linux-kernel - [RFC PATCH v2 1/4] dt-bindings: clock: renesas: Document RZ/V2H(P) SoC CPG

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Message-Id: <20240610233221.242749-2-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Tue, 11 Jun 2024 00:32:18 +0100
From: Prabhakar <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Magnus Damm <magnus.damm@...il.com>
Cc: linux-renesas-soc@...r.kernel.org,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [RFC PATCH v2 1/4] dt-bindings: clock: renesas: Document RZ/V2H(P) SoC CPG

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Document the device tree bindings for the Renesas RZ/V2H(P) SoC
Clock Pulse Generator (CPG).

CPG block handles the below operations:
- Generation and control of clock signals for the IP modules
- Generation and control of resets
- Control over booting
- Low power consumption and power supply domains

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
Hi Geert,

WRT XIN_{RTCCLK/AUDCLK/MAINCLK)clks going to CPG I have created an
internal request for clarification if the clocks are inputs to CPG
or to respective clocks. As the board schematic doesnt have any of
these. For now I have just kept qextal clk as input to CPG.

Cheers, Prabhakar

v1->v2
- Updated commit message
- Updated description for binding as suggested by Geert
- Updated descriptions for clocks and resets property
- Renamed extal->qextal
- Updated '#power-domain-cells' value
---
 .../bindings/clock/renesas,rzv2h-cpg.yaml     | 81 +++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzv2h-cpg.yaml

diff --git a/Documentation/devicetree/bindings/clock/renesas,rzv2h-cpg.yaml b/Documentation/devicetree/bindings/clock/renesas,rzv2h-cpg.yaml
new file mode 100644
index 000000000000..03085308154c
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/renesas,rzv2h-cpg.yaml
@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/renesas,rzv2h-cpg.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas RZ/V2H(P) Clock Pulse Generator (CPG)
+
+maintainers:
+  - Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
+
+description: |
+  On Renesas RZ/V2H(P) SoCs, the CPG (Clock Pulse Generator) handles generation
+  and control of clock signals for the IP modules, generation and control of resets,
+  and control over booting, low power consumption and power supply domains.
+
+properties:
+  compatible:
+    const: renesas,r9a09g057-cpg
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    description:
+      Clock source to CPG on QEXTAL pin.
+    const: qextal
+
+  '#clock-cells':
+    description: |
+      - For CPG core clocks, the two clock specifier cells must be "CPG_CORE"
+        and a core clock reference, as defined in
+        <dt-bindings/clock/r9a09g057-cpg.h>,
+      - For module clocks, the two clock specifier cells must be "CPG_MOD" and
+        a module number.  The module number is calculated as the CLKON register
+        offset index multiplied by 16, plus the actual bit in the register
+        used to turn the CLK ON. For example, for CGC_GIC_0_GICCLK, the
+        calculation is (1 * 16 + 3) = 19.
+    const: 2
+
+  '#power-domain-cells':
+    description:
+      SoC devices that are part of the CPG/Module Standby Mode Clock Domain and
+      can be power-managed through Module Standby should refer to the CPG device
+      node in their "power-domains" property, as documented by the generic PM
+      Domain bindings in Documentation/devicetree/bindings/power/power-domain.yaml.
+    const: 0
+
+  '#reset-cells':
+    description:
+      The single reset specifier cell must be the reset number. The reset number
+      is calculated as the reset register offset index multiplied by 16, plus the
+      actual bit in the register used to reset the specific IP block. For example,
+      for SYS_0_PRESETN, the calculation is (3 * 16 + 0) = 48.
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - '#clock-cells'
+  - '#power-domain-cells'
+  - '#reset-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    cpg: clock-controller@...20000 {
+            compatible = "renesas,r9a09g057-cpg";
+            reg = <0x10420000 0x10000>;
+            clocks = <&extal_clk>;
+            clock-names = "qextal";
+            #clock-cells = <2>;
+            #power-domain-cells = <0>;
+            #reset-cells = <1>;
+    };
-- 
2.34.1