[RFC,1/4] dt-bindings: net: can: add STM32 bxcan DT bindings

2299 diff mbox series

Add documentation of device tree bindings for the STM32 basic extended
CAN (bxcan) controller.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 .../devicetree/bindings/net/can/st,bxcan.yaml | 139 ++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/can/st,bxcan.yaml

On 17/08/2022 17:35, Dario Binacchi wrote:
> Add documentation of device tree bindings for the STM32 basic extended
> CAN (bxcan) controller.
> 
> Signed-off-by: Dario Binacchi <dariobin@libero.it>
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>

You do not need two SoBs. Keep only one, matching the From field.

> ---
> 
>  .../devicetree/bindings/net/can/st,bxcan.yaml | 139 ++++++++++++++++++
>  1 file changed, 139 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> 
> diff --git a/Documentation/devicetree/bindings/net/can/st,bxcan.yaml b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> new file mode 100644
> index 000000000000..f4cfd26e4785
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml

File name like compatible, so st,stm32-bxcan-core.yaml (or some other
name, see comment later)

> @@ -0,0 +1,139 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/can/st,bxcan.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: STMicroelectronics bxCAN controller Device Tree Bindings

s/Device Tree Bindings//

> +
> +description: STMicroelectronics BxCAN controller for CAN bus
> +
> +maintainers:
> +  - Dario Binacchi <dario.binacchi@amarulasolutions.com>
> +
> +allOf:
> +  - $ref: can-controller.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - st,stm32-bxcan-core

compatibles are supposed to be specific. If this is some type of
micro-SoC, then it should have its name/number. If it is dedicated
device, is the final name bxcan core? Google says  the first is true, so
you miss specific device part.
	
> +
> +  reg:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 1
> +
> +  clocks:
> +    description:
> +      Input clock for registers access
> +    maxItems: 1
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +required:
> +  - compatible
> +  - reg
> +  - resets
> +  - clocks
> +  - '#address-cells'
> +  - '#size-cells'
> +
> +additionalProperties: false
> +
> +patternProperties:

This goes after "properties: in top level (before "required").

> +  "^can@[0-9]+$":
> +    type: object
> +    description:
> +      A CAN block node contains two subnodes, representing each one a CAN
> +      instance available on the machine.
> +
> +    properties:
> +      compatible:
> +        enum:
> +          - st,stm32-bxcan

Why exactly do you need compatible for the child? Is it an entierly
separate device?

Comments about specific part are applied here as well.

> +
> +      master:

Is this a standard property? I don't see it anywhere else. Non-standard
properties require vendor prefix.

> +        description:
> +          Master and slave mode of the bxCAN peripheral is only relevant
> +          if the chip has two CAN peripherals. In that case they share
> +          some of the required logic, and that means you cannot use the
> +          slave CAN without the master CAN.
> +        type: boolean
> +
> +      reg:
> +        description: |
> +          Offset of CAN instance in CAN block. Valid values are:
> +            - 0x0:   CAN1
> +            - 0x400: CAN2
> +        maxItems: 1
> +
> +      interrupts:
> +        items:
> +          - description: transmit interrupt
> +          - description: FIFO 0 receive interrupt
> +          - description: FIFO 1 receive interrupt
> +          - description: status change error interrupt
> +
> +      interrupt-names:
> +        items:
> +          - const: tx
> +          - const: rx0
> +          - const: rx1
> +          - const: sce
> +
> +      resets:
> +        maxItems: 1
> +
> +      clocks:
> +        description:
> +          Input clock for registers access
> +        maxItems: 1
> +
> +    additionalProperties: false
> +
> +    required:
> +      - compatible
> +      - reg
> +      - interrupts
> +      - resets
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/stm32fx-clock.h>
> +    #include <dt-bindings/mfd/stm32f4-rcc.h>
> +
> +    can: can@40006400 {
> +        compatible = "st,stm32-bxcan-core";
> +        reg = <0x40006400 0x800>;
> +        resets = <&rcc STM32F4_APB1_RESET(CAN1)>;
> +        clocks = <&rcc 0 STM32F4_APB1_CLOCK(CAN1)>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        status = "disabled";

No status in examples.

> +
> +        can1: can@0 {
> +            compatible = "st,stm32-bxcan";
> +            reg = <0x0>;
> +            interrupts = <19>, <20>, <21>, <22>;
> +            interrupt-names = "tx", "rx0", "rx1", "sce";
> +            resets = <&rcc STM32F4_APB1_RESET(CAN1)>;
> +            master;
> +            status = "disabled";

No status in examples.


> +        };
> +
> +        can2: can@400 {
> +            compatible = "st,stm32-bxcan";
> +            reg = <0x400>;
> +            interrupts = <63>, <64>, <65>, <66>;
> +            interrupt-names = "tx", "rx0", "rx1", "sce";
> +            resets = <&rcc STM32F4_APB1_RESET(CAN2)>;
> +            clocks = <&rcc 0 STM32F4_APB1_CLOCK(CAN2)>;
> +            status = "disabled";

No status in examples.

> +        };
> +    };


Best regards,
Krzysztof

Hi Krzysztof,

On Mon, Aug 22, 2022 at 7:39 PM Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 20/08/2022 11:08, Dario Binacchi wrote:
> > Hi Krzysztof,
> >
> > On Thu, Aug 18, 2022 at 10:22 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski@linaro.org> wrote:
> >>
> >> On 17/08/2022 17:35, Dario Binacchi wrote:
> >>> Add documentation of device tree bindings for the STM32 basic extended
> >>> CAN (bxcan) controller.
> >>>
> >>> Signed-off-by: Dario Binacchi <dariobin@libero.it>
> >>> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> >>
> >> You do not need two SoBs. Keep only one, matching the From field.
> >
> > I started implementing this driver in my spare time, so my intention
> > was to keep track of it.
>
> SoB is not related to copyrights. Keep personal copyrights (with/next to
> work ones), but SoB is coming from a person and that's only one. Choose
> one "person".

Ok, I got it.

>
> >
> >>
> >>> ---
> >>>
> >>>  .../devicetree/bindings/net/can/st,bxcan.yaml | 139 ++++++++++++++++++
> >>>  1 file changed, 139 insertions(+)
> >>>  create mode 100644 Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/net/can/st,bxcan.yaml b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>> new file mode 100644
> >>> index 000000000000..f4cfd26e4785
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>
> >> File name like compatible, so st,stm32-bxcan-core.yaml (or some other
> >> name, see comment later)
> >
> >>
> >>> @@ -0,0 +1,139 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/net/can/st,bxcan.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: STMicroelectronics bxCAN controller Device Tree Bindings
> >>
> >> s/Device Tree Bindings//
> >
> >>
> >>> +
> >>> +description: STMicroelectronics BxCAN controller for CAN bus
> >>> +
> >>> +maintainers:
> >>> +  - Dario Binacchi <dario.binacchi@amarulasolutions.com>
> >>> +
> >>> +allOf:
> >>> +  - $ref: can-controller.yaml#
> >>> +
> >>> +properties:
> >>> +  compatible:
> >>> +    enum:
> >>> +      - st,stm32-bxcan-core
> >>
> >> compatibles are supposed to be specific. If this is some type of
> >> micro-SoC, then it should have its name/number. If it is dedicated
> >> device, is the final name bxcan core? Google says  the first is true, so
> >> you miss specific device part.
> >
> > I don't know if I understand correctly, I hope the change in version 2
> > is what you requested.
>
> What is the name of the SoC, where this is in?

STM32F4

>
> >
> >>
> >>> +
> >>> +  reg:
> >>> +    maxItems: 1
> >>> +
> >>> +  resets:
> >>> +    maxItems: 1
> >>> +
> >>> +  clocks:
> >>> +    description:
> >>> +      Input clock for registers access
> >>> +    maxItems: 1
> >>> +
> >>> +  '#address-cells':
> >>> +    const: 1
> >>> +
> >>> +  '#size-cells':
> >>> +    const: 0
> >>> +
> >>> +required:
> >>> +  - compatible
> >>> +  - reg
> >>> +  - resets
> >>> +  - clocks
> >>> +  - '#address-cells'
> >>> +  - '#size-cells'
> >>> +
> >>> +additionalProperties: false
> >>> +
> >>> +patternProperties:
> >>
> >> This goes after "properties: in top level (before "required").
> >>
> >>> +  "^can@[0-9]+$":
> >>> +    type: object
> >>> +    description:
> >>> +      A CAN block node contains two subnodes, representing each one a CAN
> >>> +      instance available on the machine.
> >>> +
> >>> +    properties:
> >>> +      compatible:
> >>> +        enum:
> >>> +          - st,stm32-bxcan
> >>
> >> Why exactly do you need compatible for the child? Is it an entierly
> >> separate device?
> >
> > I took inspiration from other drivers for ST microcontroller
> > peripherals (e. g. drivers/iio/adc/stm32-adc-core.c,
> > drivers/iio/adc/stm32-adc.c) where
> > some resources are shared between the peripheral instances. In the
> > case of CAN, master (CAN1) and slave (CAN2) share the registers for
> > configuring the filters and the clock.
> > In the core module you can find the functions about the shared
> > resources, while the childrens implement the driver.
>
> In both cases you refer to the driver, but we talk here about bindings
> which are rather not related. So I repeat the question - is the child
> entirely separate device which can be used in other devices?

IMHO, I think so.

Thanks and regards,
Dario
>
>
> Best regards,
> Krzysztof