242 lines
6.4 KiB
C
242 lines
6.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* Sensirion SHTC1 humidity and temperature sensor driver
|
|
*
|
|
* Copyright (C) 2014 Sensirion AG, Switzerland
|
|
* Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
|
|
*/
|
|
|
|
#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");
|