open-pic.rar_open

* 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)