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Message-ID: <20240131111512.25321-2-code@stefan-gloor.ch>
Date: Wed, 31 Jan 2024 12:15:12 +0100
From: Stefan Gloor <code@...fan-gloor.ch>
To: jdelvare@...e.com,
linux@...ck-us.net,
corbet@....net,
linux-hwmon@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Stefan Gloor <code@...fan-gloor.ch>
Subject: [PATCH v4 1/1] 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@...fan-gloor.ch>
---
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 <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 +42,9 @@ 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 <david.frey@...sirion.com>");
MODULE_AUTHOR("Pascal Sachs <pascal.sachs@...sirion.com>");
--
2.41.0
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