Re: [PATCH 3/4] rtc: ds1307: add calibration of_ for mt41txx chips.
From: Giulio Benetti
Date: Wed May 09 2018 - 14:34:05 EST
Hi Rob,
Il 08/05/2018 19:40, Rob Herring ha scritto:
On Tue, May 8, 2018 at 9:56 AM, Giulio Benetti
<giulio.benetti@xxxxxxxxxxxxxxxx> wrote:
m41txx chips can hold a calibration value to get really near to real
tick value.
Typo in the subject.
Add calibration property(ranging between (-31) and 31), so on every probe
calibration value will be written to rtc.
This is because ic could loose supply due to low battery.
Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
---
.../devicetree/bindings/rtc/rtc-ds1307.txt | 2 ++
Put all the binding changes in separate patch (or maybe 2: new
compatible and new properties).
drivers/rtc/rtc-ds1307.c | 33 +++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
index ce6469c1a516..d3d70a5495c5 100644
--- a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
+++ b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
@@ -34,6 +34,8 @@ Optional properties:
- trickle-diode-disable : ds1339, ds1340 and ds 1388 only
Do not use internal trickle charger diode
Should be given if internal trickle charger diode should be disabled
+- calibration: m41t0, m41t00, m41t11 only
Needs a vendor prefix.
Calibration of what and what are the units?
+ Set calibration value to correct external bias, ranging between (-31) and 31.
Example:
rtc1: ds1339@68 {
This is not a problem anymore since I've used standard rtc sysfs
"offset" instead of a dt-property as Alexandre pointed me out.
Thanks.
--
Giulio Benetti
CTO
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