diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /drivers/hwmon/sht21.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | drivers/hwmon/sht21.c | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/drivers/hwmon/sht21.c b/drivers/hwmon/sht21.c new file mode 100644 index 000000000..e23dbf287 --- /dev/null +++ b/drivers/hwmon/sht21.c @@ -0,0 +1,296 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Sensirion SHT21 humidity and temperature sensor driver + * + * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com> + * + * Data sheet available at https://www.sensirion.com/file/datasheet_sht21 + */ + +#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/jiffies.h> + +/* I2C command bytes */ +#define SHT21_TRIG_T_MEASUREMENT_HM 0xe3 +#define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5 +#define SHT21_READ_SNB_CMD1 0xFA +#define SHT21_READ_SNB_CMD2 0x0F +#define SHT21_READ_SNAC_CMD1 0xFC +#define SHT21_READ_SNAC_CMD2 0xC9 + +/** + * struct sht21 - SHT21 device specific data + * @client: I2C client device + * @lock: mutex to protect measurement values + * @last_update: time of last update (jiffies) + * @temperature: cached temperature measurement value + * @humidity: cached humidity measurement value + * @valid: only 0 before first measurement is taken + * @eic: cached electronic identification code text + */ +struct sht21 { + struct i2c_client *client; + struct mutex lock; + unsigned long last_update; + int temperature; + int humidity; + bool valid; + char eic[18]; +}; + +/** + * 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_update_measurements() - get updated measurements from device + * @dev: device + * + * Returns 0 on success, else negative errno. + */ +static int sht21_update_measurements(struct device *dev) +{ + int ret = 0; + struct sht21 *sht21 = dev_get_drvdata(dev); + struct i2c_client *client = sht21->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 = i2c_smbus_read_word_swapped(client, + SHT21_TRIG_T_MEASUREMENT_HM); + if (ret < 0) + goto out; + sht21->temperature = sht21_temp_ticks_to_millicelsius(ret); + ret = i2c_smbus_read_word_swapped(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 = true; + } +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_temperature_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sht21 *sht21 = dev_get_drvdata(dev); + int ret; + + ret = sht21_update_measurements(dev); + 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_humidity_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct sht21 *sht21 = dev_get_drvdata(dev); + int ret; + + ret = sht21_update_measurements(dev); + if (ret < 0) + return ret; + return sprintf(buf, "%d\n", sht21->humidity); +} + +static ssize_t eic_read(struct sht21 *sht21) +{ + struct i2c_client *client = sht21->client; + u8 tx[2]; + u8 rx[8]; + u8 eic[8]; + struct i2c_msg msgs[2] = { + { + .addr = client->addr, + .flags = 0, + .len = 2, + .buf = tx, + }, + { + .addr = client->addr, + .flags = I2C_M_RD, + .len = 8, + .buf = rx, + }, + }; + int ret; + + tx[0] = SHT21_READ_SNB_CMD1; + tx[1] = SHT21_READ_SNB_CMD2; + ret = i2c_transfer(client->adapter, msgs, 2); + if (ret < 0) + goto out; + eic[2] = rx[0]; + eic[3] = rx[2]; + eic[4] = rx[4]; + eic[5] = rx[6]; + + tx[0] = SHT21_READ_SNAC_CMD1; + tx[1] = SHT21_READ_SNAC_CMD2; + msgs[1].len = 6; + ret = i2c_transfer(client->adapter, msgs, 2); + if (ret < 0) + goto out; + eic[0] = rx[3]; + eic[1] = rx[4]; + eic[6] = rx[0]; + eic[7] = rx[1]; + + ret = snprintf(sht21->eic, sizeof(sht21->eic), + "%02x%02x%02x%02x%02x%02x%02x%02x\n", + eic[0], eic[1], eic[2], eic[3], + eic[4], eic[5], eic[6], eic[7]); +out: + if (ret < 0) + sht21->eic[0] = 0; + + return ret; +} + +/** + * eic_show() - show Electronic Identification Code in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where EIC is written + * + * Will be called on read access to eic sysfs attribute. + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t eic_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sht21 *sht21 = dev_get_drvdata(dev); + int ret; + + ret = sizeof(sht21->eic) - 1; + mutex_lock(&sht21->lock); + if (!sht21->eic[0]) + ret = eic_read(sht21); + if (ret > 0) + memcpy(buf, sht21->eic, ret); + mutex_unlock(&sht21->lock); + return ret; +} + +/* sysfs attributes */ +static SENSOR_DEVICE_ATTR_RO(temp1_input, sht21_temperature, 0); +static SENSOR_DEVICE_ATTR_RO(humidity1_input, sht21_humidity, 0); +static DEVICE_ATTR_RO(eic); + +static struct attribute *sht21_attrs[] = { + &sensor_dev_attr_temp1_input.dev_attr.attr, + &sensor_dev_attr_humidity1_input.dev_attr.attr, + &dev_attr_eic.attr, + NULL +}; + +ATTRIBUTE_GROUPS(sht21); + +static int sht21_probe(struct i2c_client *client) +{ + struct device *dev = &client->dev; + struct device *hwmon_dev; + struct sht21 *sht21; + + 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 = devm_kzalloc(dev, sizeof(*sht21), GFP_KERNEL); + if (!sht21) + return -ENOMEM; + + sht21->client = client; + + mutex_init(&sht21->lock); + + hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, + sht21, sht21_groups); + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +/* 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_new = sht21_probe, + .id_table = sht21_id, +}; + +module_i2c_driver(sht21_driver); + +MODULE_AUTHOR("Urs Fleisch <urs.fleisch@sensirion.com>"); +MODULE_DESCRIPTION("Sensirion SHT21 humidity and temperature sensor driver"); +MODULE_LICENSE("GPL"); |