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author | Pekka Enberg <penberg@kernel.org> | 2011-03-11 19:10:45 +0300 |
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committer | Pekka Enberg <penberg@kernel.org> | 2011-03-11 19:10:45 +0300 |
commit | c9149556756d56c68451a4a8735c37e7062fd3d7 (patch) | |
tree | a2dae56b22adaa9a23c8f92f30c3b3ad3b610850 /Documentation/devicetree/bindings/powerpc/fsl/mpic.txt | |
parent | d71f606f687ef9d0cdddfd3619ca7cb9a0b3fb63 (diff) | |
parent | 5bfe53a77e8a3ffce4a10003c75f464a138e272d (diff) | |
download | linux-c9149556756d56c68451a4a8735c37e7062fd3d7.tar.xz |
Merge branch 'slab/rcu' into slab/next
Conflicts:
mm/slub.c
Diffstat (limited to 'Documentation/devicetree/bindings/powerpc/fsl/mpic.txt')
-rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/mpic.txt | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt b/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt new file mode 100644 index 000000000000..71e39cf3215b --- /dev/null +++ b/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt @@ -0,0 +1,42 @@ +* OpenPIC and its interrupt numbers on Freescale's e500/e600 cores + +The OpenPIC specification does not specify which interrupt source has to +become which interrupt number. This is up to the software implementation +of the interrupt controller. The only requirement is that every +interrupt source has to have an unique interrupt number / vector number. +To accomplish this the current implementation assigns the number zero to +the first source, the number one to the second source and so on until +all interrupt sources have their unique number. +Usually the assigned vector number equals the interrupt number mentioned +in the documentation for a given core / CPU. This is however not true +for the e500 cores (MPC85XX CPUs) where the documentation distinguishes +between internal and external interrupt sources and starts counting at +zero for both of them. + +So what to write for external interrupt source X or internal interrupt +source Y into the device tree? Here is an example: + +The memory map for the interrupt controller in the MPC8544[0] shows, +that the first interrupt source starts at 0x5_0000 (PIC Register Address +Map-Interrupt Source Configuration Registers). This source becomes the +number zero therefore: + External interrupt 0 = interrupt number 0 + External interrupt 1 = interrupt number 1 + External interrupt 2 = interrupt number 2 + ... +Every interrupt number allocates 0x20 bytes register space. So to get +its number it is sufficient to shift the lower 16bits to right by five. +So for the external interrupt 10 we have: + 0x0140 >> 5 = 10 + +After the external sources, the internal sources follow. The in core I2C +controller on the MPC8544 for instance has the internal source number +27. Oo obtain its interrupt number we take the lower 16bits of its memory +address (0x5_0560) and shift it right: + 0x0560 >> 5 = 43 + +Therefore the I2C device node for the MPC8544 CPU has to have the +interrupt number 43 specified in the device tree. + +[0] MPC8544E PowerQUICCTM III, Integrated Host Processor Family Reference Manual + MPC8544ERM Rev. 1 10/2007 |