Mapping isa irqs to linux kernel irqs

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Taken from the the yahoo user's group...

> Is there a table or source somwhere that explains how ISA IRQs are > 'translated' to linux IRQs? Which numbers we should be looking for/at?

Basically the schematic and the kernel source code will provide this infomation. Below I'll explain where to look for this information I'll use the TS-7250 as an example...

You'll need the schematic http://www.embeddedarm.com/Manuals/TS-7250_Rev1.2.htm#AppendixE. This will allow you to find what ISA_IRQs are connected to what pins on the EP9302. You should see the following...

  • ISA_IRQ5 = EP9302 pin 168
  • ISA_IRQ6 = EP9302 pin 102
  • ISA_IRQ7 = EP9302 pin 101

Then you will need the EP9301 Data sheet http://www.cirrus.com/en/pubs/proDatasheet/EP9301_PP5.pdf to determine what signals are on each of these pins. You should see the following...

  • EP9302 pin 168 = FGPIO_3
  • EP9302 pin 102 = INT_1
  • EP9302 pin 101 = INT_3

Finally you can review the kernel source file include/asm-arm/arch/irqs.h to determine what Linux IRQs correspond to what ISA IRQs.

  • IRQGPIO2 (ISAIRQ5) = Linux IRQ 22
  • IRQEXT1 (ISAIRQ6) = Linux IRQ 33
  • IRQEXT3 (ISAIRQ7) = Linux IRQ 40
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