[PATCH RFC 1/2] dt-bindings: mfd: aspeed-lpc: Document lpcN alias for multi-instance SoCs

[Yu-Che Hsieh]

Some SoCs (e.g. AST2700) expose more than one physical LPC controller
instance. Downstream devices such as KCS channels need a stable,
globally-unique index derived from which LPC controller instance they
belong to, so document the "lpcN" alias convention on the LPC
controller node that lets DT authors assign a fixed index per
instance, mirroring the existing alias-based numbering convention used
by mmc/i2c/spi/serial.

Signed-off-by: Yu-Che Hsieh <yc_hsieh@xxxxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml b/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml
index cbc3a2485a2f..81c12e0fb312 100644
--- a/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml
+++ b/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml
@@ -35,6 +35,13 @@ description:
   configuration, therefore the host portion of the controller is exposed as a
   syscon as a means to arbitrate access.
 
+  On SoCs that expose more than one LPC controller instance, it is possible to
+  assign a fixed index to a given instance (and thus to downstream devices
+  such as KCS channels that must be uniquely identified system-wide) by
+  defining an "lpcN" alias for it in the /aliases device tree node. If no such
+  alias is present, the SoC is treated as having a single LPC controller
+  instance.
+
 properties:
   compatible:
     items:

-- 
2.34.1