On Mon, Oct 12, 2020 at 12:46:26PM +0200, Jerome Pouiller wrote:

What does this chip do? WiFi or some other wireless?

+
+  For SDIO':'
+
+    The driver is able to detect a WFxxx chip on SDIO bus by matching its Vendor
+    ID and Product ID. However, driver will only provide limited features in
+    this case. Thus declaring WFxxx chip in device tree is recommended (and may
+    become mandatory in the future).
+
+    In addition, it is recommended to declare a mmc-pwrseq on SDIO host above
+    WFx. Without it, you may encounter issues with warm boot. The mmc-pwrseq
+    should be compatible with mmc-pwrseq-simple. Please consult
+    Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt for more
+    information.
+
+  For SPI':'
+
+    In add of the properties below, please consult
+    Documentation/devicetree/bindings/spi/spi-controller.yaml for optional SPI
+    related properties.
+
+  Note that in add of the properties below, the WFx driver also supports
+  `mac-address` and `local-mac-address` as described in
+  Documentation/devicetree/bindings/net/ethernet.txt

Note what ethernet.txt contains... This should have a $ref to 
ethernet-controller.yaml to express the above.

You can add 'mac-address: true' if you want to be explicit about what 
properties are used.

+
+properties:
+  compatible:
+    const: silabs,wf200

blank line between each DT property.

+  reg:
+    description:
+      When used on SDIO bus, <reg> must be set to 1. When used on SPI bus, it is
+      the chip select address of the device as defined in the SPI devices
+      bindings.
+    maxItems: 1
+  spi-max-frequency:
+    description: (SPI only) Maximum SPI clocking speed of device in Hz.

No need to redefine a common property.

+    maxItems: 1

Not an array. Just need:

spi-max-frequency: true

+  interrupts:
+    description: The interrupt line. Triggers IRQ_TYPE_LEVEL_HIGH and
+      IRQ_TYPE_EDGE_RISING are both supported by the chip and the driver. When
+      SPI is used, this property is required. When SDIO is used, the "in-band"
+      interrupt provided by the SDIO bus is used unless an interrupt is defined
+      in the Device Tree.
+    maxItems: 1
+  reset-gpios:
+    description: (SPI only) Phandle of gpio that will be used to reset chip
+      during probe. Without this property, you may encounter issues with warm
+      boot. (For legacy purpose, the gpio in inverted when compatible ==
+      "silabs,wfx-spi")
+
+      For SDIO, the reset gpio should declared using a mmc-pwrseq.
+    maxItems: 1
+  wakeup-gpios:
+    description: Phandle of gpio that will be used to wake-up chip. Without this
+      property, driver will disable most of power saving features.
+    maxItems: 1
+  config-file:
+    description: Use an alternative file as PDS. Default is `wf200.pds`. Only
+      necessary for development/debug purpose.

'firmware-name' is typically what we'd use here. Though if just for 
debug/dev, perhaps do a debugfs interface for this instead. As DT should 
come from the firmware/bootloader, requiring changing the DT for 
dev/debug is not the easiest workflow compared to doing something from 
userspace.

+    maxItems: 1

Looks like a string, not an array.

+
+required:
+  - compatible
+  - reg

Will need additionalProperties or unevaluatedProperties depending on 
whether you list out properties from ethernet-controller.yaml or not.

Rob