hwmon: (lm63) Add Sensylink CTF2301 support

Sensylink CTF2301 is a system-level thermal management solution chip.

The CTF2301 is an I2C/SMBus compatible device featuring:
- One local temperature sensor with +/-0.5 degree C accuracy and

    0.0625 degree C resolution.

- One remote temperature sensor for external diode-connected transistors, offering +/-1 degree C accuracy and 0.125 degree C resolution (temperature range: -40 degree C to +125 degree C).
- An integrated PWM fan controller capable of operating in two modes:
1. Direct-DCY: Open-loop direct duty cycle control.
2. Auto-Temp: Closed-loop automatic fan speed control based on measured temperature.
- A 1-channel fan speed monitor (TACH input) for RPM measurement.

As Guenter pointed out on v1, the CTF2301 register map is a near match for the LM63/LM96163 family (local and remote temperature, tachometer and PWM fan control), so this version drops the standalone ctf2301 driver and instead adds CTF2301 as a new chip type in the existing lm63 driver. This reuses the shared temperature, limit, alarm and PWM handling instead of duplicating it.

The CTF2301-specific differences are handled on top of lm63: 12-bit local temperature input and high-limit values, nine conversion rates, 12 fan-control lookup table entries, and optional 22.5 kHz high-resolution PWM. When no IRQ is described, the shared ALERT/TACH pin is configured as a tachometer input. The LM63 family can also register as a thermal cooling device when the device tree provides the #cooling-cells property.

The required SpacemiT I2C controller clock series has been merged but is not yet included in an rc release:
https://lore.kernel.org/all/[email protected]/

Apply that series before testing this series on K3. Without it, the I2C controller cannot generate an accurate 400 kHz SCL clock and CTF2301 accesses may fail.

Tested on a SpacemiT K3 CoM260 by booting an initramfs and verifying the CTF2301 probe. Temperature, tachometer, PWM, and conversion-rate behavior were checked against direct I2C register accesses and the datasheet.

Datasheet:
https://www.sensylink.com/upload/1/net.sensylink.portal/1689557281035.pdf

Register description:
https://github.com/TroyMitchell911/ctf2301-datasheet

---
Changes in v2:
- Replace the standalone CTF2301 driver with a new lm63 chip type, as suggested by Guenter, reusing the existing temperature, limit, alarm, tachometer, PWM, and automatic fan-control paths.
- Add the temperature thresholds, alarms, and automatic fan-control lookup table support which were missing from the v1 driver.
- Handle CTF2301-specific 12-bit local temperature values, nine conversion rates, 12 lookup table entries, shared ALERT/TACH pin, and optional 22.5 kHz high-resolution PWM.
- Propagate SMBus failures from lm63 initialization and write paths.
- Add optional thermal cooling-device support for the LM63 family using the existing manual PWM control path.
- Move the National LM63-family compatibles from trivial-devices.yaml to a dedicated binding which permits #cooling-cells.
- Add CTF2301 to the LM63-family binding instead of keeping the standalone schema from v1. Do not declare #cooling-cells on K3 CoM260 yet because the board has no thermal consumer.
- Fix the binding errors reported by Rob by using a plain compatible string and wrapping the description.
- Document CTF2301 support in the lm63 hwmon documentation and provide the detailed register description used for review.
- Add the K3 CoM260 I2C6 pinctrl state and CTF2301 device node for hardware testing.
- Link to v1: https://lore.kernel.org/r/[email protected]

To: Rob Herring <[email protected]>
To: Krzysztof Kozlowski <[email protected]>
To: Conor Dooley <[email protected]>
To: Guenter Roeck <[email protected]>
To: Paul Walmsley <[email protected]>
To: Palmer Dabbelt <[email protected]>
To: Albert Ou <[email protected]>
To: Alexandre Ghiti <[email protected]>
To: Yixun Lan <[email protected]>
To: Jonathan Corbet <[email protected]>
To: Shuah Khan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

---
Troy Mitchell (6):
dt-bindings: vendor-prefixes: Add Sensylink
dt-bindings: hwmon: Move LM63 family to a dedicated binding
dt-bindings: hwmon: Add Sensylink CTF2301
hwmon: (lm63) Add Sensylink CTF2301 support
riscv: dts: spacemit: Add K3 I2C6 pinctrl state
riscv: dts: spacemit: Add CTF2301 on K3 CoM260

 .../devicetree/bindings/hwmon/national,lm63.yaml   |  52 +++
 .../devicetree/bindings/trivial-devices.yaml       |   6 -
 .../devicetree/bindings/vendor-prefixes.yaml       |   2 +
 Documentation/hwmon/lm63.rst                       |  22 ++
 arch/riscv/boot/dts/spacemit/k3-com260.dtsi        |  19 +
 arch/riscv/boot/dts/spacemit/k3-pinctrl.dtsi       |  11 +
 drivers/hwmon/Kconfig                              |   8 +-
 drivers/hwmon/lm63.c                               | 393 +++++++++++++++++----
 8 files changed, 433 insertions(+), 80 deletions(-)

---
base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
change-id: 20250916-ctl2301-0416b073c280

Best regards,

Troy Mitchell <[email protected]>

Add the vendor prefix for Sensylink Microelectronics.

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

index 396044f368e7..22d0d26f1bbd 100644
@@ -1467,6 +1467,8 @@ patternProperties:
     description: Sensirion AG
   "^sensortek,.*":
     description: Sensortek Technology Corporation
+  "^sensylink,.*":
+    description: Sensylink Microelectronics Technology Co., Ltd.
   "^sercomm,.*":
     description: Sercomm (Suzhou) Corporation
   "^sff,.*":

2.55.0

Asking Google search: "Why the two names ? Did they rename themselves at some point ?"

Response:

Understanding the Name Structure

1. English Legal Name vs. Marketing Abbreviation

Sensylink Microelectronics Technology Co., Ltd.:
This is the literal translation of their full, formal registered corporate name used for international trade, customs, and legal documentation.

Sensylink Microelectronics Inc.:
This is a simplified, Westernized abbreviation used on their official English website and marketing materials for cleaner global branding.

2. The Native Chinese Name

上海申矽凌微电子科技股份有限公司 (Shanghai Shenxiling Microelectronics Technology Co., Ltd.): This is the company's sole, official legal name registered with the Chinese government.

"Sensylink" is a portmanteau created specifically for international markets, blending "Sensing" (their core technology) and "Link" (their interface and connectivity products).

Prodding further, asking if the previous response was complete, it tells me that there was a name change:

According to Chinese corporate registry data (via Tianyancha and Qcc), they did change their official Chinese legal name:

Old Name: 上海申矽凌微电子科技有限公司 (Shanghai Sensylink Microelectronics Technology Co., Ltd.)

New Name: 上海申矽凌微电子科技股份有限公司 (Shanghai Sensylink Microelectronics Technology Co., Ltd. by Shares / Joint-Stock Company)

I don't know if Linux has a policy about Legal vs. Marketing names. Personally I don't have an opinion. Your call, really.

Guenter

The google search "AI" response was what showed me the different name, sounds like I should have questioned it some more!

I don't know what the policy is, or if there is one, but personally I wouldn't use the westernised abbreviation since they may decide to rebrand that etc and the vendor prefix information should remain static.

So this is probably fine as-is, just I'd like to see that link added to their website.

Thanks (and thanks for doing the extra digging),
Conor.

Part of that extra digging nowadays is to ask it if its initial response is real or if it was hallucinated. Sadly enough, most of the time it will admit that at least part of the initial response does not match reality. That was the case here as well, because it initially did claim that the company never changed their name (of course, the next question to ask would be if it really changed its name or if that was another hallucination ;-).

Guenter

Understood. I will keep the current vendor name and add the following link to the commit message in the next version:

- Troy

Move the National Semiconductor LM63, LM64, and LM96163 compatibles out of trivial-devices.yaml and into a dedicated binding. Describe their integrated fan control and permit use as thermal cooling devices through the #cooling-cells property.

---
 .../devicetree/bindings/hwmon/national,lm63.yaml   | 50 ++++++++++++++++++++++
 .../devicetree/bindings/trivial-devices.yaml       |  6 ---
 2 files changed, 50 insertions(+), 6 deletions(-)

new file mode 100644
index 000000000000..92b0094ff303
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/national,lm63.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LM63-compatible temperature sensors with integrated fan control
+
+maintainers:
+  - Guenter Roeck <[email protected]>
+
+description: |
+  The LM63 family provides local and remote temperature monitoring together
+  with fan speed monitoring and PWM fan control. Supported devices include
+  the National Semiconductor LM63, LM64 and LM96163.
+
+allOf:
+  - $ref: hwmon-common.yaml#
+
+properties:
+  compatible:
+    enum:
+      - national,lm63
+      - national,lm64
+      - national,lm96163
+
+  reg:
+    maxItems: 1
+
+  "#cooling-cells":
+    const: 2
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        temperature-sensor@4c {
+            compatible = "national,lm63";
+            reg = <0x4c>;
+            #cooling-cells = <2>;
+        };
+    };

index 435c4baab436..aa62d245464c 100644
@@ -364,16 +364,10 @@ properties:
           - mps,mp9945
             # Murata D1U74T-W power supply unit
           - murata,d1u74t
-            # Temperature sensor with integrated fan control
-          - national,lm63
-            # Temperature sensor with integrated fan control
-          - national,lm64
             # Temperature sensor
           - national,lm95235
             # Temperature sensor
           - national,lm95245
-            # Temperature sensor with integrated fan control
-          - national,lm96163
             # Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor
           - national,lm80
             # Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor

2.55.0

Good catch. The trivial-devices binding allowed one interrupt, and the LM63 family has an ALERT output. I will preserve that part of the existing binding contract by adding the following to the dedicated binding:

interrupts:
maxItems: 1

- Troy

Add the Sensylink CTF2301 temperature sensor and fan controller to the LM63 family binding. The chip follows the LM63 register model and can provide a thermal cooling device when #cooling-cells is present.

---
 Documentation/devicetree/bindings/hwmon/national,lm63.yaml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 92b0094ff303..4a1ffebfdbef 100644
@@ -12,7 +12,8 @@ maintainers:
 description: |
   The LM63 family provides local and remote temperature monitoring together
   with fan speed monitoring and PWM fan control. Supported devices include
-  the National Semiconductor LM63, LM64 and LM96163.
+  the National Semiconductor LM63, LM64 and LM96163, and the Sensylink
+  CTF2301.
 
 allOf:
   - $ref: hwmon-common.yaml#

@@ -23,6 +24,7 @@ properties:
       - national,lm63
       - national,lm64
       - national,lm96163
+      - sensylink,ctf2301
 
   reg:
     maxItems: 1

2.55.0

Commit message should explain why a fallback compatible is not suitable.

pw-bot: changes-requested

Thanks,
Conor.

The CTF2301 shares the overall register layout with LM63, but it is not fully compatible. In particular, it uses different conversion-rate encodings, extended local-temperature registers, additional fan lookup table entries, and device-specific PWM and ALERT/TACH configuration. An older driver matching the "national,lm63" fallback would therefore not operate the device correctly.

I will explain why a fallback compatible is not suitable in the commit message in the next version.

- Troy

The CTF2301 shares the overall register layout with LM63, but it is not fully compatible. In particular, it uses different conversion-rate encodings, extended local-temperature registers, additional fan lookup table entries, and device-specific PWM and ALERT/TACH configuration. An older driver matching the "national,lm63" fallback would therefore not operate the device correctly.

I will explain why a fallback compatible is not suitable in the commit message in the next version.

- Troy

Add Sensylink CTF2301 support to the LM63 driver. CTF2301 follows the LM63-style temperature, tachometer, and PWM register layout, while using a 12-bit local temperature register and requiring the ALERT/TACH pin to be configured for tachometer input.

Register an optional thermal cooling device when the device tree node provides #cooling-cells, allowing thermal zones to control the fan through the existing PWM path without changing behavior for existing LM63-family users.

---
 Documentation/hwmon/lm63.rst |  22 +++
 drivers/hwmon/Kconfig        |   8 +-
 drivers/hwmon/lm63.c         | 393 +++++++++++++++++++++++++++++++++++--------
 3 files changed, 349 insertions(+), 74 deletions(-)

index 9e27367d7405..c40bd0dfe591 100644
@@ -33,6 +33,16 @@ Supported chips:
 
 	       http://www.national.com/pf/LM/LM96163.html
 
+  * Sensylink CTF2301
+
+    Prefix: 'ctf2301'
+
+    Addresses scanned: none
+
+    Datasheet: https://www.sensylink.com/upload/1/net.sensylink.portal/1689557281035.pdf
+
+    Register description: https://github.com/TroyMitchell911/ctf2301-datasheet
+
 
 Author: Jean Delvare <[email protected]>
 

@@ -62,6 +72,8 @@ value have to be masked out. The value is still 16 bit in width.
 
 All temperature values are given in degrees Celsius. Resolution is 1.0
 degree for the local temperature, 0.125 degree for the remote temperature.
+The CTF2301 local temperature input and limit have a resolution of 0.0625
+degree.
 
 The fan speed is measured using a tachometer. Contrary to most chips which
 store the value in an 8-bit register and have a selectable clock divider

@@ -93,3 +105,13 @@ support these GPIO lines at present.
 The LM96163 is an enhanced version of LM63 with improved temperature accuracy
 and better PWM resolution. For LM96163, the external temperature sensor type is
 configurable as CPU embedded diode(1) or 3904 transistor(2).
+
+The CTF2301 is register-compatible with the LM63 family and provides 12 fan
+control lookup table entries. It supports 8-bit PWM resolution when configured
+for a 22.5 kHz PWM frequency.
+
+Device tree nodes may declare ``#cooling-cells`` to register the fan controller
+with the thermal framework. The cooling state is mapped to the existing
+``pwm1`` range from 0 to 255. The driver keeps the current automatic or manual
+fan control mode during probe and switches to manual control when the thermal
+framework first requests a cooling state.

index 2bfbcc033d59..abb1af8664fb 100644
@@ -1501,10 +1501,10 @@ config SENSORS_LM63
 	depends on I2C
 	help
 	  If you say yes here you get support for the National
-	  Semiconductor LM63, LM64, and LM96163 remote diode digital temperature
-	  sensors with integrated fan control.  Such chips are found
-	  on the Tyan S4882 (Thunder K8QS Pro) motherboard, among
-	  others.
+	  Semiconductor LM63, LM64, LM96163, and Sensylink CTF2301
+	  remote diode digital temperature sensors with integrated fan
+	  control. Such chips are found on the Tyan S4882 (Thunder K8QS
+	  Pro) motherboard, among others.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called lm63.

2.55.0

Good catch. A failed read must not be combined with the other temperature byte. I will read both bytes into temporary integers, check both return values, and update the cached 12-bit value only after both reads succeed.

The existing lm63_update_device() also truncates or combines unchecked i2c_smbus_read_byte_data() results in several other paths. I will address those existing error-handling issues in a separate patch, rather than mix that broader change into the CTF2301 support patch.

- Troy

Add the K3 I2C6 pinctrl state used by boards that route I2C6 to pads 7 and 8. Leave board-specific IO voltage selection to board files.

---
 arch/riscv/boot/dts/spacemit/k3-pinctrl.dtsi | 11 +++++++++++
 1 file changed, 11 insertions(+)

index 3ee1471f3798..91cd08099e27 100644
@@ -78,6 +78,17 @@ gmac1-phy-0-pins {
 		};
 	};
 
+	/omit-if-no-ref/
+	i2c6_1_cfg: i2c6-1-cfg {
+		i2c6-1-pins {
+			pinmux = <K3_PADCONF(7, 6)>,	/* i2c6 scl */
+				 <K3_PADCONF(8, 6)>;	/* i2c6 sda */
+
+			bias-pull-up = <0>;
+			drive-strength = <18>;
+		};
+	};
+
 	/omit-if-no-ref/
 	i2c8_cfg: i2c8-cfg {
 		i2c8-pins {

2.55.0

Good catch. This pin group uses the 3.3 V power domain, for which 18 mA is not a valid K3 drive-strength value. The driver rounds that request up to 25 mA, so I will use 25 mA in the devicetree to describe the configuration that is actually programmed and to satisfy the binding.

- Troy

Enable I2C6 on the K3 CoM260 module and describe the Sensylink CTF2301 temperature sensor and fan controller at address 0x4c.

Set the I2C6 pin power source in the board-level pinctrl node because the IO rail voltage is board-specific.

---
 arch/riscv/boot/dts/spacemit/k3-com260.dtsi | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

index a38d7b738258..95a60fbb411f 100644
@@ -26,6 +26,25 @@ reg_5v_sys: regulator-5v-sys {
 	};
 };
 
+&pinctrl {
+	i2c6-1-cfg {
+		i2c6-1-pins {
+			power-source = <3300>;
+		};
+	};
+};
+
+&i2c6 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&i2c6_1_cfg>;
+	status = "okay";
+
+	temperature-sensor@4c {
+		compatible = "sensylink,ctf2301";
+		reg = <0x4c>;
+	};
+};
+
 &i2c8 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c8_cfg>;

2.55.0