = i2c_transfer(client->adapter, msgs, 1);
if (ret < 0)
goto out;
if ((tmp[0] & 0xC0) != 0) {
dev_err(&client->dev, "Error while reading measurement result\n");
ret = -EIO;
goto out;
}
t = (tmp[0] << 8) + tmp[1];
hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);
t = (tmp[2] << 8) + tmp[3];
hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);
hih6130->last_update = jiffies;
hih6130->valid = true;
}
out:
mutex_unlock(&hih6130->lock);
return ret >= 0 ? 0 : ret;
}
/**
* hih6130_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 hih6130_temperature_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct hih6130 *hih6130 = dev_get_drvdata(dev);
int ret;
ret = hih6130_update_measurements(dev);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", hih6130->temperature);
}
/**
* hih6130_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 hih6130_humidity_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct hih6130 *hih6130 = dev_get_drvdata(dev);
int ret;
ret = hih6130_update_measurements(dev);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", hih6130->humidity);
}
/* sysfs attributes */
static SENSOR_DEVICE_ATTR_RO(temp1_input, hih6130_temperature, 0);
static SENSOR_DEVICE_ATTR_RO(humidity1_input, hih6130_humidity, 0);
static struct attribute *hih6130_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_humidity1_input.dev_attr.attr,
NULL
};
ATTRIBUTE_GROUPS(hih6130);
static int hih6130_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct hih6130 *hih6130;
struct device *hwmon_dev;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(&client->dev, "adapter does not support true I2C\n");
return -ENODEV;
}
hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL);
if (!hih6130)
return -ENOMEM;
hih6130->client = client;
mutex_init(&hih6130->lock);
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
hih6130->write_length = 1;
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
hih6130,
hih6130_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
/* Device ID table */
static const struct i2c_device_id hih6130_id[] = {
{ "hih6130", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, hih6130_id);
static const struct of_device_id __maybe_unused hih6130_of_match[] = {
{ .compatible = "honeywell,hih6130", },
{ }
};
MODULE_DEVICE_TABLE(of, hih6130_of_match);
static struct i2c_driver hih6130_driver = {
.driver = {
.name = "hih6130",
.of_match_table = of_match_ptr(hih6130_of_match),
},
.probe = hih6130_probe,
.id_table = hih6130_id,
};
module_i2c_driver(hih6130_driver);
MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
MODULE_LICENSE("GPL");