The ST m41t82 and m41t83 support programmable load capacitance from 3.5
pF to 17.4 pF. The hardware defaults to 12.5 pF.
The accuracy of the xtal can be calibrated precisely by adjusting the
load capacitance.
Add default, minimum, and maximum for the standard rtc property
quartz-load-femtofarads on compatible devices.
Signed-off-by: Dennis Lambe Jr <dennis@xxxxxxxxxxxxxx>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
---
Notes:
v2 -> v3:
added "Reviewed-by: Krzysztof Kozlowski" to changelog
v1 -> v2:
remove accidental wakeup-sources line
suggested by Krzysztof Kozlowski
spelling fix in changelog
.../devicetree/bindings/rtc/st,m41t80.yaml | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/Documentation/devicetree/bindings/rtc/st,m41t80.yaml b/Documentation/devicetree/bindings/rtc/st,m41t80.yaml
index fc9c6da6483f..6673adf6e99b 100644
--- a/Documentation/devicetree/bindings/rtc/st,m41t80.yaml
+++ b/Documentation/devicetree/bindings/rtc/st,m41t80.yaml
@@ -33,6 +33,11 @@ properties:
"#clock-cells":
const: 1
+ quartz-load-femtofarads:
+ default: 12500
+ minimum: 3500
+ maximum: 17375
+
clock-output-names:
maxItems: 1
description: From common clock binding to override the default output clock name.
@@ -46,6 +51,17 @@ properties:
allOf:
- $ref: rtc.yaml
+ - if:
+ not:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - st,m41t82
+ - st,m41t83
+ then:
+ properties:
+ quartz-load-femtofarads: false
unevaluatedProperties: false
--
2.25.1
