From 9d613d9b8a9e54cc21379a40de29294adc1e6594 Mon Sep 17 00:00:00 2001 From: Stefan Gloor Date: Wed, 31 Jan 2024 12:15:12 +0100 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20240131111512.25321-2-code@stefan-gloor.ch Signed-off-by: Guenter Roeck --- Documentation/hwmon/sht3x.rst | 11 ++++++ drivers/hwmon/sht3x.c | 66 ++++++++++++++++++++++++++++++++++- 2 files changed, 76 insertions(+), 1 deletion(-) diff --git a/Documentation/hwmon/sht3x.rst b/Documentation/hwmon/sht3x.rst index 957c854f5d08..9585fa7c5a5d 100644 --- a/Documentation/hwmon/sht3x.rst +++ b/Documentation/hwmon/sht3x.rst @@ -65,6 +65,10 @@ When the temperature and humidity readings move back between the hysteresis values, the alert bit is set to 0 and the alert pin on the sensor is set to low. +The serial number exposed to debugfs allows for unique identification of the +sensors. For sts32, sts33 and sht33, the manufacturer provides calibration +certificates through an API. + sysfs-Interface --------------- @@ -99,3 +103,10 @@ repeatability: write or read repeatability, higher repeatability means - 1: medium repeatability - 2: high repeatability =================== ============================================================ + +debugfs-Interface +----------------- + +=================== ============================================================ +serial_number: unique serial number of the sensor in decimal +=================== ============================================================ diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c index 79657910b79e..c0d02fbcdb76 100644 --- a/drivers/hwmon/sht3x.c +++ b/drivers/hwmon/sht3x.c @@ -10,6 +10,7 @@ #include #include +#include #include #include #include @@ -41,6 +42,9 @@ static const unsigned char sht3x_cmd_heater_off[] = { 0x30, 0x66 }; /* other commands */ static const unsigned char sht3x_cmd_read_status_reg[] = { 0xf3, 0x2d }; static const unsigned char sht3x_cmd_clear_status_reg[] = { 0x30, 0x41 }; +static const unsigned char sht3x_cmd_read_serial_number[] = { 0x37, 0x80 }; + +static struct dentry *debugfs; /* delays for single-shot mode i2c commands, both in us */ #define SHT3X_SINGLE_WAIT_TIME_HPM 15000 @@ -163,12 +167,14 @@ struct sht3x_data { enum sht3x_chips chip_id; struct mutex i2c_lock; /* lock for sending i2c commands */ struct mutex data_lock; /* lock for updating driver data */ + struct dentry *sensor_dir; u8 mode; const unsigned char *command; u32 wait_time; /* in us*/ unsigned long last_update; /* last update in periodic mode*/ enum sht3x_repeatability repeatability; + u32 serial_number; /* * cached values for temperature and humidity and limits @@ -831,6 +837,40 @@ static int sht3x_write(struct device *dev, enum hwmon_sensor_types type, } } +static void sht3x_debugfs_init(struct sht3x_data *data) +{ + char name[32]; + + snprintf(name, sizeof(name), "i2c%u-%02x", + data->client->adapter->nr, data->client->addr); + data->sensor_dir = debugfs_create_dir(name, debugfs); + debugfs_create_u32("serial_number", 0444, + data->sensor_dir, &data->serial_number); +} + +static void sht3x_debugfs_remove(void *sensor_dir) +{ + debugfs_remove_recursive(sensor_dir); +} + +static int sht3x_serial_number_read(struct sht3x_data *data) +{ + int ret; + char buffer[SHT3X_RESPONSE_LENGTH]; + struct i2c_client *client = data->client; + + ret = sht3x_read_from_command(client, data, + sht3x_cmd_read_serial_number, + buffer, + SHT3X_RESPONSE_LENGTH, 0); + if (ret) + return ret; + + data->serial_number = (buffer[0] << 24) | (buffer[1] << 16) | + (buffer[3] << 8) | buffer[4]; + return ret; +} + static const struct hwmon_ops sht3x_ops = { .is_visible = sht3x_is_visible, .read = sht3x_read, @@ -899,6 +939,18 @@ static int sht3x_probe(struct i2c_client *client) if (ret) return ret; + ret = sht3x_serial_number_read(data); + if (ret) { + dev_dbg(dev, "unable to read serial number\n"); + } else { + sht3x_debugfs_init(data); + ret = devm_add_action_or_reset(dev, + sht3x_debugfs_remove, + data->sensor_dir); + if (ret) + return ret; + } + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data, @@ -917,7 +969,19 @@ static struct i2c_driver sht3x_i2c_driver = { .id_table = sht3x_ids, }; -module_i2c_driver(sht3x_i2c_driver); +static int __init sht3x_init(void) +{ + debugfs = debugfs_create_dir("sht3x", NULL); + return i2c_add_driver(&sht3x_i2c_driver); +} +module_init(sht3x_init); + +static void __exit sht3x_cleanup(void) +{ + debugfs_remove_recursive(debugfs); + i2c_del_driver(&sht3x_i2c_driver); +} +module_exit(sht3x_cleanup); MODULE_AUTHOR("David Frey "); MODULE_AUTHOR("Pascal Sachs ");