Add fan child nodes that allow describing the connections for the
ADT7475 to the fans it controls. This also allows setting some
initial values for the pwm duty cycle and frequency.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v5:
    - Use nanoseconds for PWM frequency and duty cycle as per existing
      conventions for PWMs
    - Set flags to 0 in example to match adi,pwm-active-state setting
    Changes in v4:
    - 0 is not a valid frequency value
    Changes in v3:
    - Use the pwm provider/consumer bindings
    Changes in v2:
    - Document 0 as a valid value (leaves hardware as-is)

 .../devicetree/bindings/hwmon/adt7475.yaml    | 35 ++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
index 051c976ab711..df2b5b889e4d 100644
--- a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
+++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
@@ -51,6 +51,24 @@ properties:
       enum: [0, 1]
       default: 1
 
+  "#pwm-cells":
+    const: 4
+    description: |
+      Number of cells in a PWM specifier.
+      - 0: The PWM channel
+      - 1: The PWM period in nanoseconds
+           - 90909091 (11 Hz)
+           - 71428571 (14 Hz)
+           - 45454545 (22 Hz)
+           - 34482759 (29 Hz)
+           - 28571429 (35 Hz)
+           - 22727273 (44 Hz)
+           - 17241379 (58 Hz)
+           - 11363636 (88 Hz)
+           - 44444 (22 kHz)
+      - 2: PWM flags 0 or PWM_POLARITY_INVERTED
+      - 3: The default PWM duty cycle in nanoseconds
+
 patternProperties:
   "^adi,bypass-attenuator-in[0-4]$":
     description: |
@@ -81,6 +99,10 @@ patternProperties:
       - smbalert#
       - gpio
 
+  "^fan-[0-9]+$":
+    $ref: fan-common.yaml#
+    unevaluatedProperties: false
+
 required:
   - compatible
   - reg
@@ -89,11 +111,12 @@ additionalProperties: false
 
 examples:
   - |
+    #include <dt-bindings/pwm/pwm.h>
     i2c {
       #address-cells = <1>;
       #size-cells = <0>;
 
-      hwmon@2e {
+      pwm: hwmon@2e {
         compatible = "adi,adt7476";
         reg = <0x2e>;
         adi,bypass-attenuator-in0 = <1>;
@@ -101,5 +124,15 @@ examples:
         adi,pwm-active-state = <1 0 1>;
         adi,pin10-function = "smbalert#";
         adi,pin14-function = "tach4";
+        #pwm-cells = <4>;
+
+        /* PWMs at 22.5 kHz frequency, 50% duty*/
+        fan-0 {
+          pwms = <&pwm 0 44444 0 22222>;
+        };
+
+        fan-1 {
+          pwms = <&pwm 2 44444 0 22222>;
+        };
       };
     };
-- 
2.45.2

On Fri, 12 Jul 2024 11:46:12 +1200, Chris Packham wrote:
> Add fan child nodes that allow describing the connections for the
> ADT7475 to the fans it controls. This also allows setting some
> initial values for the pwm duty cycle and frequency.
> 
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
> 
> Notes:
>     Changes in v5:
>     - Use nanoseconds for PWM frequency and duty cycle as per existing
>       conventions for PWMs
>     - Set flags to 0 in example to match adi,pwm-active-state setting
>     Changes in v4:
>     - 0 is not a valid frequency value
>     Changes in v3:
>     - Use the pwm provider/consumer bindings
>     Changes in v2:
>     - Document 0 as a valid value (leaves hardware as-is)
> 
>  .../devicetree/bindings/hwmon/adt7475.yaml    | 35 ++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>