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@xxxxxxxxxxxxxxx>
---
Documentation/hwmon/sht3x.rst | 11 +++++++
drivers/hwmon/sht3x.c | 55 +++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
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..537365c6213b 100644
--- a/drivers/hwmon/sht3x.c
+++ b/drivers/hwmon/sht3x.c
@@ -10,6 +10,7 @@
#include <asm/page.h>
#include <linux/crc8.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/hwmon.h>
@@ -41,6 +42,7 @@ 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 };
/* delays for single-shot mode i2c commands, both in us */
#define SHT3X_SINGLE_WAIT_TIME_HPM 15000
@@ -163,12 +165,14 @@ 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 *debugfs;
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 +835,50 @@ static int sht3x_write(struct device *dev, enum hwmon_sensor_types type,
}
}
+#ifdef CONFIG_DEBUG_FS
+
+static void sht3x_debugfs_init(struct sht3x_data *data)
+{
+ char name[32];
+ struct dentry *sensor_dir;
+
+ data->debugfs = debugfs_lookup("sht3x", NULL);
+ if (IS_ERR_OR_NULL(data->debugfs))
+ data->debugfs = debugfs_create_dir("sht3x", NULL);
+
+ snprintf(name, sizeof(name), "i2c%u-%02x",
+ data->client->adapter->nr, data->client->addr);
+ sensor_dir = debugfs_create_dir(name, data->debugfs);
+ debugfs_create_u32("serial_number", 0444,
+ sensor_dir, &data->serial_number);
+}
+
+#else
+
+static void sht3x_debugfs_init(struct sht3x_data *data)
+{
+}
+
+#endif
+
+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 +947,13 @@ 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");
+ data->serial_number = 0;
+ }
+ sht3x_debugfs_init(data);
+
hwmon_dev = devm_hwmon_device_register_with_info(dev,
client->name,
data,
--
2.41.0
