powerpc: document the FSL MPIC message register binding

This binding documents how the message register blocks found in some FSL
MPIC implementations shall be represented in a device tree.

Signed-off-by: Meador Inge <meador_inge@mentor.com>
Signed-off-by: Jia Hongtao <B38951@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This commit is contained in:
Jia Hongtao 2012-03-01 17:32:34 +08:00 committed by Kumar Gala
parent 8626816e90
commit e96dde2b5e

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* FSL MPIC Message Registers
This binding specifies what properties must be available in the device tree
representation of the message register blocks found in some FSL MPIC
implementations.
Required properties:
- compatible: Specifies the compatibility list for the message register
block. The type shall be <string-list> and the value shall be of the form
"fsl,mpic-v<version>-msgr", where <version> is the version number of
the MPIC containing the message registers.
- reg: Specifies the base physical address(s) and size(s) of the
message register block's addressable register space. The type shall be
<prop-encoded-array>.
- interrupts: Specifies a list of interrupt-specifiers which are available
for receiving interrupts. Interrupt-specifier consists of two cells: first
cell is interrupt-number and second cell is level-sense. The type shall be
<prop-encoded-array>.
Optional properties:
- mpic-msgr-receive-mask: Specifies what registers in the containing block
are allowed to receive interrupts. The value is a bit mask where a set
bit at bit 'n' indicates that message register 'n' can receive interrupts.
Note that "bit 'n'" is numbered from LSB for PPC hardware. The type shall
be <u32>. If not present, then all of the message registers in the block
are available.
Aliases:
An alias should be created for every message register block. They are not
required, though. However, a particular implementation of this binding
may require aliases to be present. Aliases are of the form
'mpic-msgr-block<n>', where <n> is an integer specifying the block's number.
Numbers shall start at 0.
Example:
aliases {
mpic-msgr-block0 = &mpic_msgr_block0;
mpic-msgr-block1 = &mpic_msgr_block1;
};
mpic_msgr_block0: mpic-msgr-block@41400 {
compatible = "fsl,mpic-v3.1-msgr";
reg = <0x41400 0x200>;
// Message registers 0 and 2 in this block can receive interrupts on
// sources 0xb0 and 0xb2, respectively.
interrupts = <0xb0 2 0xb2 2>;
mpic-msgr-receive-mask = <0x5>;
};
mpic_msgr_block1: mpic-msgr-block@42400 {
compatible = "fsl,mpic-v3.1-msgr";
reg = <0x42400 0x200>;
// Message registers 0 and 2 in this block can receive interrupts on
// sources 0xb4 and 0xb6, respectively.
interrupts = <0xb4 2 0xb6 2>;
mpic-msgr-receive-mask = <0x5>;
};