April 8, 2001
J. D. Monnier

Notes on Interrupts Programming
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We have been able to get the PCI-PMC interrupts to work.  I appreciate
all of your help. We were VERY close to getting them work at the time
of my last email and I will tell you what worked below.

ps. -- one last EASY question, before I sign off: what is the maximum
update rate for the tick routines?  they are set at 1000 Hz, but I
couldn't see any good reason we can't run faster -- we might want to.
[see sysClkRateSet( ) in mv2400 BSP sysLib docs, and in configuration
files].


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Important Steps:

 1. From FPGA point of view, we had to enable the PCI-PMC interrupts on
the plx9050:

Outl((unsigned long)(plx9050regs + intcsr),swaplong(0x43));  
/* Make LINT1 active high  and enable PCI interrupts*/
// See plx9050 manuals (/home/iota/Documentation/plx9050.pdf) for all bits
//    of control register

This code is in files like: /home/iota/mc/DAQ/PICNIC.cpp

 2. From the mv2400 pint of view: As others said, it turns out the MPIC
(Multi-Processor Interrupt Controller) was enabled already and that the
MASKBIT can be set through the intEnable command [I confirmed through
direct PCIbus read/writes to the appropriate interrupt registers].

   For some not-quite-clear reason, the interrupt is coming on the
PMC_INT_LVL4 interrupt level rather than the PMC_INT_LVL1 interrupt which
we thought was mapped from the PCI INTA interrupt.  Based on some
documentation (/home/iota/Documentation/PowerPlusII.html), this can be
understood if the PMC is on the "secondary" PCI bus rather than the
"primary" PCI bus -- however, we could not find this discussed anywhere
else -- any help in understanding this small mystery would be interested.

So:  to connect and enable the interrupt to our function test_handler:

connectStatus = intConnect(INUM_TO_IVEC(INT_VEC_IRQ0 +
 PMC_INT_LVL4),(VOIDFUNCPTR)test_handler,(int)PMC_INT_LVL4);
enableStatus = intEnable( PMC_INT_LVL4 ) ;

Note: intConnect and intEnable are wired to the mv2400 dependent routines
in /home/iota/target/config/mv2400/hawkMPIC.c routines: sysMpicIntConnect
and sysMpicIntEnable

3. Another interesting thing, is that to include the proper defines 
(e.g., for INT_VEC_IRQ0 and PMC_INT_LVL4) we had to include a number of
header files.  Importantly we had to also include the statement

#define INCLUDE_MPIC so the header files are interpreted correctly!!


A minimal set of header files that does the job:

#include "intLib.h"
#include "iv.h"  // or #include "arch/ppc/ivPpc.h"
#define INCLUDE_MPIC   // Required for correct MACROS in mv2400.h
#include "mv2400.h"