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![Axel Lin](/assets/img/avatar_default.png)
Use ATTRIBUTE_GROUPS macro and devm_hwmon_device_register_with_groups() to simplify the code a bit. Signed-off-by: Axel Lin <axel.lin@ingics.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
174 lines
4.4 KiB
C
174 lines
4.4 KiB
C
/*
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* Measurement Specialties HTU21D humidity and temperature sensor driver
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*
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* Copyright (C) 2013 William Markezana <william.markezana@meas-spec.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/err.h>
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#include <linux/mutex.h>
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#include <linux/device.h>
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#include <linux/jiffies.h>
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/* HTU21 Commands */
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#define HTU21_T_MEASUREMENT_HM 0xE3
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#define HTU21_RH_MEASUREMENT_HM 0xE5
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struct htu21 {
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struct i2c_client *client;
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struct mutex lock;
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bool valid;
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unsigned long last_update;
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int temperature;
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int humidity;
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};
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static inline int htu21_temp_ticks_to_millicelsius(int ticks)
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{
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ticks &= ~0x0003; /* clear status bits */
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/*
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* Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
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* optimized for integer fixed point (3 digits) arithmetic
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*/
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return ((21965 * ticks) >> 13) - 46850;
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}
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static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
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{
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ticks &= ~0x0003; /* clear status bits */
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/*
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* Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
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* optimized for integer fixed point (3 digits) arithmetic
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*/
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return ((15625 * ticks) >> 13) - 6000;
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}
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static int htu21_update_measurements(struct device *dev)
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{
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struct htu21 *htu21 = dev_get_drvdata(dev);
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struct i2c_client *client = htu21->client;
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int ret = 0;
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mutex_lock(&htu21->lock);
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if (time_after(jiffies, htu21->last_update + HZ / 2) ||
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!htu21->valid) {
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ret = i2c_smbus_read_word_swapped(client,
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HTU21_T_MEASUREMENT_HM);
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if (ret < 0)
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goto out;
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htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
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ret = i2c_smbus_read_word_swapped(client,
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HTU21_RH_MEASUREMENT_HM);
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if (ret < 0)
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goto out;
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htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
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htu21->last_update = jiffies;
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htu21->valid = true;
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}
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out:
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mutex_unlock(&htu21->lock);
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return ret >= 0 ? 0 : ret;
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}
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static ssize_t htu21_show_temperature(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct htu21 *htu21 = dev_get_drvdata(dev);
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int ret;
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ret = htu21_update_measurements(dev);
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if (ret < 0)
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return ret;
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return sprintf(buf, "%d\n", htu21->temperature);
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}
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static ssize_t htu21_show_humidity(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct htu21 *htu21 = dev_get_drvdata(dev);
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int ret;
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ret = htu21_update_measurements(dev);
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if (ret < 0)
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return ret;
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return sprintf(buf, "%d\n", htu21->humidity);
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}
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static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
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htu21_show_temperature, NULL, 0);
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static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
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htu21_show_humidity, NULL, 0);
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static struct attribute *htu21_attrs[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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&sensor_dev_attr_humidity1_input.dev_attr.attr,
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NULL
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};
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ATTRIBUTE_GROUPS(htu21);
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static int htu21_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct device *dev = &client->dev;
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struct htu21 *htu21;
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struct device *hwmon_dev;
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_READ_WORD_DATA)) {
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dev_err(&client->dev,
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"adapter does not support SMBus word transactions\n");
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return -ENODEV;
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}
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htu21 = devm_kzalloc(dev, sizeof(*htu21), GFP_KERNEL);
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if (!htu21)
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return -ENOMEM;
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htu21->client = client;
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mutex_init(&htu21->lock);
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
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htu21,
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htu21_groups);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct i2c_device_id htu21_id[] = {
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{ "htu21", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, htu21_id);
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static struct i2c_driver htu21_driver = {
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.class = I2C_CLASS_HWMON,
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.driver = {
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.name = "htu21",
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},
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.probe = htu21_probe,
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.id_table = htu21_id,
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};
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module_i2c_driver(htu21_driver);
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MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
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MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
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MODULE_LICENSE("GPL");
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