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hwmon: (sht3x) read out sensor serial number
The temperature/humidity sensors of the STS3x/SHT3x family are calibrated and factory-programmed with a unique serial number. For some sensors, this serial number can be used to obtain a calibration certificate via an API provided by the manufacturer (Sensirion). Expose the serial number via debugfs. Tested with: 2x STS31, 1x STS32, 1x SHT31 Signed-off-by: Stefan Gloor <code@stefan-gloor.ch> Link: https://lore.kernel.org/r/20240131111512.25321-2-code@stefan-gloor.ch Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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@ -65,6 +65,10 @@ When the temperature and humidity readings move back between the hysteresis
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values, the alert bit is set to 0 and the alert pin on the sensor is set to
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low.
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The serial number exposed to debugfs allows for unique identification of the
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sensors. For sts32, sts33 and sht33, the manufacturer provides calibration
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certificates through an API.
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sysfs-Interface
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---------------
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@ -99,3 +103,10 @@ repeatability: write or read repeatability, higher repeatability means
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- 1: medium repeatability
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- 2: high repeatability
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=================== ============================================================
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debugfs-Interface
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-----------------
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=================== ============================================================
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serial_number: unique serial number of the sensor in decimal
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=================== ============================================================
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@ -10,6 +10,7 @@
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#include <asm/page.h>
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#include <linux/crc8.h>
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#include <linux/debugfs.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/hwmon.h>
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@ -41,6 +42,9 @@ static const unsigned char sht3x_cmd_heater_off[] = { 0x30, 0x66 };
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/* other commands */
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static const unsigned char sht3x_cmd_read_status_reg[] = { 0xf3, 0x2d };
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static const unsigned char sht3x_cmd_clear_status_reg[] = { 0x30, 0x41 };
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static const unsigned char sht3x_cmd_read_serial_number[] = { 0x37, 0x80 };
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static struct dentry *debugfs;
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/* delays for single-shot mode i2c commands, both in us */
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#define SHT3X_SINGLE_WAIT_TIME_HPM 15000
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@ -163,12 +167,14 @@ struct sht3x_data {
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enum sht3x_chips chip_id;
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struct mutex i2c_lock; /* lock for sending i2c commands */
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struct mutex data_lock; /* lock for updating driver data */
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struct dentry *sensor_dir;
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u8 mode;
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const unsigned char *command;
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u32 wait_time; /* in us*/
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unsigned long last_update; /* last update in periodic mode*/
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enum sht3x_repeatability repeatability;
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u32 serial_number;
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/*
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* cached values for temperature and humidity and limits
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@ -831,6 +837,40 @@ static int sht3x_write(struct device *dev, enum hwmon_sensor_types type,
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}
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}
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static void sht3x_debugfs_init(struct sht3x_data *data)
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{
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char name[32];
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snprintf(name, sizeof(name), "i2c%u-%02x",
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data->client->adapter->nr, data->client->addr);
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data->sensor_dir = debugfs_create_dir(name, debugfs);
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debugfs_create_u32("serial_number", 0444,
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data->sensor_dir, &data->serial_number);
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}
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static void sht3x_debugfs_remove(void *sensor_dir)
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{
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debugfs_remove_recursive(sensor_dir);
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}
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static int sht3x_serial_number_read(struct sht3x_data *data)
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{
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int ret;
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char buffer[SHT3X_RESPONSE_LENGTH];
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struct i2c_client *client = data->client;
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ret = sht3x_read_from_command(client, data,
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sht3x_cmd_read_serial_number,
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buffer,
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SHT3X_RESPONSE_LENGTH, 0);
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if (ret)
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return ret;
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data->serial_number = (buffer[0] << 24) | (buffer[1] << 16) |
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(buffer[3] << 8) | buffer[4];
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return ret;
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}
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static const struct hwmon_ops sht3x_ops = {
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.is_visible = sht3x_is_visible,
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.read = sht3x_read,
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@ -899,6 +939,18 @@ static int sht3x_probe(struct i2c_client *client)
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if (ret)
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return ret;
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ret = sht3x_serial_number_read(data);
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if (ret) {
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dev_dbg(dev, "unable to read serial number\n");
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} else {
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sht3x_debugfs_init(data);
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ret = devm_add_action_or_reset(dev,
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sht3x_debugfs_remove,
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data->sensor_dir);
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if (ret)
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return ret;
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}
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hwmon_dev = devm_hwmon_device_register_with_info(dev,
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client->name,
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data,
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@ -917,7 +969,19 @@ static struct i2c_driver sht3x_i2c_driver = {
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.id_table = sht3x_ids,
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};
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module_i2c_driver(sht3x_i2c_driver);
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static int __init sht3x_init(void)
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{
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debugfs = debugfs_create_dir("sht3x", NULL);
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return i2c_add_driver(&sht3x_i2c_driver);
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}
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module_init(sht3x_init);
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static void __exit sht3x_cleanup(void)
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{
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debugfs_remove_recursive(debugfs);
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i2c_del_driver(&sht3x_i2c_driver);
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}
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module_exit(sht3x_cleanup);
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MODULE_AUTHOR("David Frey <david.frey@sensirion.com>");
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MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
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