[PATCH v8 2/3] dt-bindings: pwm: dwc: Add eswin compatible

[dongxuyang@eswincomputing.com]

From: Xuyang Dong <dongxuyang@eswincomputing.com>

EIC7700 integrates the DesignWare PWM IP described by the generic
snps,dw-apb-timers-pwm2 binding. On this SoC, the presetn and
timer_N_resetn inputs are physically tied together to a single reset
line, so exactly one reset is both required and sufficient, unlike
the generic binding where up to two independent lines are optional.

Add the eswin,eic7700-pwm compatible string and constrain its resets
property to exactly one entry.

Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
---
 .../bindings/pwm/snps,dw-apb-timers-pwm2.yaml | 32 ++++++++++++++++---
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
index 213fdaef25d9..9a9a24ddc61b 100644
--- a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
+++ b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
@@ -20,12 +20,11 @@ description:
   instead of having to encode the IP version number in the device tree
   compatible.
 
-allOf:
-  - $ref: pwm.yaml#
-
 properties:
   compatible:
-    const: snps,dw-apb-timers-pwm2
+    enum:
+      - snps,dw-apb-timers-pwm2
+      - eswin,eic7700-pwm
 
   reg:
     maxItems: 1
@@ -44,6 +43,7 @@ properties:
       - const: timer
 
   resets:
+    minItems: 1
     items:
       - description: Interface bus (presetn) reset
       - description: PWM timer logic (timer_N_resetn) reset
@@ -59,6 +59,21 @@ required:
   - clocks
   - clock-names
 
+allOf:
+  - $ref: pwm.yaml#
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: eswin,eic7700-pwm
+    then:
+      properties:
+        resets:
+          maxItems: 1
+      required:
+        - resets
+
 additionalProperties: false
 
 examples:
@@ -70,3 +85,12 @@ examples:
       clocks = <&bus>, <&timer>;
       clock-names = "bus", "timer";
     };
+  - |
+    pwm@50818000 {
+      compatible = "eswin,eic7700-pwm";
+      reg = <0x50818000 0x4000>;
+      #pwm-cells = <3>;
+      clocks = <&bus>, <&timer>;
+      clock-names = "bus", "timer";
+      resets = <&reset>;
+    };
-- 
2.34.1