kernel: backport adt7470 PWM/thermal support from v7.3

Backport a series of upstream patches for the adt7470 hwmon driver,
accepted for kernel v7.3. It exposes the fan control lines via the
generic PWM framework and thermal zone sensors.

Instead of relying on userland scripts, the kernel can now control
the fan speed directly through standard cooling maps and PWM fans
configured in the DTS. Currently in the tree, only edgecore_ecs4100-12ph
seems to use this chip.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Link: openwrt#24803
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

Author: luizluca

target/linux/bcm27xx/patches-6.18/0310-hwmon-Add-RP1-ADC-and-temperature-driver.patch

@@ -21,7 +21,7 @@ Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
 
 --- a/drivers/hwmon/Kconfig
 +++ b/drivers/hwmon/Kconfig
-@@ -2663,6 +2663,13 @@ config SENSORS_INTEL_M10_BMC_HWMON
+@@ -2664,6 +2664,13 @@ config SENSORS_INTEL_M10_BMC_HWMON
  	  sensors monitor various telemetry data of different components on the
  	  card, e.g. board temperature, FPGA core temperature/voltage/current.
 

target/linux/generic/backport-6.18/851-01-v7.3-dt-bindings-hwmon-add-adi-adt7470.patch

@@ -0,0 +1,84 @@
+From 9f446d82bdbcea89c2795a8a6ce7a7c2cac02129 Mon Sep 17 00:00:00 2001
+From: Luiz Angelo Daros de Luca <luizluca@gmail.com>
+Date: Wed, 5 Aug 2026 10:15:17 -0300
+Subject: [PATCH 1/4] dt-bindings: hwmon: add adi,adt7470
+
+The Analog Devices ADT7470 is a multichannel temperature sensor and
+PWM fan controller. It supports monitoring up to 10 external
+temperature sensors and controlling up to 4 fans.
+
+Add the device tree binding documentation for it. This includes
+support for the thermal framework by defining the "#thermal-sensor-cells"
+property, and models the fan control lines as PWM channels by
+defining the "#pwm-cells" property.
+
+Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
+Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
+Link: https://lore.kernel.org/r/20260805-adt7470_thermalzone-v6-1-5605a5f95467@gmail.com
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+---
+ .../bindings/hwmon/adi,adt7470.yaml           | 58 +++++++++++++++++++
+ 1 file changed, 58 insertions(+)
+ create mode 100644 Documentation/devicetree/bindings/hwmon/adi,adt7470.yaml
+
+--- /dev/null
++++ b/Documentation/devicetree/bindings/hwmon/adi,adt7470.yaml
+@@ -0,0 +1,58 @@
++# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
++%YAML 1.2
++---
++$id: http://devicetree.org/schemas/hwmon/adi,adt7470.yaml#
++$schema: http://devicetree.org/meta-schemas/core.yaml#
++
++title: Analog Devices ADT7470 hwmon sensor
++
++maintainers:
++  - Luiz Angelo Daros de Luca <luizluca@gmail.com>
++
++description:
++  Multi-channel temperature monitor and PWM fan controller.
++  It supports monitoring up to 10 external temperature sensors and
++  controlling up to 4 fans. The fan control lines are modeled
++  as standard PWM channels.
++
++properties:
++  compatible:
++    const: adi,adt7470
++
++  reg:
++    maxItems: 1
++
++  "#pwm-cells":
++    const: 3
++
++  "#thermal-sensor-cells":
++    const: 1
++    description:
++      Valid index values are 0 to 9, corresponding to temp1 through temp10.
++
++required:
++  - compatible
++  - reg
++
++allOf:
++  - if:
++      required:
++        - "#thermal-sensor-cells"
++    then:
++      $ref: /schemas/thermal/thermal-sensor.yaml#
++
++unevaluatedProperties: false
++
++examples:
++  - |
++    i2c {
++        #address-cells = <1>;
++        #size-cells = <0>;
++
++        hwmon@2f {
++            compatible = "adi,adt7470";
++            reg = <0x2f>;
++            #pwm-cells = <3>;
++            #thermal-sensor-cells = <1>;
++        };
++    };

target/linux/generic/backport-6.18/851-02-v7.3-hwmon-adt7470-Add-ADT7470_PWM_MAX-macro.patch

@@ -0,0 +1,51 @@
+From bdec2083b9d8a4a29b717686e573e7113f8d9470 Mon Sep 17 00:00:00 2001
+From: Luiz Angelo Daros de Luca <luizluca@gmail.com>
+Date: Wed, 5 Aug 2026 10:15:18 -0300
+Subject: [PATCH 2/4] hwmon: (adt7470) Add ADT7470_PWM_MAX macro
+
+Instead of a magic 255, use a macro to refer to it.
+
+Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
+Link: https://lore.kernel.org/r/20260805-adt7470_thermalzone-v6-2-5605a5f95467@gmail.com
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+---
+ drivers/hwmon/adt7470.c | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+--- a/drivers/hwmon/adt7470.c
++++ b/drivers/hwmon/adt7470.c
+@@ -100,6 +100,7 @@ static const unsigned short normal_i2c[]
+ #define ADT7470_REG_FAN_MAX(x)	(ADT7470_REG_FAN_MAX_BASE_ADDR + ((x) * 2))
+ 
+ #define ADT7470_PWM_COUNT	4
++#define ADT7470_PWM_MAX		255
+ #define ADT7470_REG_PWM(x)	(ADT7470_REG_PWM_BASE_ADDR + (x))
+ #define ADT7470_REG_PWM_MAX(x)	(ADT7470_REG_PWM_MAX_BASE_ADDR + (x))
+ #define ADT7470_REG_PWM_MIN(x)	(ADT7470_REG_PWM_MIN_BASE_ADDR + (x))
+@@ -850,7 +851,7 @@ static int adt7470_pwm_write(struct devi
+ 
+ 	switch (attr) {
+ 	case hwmon_pwm_input:
+-		val = clamp_val(val, 0, 255);
++		val = clamp_val(val, 0, ADT7470_PWM_MAX);
+ 		mutex_lock(&data->lock);
+ 		err = regmap_write(data->regmap, ADT7470_REG_PWM(channel),
+ 				   val);
+@@ -910,7 +911,7 @@ static ssize_t pwm_max_store(struct devi
+ 	if (kstrtol(buf, 10, &temp))
+ 		return -EINVAL;
+ 
+-	temp = clamp_val(temp, 0, 255);
++	temp = clamp_val(temp, 0, ADT7470_PWM_MAX);
+ 
+ 	mutex_lock(&data->lock);
+ 	data->pwm_max[attr->index] = temp;
+@@ -945,7 +946,7 @@ static ssize_t pwm_min_store(struct devi
+ 	if (kstrtol(buf, 10, &temp))
+ 		return -EINVAL;
+ 
+-	temp = clamp_val(temp, 0, 255);
++	temp = clamp_val(temp, 0, ADT7470_PWM_MAX);
+ 
+ 	mutex_lock(&data->lock);
+ 	data->pwm_min[attr->index] = temp;