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- /* Sensirion SHTC1 humidity and temperature sensor driver
- *
- * Copyright (C) 2014 Sensirion AG, Switzerland
- * Author: Johannes Winkelmann <johannes.winkelmann@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.
- *
- */
- #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/delay.h>
- #include <linux/platform_data/shtc1.h>
- /* commands (high precision mode) */
- static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
- static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
- /* commands (low precision mode) */
- static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
- static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
- /* command for reading the ID register */
- static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };
- /* constants for reading the ID register */
- #define SHTC1_ID 0x07
- #define SHTC1_ID_REG_MASK 0x1f
- /* delays for non-blocking i2c commands, both in us */
- #define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400
- #define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000
- #define SHTC1_CMD_LENGTH 2
- #define SHTC1_RESPONSE_LENGTH 6
- struct shtc1_data {
- struct i2c_client *client;
- struct mutex update_lock;
- bool valid;
- unsigned long last_updated; /* in jiffies */
- const unsigned char *command;
- unsigned int nonblocking_wait_time; /* in us */
- struct shtc1_platform_data setup;
- int temperature; /* 1000 * temperature in dgr C */
- int humidity; /* 1000 * relative humidity in %RH */
- };
- static int shtc1_update_values(struct i2c_client *client,
- struct shtc1_data *data,
- char *buf, int bufsize)
- {
- int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
- if (ret != SHTC1_CMD_LENGTH) {
- dev_err(&client->dev, "failed to send command: %d\n", ret);
- return ret < 0 ? ret : -EIO;
- }
- /*
- * In blocking mode (clock stretching mode) the I2C bus
- * is blocked for other traffic, thus the call to i2c_master_recv()
- * will wait until the data is ready. For non blocking mode, we
- * have to wait ourselves.
- */
- if (!data->setup.blocking_io)
- usleep_range(data->nonblocking_wait_time,
- data->nonblocking_wait_time + 1000);
- ret = i2c_master_recv(client, buf, bufsize);
- if (ret != bufsize) {
- dev_err(&client->dev, "failed to read values: %d\n", ret);
- return ret < 0 ? ret : -EIO;
- }
- return 0;
- }
- /* sysfs attributes */
- static struct shtc1_data *shtc1_update_client(struct device *dev)
- {
- struct shtc1_data *data = dev_get_drvdata(dev);
- struct i2c_client *client = data->client;
- unsigned char buf[SHTC1_RESPONSE_LENGTH];
- int val;
- int ret = 0;
- mutex_lock(&data->update_lock);
- if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
- ret = shtc1_update_values(client, data, buf, sizeof(buf));
- if (ret)
- goto out;
- /*
- * From datasheet:
- * T = -45 + 175 * ST / 2^16
- * RH = 100 * SRH / 2^16
- *
- * Adapted for integer fixed point (3 digit) arithmetic.
- */
- val = be16_to_cpup((__be16 *)buf);
- data->temperature = ((21875 * val) >> 13) - 45000;
- val = be16_to_cpup((__be16 *)(buf + 3));
- data->humidity = ((12500 * val) >> 13);
- data->last_updated = jiffies;
- data->valid = true;
- }
- out:
- mutex_unlock(&data->update_lock);
- return ret == 0 ? data : ERR_PTR(ret);
- }
- static ssize_t temp1_input_show(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- struct shtc1_data *data = shtc1_update_client(dev);
- if (IS_ERR(data))
- return PTR_ERR(data);
- return sprintf(buf, "%d\n", data->temperature);
- }
- static ssize_t humidity1_input_show(struct device *dev,
- struct device_attribute *attr, char *buf)
- {
- struct shtc1_data *data = shtc1_update_client(dev);
- if (IS_ERR(data))
- return PTR_ERR(data);
- return sprintf(buf, "%d\n", data->humidity);
- }
- static DEVICE_ATTR_RO(temp1_input);
- static DEVICE_ATTR_RO(humidity1_input);
- static struct attribute *shtc1_attrs[] = {
- &dev_attr_temp1_input.attr,
- &dev_attr_humidity1_input.attr,
- NULL
- };
- ATTRIBUTE_GROUPS(shtc1);
- static void shtc1_select_command(struct shtc1_data *data)
- {
- if (data->setup.high_precision) {
- data->command = data->setup.blocking_io ?
- shtc1_cmd_measure_blocking_hpm :
- shtc1_cmd_measure_nonblocking_hpm;
- data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_HPM;
- } else {
- data->command = data->setup.blocking_io ?
- shtc1_cmd_measure_blocking_lpm :
- shtc1_cmd_measure_nonblocking_lpm;
- data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_LPM;
- }
- }
- static int shtc1_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
- {
- int ret;
- char id_reg[2];
- struct shtc1_data *data;
- struct device *hwmon_dev;
- struct i2c_adapter *adap = client->adapter;
- struct device *dev = &client->dev;
- if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
- dev_err(dev, "plain i2c transactions not supported\n");
- return -ENODEV;
- }
- ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
- if (ret != SHTC1_CMD_LENGTH) {
- dev_err(dev, "could not send read_id_reg command: %d\n", ret);
- return ret < 0 ? ret : -ENODEV;
- }
- ret = i2c_master_recv(client, id_reg, sizeof(id_reg));
- if (ret != sizeof(id_reg)) {
- dev_err(dev, "could not read ID register: %d\n", ret);
- return -ENODEV;
- }
- if ((id_reg[1] & SHTC1_ID_REG_MASK) != SHTC1_ID) {
- dev_err(dev, "ID register doesn't match\n");
- return -ENODEV;
- }
- data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
- data->setup.blocking_io = false;
- data->setup.high_precision = true;
- data->client = client;
- if (client->dev.platform_data)
- data->setup = *(struct shtc1_platform_data *)dev->platform_data;
- shtc1_select_command(data);
- mutex_init(&data->update_lock);
- hwmon_dev = devm_hwmon_device_register_with_groups(dev,
- client->name,
- data,
- shtc1_groups);
- if (IS_ERR(hwmon_dev))
- dev_dbg(dev, "unable to register hwmon device\n");
- return PTR_ERR_OR_ZERO(hwmon_dev);
- }
- /* device ID table */
- static const struct i2c_device_id shtc1_id[] = {
- { "shtc1", 0 },
- { "shtw1", 0 },
- { }
- };
- MODULE_DEVICE_TABLE(i2c, shtc1_id);
- static struct i2c_driver shtc1_i2c_driver = {
- .driver.name = "shtc1",
- .probe = shtc1_probe,
- .id_table = shtc1_id,
- };
- module_i2c_driver(shtc1_i2c_driver);
- MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
- MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
- MODULE_LICENSE("GPL");
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