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

Prabhakar
2024-06-10T23:32:32Z

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.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@bp.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@bp.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@10420000 {
+ 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