dts: bindings: improve base.yaml descriptions

This file defines some of the most important properties in the
devicetree, including core concepts like 'compatible', 'reg', and
'interrupts'. For some reason, we've never prioritized writing up
proper descriptions that indicate their importance or show where the
user can get more information about them in the specs or elsewhere.

Give this file a once-over to improve the situation.

Signed-off-by: Martí Bolívar <[email protected]>
Signed-off-by: Martí Bolívar <[email protected]>

Author: mbolivar

dts/bindings/base/base.yaml

@@ -5,7 +5,16 @@ include: [pm.yaml]
 properties:
   status:
     type: string
-    description: indicates the operational status of a device
+    description: |
+      Indicates the operational status of the hardware or other
+      resource that the node represents. In particular:
+
+        - "okay" means the resource is operational and, for example,
+          can be used by device drivers
+        - "disabled" means the resource is not operational and the system
+          should treat it as if it is not present
+
+      For details, see "2.3.4 status" in Devicetree Specification v0.4.
     enum:
       - "ok" # Deprecated form
       - "okay"
@@ -17,93 +26,189 @@ properties:
   compatible:
     type: string-array
     required: true
-    description: compatible strings
+    description: |
+      This property is a list of strings that essentially define what
+      type of hardware or other resource this devicetree node
+      represents. Each device driver checks for specific compatible
+      property values to find the devicetree nodes that represent
+      resources that the driver should manage.
+
+      The recommended format is "vendor,device", The "vendor" part is
+      an abbreviated name of the vendor. The "device" is usually from
+      the datasheet.
+
+      The compatible property can have multiple values, ordered from
+      most- to least-specific. Having additional values is useful when the
+      device is a specific instance of a more general family, to allow the
+      system to match the most specific driver available.
+
+      For details, see "2.3.1 compatible" in Devicetree Specification v0.4.
 
   reg:
     type: array
-    description: register space
+    description: |
+      Information used to address the device. The value is specific to
+      the device (i.e. is different depending on the compatible
+      property).
+
+      The "reg" property is typically a sequence of (address, length) pairs.
+      Each pair is called a "register block". Values are
+      conventionally written in hex.
+
+      For details, see "2.3.6 reg" in Devicetree Specification v0.4.
 
   reg-names:
     type: string-array
-    description: name of each register space
+    description: |
+      Optional names given to each register block in the "reg" property.
+      For example:
+
+        / {
+             soc {
+                 #address-cells = <1>;
+                 #size-cells = <1>;
+
+                 uart@1000 {
+                     reg = <0x1000 0x2000>, <0x3000 0x4000>;
+                     reg-names = "foo", "bar";
+                 };
+             };
+        };
+
+      The uart@1000 node has two register blocks:
+
+        - one with base address 0x1000, size 0x2000, and name "foo"
+        - another with base address 0x3000, size 0x4000, and name "bar"
 
   interrupts:
     type: array
-    description: interrupts for device
+    description: |
+      Information about interrupts generated by the device, encoded as an array
+      of one or more interrupt specifiers. The format of the data in this property
+      varies by where the device appears in the interrupt tree. Devices with the same
+      "interrupt-parent" will use the same format in their interrupts properties.
+
+      For details, see "2.4 Interrupts and Interrupt Mapping" in
+      Devicetree Specification v0.4.
 
   # Does not follow the 'type: phandle-array' scheme, but gets type-checked
   # by the code. Declare it here just so that other bindings can make it
   # 'required: true' easily if they want to.
   interrupts-extended:
     type: compound
-    description: extended interrupt specifier for device
+    description: |
+      Extended interrupt specifier for device, used as an alternative to
+      the "interrupts" property.
+
+      For details, see "2.4 Interrupts and Interrupt Mapping" in
+      Devicetree Specification v0.4.
 
   interrupt-names:
     type: string-array
-    description: name of each interrupt
+    description: |
+      Optional names given to each interrupt generated by a device.
+      The interrupts themselves are defined in either "interrupts" or
+      "interrupts-extended" properties.
+
+      For details, see "2.4 Interrupts and Interrupt Mapping" in
+      Devicetree Specification v0.4.
 
   interrupt-parent:
     type: phandle
-    description: phandle to interrupt controller node
+    description: |
+      If present, this refers to the node which handles interrupts generated
+      by this device.
+
+      For details, see "2.4 Interrupts and Interrupt Mapping" in
+      Devicetree Specification v0.4.
 
   # description of label should be given in bindings inheriting base.yaml
   # label property is included here to help enforce its type being string
   label:
     type: string
-    description: No description provided for this label
+    description: |
+      Human readable string describing the device. Use of this property is
+      deprecated except as needed on a case-by-case basis.
+
+      For details, see "4.1.2 Miscellaneous Properties" in Devicetree
+      Specification v0.4.
 
   clocks:
     type: phandle-array
-    description: Clock gate information
+    description: |
+      Information about the device's clock providers. In general, this property
+      should follow conventions established in the dt-schema binding:
+
+        https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml
 
   clock-names:
     type: string-array
-    description: name of each clock
+    description: |
+      Optional names given to each clock provider in the "clocks" property.
 
   "#address-cells":
     type: int
-    description: number of address cells in reg property
+    description: |
+      This property encodes the number of <u32> cells used by address fields
+      in "reg" properties in this node's children.
+
+      For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
+      Specification v0.4.
 
   "#size-cells":
     type: int
-    description: number of size cells in reg property
+    description: |
+      This property encodes the number of <u32> cells used by size fields in
+      "reg" properties in this node's children.
+
+      For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
+      Specification v0.4.
 
   dmas:
     type: phandle-array
-    description: DMA channels specifiers
+    description: |
+      DMA channel specifiers relevant to the device.
 
   dma-names:
     type: string-array
-    description: Provided names of DMA channel specifiers
+    description: |
+      Optional names given to the DMA channel specifiers in the "dmas" property.
 
   io-channels:
     type: phandle-array
-    description: IO channels specifiers
+    description: |
+      IO channel specifiers relevant to the device.
 
   io-channel-names:
     type: string-array
-    description: Provided names of IO channel specifiers
+    description: |
+      Optional names given to the IO channel specifiers in the "io-channels" property.
 
   mboxes:
     type: phandle-array
-    description: mailbox / IPM channels specifiers
+    description: |
+      Mailbox / IPM channel specifiers relevant to the device.
     specifier-space: mbox
 
   mbox-names:
     type: string-array
-    description: Provided names of mailbox / IPM channel specifiers
+    description: |
+      Optional names given to the mbox specifiers in the "mboxes" property.
 
   power-domains:
     type: phandle-array
-    description: Power domain specifiers
+    description: |
+      Power domain specifiers relevant to the device.
 
   power-domain-names:
     type: string-array
-    description: Provided names of power domain specifiers
+    description: |
+      Optional names given to the power domain specifiers in the "power-domains" property.
 
   "#power-domain-cells":
     type: int
-    description: Number of cells in power-domains property
+    description: |
+      Number of cells in power-domains property
 
   zephyr,deferred-init:
     type: boolean