hwmon: (sht3x) Add support for GXCAS GXHT30

This series adds devicetree support to the sht3x driver and support for the GXCAS GXHT30 humidity and temperature sensor, a drop-in replacement for the Sensirion SHT30.

Apologies for the long delay since v6.

Changes in v7:
- Model the higher accuracy parts as compatible with the base part of their group in the binding: SHT31/SHT35/SHT85 and GXHT30 fall back to "sensirion,sht30", STS31/STS32/STS35 fall back to "sensirion,sts30", and explain the grouping in the commit message (Krzysztof).
- Drop the "gxcas,gxht30" of_device_id entry and the "gxht30" i2c_device_id entry: the GXHT30 is handled entirely by the "sensirion,sht30" fallback, with no driver changes (Krzysztof). Patch 4 now only documents the chip in Documentation/hwmon/ sht3x.rst and the Kconfig help text, following how SHT85 support was documented.
- Start enum sht3x_chips at 1 so the OF match data is never NULL and i2c_get_match_data() does not silently fall back to i2c_device_id name matching (reported by Sashiko AI review on v6).
- Mention all optional properties in the binding commit message (Sashiko AI review on v6).
- Rebase onto hwmon-next to account for the conversion of i2c_device_id tables to named initializers.
- Drop the MODULE_AUTHOR addition; authorship is recorded in git.

Changes in v6:
- Drop the trivial-devices.yaml approach from v5; add a dedicated binding and a proper of_device_id table. (Guenter)
- Split into 4 patches: vendor prefix, binding, driver DT support, GXHT30 support.

Changes in v5:
- Move to trivial-devices.yaml and drop of_match_table (wrong approach, reverted in v6).
- Drop wildcards, list specific models.

Changes in v3/v4:
- Standalone YAML binding, split driver changes from binding changes.

Changes in v2:
- Fix placeholder in MODULE_AUTHOR, fix commit message wrapping.

Zaixiang Xu (4):
dt-bindings: vendor-prefixes: Add GXCAS Technology
dt-bindings: hwmon: Add Sensirion SHT30 series
hwmon: (sht3x) Add devicetree support
hwmon: (sht3x) Document support for GXCAS GXHT30

 .../bindings/hwmon/sensirion,sht30.yaml       | 71 +++++++++++++++++++
 .../devicetree/bindings/vendor-prefixes.yaml  |  2 +
 Documentation/hwmon/sht3x.rst                 | 17 ++++-
 drivers/hwmon/Kconfig                         |  5 +-
 drivers/hwmon/sht3x.c                         | 15 +++-
 5 files changed, 103 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/sensirion,sht30.yaml

base-commit: ca078d004cf58137bcf8cb24a8b271397431ba58

2.34.1

Add vendor prefix for Beijing Galaxy-CAS Technology Co., Ltd. (GXCAS). The prefix was confirmed from the manufacturer's website:
https://www.gxcas.com/en/index.html

---
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

index 396044f368e7..6793125d6cc6 100644
@@ -692,6 +692,8 @@ patternProperties:
     description: Gateworks Corporation
                  use "gateworks" vendor prefix
     deprecated: true
+  "^gxcas,.*":
+    description: Beijing Galaxy-CAS Technology Co., Ltd.
   "^hannstar,.*":
     description: HannStar Display Corporation
   "^haochuangyi,.*":

2.34.1

Applied.

Thanks,
Guenter

Add a YAML devicetree binding for the Sensirion SHT3x/STS3x sensor family and the compatible GXCAS GXHT30, with the ALERT interrupt, nRESET GPIO and VDD supply as optional properties.

The SHT30, SHT31, SHT35 and SHT85 measure humidity and temperature and differ only in accuracy and packaging, while the STS30, STS31, STS32 and STS35 are temperature-only parts. Within each group the parts share the same software interface, so model them with a fallback to the base part of their group: "sensirion,sht30" for the SHT parts and "sensirion,sts30" for the STS parts.

The GXCAS GXHT30 is a drop-in replacement for the SHT30 and uses it as fallback as well.

---
 .../bindings/hwmon/sensirion,sht30.yaml       | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/sensirion,sht30.yaml

new file mode 100644
index 000000000000..dee0252941c2
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/sensirion,sht30.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sensirion SHT3x and GXCAS GXHT30 humidity and temperature sensors
+
+maintainers:
+  - Zaixiang Xu <[email protected]>
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - sensirion,sht30
+          - sensirion,sts30
+      - items:
+          - enum:
+              - gxcas,gxht30
+              - sensirion,sht31
+              - sensirion,sht35
+              - sensirion,sht85
+          - const: sensirion,sht30
+      - items:
+          - enum:
+              - sensirion,sts31
+              - sensirion,sts32
+              - sensirion,sts35
+          - const: sensirion,sts30
+
+  reg:
+    maxItems: 1
+
+  vdd-supply:
+    description: Regulator that provides power to the VDD pin.
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the nRESET pin. Active low.
+
+  interrupts:
+    maxItems: 1
+    description:
+      Interrupt connected to the ALERT pin.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        humidity-sensor@44 {
+            compatible = "gxcas,gxht30", "sensirion,sht30";
+            reg = <0x44>;
+            vdd-supply = <&vcc_3v3_reg>;
+            reset-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <16 IRQ_TYPE_LEVEL_HIGH>;
+        };
+    };

2.34.1

[...]

The of_device_id table is added by patch 3/4 of this series ("hwmon: (sht3x) Add devicetree support"), so there is no gap once the series is applied. Within the series the binding intentionally comes first, following the usual convention that dt-bindings changes precede the driver changes that implement them.

The compatibles introduced here did not probe before this series either, so no bisection point regresses.

Thanks,
Zaixiang

Best regards,
Krzysztof

Applied.

Thanks,
Guenter

Add an of_device_id table to support devicetree based instantiation of the supported sensors.

The devicetree binding models all higher accuracy parts with a fallback to the base part of their group, so only the two base compatibles need to be listed. The match data distinguishes the humidity and temperature parts (SHT3x) from the temperature-only parts (STS3x), which require different configuration.

Start enum sht3x_chips at 1: with sht3x equal to 0, the OF match data for the SHT devices would be NULL, causing i2c_get_match_data() to fall back to i2c_device_id name matching, which fails for devicetree names. The devices would then only work because the resulting chip id 0 happens to equal sht3x. Non-zero match data avoids relying on that coincidence.

---
 drivers/hwmon/sht3x.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

index c2f6b73aa7f3..6d47cfd340f8 100644
@@ -61,7 +61,7 @@ static const unsigned char sht3x_cmd_read_serial_number[]      = { 0x37, 0x80 };
 #define SHT3X_MAX_HUMIDITY     100000
 
 enum sht3x_chips {
-	sht3x,
+	sht3x = 1,
 	sts3x,
 };
 

@@ -939,8 +939,19 @@ static const struct i2c_device_id sht3x_ids[] = {
 
 MODULE_DEVICE_TABLE(i2c, sht3x_ids);
 
+static const struct of_device_id sht3x_of_match[] = {
+	{ .compatible = "sensirion,sht30", .data = (void *)(uintptr_t)sht3x },
+	{ .compatible = "sensirion,sts30", .data = (void *)(uintptr_t)sts3x },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, sht3x_of_match);
+
 static struct i2c_driver sht3x_i2c_driver = {
-	.driver.name = "sht3x",
+	.driver = {
+		.name = "sht3x",
+		.of_match_table = sht3x_of_match,
+	},
 	.probe       = sht3x_probe,
 	.id_table    = sht3x_ids,
 };

2.34.1

[...]

Thanks for the report. All five findings are in pre-existing code and are not touched by this series, so I would prefer to keep them separate from the devicetree support here.

I checked the first two: the unaligned access in sht3x_update_client() (buf + 3 is an odd offset into a byte buffer, so it needs get_unaligned_be16()), and the limit_write() overflow (temperature is clamped to 130000, and (130000 + 45000) * 24543 = 4295025000 just exceeds U32_MAX, so writing the maximum limit wraps the raw temperature field to 0). Both look real.

I plan to go through all five and send fixes as a separate series after this one.

Thanks,
Zaixiang

Applied.

Thanks,
Guenter

The GXCAS GXHT30 is a humidity and temperature sensor that is a drop-in replacement for and fully software compatible with the Sensirion SHT30.

It is handled by the "sensirion,sht30" fallback compatible without any driver changes; manual instantiation works with the existing sht3x device name. Document the chip as supported.

---
 Documentation/hwmon/sht3x.rst | 17 ++++++++++++++---
 drivers/hwmon/Kconfig         |  5 +++--
 2 files changed, 17 insertions(+), 5 deletions(-)

index ea1642920295..4f67671eb0cd 100644
@@ -31,6 +31,14 @@ Supported chips:
 
     Datasheet: https://sensirion.com/media/documents/4B40CEF3/640B2346/Sensirion_Humidity_Sensors_SHT85_Datasheet.pdf
 
+  * GXCAS GXHT30
+
+    Prefix: 'sht3x'
+
+    Addresses scanned: none
+
+    Datasheet: https://www.galaxy-cas.com/uploads/files/202509/GXHT30_datasheet_V3.9_20250919170350.pdf
+
 Author:
 
   - David Frey <[email protected]>

@@ -40,9 +48,12 @@ Description
 -----------
 
 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.
+series of humidity and temperature sensors, as well as the compatible GXCAS
+GXHT30. The GXHT30 is a drop-in replacement for the SHT30: instantiate it from
+devicetree with the "gxcas,gxht30", "sensirion,sht30" compatibles, or manually
+using the sht3x device name. 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.
 
 The device communicates with the I2C protocol. SHT3x sensors can have the I2C
 addresses 0x44 or 0x45 (0x4a or 0x4b for sts3x), depending on the wiring. SHT85

index 08c29685126a..64fc00ade5ca 100644
@@ -2023,8 +2023,9 @@ config SENSORS_SHT3x
 	depends on I2C
 	select CRC8
 	help
-	  If you say yes here you get support for the Sensiron SHT30, SHT31 and
-	  SHT85 humidity and temperature sensors.
+	  If you say yes here you get support for the Sensiron SHT30, SHT31,
+	  SHT85 and the compatible GXCAS GXHT30 humidity and temperature
+	  sensors.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called sht3x.

2.34.1

Applied.

Thanks,
Guenter