Re: [PATCH v1 2/6] dt-bindings: i2c: convert ocores binding to yaml

From: Krzysztof Kozlowski
Date: Mon Jun 06 2022 - 04:02:46 EST

On 05/06/2022 15:32, mail@xxxxxxxxxxx wrote:
> From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
>
> Convert the open cores i2c controller binding from text to yaml.
>
> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/i2c/i2c-ocores.txt | 78 -----------
> .../devicetree/bindings/i2c/i2c-ocores.yaml | 132 ++++++++++++++++++
> 2 files changed, 132 insertions(+), 78 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> create mode 100644 Documentation/devicetree/bindings/i2c/i2c-ocores.yaml
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> deleted file mode 100644
> index a37c9455b244..000000000000
> --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> +++ /dev/null
> @@ -1,78 +0,0 @@
> -Device tree configuration for i2c-ocores
> -
> -Required properties:
> -- compatible : "opencores,i2c-ocores"
> - "aeroflexgaisler,i2cmst"
> - "sifive,fu540-c000-i2c", "sifive,i2c0"
> - For Opencore based I2C IP block reimplemented in
> - FU540-C000 SoC.
> - "sifive,fu740-c000-i2c", "sifive,i2c0"
> - For Opencore based I2C IP block reimplemented in
> - FU740-C000 SoC.
> - Please refer to sifive-blocks-ip-versioning.txt for
> - additional details.
> -- reg : bus address start and address range size of device
> -- clocks : handle to the controller clock; see the note below.
> - Mutually exclusive with opencores,ip-clock-frequency
> -- opencores,ip-clock-frequency: frequency of the controller clock in Hz;
> - see the note below. Mutually exclusive with clocks
> -- #address-cells : should be <1>
> -- #size-cells : should be <0>
> -
> -Optional properties:
> -- interrupts : interrupt number.
> -- clock-frequency : frequency of bus clock in Hz; see the note below.
> - Defaults to 100 KHz when the property is not specified
> -- reg-shift : device register offsets are shifted by this value
> -- reg-io-width : io register width in bytes (1, 2 or 4)
> -- regstep : deprecated, use reg-shift above
> -
> -Note
> -clock-frequency property is meant to control the bus frequency for i2c bus
> -drivers, but it was incorrectly used to specify i2c controller input clock
> -frequency. So the following rules are set to fix this situation:
> -- if clock-frequency is present and neither opencores,ip-clock-frequency nor
> - clocks are, then clock-frequency specifies i2c controller clock frequency.
> - This is to keep backwards compatibility with setups using old DTB. i2c bus
> - frequency is fixed at 100 KHz.
> -- if clocks is present it specifies i2c controller clock. clock-frequency
> - property specifies i2c bus frequency.
> -- if opencores,ip-clock-frequency is present it specifies i2c controller
> - clock frequency. clock-frequency property specifies i2c bus frequency.
> -
> -Examples:
> -
> - i2c0: ocores@a0000000 {
> - #address-cells = <1>;
> - #size-cells = <0>;
> - compatible = "opencores,i2c-ocores";
> - reg = <0xa0000000 0x8>;
> - interrupts = <10>;
> - opencores,ip-clock-frequency = <20000000>;
> -
> - reg-shift = <0>; /* 8 bit registers */
> - reg-io-width = <1>; /* 8 bit read/write */
> -
> - dummy@60 {
> - compatible = "dummy";
> - reg = <0x60>;
> - };
> - };
> -or
> - i2c0: ocores@a0000000 {
> - #address-cells = <1>;
> - #size-cells = <0>;
> - compatible = "opencores,i2c-ocores";
> - reg = <0xa0000000 0x8>;
> - interrupts = <10>;
> - clocks = <&osc>;
> - clock-frequency = <400000>; /* i2c bus frequency 400 KHz */
> -
> - reg-shift = <0>; /* 8 bit registers */
> - reg-io-width = <1>; /* 8 bit read/write */
> -
> - dummy@60 {
> - compatible = "dummy";
> - reg = <0x60>;
> - };
> - };
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.yaml b/Documentation/devicetree/bindings/i2c/i2c-ocores.yaml
> new file mode 100644
> index 000000000000..1693ffffbe31
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.yaml
> @@ -0,0 +1,132 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/i2c/i2c-ocores.yaml#

This should be rather named with vendor prefix, so:
opencores,i2c-ocores.yaml

> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: OpenCores I2C controller
> +
> +maintainers:
> + - Peter Korsgaard <peter@xxxxxxxxxxxxx>
> + - Andrew Lunn <andrew@xxxxxxx>
> +
> +allOf:
> + - $ref: /schemas/i2c/i2c-controller.yaml#
> +
> +properties:
> + compatible:
> + oneOf:
> + - items:
> + - enum:
> + - sifive,fu740-c000-i2c # Opencore based IP block FU740-C000 SoC
> + - sifive,fu540-c000-i2c # Opencore based IP block FU540-C000 SoC
> + - const: sifive,i2c0
> + - const: opencores,i2c-ocores
> + - const: aeroflexgaisler,i2cmst

The last two are just enum
> +
> + reg:
> + maxItems: 1
> +
> + interrupts:
> + maxItems: 1
> +
> + clocks:
> + maxItems: 1
> +
> + "#address-cells":
> + const: 1
> +
> + "#size-cells":
> + const: 0
> +
> + clock-frequency:
> + description: |
> + Desired I2C bus clock frequency in Hz. As only Standard and Fast
> + modes are supported, possible values are 100000 and 400000.

Add enum with the two values.

> + Note:
> + clock-frequency property is meant to control the bus frequency for i2c bus
> + drivers, but it was incorrectly used to specify i2c controller input clock
> + frequency. So the following rules are set to fix this situation:
> + - if clock-frequency is present and neither opencores,ip-clock-frequency nor
> + clocks are, then clock-frequency specifies i2c controller clock frequency.
> + This is to keep backwards compatibility with setups using old DTB. i2c bus
> + frequency is fixed at 100 KHz.
> + - if clocks is present it specifies i2c controller clock. clock-frequency
> + property specifies i2c bus frequency.
> + - if opencores,ip-clock-frequency is present it specifies i2c controller
> + clock frequency. clock-frequency property specifies i2c bus frequency.
> + default: 100000
> +
> + reg-io-width:
> + $ref: /schemas/types.yaml#/definitions/uint32

No need for ref, it is coming from the dtschema.

> + description: |
> + io register width in bytes
> + enum: [1, 2, 4]
> +
> + reg-shift:
> + $ref: /schemas/types.yaml#/definitions/uint32

No need for ref, it is coming from the dtschema.

> + description: |
> + device register offsets are shifted by this value

I guess 0 is default?

> +
> + regstep:
> + description: |
> + deprecated, use reg-shift above
> + deprecated: true
> +
> + opencores,ip-clock-frequency:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description: |
> + Frequency of the controller clock in Hz. Mutually exclusive with clocks.
> + See the note above.
> +
> +required:
> + - compatible
> + - reg
> + - "#address-cells"
> + - "#size-cells"
> +
> +oneOf:
> + - required:
> + - opencores,ip-clock-frequency
> + - required:
> + - clocks

This is correct if your intention was to require one of these
properties, which seems to match the old bindings.

> +
> +unevaluatedProperties: false
> +
> +examples:
> + - |
> + i2c@a0000000 {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "opencores,i2c-ocores";
> + reg = <0xa0000000 0x8>;

Reorder the properties in the node so first goes compatible then reg,
then the rest.

> + interrupts = <10>;
> + opencores,ip-clock-frequency = <20000000>;
> +
> + reg-shift = <0>; /* 8 bit registers */
> + reg-io-width = <1>; /* 8 bit read/write */
> +
> + dummy@60 {
> + compatible = "dummy";
> + reg = <0x60>;
> + };
> + };
> +
> + i2c@b0000000 {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "opencores,i2c-ocores";
> + reg = <0xa0000000 0x8>;
> + interrupts = <10>;
> + clocks = <&osc>;
> + clock-frequency = <400000>; /* i2c bus frequency 400 KHz */
> +
> + reg-shift = <0>; /* 8 bit registers */
> + reg-io-width = <1>; /* 8 bit read/write */
> +
> + dummy@60 {
> + compatible = "dummy";
> + reg = <0x60>;
> + };
> + };
> +...


Best regards,
Krzysztof