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260 lines
7.1 KiB
260 lines
7.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver |
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* |
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* Copyright (C) 2012 Iain Paton <[email protected]> |
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* |
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* heavily based on the sht21 driver |
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* Copyright (C) 2010 Urs Fleisch <[email protected]> |
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* |
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* Data sheets available (2012-06-22) at |
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* http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872 |
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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/delay.h> |
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#include <linux/jiffies.h> |
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/** |
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* struct hih6130 - HIH-6130 device specific data |
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* @client: pointer to I2C client device |
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* @lock: mutex to protect measurement values |
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* @valid: only false before first measurement is taken |
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* @last_update: time of last update (jiffies) |
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* @temperature: cached temperature measurement value |
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* @humidity: cached humidity measurement value |
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* @write_length: length for I2C measurement request |
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*/ |
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struct hih6130 { |
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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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size_t write_length; |
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}; |
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/** |
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* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to |
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* milli celsius |
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* @ticks: temperature ticks value received from sensor |
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*/ |
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static inline int hih6130_temp_ticks_to_millicelsius(int ticks) |
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{ |
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ticks = ticks >> 2; |
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/* |
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* from data sheet section 5.0 |
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* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 |
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*/ |
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return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100; |
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} |
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/** |
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* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to |
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* one-thousandths of a percent relative humidity |
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* @ticks: humidity ticks value received from sensor |
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*/ |
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static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks) |
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{ |
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ticks &= ~0xC000; /* clear status bits */ |
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/* |
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* from data sheet section 4.0 |
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* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 |
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*/ |
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return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100; |
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} |
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/** |
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* hih6130_update_measurements() - get updated measurements from device |
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* @dev: device |
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* |
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* Returns 0 on success, else negative errno. |
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*/ |
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static int hih6130_update_measurements(struct device *dev) |
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{ |
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struct hih6130 *hih6130 = dev_get_drvdata(dev); |
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struct i2c_client *client = hih6130->client; |
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int ret = 0; |
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int t; |
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unsigned char tmp[4]; |
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struct i2c_msg msgs[1] = { |
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{ |
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.addr = client->addr, |
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.flags = I2C_M_RD, |
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.len = 4, |
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.buf = tmp, |
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} |
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}; |
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mutex_lock(&hih6130->lock); |
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/* |
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* While the measurement can be completed in ~40ms the sensor takes |
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* much longer to react to a change in external conditions. How quickly |
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* it reacts depends on airflow and other factors outwith our control. |
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* The datasheet specifies maximum 'Response time' for humidity at 8s |
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* and temperature at 30s under specified conditions. |
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* We therefore choose to only read the sensor at most once per second. |
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* This trades off pointless activity polling the sensor much faster |
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* than it can react against better response times in conditions more |
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* favourable than specified in the datasheet. |
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*/ |
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if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { |
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/* |
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* Write to slave address to request a measurement. |
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* According with the datasheet it should be with no data, but |
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* for systems with I2C bus drivers that do not allow zero |
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* length packets we write one dummy byte to allow sensor |
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* measurements on them. |
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*/ |
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tmp[0] = 0; |
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ret = i2c_master_send(client, tmp, hih6130->write_length); |
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if (ret < 0) |
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goto out; |
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/* measurement cycle time is ~36.65msec */ |
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msleep(40); |
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ret = i2c_transfer(client->adapter, msgs, 1); |
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if (ret < 0) |
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goto out; |
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if ((tmp[0] & 0xC0) != 0) { |
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dev_err(&client->dev, "Error while reading measurement result\n"); |
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ret = -EIO; |
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goto out; |
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} |
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t = (tmp[0] << 8) + tmp[1]; |
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hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t); |
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t = (tmp[2] << 8) + tmp[3]; |
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hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t); |
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hih6130->last_update = jiffies; |
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hih6130->valid = true; |
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} |
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out: |
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mutex_unlock(&hih6130->lock); |
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return ret >= 0 ? 0 : ret; |
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} |
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/** |
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* hih6130_show_temperature() - show temperature measurement value in sysfs |
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* @dev: device |
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* @attr: device attribute |
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* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to |
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* |
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* Will be called on read access to temp1_input sysfs attribute. |
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* Returns number of bytes written into buffer, negative errno on error. |
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*/ |
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static ssize_t hih6130_temperature_show(struct device *dev, |
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struct device_attribute *attr, |
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char *buf) |
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{ |
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struct hih6130 *hih6130 = dev_get_drvdata(dev); |
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int ret; |
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ret = hih6130_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", hih6130->temperature); |
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} |
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/** |
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* hih6130_show_humidity() - show humidity measurement value in sysfs |
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* @dev: device |
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* @attr: device attribute |
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* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to |
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* |
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* Will be called on read access to humidity1_input sysfs attribute. |
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* Returns number of bytes written into buffer, negative errno on error. |
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*/ |
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static ssize_t hih6130_humidity_show(struct device *dev, |
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struct device_attribute *attr, char *buf) |
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{ |
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struct hih6130 *hih6130 = dev_get_drvdata(dev); |
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int ret; |
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ret = hih6130_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", hih6130->humidity); |
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} |
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/* sysfs attributes */ |
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static SENSOR_DEVICE_ATTR_RO(temp1_input, hih6130_temperature, 0); |
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static SENSOR_DEVICE_ATTR_RO(humidity1_input, hih6130_humidity, 0); |
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static struct attribute *hih6130_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(hih6130); |
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static int hih6130_probe(struct i2c_client *client) |
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{ |
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struct device *dev = &client->dev; |
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struct hih6130 *hih6130; |
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struct device *hwmon_dev; |
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { |
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dev_err(&client->dev, "adapter does not support true I2C\n"); |
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return -ENODEV; |
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} |
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hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL); |
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if (!hih6130) |
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return -ENOMEM; |
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hih6130->client = client; |
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mutex_init(&hih6130->lock); |
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) |
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hih6130->write_length = 1; |
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, |
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hih6130, |
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hih6130_groups); |
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return PTR_ERR_OR_ZERO(hwmon_dev); |
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} |
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/* Device ID table */ |
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static const struct i2c_device_id hih6130_id[] = { |
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{ "hih6130", 0 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, hih6130_id); |
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static const struct of_device_id __maybe_unused hih6130_of_match[] = { |
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{ .compatible = "honeywell,hih6130", }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(of, hih6130_of_match); |
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static struct i2c_driver hih6130_driver = { |
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.driver = { |
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.name = "hih6130", |
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.of_match_table = of_match_ptr(hih6130_of_match), |
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}, |
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.probe_new = hih6130_probe, |
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.id_table = hih6130_id, |
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}; |
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module_i2c_driver(hih6130_driver); |
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MODULE_AUTHOR("Iain Paton <[email protected]>"); |
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MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver"); |
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MODULE_LICENSE("GPL");
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