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authorSascha Hauer <s.hauer@pengutronix.de>2014-04-25 11:22:32 +0200
committerSascha Hauer <s.hauer@pengutronix.de>2014-04-28 09:08:46 +0200
commit00ce25c6dcdae5582ae4be37147ab33678adc995 (patch)
tree41c93102ae304a61738c31353e3cb5336ef0b297 /dts/Bindings/gpio/spear_spics.txt
parent0af79fbb6779921d3f1962773adb7fb57d3c89d4 (diff)
downloadbarebox-00ce25c6dcdae5582ae4be37147ab33678adc995.tar.gz
barebox-00ce25c6dcdae5582ae4be37147ab33678adc995.tar.xz
Add devicetree source files as of Linux-3.15-rc2
This adds the Linux dts files to barebox. The dts files are generated from Ian Campbells device-tree-rebasing.git: git://xenbits.xen.org/people/ianc/device-tree-rebasing.git The dts are found in dts/ in the barebox repository and will be updated from upstream regularly, probably for each upstream -rc. To keep the synchronization with upstream easy no changes to the original files are allowed under dts/. Instead changes to upstream dts files will be done using overlays in arch/$ARCH/dts/. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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diff --git a/dts/Bindings/gpio/spear_spics.txt b/dts/Bindings/gpio/spear_spics.txt
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+=== ST Microelectronics SPEAr SPI CS Driver ===
+
+SPEAr platform provides a provision to control chipselects of ARM PL022 Prime
+Cell spi controller through its system registers, which otherwise remains under
+PL022 control. If chipselect remain under PL022 control then they would be
+released as soon as transfer is over and TxFIFO becomes empty. This is not
+desired by some of the device protocols above spi which expect (multiple)
+transfers without releasing their chipselects.
+
+Chipselects can be controlled by software by turning them as GPIOs. SPEAr
+provides another interface through system registers through which software can
+directly control each PL022 chipselect. Hence, it is natural for SPEAr to export
+the control of this interface as gpio.
+
+Required properties:
+
+ * compatible: should be defined as "st,spear-spics-gpio"
+ * reg: mentioning address range of spics controller
+ * st-spics,peripcfg-reg: peripheral configuration register offset
+ * st-spics,sw-enable-bit: bit offset to enable sw control
+ * st-spics,cs-value-bit: bit offset to drive chipselect low or high
+ * st-spics,cs-enable-mask: chip select number bit mask
+ * st-spics,cs-enable-shift: chip select number program offset
+ * gpio-controller: Marks the device node as gpio controller
+ * #gpio-cells: should be 1 and will mention chip select number
+
+All the above bit offsets are within peripcfg register.
+
+Example:
+-------
+spics: spics@e0700000{
+ compatible = "st,spear-spics-gpio";
+ reg = <0xe0700000 0x1000>;
+ st-spics,peripcfg-reg = <0x3b0>;
+ st-spics,sw-enable-bit = <12>;
+ st-spics,cs-value-bit = <11>;
+ st-spics,cs-enable-mask = <3>;
+ st-spics,cs-enable-shift = <8>;
+ gpio-controller;
+ #gpio-cells = <2>;
+};
+
+
+spi0: spi@e0100000 {
+ status = "okay";
+ num-cs = <3>;
+ cs-gpios = <&gpio1 7 0>, <&spics 0>,
+ <&spics 1>;
+ ...
+}