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Interrupt occurs but UIC0 MSR is still 0

DISCUSSION Chris Dumoulin 2 participants 3 messages Jun 15, 2006 – Jun 16, 2006

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Chris Dumoulin

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#0 lore raw

Hi All,
I'm working with a 2.6 linux kernel in a board with a PPC405 in a Virtex II Pro FPGA. I'm trying to generate interrupts and handle them in a device driver that I've written. Here is the sequence of events that happen currently:
1. I generate an interrupt by setting registers in an interrupt controller we've got in the FPGA (it's a Xilinx LogicCORE OPB Interrupt Controller).
2. The function do_IRQ, in arch/powerpc/kernel/irq.c, is called.
3. ppc_md.get_irq is called from do_IRQ.
4. ppc_md.get_irq points to ppc4xx_pic_get_irq in arch/ppc/syslib/ppc4xx_pic.c.
5. ppc4xx_pic_get_irq reads the MSR from UIC0 to determine the IRQ. In my case, the MSR is all zero, so ppc4xx_pic_get_irq returns -1.
6. After this, we return from the interrupt, and do_IRQ is called again and again, going through the same steps indefinitely.

I've looked at the UIC0 registers, and the SR, MSR, and ER registers are all 0. How can an interrupt be triggered, but all the UIC0 bits are 0? Is it possible that I'm not actually accessing UIC0? I've got the following in my arch/ppc/platforms/4xx/my_board.h file:
#define DCRN_UIC0_BASE 0x0C0
#define UIC0 DCRN_UIC0_BASE

Any ideas would be appreciated.

Cheers,
Chris Dumoulin

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*--Christopher Dumoulin--*
Software Team Leader

<http://ics-ltd.com/>
<http://ics-ltd.com/>

Interactive Circuits and Systems Ltd.
5430 Canotek Road
Ottawa, ON
K1J 9G2
(613)749-9241
1-800-267-9794 (USA only)

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#1 lore raw
Quoted 8 lines · Chris Dumoulin

Hi All,
I'm working with a 2.6 linux kernel in a board with a PPC405 in a Virtex II Pro FPGA. I'm trying to generate interrupts and handle them in a device driver that I've written.
Here is the sequence of events that happen currently:
1. I generate an interrupt by setting registers in an interrupt controller we've got in the FPGA (it's a Xilinx LogicCORE OPB Interrupt Controller).

Quoted 8 lines

2. The function do_IRQ, in arch/powerpc/kernel/irq.c, is called.
3. ppc_md.get_irq is called from do_IRQ.
4. ppc_md.get_irq points to ppc4xx_pic_get_irq in arch/ppc/syslib/ppc4xx_pic.c.
5. ppc4xx_pic_get_irq reads the MSR from UIC0 to determine the IRQ. In my case, the MSR is all zero, so ppc4xx_pic_get_irq returns -1.
6. After this, we return from the interrupt, and do_IRQ is called again and again, going through the same steps indefinitely.

I don't think ppc4xx_pic.c is correct file for Xilinx Virtex II Pro. You should be using xilinx_pic.c probably.

Signature · 1 line
Eugene
author
#2 lore raw

Thanks Eugene,
You were right on the money. I changed the appropriate Makefile to include xilinx_pic.c, instead of ppc4xx_pic.c, and things are now working. It seems like the UIC of the PPC405 isn't used (or doesn't exist) in the Virtex II Pro. The interrupt servicing code interfaces with an external interrupt controller (OPB Interrupt Controller, in my case) instead.

Regards,
Chris Dumoulin

Quoted 16 lines · Eugene Surovegin
Quoted 10 lines · Chris Dumoulin

Hi All,
I'm working with a 2.6 linux kernel in a board with a PPC405 in a Virtex II Pro FPGA. I'm trying to generate interrupts and handle them in a device driver that I've written. Here is the sequence of events that happen currently:
1. I generate an interrupt by setting registers in an interrupt controller we've got in the FPGA (it's a Xilinx LogicCORE OPB Interrupt Controller).
2. The function do_IRQ, in arch/powerpc/kernel/irq.c, is called.
3. ppc_md.get_irq is called from do_IRQ.
4. ppc_md.get_irq points to ppc4xx_pic_get_irq in arch/ppc/syslib/ppc4xx_pic.c.
5. ppc4xx_pic_get_irq reads the MSR from UIC0 to determine the IRQ. In my case, the MSR is all zero, so ppc4xx_pic_get_irq returns -1.
6. After this, we return from the interrupt, and do_IRQ is called again and again, going through the same steps indefinitely.

I don't think ppc4xx_pic.c is correct file for Xilinx Virtex II Pro. You should be using xilinx_pic.c probably.

Signature · 15 lines
*--Christopher Dumoulin--*
Software Team Leader

<http://ics-ltd.com/>
<http://ics-ltd.com/>

Interactive Circuits and Systems Ltd.
5430 Canotek Road
Ottawa, ON
K1J 9G2
(613)749-9241
1-800-267-9794 (USA only)

------------------------------------------------------------------------
This e-mail is private and confidential and is for the addressee only. If misdirected, please notify us by telephone and confirm that it has been deleted from your system and any hard copies destroyed. You are strictly prohibited from using, printing, distributing or disseminating it or any information contained in it save to the intended recipient.