[v2,2/4] dt-bindings: clock: st,stm32-rcc: support spread spectrum clocking

Commit Message

Dario Binacchi Jan. 9, 2025, 9:18 p.m. UTC

The addition of DT bindings for enabling and tuning spread spectrum
clocking generation is available only for the main PLL of stm32f{4,7}
platforms.

Signed-off-by: Dario Binacchi <[e-mail]>

---

Changes in v2:
- Update the commit message
- Change st,ssc-modmethod type from non-unique-string-array to string

 .../bindings/clock/st,stm32-rcc.yaml          | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)

Patch

diff --git a/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml b/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml
index 779e547700be..628bbbcf2875 100644
--- a/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml
+++ b/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml
@@ -56,6 +56,26 @@  properties:
       Phandle to system configuration controller. It can be used to control the
       power domain circuitry.
 
+  st,ssc-modfreq-hz:
+    description:
+      The modulation frequency for main PLL (in Hz)
+
+  st,ssc-moddepth-permyriad:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      The modulation rate for main PLL (in permyriad, i.e. 0.01%)
+    minimum: 25
+    maximum: 200
+
+  st,ssc-modmethod:
+    $ref: /schemas/types.yaml#/definitions/string
+    description:
+      The modulation techniques for main PLL.
+    items:
+      enum:
+        - center-spread
+        - down-spread
+
 required:
   - compatible
   - reg
@@ -81,6 +101,10 @@  allOf:
             - description: high speed external (HSE) clock input
             - description: low speed external (LSE) clock input
             - description: Inter-IC sound (I2S) clock input
+        st,ssc-modfreq-hz: false
+        st,ssc-moddepth-permyriad: false
+        st,ssc-modmethod: false
+
     else:
       properties:
         '#clock-cells':
@@ -98,6 +122,18 @@  additionalProperties: false
 
 examples:
   # Reset and Clock Control Module node:
+  - |
+    clock-controller@40023800 {
+        compatible = "st,stm32f42xx-rcc", "st,stm32-rcc";
+        reg = <0x40023800 0x400>;
+        #clock-cells = <2>;
+        #reset-cells = <1>;
+        clocks = <&clk_hse>, <&clk_i2s_ckin>;
+        st,syscfg = <&pwrcfg>;
+        st,ssc-modfreq-hz = <10000>;
+        st,ssc-moddepth-permyriad = <200>;
+        st,ssc-modmethod = "center-spread";
+    };
   - |
     clock-controller@58024400 {
         compatible = "st,stm32h743-rcc", "st,stm32-rcc";