[PATCH v1 1/2] hwmon: (aspeed-g6-pwm-tacho): Extend the #pwm-cells to 4

[Billy Tsai]

Add an option to support #pwm-cells up to 4. The additional cell is used
to enable the WDT reset feature, which is specific to the ASPEED PWM
controller.

Signed-off-by: Billy Tsai <billy_tsai at aspeedtech.com>
Change-Id: Iefcc9622ac3dc684441d3e77aeb53c00f2ce4097
---
 .../bindings/hwmon/aspeed,g6-pwm-tach.yaml    | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml b/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
index 9e5ed901ae54..0cc92ce29ece 100644
--- a/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
+++ b/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
@@ -31,7 +31,11 @@ properties:
     maxItems: 1
 
   "#pwm-cells":
-    const: 3
+    enum: [3, 4]
+    description: |
+      The value should be 4 to enable the WDT reload feature, which will change the duty cycle to
+      a preprogrammed value after WDT/EXTRST#.
+      The range for the fourth cell value supported by this binding is 0 to 255.
 
 patternProperties:
   "^fan-[0-9]+$":
@@ -69,3 +73,22 @@ examples:
         pwms = <&pwm_tach 1 40000 0>;
       };
     };
+  - |
+    #include <dt-bindings/clock/aspeed-clock.h>
+    pwm_tach: pwm-tach-controller at 1e610000 {
+      compatible = "aspeed,ast2600-pwm-tach";
+      reg = <0x1e610000 0x100>;
+      clocks = <&syscon ASPEED_CLK_AHB>;
+      resets = <&syscon ASPEED_RESET_PWM>;
+      #pwm-cells = <4>;
+
+      fan-0 {
+        tach-ch = /bits/ 8 <0x0>;
+        pwms = <&pwm_tach 0 40000 0 128>;
+      };
+
+      fan-1 {
+        tach-ch = /bits/ 8 <0x1 0x2>;
+        pwms = <&pwm_tach 1 40000 0 160>;
+      };
+    };
-- 
2.25.1