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

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Message-ID: <20250109211908.1553072-3-dario.binacchi@amarulasolutions.com>
Date: Thu,  9 Jan 2025 22:18:29 +0100
From: Dario Binacchi <dario.binacchi@...rulasolutions.com>
To: linux-kernel@...r.kernel.org
Cc: linux-amarula@...rulasolutions.com,
	Dario Binacchi <dario.binacchi@...rulasolutions.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Conor Dooley <conor+dt@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Rob Herring <robh@...nel.org>,
	Stephen Boyd <sboyd@...nel.org>,
	devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-clk@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: [PATCH v2 2/4] dt-bindings: clock: st,stm32-rcc: support spread spectrum clocking

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 <dario.binacchi@...rulasolutions.com>

---

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(+)

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@...23800 {
+        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@...24400 {
         compatible = "st,stm32h743-rcc", "st,stm32-rcc";
-- 
2.43.0