shtc1.rar_SHTC1_Sensirion SHTC1

/* 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");