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SubjectRe: [PATCH v6 3/6] dt-bindings: clock: renesas,rzn1-clocks: document RZ/N1 clock driver
On Tue, May 22, 2018 at 11:01:23AM +0100, Michel Pollet wrote:
> The Renesas RZ/N1 Family (Part #R9A06G0xx) requires a driver
> to provide the SoC clock infrastructure for Linux.
>
> This documents the driver bindings.
>
> Signed-off-by: Michel Pollet <michel.pollet@bp.renesas.com>
> ---
> .../bindings/clock/renesas,rzn1-clocks.txt | 44 ++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzn1-clocks.txt
>
> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzn1-clocks.txt b/Documentation/devicetree/bindings/clock/renesas,rzn1-clocks.txt
> new file mode 100644
> index 0000000..0c41137
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/renesas,rzn1-clocks.txt
> @@ -0,0 +1,44 @@
> +* Renesas RZ/N1 Clock Driver
> +
> +This driver provides the clock infrastructure used by all the other drivers.

Bindings document h/w not drivers.

> +
> +One of the 'special' feature of this infrastructure is that Linux doesn't

Bindings are not just for Linux.

> +necessary 'own' all the clocks on the SoC, some other OS runs on
> +the Cortex-M3 core and that OS can access and claim it's own clocks.

How is this relevant to the binding?

> +
> +Required Properties:
> +
> + - compatible: Must be
> + - "renesas,r9a06g032-clocks" for the RZ/N1D
> + and "renesas,rzn1-clocks" as a fallback.

Is "clocks" how the chip reference manual refers to this block?

> + - reg: Base address and length of the memory resource used by the driver
> + - #clock-cells: Must be 1
> +
> +Examples
> +--------
> +
> + - Clock driver device node:
> +
> + clock: clocks@4000c000 {

clock-controller@...

> + compatible = "renesas,r9a06g032-clocks",
> + "renesas,rzn1-clocks";
> + reg = <0x4000c000 0x1000>;
> + status = "okay";

Don't show status in examples. (Plus, I doubt you ever want to have this
disabled, so you don't need the property in your dts files either).

> + #clock-cells = <1>;
> + };
> +
> +
> + - Other drivers can use the clocks as in:

s/drivers/nodes/

> +
> + uart0: serial@40060000 {
> + compatible = "snps,dw-apb-uart";
> + reg = <0x40060000 0x400>;
> + interrupts = <GIC_SPI 6 IRQ_TYPE_LEVEL_HIGH>;
> + reg-shift = <2>;
> + reg-io-width = <4>;
> + clocks = <&clock RZN1_CLK_UART0>;
> + clock-names = "baudclk";
> + };
> + Note the use of RZN1_CLK_UART0 -- these constants are declared in
> + the rzn1-clocks.h header file. These are not hardware based constants
> + and are Linux specific.

No, they are not Linux specific. They are part of the DT ABI.

While it is not a requirement to base them on some h/w numbering, it is
preferred if you can. That usually only works if you can base them on
bit positions or register offsets.

Rob

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