Re: [PATCH v2 05/13] dt-bindings: serial: atmel,at91-usart: convert to json-schema

[<Sergiu.Moga@xxxxxxxxxxxxx>]

On 08.09.2022 15:29, Krzysztof Kozlowski wrote:
> On 06/09/2022 15:55, Sergiu Moga wrote:
>> Convert at91 USART DT Binding for Atmel/Microchip SoCs to
>> json-schema format. Furthermore, move this binding to the
>> serial directory, since binding directories match hardware,
>> unlike the driver subsystems which match Linux convention.
>>
>> Signed-off-by: Sergiu Moga <sergiu.moga@xxxxxxxxxxxxx>
>> ---
>>
>>
>>
>> v1 -> v2:
>> - only do what the commit says, split the addition of other compatibles and
>> properties in other patches
>> - remove unnecessary "|"'s
>> - mention header in `atmel,usart-mode`'s description
>> - place `if:` under `allOf:`
>> - respect order of spi0's DT properties: compatible, then reg then the reset of properties
>>
>>
>>
>>
>>
>>   .../devicetree/bindings/mfd/atmel-usart.txt   |  98 ----------
>>   .../bindings/serial/atmel,at91-usart.yaml     | 183 ++++++++++++++++++
>>   2 files changed, 183 insertions(+), 98 deletions(-)
>>   delete mode 100644 Documentation/devicetree/bindings/mfd/atmel-usart.txt
>>   create mode 100644 Documentation/devicetree/bindings/serial/atmel,at91-usart.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/atmel-usart.txt b/Documentation/devicetree/bindings/mfd/atmel-usart.txt
>> deleted file mode 100644
>> index a09133066aff..000000000000
>> --- a/Documentation/devicetree/bindings/mfd/atmel-usart.txt
>> +++ /dev/null
>> @@ -1,98 +0,0 @@
>> -* Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART)
>> -
>> -Required properties for USART:
>> -- compatible: Should be one of the following:
>> -     - "atmel,at91rm9200-usart"
>> -     - "atmel,at91sam9260-usart"
>> -     - "microchip,sam9x60-usart"
>> -     - "atmel,at91rm9200-dbgu", "atmel,at91rm9200-usart"
>> -     - "atmel,at91sam9260-dbgu", "atmel,at91sam9260-usart"
>> -     - "microchip,sam9x60-dbgu", "microchip,sam9x60-usart"
>> -- reg: Should contain registers location and length
>> -- interrupts: Should contain interrupt
>> -- clock-names: tuple listing input clock names.
>> -     Required elements: "usart"
>> -- clocks: phandles to input clocks.
>> -
>> -Required properties for USART in SPI mode:
>> -- #size-cells      : Must be <0>
>> -- #address-cells   : Must be <1>
>> -- cs-gpios: chipselects (internal cs not supported)
>> -- atmel,usart-mode : Must be <AT91_USART_MODE_SPI> (found in dt-bindings/mfd/at91-usart.h)
>> -
>> -Optional properties in serial and SPI mode:
>> -- dma bindings for dma transfer:
>> -     - dmas: DMA specifier, consisting of a phandle to DMA controller node,
>> -             memory peripheral interface and USART DMA channel ID, FIFO configuration.
>> -             The order of DMA channels is fixed. The first DMA channel must be TX
>> -             associated channel and the second one must be RX associated channel.
>> -             Refer to dma.txt and atmel-dma.txt for details.
>> -     - dma-names: "tx" for TX channel.
>> -                  "rx" for RX channel.
>> -                  The order of dma-names is also fixed. The first name must be "tx"
>> -                  and the second one must be "rx" as in the examples below.
>> -
>> -Optional properties in serial mode:
>> -- atmel,use-dma-rx: use of PDC or DMA for receiving data
>> -- atmel,use-dma-tx: use of PDC or DMA for transmitting data
>> -- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD line respectively.
>> -  It will use specified PIO instead of the peripheral function pin for the USART feature.
>> -  If unsure, don't specify this property.
>> -- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO
>> -  capable USARTs.
>> -- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt
>> -
>> -<chip> compatible description:
>> -- at91rm9200:  legacy USART support
>> -- at91sam9260: generic USART implementation for SAM9 SoCs
>> -
>> -Example:
>> -- use PDC:
>> -     usart0: serial@fff8c000 {
>> -             compatible = "atmel,at91sam9260-usart";
>> -             reg = <0xfff8c000 0x4000>;
>> -             interrupts = <7>;
>> -             clocks = <&usart0_clk>;
>> -             clock-names = "usart";
>> -             atmel,use-dma-rx;
>> -             atmel,use-dma-tx;
>> -             rts-gpios = <&pioD 15 GPIO_ACTIVE_LOW>;
>> -             cts-gpios = <&pioD 16 GPIO_ACTIVE_LOW>;
>> -             dtr-gpios = <&pioD 17 GPIO_ACTIVE_LOW>;
>> -             dsr-gpios = <&pioD 18 GPIO_ACTIVE_LOW>;
>> -             dcd-gpios = <&pioD 20 GPIO_ACTIVE_LOW>;
>> -             rng-gpios = <&pioD 19 GPIO_ACTIVE_LOW>;
>> -     };
>> -
>> -- use DMA:
>> -     usart0: serial@f001c000 {
>> -             compatible = "atmel,at91sam9260-usart";
>> -             reg = <0xf001c000 0x100>;
>> -             interrupts = <12 4 5>;
>> -             clocks = <&usart0_clk>;
>> -             clock-names = "usart";
>> -             atmel,use-dma-rx;
>> -             atmel,use-dma-tx;
>> -             dmas = <&dma0 2 0x3>,
>> -                    <&dma0 2 0x204>;
>> -             dma-names = "tx", "rx";
>> -             atmel,fifo-size = <32>;
>> -     };
>> -
>> -- SPI mode:
>> -     #include <dt-bindings/mfd/at91-usart.h>
>> -
>> -     spi0: spi@f001c000 {
>> -             #address-cells = <1>;
>> -             #size-cells = <0>;
>> -             compatible = "atmel,at91rm9200-usart", "atmel,at91sam9260-usart";
>> -             atmel,usart-mode = <AT91_USART_MODE_SPI>;
>> -             reg = <0xf001c000 0x100>;
>> -             interrupts = <12 IRQ_TYPE_LEVEL_HIGH 5>;
>> -             clocks = <&usart0_clk>;
>> -             clock-names = "usart";
>> -             dmas = <&dma0 2 AT91_DMA_CFG_PER_ID(3)>,
>> -                    <&dma0 2 (AT91_DMA_CFG_PER_ID(4) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>> -             dma-names = "tx", "rx";
>> -             cs-gpios = <&pioB 3 0>;
>> -     };
>> diff --git a/Documentation/devicetree/bindings/serial/atmel,at91-usart.yaml b/Documentation/devicetree/bindings/serial/atmel,at91-usart.yaml
>> new file mode 100644
>> index 000000000000..b25535b7a4d2
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/serial/atmel,at91-usart.yaml
>> @@ -0,0 +1,183 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +# Copyright (C) 2022 Microchip Technology, Inc. and its subsidiaries
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/serial/atmel,at91-usart.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART)
>> +
>> +maintainers:
>> +  - Richard Genoud <richard.genoud@xxxxxxxxx>
>> +
>> +properties:
>> +  compatible:
>> +    oneOf:
>> +      - enum:
>> +          - atmel,at91rm9200-usart
>> +          - atmel,at91sam9260-usart
>> +          - microchip,sam9x60-usart
>> +      - items:
>> +          - const: atmel,at91rm9200-dbgu
>> +          - const: atmel,at91rm9200-usart
>> +      - items:
>> +          - const: atmel,at91sam9260-dbgu
>> +          - const: atmel,at91sam9260-usart
>> +      - items:
>> +          - const: microchip,sam9x60-dbgu
>> +          - const: microchip,sam9x60-usart
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    const: usart
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  dmas:
>> +    items:
>> +      - description: TX DMA Channel
>> +      - description: RX DMA Channel
>> +
>> +  dma-names:
>> +    items:
>> +      - const: tx
>> +      - const: rx
>> +
>> +  atmel,usart-mode:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    description:
>> +      Must be either <AT91_USART_MODE_SPI> for SPI or
>> +      <AT91_USART_MODE_SERIAL> for USART (found in dt-bindings/mfd/at91-usart.h).
>> +    enum: [ 0, 1 ]
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +  - clock-names
>> +  - clocks
>> +
>> +allOf:
>> +  - if:
>> +      properties:
>> +        $nodename:
>> +          pattern: "^serial@[0-9a-f]+$"
> 
> You should rather check value of atmel,usart-mode, because now you won't
> properly match device nodes called "foobar". Since usart-mode has only
> two possible values, this will nicely simplify you if-else.
> 
> 


I did think of that but the previous binding specifies that 
atmel,usart-mode is required only for the SPI mode and it is optional 
for the USART mode. That is why I went for the node's regex since I 
thought it is something that both nodes would have.


>> +    then:
>> +      allOf:
>> +        - $ref: /schemas/serial/serial.yaml#
>> +        - $ref: /schemas/serial/rs485.yaml#
>> +
>> +      properties:
>> +        atmel,use-dma-rx:
>> +          type: boolean
>> +          description: use of PDC or DMA for receiving data
>> +
>> +        atmel,use-dma-tx:
>> +          type: boolean
>> +          description: use of PDC or DMA for transmitting data
>> +
>> +        atmel,fifo-size:
>> +          $ref: /schemas/types.yaml#/definitions/uint32
>> +          description:
>> +            Maximum number of data the RX and TX FIFOs can store for FIFO
>> +            capable USARTS.
>> +          enum: [ 16, 32 ]
> 
> I did not mention it last time, but I think it should follow generic
> practice, so define all properties top-level and disallow them for other
> type. This allows you to simply use additionalProperties:false at the end.
> 


What would be a good example binding in this case?


>> +
>> +    else:
>> +      if:
>> +        properties:
>> +          $nodename:
>> +            pattern: "^spi@[0-9a-f]+$"
>> +      then:
>> +        allOf:
>> +          - $ref: /schemas/spi/spi-controller.yaml#
>> +
>> +        properties:
>> +          atmel,usart-mode:
>> +            const: 1
>> +
>> +          "#size-cells":
>> +            const: 0
>> +
>> +          "#address-cells":
>> +            const: 1
> 
> The same - top level and disallow them for uart.
> 


These values of #size-cells and #address-cells are only meant for the 
SPI so I guess I would still have to specify their mandatory const 
values here.


>> +
>> +        required:
>> +          - atmel,usart-mode
>> +          - "#size-cells"
>> +          - "#address-cells"
> 
> End else in this branch is what?
> 


You are right, I will remove the useless if: after else:


>> +
>> +unevaluatedProperties: false
>> +
> 
> Best regards,
> Krzysztof


Regards,
	Sergiu