MPIC ISU

[Kumar Gala]

On Jan 16, 2008, at 12:03 AM, vb wrote:

> Greetings,
>
> I am trying to write a BSP for an 8245 based device. One thing which
> really gets me puzzled is the 'ISU' facility in
> arch/powerpc/sysdev/mpic.c, there is also a notion of ISU-less
> platforms, etc. I looked through the chip's programmer's reference,
> even read the original AMD/Cypress OpenPIC specification - not a clue.
>
> What is it, at the very least - what does ISU stand for?
>
> I would really appreciate any hints,

Interrupt service unit.  I believe its an IBM concept.

For 8245 can you look at what the linkstation port is doing and mimic  
that.  I believe its an 8245 or 8241 so it should be close to what you  
need.

         mpic = mpic_alloc(dnp, paddr, MPIC_PRIMARY |  
MPIC_WANTS_RESET, 4, 32, " EPIC     ");
         BUG_ON(mpic == NULL);

         /* PCI IRQs */
         mpic_assign_isu(mpic, 0, paddr + 0x10200);

         /* I2C */
         mpic_assign_isu(mpic, 1, paddr + 0x11000);

         /* ttyS0, ttyS1 */
         mpic_assign_isu(mpic, 2, paddr + 0x11100);

         mpic_init(mpic);

- k