This binding documents several properties that have been in use for quite
some time, and adds one new property 'no-reset', which controls whether the
Open PIC should be reset during runtime initialization.
The general formatting and interrupt specifier definition is based off of
Stuart Yoder's FSL MPIC binding.
Signed-off-by: Meador Inge <meador_i...@mentor.com>
CC: Hollis Blanchard <hollis_blanch...@mentor.com>
CC: Stuart Yoder <stuart.yo...@freescale.com>
---
Documentation/powerpc/dts-bindings/open-pic.txt | 115 +++++++++++++++++++++++
1 files changed, 115 insertions(+), 0 deletions(-)
create mode 100644 Documentation/powerpc/dts-bindings/open-pic.txt
diff --git a/Documentation/powerpc/dts-bindings/open-pic.txt
b/Documentation/powerpc/dts-bindings/open-pic.txt
new file mode 100644
index 0000000..447ef65
--- /dev/null
+++ b/Documentation/powerpc/dts-bindings/open-pic.txt
@@ -0,0 +1,115 @@
+* 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.
+
+PROPERTIES
+
+ NOTE: Many of these descriptions were paraphrased here from [1] to aid
+ readability.
+
+ - compatible
+ Usage: required
+ Value type: <string>
+ Definition: Specifies the compatibility list for the PIC. The
+ property value shall include "open-pic".
+
+ - reg
+ Usage: required
+ Value type: <prop-encoded-array>
+ Definition: Specifies the base physical address(s) and size(s) of this
+ PIC's addressable register space.
+
+ - interrupt-controller
+ Usage: required
+ Value type: <empty>
+ Definition: The presence of this property identifies the node
+ as an Open PIC. No property value should be defined.
+
+ - #interrupt-cells
+ Usage: required
+ Value type: <u32>
+ Definition: Specifies the number of cells needed to encode an
+ interrupt source. Shall be 2.
+
+ - #address-cells
+ Usage: required
+ Value type: <u32>
+ Definition: Specifies the number of cells needed to encode an
+ address. The value of this property shall always be 0.
+ As such, 'interrupt-map' nodes do not have to specify a
+ parent unit address.
+
+ - no-reset
+ Usage: optional
+ Value type: <empty>
+ Definition: The presence of this property indicates that the PIC
+ should not be reset during runtime initialization. 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> interrupt-number
+
+ Identifies the interrupt source.
+
+ <2nd-cell> 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
+
+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 should not be reset.
+ 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)
+
--
1.6.3.3
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
