From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sam Ravnborg Subject: [PATCH v2 2/5] dt-binding: pcf8523: add xtal load capacitance Date: Tue, 8 Jan 2019 19:54:11 +0100 Message-ID: <20190108185414.26922-3-sam@ravnborg.org> References: <20190108185414.26922-1-sam@ravnborg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190108185414.26922-1-sam@ravnborg.org> Sender: linux-kernel-owner@vger.kernel.org To: Alessandro Zummo , Alexandre Belloni , Andrew Jeffery , Fabio Estevam , Joel Stanley , Mark Rutland , Rob Herring , Russell King , Sascha Hauer , =?UTF-8?q?Urs=20F=C3=A4ssler?= , Shawn Guo , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org Cc: Sam Ravnborg , =?UTF-8?q?S=C3=B8ren=20Andersen?= List-Id: devicetree@vger.kernel.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 Signed-off-by: Sam Ravnborg Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: Rob Herring Cc: Mark Rutland --- 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..214ac5d26df7 --- /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: pcf8523@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 7c8da6926095..e07b15d151ac 100644 --- a/Documentation/devicetree/bindings/rtc/rtc.txt +++ b/Documentation/devicetree/bindings/rtc/rtc.txt @@ -51,7 +51,6 @@ 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