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.

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 v4:
- Rebase onto v7.3-rc1, which includes the SpacemiT I2C timing prerequisite, and remove the obsolete dependency note.
- Do not add the SENSORS_LM63 THERMAL dependency suggested on v3 because CONFIG_THERMAL is boolean and v7.3-rc1 removes such tautological expressions.
- Preserve the upstream five-bit PWM frequency multiplier mask in the LM63 initialization error-handling path.
- Sort the chip type enum and remove redundant CTF2301 8-bit local temperature cache updates.
- Serialize CTF2301 12-bit local temperature cache reads.
- Keep PWM configuration caches synchronized after partial I2C write failures.
- Override the CoM260 I2C6 pin configuration through &i2c6_1_cfg,
as suggested by Yixun.
- Add Krzysztof's Acked-by and Reviewed-by tags.
- Link to v3: https://patch.msgid.link/[email protected]

Changes in v3:
- Add the Sensylink website link to the vendor-prefix commit.
- Preserve the optional interrupt from the trivial-devices binding.
- Explain in the commit message of patch 3/6 why CTF2301 cannot use national,lm63 as a fallback compatible.
- Check both bytes of CTF2301 local temperature values before caching them.
- Use the schema-valid 25 mA drive strength for the K3 I2C6 pins.
- Link to v2: https://patch.msgid.link/[email protected]

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]>
To: Randy Dunlap <[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   |  55 +++
 .../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        |  17 +
 arch/riscv/boot/dts/spacemit/k3-pinctrl.dtsi       |  11 +
 drivers/hwmon/Kconfig                              |   8 +-
 drivers/hwmon/lm63.c                               | 426 +++++++++++++++++----
 8 files changed, 462 insertions(+), 85 deletions(-)

---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
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 ba2002969373..4a5cf436eb14 100644
@@ -1495,6 +1495,8 @@ 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

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 preserve the optional interrupt used by the ALERT output. Permit use as thermal cooling devices via #cooling-cells.

---
 .../devicetree/bindings/hwmon/national,lm63.yaml   | 53 ++++++++++++++++++++++
 .../devicetree/bindings/trivial-devices.yaml       |  6 ---
 2 files changed, 53 insertions(+), 6 deletions(-)

new file mode 100644
index 000000000000..f2e0993cfbef
@@ -0,0 +1,53 @@
+# 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
+
+  interrupts:
+    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 2de8eb09cb7d..e46912ba2fd6 100644
@@ -368,16 +368,10 @@ properties:
           - mps,mpq82d00
             # 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

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.

Do not provide a national,lm63 fallback because the CTF2301 is not fully compatible with LM63. 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 LM63 driver would therefore not operate the device correctly.

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

index f2e0993cfbef..4c8d0a15fbd1 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

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         | 426 +++++++++++++++++++++++++++++++++++--------
 3 files changed, 377 insertions(+), 79 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 fecff8610ea8..5d87ad3e7a20 100644
@@ -1521,10 +1521,10 @@ 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

This is a bug. TEMP12_TO_REG() currently produces an unaligned 8.8 fixed-point value. The register write discards bits 3:0, while the cache retains them, so an immediate sysfs read can differ from the value read back from the device after the next update.

I will fix this in the next version by quantizing the converted value to the CTF2301's 0.0625 degree C resolution before using it for both the register writes and the cache update.

- Troy

Add the K3 I2C6 pinctrl state used by boards that route I2C6 to pads 7 and 8. Use a 25 mA drive strength, which is supported for both K3 IO voltage domains, and leave board-specific IO voltage selection to board files.

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

index 6482d24be139..cb4f4f4e33af 100644
@@ -101,6 +101,17 @@ i2c2-1-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 = <25>;
+		};
+	};
+
 	/omit-if-no-ref/
 	i2c8_cfg: i2c8-cfg {
 		i2c8-pins {

2.55.0

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

Override the I2C6 pin power source at board level because the IO rail voltage is board-specific.

---
 arch/riscv/boot/dts/spacemit/k3-com260.dtsi | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

index 37627963a649..92dea8639779 100644
@@ -58,6 +58,23 @@ serial-number {
 	};
 };
 
+&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