From: Sam Ravnborg <sam@ravnborg.org>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: "Alessandro Zummo" <a.zummo@towertech.it>,
"Andrew Jeffery" <andrew@aj.id.au>,
"Fabio Estevam" <fabio.estevam@nxp.com>,
"Joel Stanley" <joel@jms.id.au>,
"Mark Rutland" <mark.rutland@arm.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Russell King" <linux@armlinux.org.uk>,
"Sascha Hauer" <s.hauer@pengutronix.de>,
"Urs Fässler" <urs.fassler@bbv.ch>,
"Shawn Guo" <shawnguo@kernel.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-rtc@vger.kernel.org, "Sam Ravnborg" <sam@ravnborg.org>,
"Søren Andersen" <san@skov.dk>
Subject: [PATCH v3 3/6] dt-binding: pcf8523: add xtal load capacitance
Date: Sat, 19 Jan 2019 10:00:28 +0100 [thread overview]
Message-ID: <20190119090031.29147-4-sam@ravnborg.org> (raw)
In-Reply-To: <20190119090031.29147-1-sam@ravnborg.org>
The NXP pcf8523 supports two different xtal load capacitance
- 7000fF (7pF) HW default
- 12500fF (12.5pF) Minimum power consumption, driver default
To obtain a precise RTC the pcf8523 must be configured
with the correct capacitance load of the xtal.
Add a property to specify the xtal capacitance load.
The default value matches that of the current Linux driver.
With a dedicated binding remove the entry in rtc.txt
Signed-off-by: Søren Andersen <san@skov.dk>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Mark Rutland <mark.rutland@arm.com>
---
Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt | 18 ++++++++++++++++++
Documentation/devicetree/bindings/rtc/rtc.txt | 1 -
2 files changed, 18 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
new file mode 100644
index 000000000000..0b1080c60f63
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
@@ -0,0 +1,18 @@
+* NXP PCF8523 Real Time Clock
+
+Required properties:
+- compatible: Should contain "nxp,pcf8523".
+- reg: I2C address for chip.
+
+Optional property:
+- quartz-load-femtofarads: The capacitive load of the quartz(x-tal),
+ expressed in femto Farad (fF). Valid values are 7000 and 12500.
+ Default value (if no value is specified) is 12500fF.
+
+Example:
+
+pcf8523: rtc@68 {
+ compatible = "nxp,pcf8523";
+ reg = <0x68>;
+ quartz-load-femtofarads = <7000>;
+};
diff --git a/Documentation/devicetree/bindings/rtc/rtc.txt b/Documentation/devicetree/bindings/rtc/rtc.txt
index 41eb335ea816..6d726a801d21 100644
--- a/Documentation/devicetree/bindings/rtc/rtc.txt
+++ b/Documentation/devicetree/bindings/rtc/rtc.txt
@@ -55,7 +55,6 @@ isil,isl12022 Intersil ISL12022 Real-time Clock
microcrystal,rv3029 Real Time Clock Module with I2C-Bus
nxp,pcf2127 Real-time clock
nxp,pcf2129 Real-time clock
-nxp,pcf8523 Real-time Clock
nxp,pcf8563 Real-time clock/calendar
nxp,pcf85063 Tiny Real-Time Clock
pericom,pt7c4338 Real-time Clock Module
--
2.12.0
next prev parent reply other threads:[~2019-01-19 9:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-19 9:00 [PATCH v3 0/6] add quartz load support to NXP rtc drivers Sam Ravnborg
2019-01-19 9:00 ` [PATCH v3 1/6] devicetree: property-units: Add femtofarads unit Sam Ravnborg
2019-01-19 9:00 ` [PATCH v3 2/6] dt-bindings: rtc: Add quartz-load-femtofarads property Sam Ravnborg
2019-01-21 15:24 ` Rob Herring
2019-01-19 9:00 ` Sam Ravnborg [this message]
2019-01-19 9:00 ` [PATCH v3 4/6] dt-binding: pcf85063: add xtal load capacitance Sam Ravnborg
2019-01-21 15:25 ` Rob Herring
2019-01-19 9:00 ` [PATCH v3 5/6] rtc: pcf8523: set xtal load capacitance from DT Sam Ravnborg
2019-01-19 9:00 ` [PATCH v3 6/6] rtc: pcf85063: " Sam Ravnborg
2019-01-22 17:57 ` [PATCH v3 0/6] add quartz load support to NXP rtc drivers Alexandre Belloni
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