Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 93 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/writing-bindings.rst b/Documentation/devicetree/bindings/writing-bindings.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+============================================================
+DOs and DON'Ts for designing and writing Devicetree bindings
+============================================================
+
+This is a list of common review feedback items focused on binding design. With
+every rule, there are exceptions and bindings have many gray areas.
+
+For guidelines related to patches, see
+Documentation/devicetree/bindings/submitting-patches.rst
+
+
+Overall design
+==============
+
+- DO attempt to make bindings complete even if a driver doesn't support some
+  features. For example, if a device has an interrupt, then include the
+  'interrupts' property even if the driver is only polled mode.
+
+- DON'T refer to Linux or "device driver" in bindings. Bindings should be
+  based on what the hardware has, not what an OS and driver currently support.
+
+- DO use node names matching the class of the device. Many standard names are
+  defined in the DT Spec. If there isn't one, consider adding it.
+
+- DO check that the example matches the documentation especially after making
+  review changes.
+
+- DON'T create nodes just for the sake of instantiating drivers. Multi-function
+  devices only need child nodes when the child nodes have their own DT
+  resources. A single node can be multiple providers (e.g. clocks and resets).
+
+- DON'T use 'syscon' alone without a specific compatible string. A 'syscon'
+  hardware block should have a compatible string unique enough to infer the
+  register layout of the entire block (at a minimum).
+
+
+Properties
+==========
+
+- DO make 'compatible' properties specific. DON'T use wildcards in compatible
+  strings. DO use fallback compatibles when devices are the same as or a subset
+  of prior implementations. DO add new compatibles in case there are new
+  features or bugs.
+
+- DO use a vendor prefix on device-specific property names. Consider if
+  properties could be common among devices of the same class. Check other
+  existing bindings for similar devices.
+
+- DON'T redefine common properties. Just reference the definition and define
+  constraints specific to the device.
+
+- DO use common property unit suffixes for properties with scientific units.
+  Recommended suffixes are listed at
+  https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
+
+- DO define properties in terms of constraints. How many entries? What are
+  possible values? What is the order?
+
+Typical cases and caveats
+=========================
+
+- Phandle entries, like clocks/dmas/interrupts/resets, should always be
+  explicitly ordered. Include the {clock,dma,interrupt,reset}-names if there is
+  more than one phandle. When used, both of these fields need the same
+  constraints (e.g.  list of items).
+
+- For names used in {clock,dma,interrupt,reset}-names, do not add any suffix,
+  e.g.: "tx" instead of "txirq" (for interrupt).
+
+- Properties without schema types (e.g. without standard suffix or not defined
+  by schema) need the type, even if this is an enum.
+
+- If schema includes other schema (e.g. /schemas/i2c/i2c-controller.yaml) use
+  "unevaluatedProperties:false". In other cases, usually use
+  "additionalProperties:false".
+
+- For sub-blocks/components of bigger device (e.g. SoC blocks) use rather
+  device-based compatible (e.g. SoC-based compatible), instead of custom
+  versioning of that component.
+  For example use "vendor,soc1234-i2c" instead of "vendor,i2c-v2".
+
+- "syscon" is not a generic property. Use vendor and type, e.g.
+  "vendor,power-manager-syscon".
+
+Board/SoC .dts Files
+====================
+
+- DO put all MMIO devices under a bus node and not at the top-level.
+
+- DO use non-empty 'ranges' to limit the size of child buses/devices. 64-bit
+  platforms don't need all devices to have 64-bit address and size.