[PATCH v3 01/13] spi: dt-bindings: allow spi-max-frequency to specify a frequency pair

[Santhosh Kumar K]

Some SPI controllers support high-speed operating modes that require
controller-side configuration before the device can be driven at its
rated maximum frequency. In these cases two frequencies are relevant:
a conservative speed usable without any such configuration, and the
maximum speed achievable once the controller is set up accordingly.

The existing spi-max-frequency property accepts only a single u32,
which cannot express this distinction. Extend it to accept either a
single value (retaining full backward compatibility) or a two-element
array [base-frequency, max-frequency], where base-frequency is the
conservative operating speed and max-frequency is the highest speed
the device supports after controller-side configuration.

Signed-off-by: Santhosh Kumar K <s-k6@xxxxxx>
---
 .../devicetree/bindings/spi/spi-peripheral-props.yaml  | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 880a9f624566..c88f6f3a1801 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -41,9 +41,15 @@ properties:
       The device requires the LSB first mode.
 
   spi-max-frequency:
-    $ref: /schemas/types.yaml#/definitions/uint32
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 1
+    maxItems: 2
     description:
-      Maximum SPI clocking speed of the device in Hz.
+      SPI clocking speed of the device in Hz. Either a single maximum
+      frequency, or two values [base-frequency, max-frequency] where
+      base-frequency is the conservative speed and max-frequency is the
+      highest speed the device supports after controller-side configurations
+      such as data training.
 
   spi-cs-setup-delay-ns:
     description:
-- 
2.34.1