On 08.09.2022 15:29, Krzysztof Kozlowski wrote:

On 06/09/2022 15:55, Sergiu Moga wrote:

quoted

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 <redacted>
---



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@gmail.com>
+
+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.

quoted

+    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?

quoted

+
+    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.

quoted

+
+        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:

quoted

+
+unevaluatedProperties: false
+

Best regards,
Krzysztof

Regards,
	Sergiu
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