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author | Sascha Hauer <s.hauer@pengutronix.de> | 2014-04-25 11:22:32 +0200 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2014-04-28 09:08:46 +0200 |
commit | 00ce25c6dcdae5582ae4be37147ab33678adc995 (patch) | |
tree | 41c93102ae304a61738c31353e3cb5336ef0b297 /dts/Bindings/open-pic.txt | |
parent | 0af79fbb6779921d3f1962773adb7fb57d3c89d4 (diff) | |
download | barebox-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>
Diffstat (limited to 'dts/Bindings/open-pic.txt')
-rw-r--r-- | dts/Bindings/open-pic.txt | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/dts/Bindings/open-pic.txt b/dts/Bindings/open-pic.txt new file mode 100644 index 0000000000..909a902dff --- /dev/null +++ b/dts/Bindings/open-pic.txt @@ -0,0 +1,98 @@ +* Open PIC Binding + +This binding specifies what properties must be available in the device tree +representation of an Open PIC compliant interrupt controller. This binding is +based on the binding defined for Open PIC in [1] and is a superset of that +binding. + +Required properties: + + NOTE: Many of these descriptions were paraphrased here from [1] to aid + readability. + + - compatible: Specifies the compatibility list for the PIC. The type + shall be <string> and the value shall include "open-pic". + + - reg: Specifies the base physical address(s) and size(s) of this + PIC's addressable register space. The type shall be <prop-encoded-array>. + + - interrupt-controller: The presence of this property identifies the node + as an Open PIC. No property value shall be defined. + + - #interrupt-cells: Specifies the number of cells needed to encode an + interrupt source. The type shall be a <u32> and the value shall be 2. + + - #address-cells: Specifies the number of cells needed to encode an + address. The type shall be <u32> and the value shall be 0. As such, + 'interrupt-map' nodes do not have to specify a parent unit address. + +Optional properties: + + - pic-no-reset: The presence of this property indicates that the PIC + shall not be reset during runtime initialization. No property value shall + be defined. The presence of this property also mandates that any + initialization related to interrupt sources shall be limited to sources + explicitly referenced in the device tree. + +* Interrupt Specifier Definition + + Interrupt specifiers consists of 2 cells encoded as + follows: + + - <1st-cell>: The interrupt-number that identifies the interrupt source. + + - <2nd-cell>: The level-sense information, encoded as follows: + 0 = low-to-high edge triggered + 1 = active low level-sensitive + 2 = active high level-sensitive + 3 = high-to-low edge triggered + +* Examples + +Example 1: + + /* + * An Open PIC interrupt controller + */ + mpic: pic@40000 { + // This is an interrupt controller node. + interrupt-controller; + + // No address cells so that 'interrupt-map' nodes which reference + // this Open PIC node do not need a parent address specifier. + #address-cells = <0>; + + // Two cells to encode interrupt sources. + #interrupt-cells = <2>; + + // Offset address of 0x40000 and size of 0x40000. + reg = <0x40000 0x40000>; + + // Compatible with Open PIC. + compatible = "open-pic"; + + // The PIC shall not be reset. + pic-no-reset; + }; + +Example 2: + + /* + * An interrupt generating device that is wired to an Open PIC. + */ + serial0: serial@4500 { + // Interrupt source '42' that is active high level-sensitive. + // Note that there are only two cells as specified in the interrupt + // parent's '#interrupt-cells' property. + interrupts = <42 2>; + + // The interrupt controller that this device is wired to. + interrupt-parent = <&mpic>; + }; + +* References + +[1] Power.org (TM) Standard for Embedded Power Architecture (TM) Platform + Requirements (ePAPR), Version 1.0, July 2008. + (http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf) + |