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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 123 |
1 files changed, 87 insertions, 36 deletions
diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index eaa0c3285ac..6d5a5a0fa5e 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -1108,42 +1108,7 @@ See appendix A for an example partial SOC node definition for the MPC8540. -2) Specifying interrupt information for SOC devices ---------------------------------------------------- - -Each device that is part of an SOC and which generates interrupts -should have the following properties: - - - interrupt-parent : contains the phandle of the interrupt - controller which handles interrupts for this device - - interrupts : a list of tuples representing the interrupt - number and the interrupt sense and level for each interrupt - for this device. - -This information is used by the kernel to build the interrupt table -for the interrupt controllers in the system. - -Sense and level information should be encoded as follows: - - Devices connected to openPIC-compatible controllers should encode - sense and polarity as follows: - - 0 = low to high edge sensitive type enabled - 1 = active low level sensitive type enabled - 2 = active high level sensitive type enabled - 3 = high to low edge sensitive type enabled - - ISA PIC interrupt controllers should adhere to the ISA PIC - encodings listed below: - - 0 = active low level sensitive type enabled - 1 = active high level sensitive type enabled - 2 = high to low edge sensitive type enabled - 3 = low to high edge sensitive type enabled - - - -3) Representing devices without a current OF specification +2) Representing devices without a current OF specification ---------------------------------------------------------- Currently, there are many devices on SOCs that do not have a standard @@ -1732,6 +1697,92 @@ platforms are moved over to use the flattened-device-tree model. More devices will be defined as this spec matures. +VII - Specifying interrupt information for devices +=================================================== + +The device tree represents the busses and devices of a hardware +system in a form similar to the physical bus topology of the +hardware. + +In addition, a logical 'interrupt tree' exists which represents the +hierarchy and routing of interrupts in the hardware. + +The interrupt tree model is fully described in the +document "Open Firmware Recommended Practice: Interrupt +Mapping Version 0.9". The document is available at: +<http://playground.sun.com/1275/practice>. + +1) interrupts property +---------------------- + +Devices that generate interrupts to a single interrupt controller +should use the conventional OF representation described in the +OF interrupt mapping documentation. + +Each device which generates interrupts must have an 'interrupt' +property. The interrupt property value is an arbitrary number of +of 'interrupt specifier' values which describe the interrupt or +interrupts for the device. + +The encoding of an interrupt specifier is determined by the +interrupt domain in which the device is located in the +interrupt tree. The root of an interrupt domain specifies in +its #interrupt-cells property the number of 32-bit cells +required to encode an interrupt specifier. See the OF interrupt +mapping documentation for a detailed description of domains. + +For example, the binding for the OpenPIC interrupt controller +specifies an #interrupt-cells value of 2 to encode the interrupt +number and level/sense information. All interrupt children in an +OpenPIC interrupt domain use 2 cells per interrupt in their interrupts +property. + +The PCI bus binding specifies a #interrupt-cell value of 1 to encode +which interrupt pin (INTA,INTB,INTC,INTD) is used. + +2) interrupt-parent property +---------------------------- + +The interrupt-parent property is specified to define an explicit +link between a device node and its interrupt parent in +the interrupt tree. The value of interrupt-parent is the +phandle of the parent node. + +If the interrupt-parent property is not defined for a node, it's +interrupt parent is assumed to be an ancestor in the node's +_device tree_ hierarchy. + +3) OpenPIC Interrupt Controllers +-------------------------------- + +OpenPIC interrupt controllers require 2 cells to encode +interrupt information. The first cell defines the interrupt +number. The second cell defines the sense and level +information. + +Sense and level information should be encoded as follows: + + 0 = low to high edge sensitive type enabled + 1 = active low level sensitive type enabled + 2 = active high level sensitive type enabled + 3 = high to low edge sensitive type enabled + +4) ISA Interrupt Controllers +---------------------------- + +ISA PIC interrupt controllers require 2 cells to encode +interrupt information. The first cell defines the interrupt +number. The second cell defines the sense and level +information. + +ISA PIC interrupt controllers should adhere to the ISA PIC +encodings listed below: + + 0 = active low level sensitive type enabled + 1 = active high level sensitive type enabled + 2 = high to low edge sensitive type enabled + 3 = low to high edge sensitive type enabled + Appendix A - Sample SOC node for MPC8540 ======================================== |