linux-kernel - [PATCH] hwmon: (sht3x) add support for SHT85

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Message-Id: <20251209175848.5739-1-apokusinski01@gmail.com>
Date: Tue,  9 Dec 2025 18:58:49 +0100
From: Antoni Pokusinski <apokusinski01@...il.com>
To: jdelvare@...e.com,
	linux@...ck-us.net,
	corbet@....net
Cc: linux-hwmon@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Antoni Pokusinski <apokusinski01@...il.com>
Subject: [PATCH] hwmon: (sht3x) add support for SHT85

SHT85 is a temperature and humidity sensor with an interface very
similar to SHT3x. However, it does not feature alerts (and therefore
limits).

Signed-off-by: Antoni Pokusinski <apokusinski01@...il.com>
---
 Documentation/hwmon/sht3x.rst | 11 ++++++++++-
 drivers/hwmon/sht3x.c         | 26 +++++++++++++++++---------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/Documentation/hwmon/sht3x.rst b/Documentation/hwmon/sht3x.rst
index 9585fa7c5a5d..25c7428f0a77 100644
--- a/Documentation/hwmon/sht3x.rst
+++ b/Documentation/hwmon/sht3x.rst
@@ -23,6 +23,15 @@ Supported chips:
         - https://sensirion.com/media/documents/1DA31AFD/61641F76/Sensirion_Temperature_Sensors_STS3x_Datasheet.pdf
         - https://sensirion.com/media/documents/292A335C/65537BAF/Sensirion_Datasheet_STS32_STS33.pdf
 
+  * Sensirion SHT85
+
+    Prefix: 'sht85'
+
+    Addresses scanned: none
+
+    Datasheets:
+        - https://sensirion.com/media/documents/4B40CEF3/640B2346/Sensirion_Humidity_Sensors_SHT85_Datasheet.pdf
+
 Author:
 
   - David Frey <david.frey@...sirion.com>
@@ -31,7 +40,7 @@ Author:
 Description
 -----------
 
-This driver implements support for the Sensirion SHT3x-DIS and STS3x-DIS
+This driver implements support for the Sensirion SHT3x-DIS, STS3x-DIS and SHT85
 series of humidity and temperature sensors. Temperature is measured in degrees
 celsius, relative humidity is expressed as a percentage. In the sysfs interface,
 all values are scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
index f36c0229328f..eff915d31452 100644
--- a/drivers/hwmon/sht3x.c
+++ b/drivers/hwmon/sht3x.c
@@ -63,6 +63,7 @@ static const unsigned char sht3x_cmd_read_serial_number[]      = { 0x37, 0x80 };
 enum sht3x_chips {
 	sht3x,
 	sts3x,
+	sht85,
 };
 
 enum sht3x_limits {
@@ -668,6 +669,8 @@ static umode_t sht3x_is_visible(const void *data, enum hwmon_sensor_types type,
 		}
 		break;
 	case hwmon_temp:
+		if (chip_data->chip_id == sht85 && attr != hwmon_temp_input)
+			break;
 		switch (attr) {
 		case hwmon_temp_input:
 		case hwmon_temp_alarm:
@@ -684,6 +687,8 @@ static umode_t sht3x_is_visible(const void *data, enum hwmon_sensor_types type,
 	case hwmon_humidity:
 		if (chip_data->chip_id == sts3x)
 			break;
+		if (chip_data->chip_id == sht85 && attr != hwmon_humidity_input)
+			break;
 		switch (attr) {
 		case hwmon_humidity_input:
 		case hwmon_humidity_alarm:
@@ -908,16 +913,18 @@ static int sht3x_probe(struct i2c_client *client)
 	mutex_init(&data->i2c_lock);
 	mutex_init(&data->data_lock);
 
-	/*
-	 * An attempt to read limits register too early
-	 * causes a NACK response from the chip.
-	 * Waiting for an empirical delay of 500 us solves the issue.
-	 */
-	usleep_range(500, 600);
+	if (data->chip_id == sht3x || data->chip_id == sts3x) {
+		/*
+		 * An attempt to read limits register too early
+		 * causes a NACK response from the chip.
+		 * Waiting for an empirical delay of 500 us solves the issue.
+		 */
+		usleep_range(500, 600);
 
-	ret = limits_update(data);
-	if (ret)
-		return ret;
+		ret = limits_update(data);
+		if (ret)
+			return ret;
+	}
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
 							 &sht3x_chip_info, sht3x_groups);
@@ -933,6 +940,7 @@ static int sht3x_probe(struct i2c_client *client)
 static const struct i2c_device_id sht3x_ids[] = {
 	{"sht3x", sht3x},
 	{"sts3x", sts3x},
+	{"sht85", sht85},
 	{}
 };
 
-- 
2.25.1