----- Original Message ----
From: Marc Jones <[EMAIL PROTECTED]>
To: Jonathan Sturges <[EMAIL PROTECTED]>
Cc: LinuxBIOS mailing list <[email protected]>
Sent: Tuesday, September 25, 2007 12:05:19 PM
Subject: Re: [LinuxBIOS] Two more CS5530 IRQ steering questions
Jonathan Sturges wrote:
>>> Jonathan Sturges wrote:
>>> Two additional questions about CS5530 IRQ steering:
>>> 1) Comments from Uwe Hermann and Peter Stuge have indicated that it's
>>> really better for the kernel to setup the steering registers. Why is this?
>>> It sounds like the BIOS is a good place to set these. I assume that a
>>> knowledgeable OS could change them if necessary? At the very least, it
>>> does sound like we all agree that it's OK to have LB setup the steering
>>> until Linux is fixed.
>>>
>>> 2) Question about irq_tables.c. Many of the CS5536 systems have a
>>> write_pirq_routing_table() in irq_tables.c that sets the steering
>>> registers. I'd like to be able to set the steering registers in CS5530
>>> systems too, but I'm not a software developer and I need some help. So in
>>> src/mainboard/artecgroup/dbe61/irq_tables.c, you have:
>>> /* Set up chipset IRQ steering. */
>>> pciAddr = 0x80000000 | (CHIPSET_DEV_NUM << 11) | 0x5C;
>>> chipset_irq_map = (PIRQD << 12 | PIRQC << 8 | PIRQB << 4 | PIRQA);
>>> printk_debug("%s(%08X, %04X)\n", __FUNCTION__, pciAddr,
>>> chipset_irq_map);
>>> outl(pciAddr & ~3, 0xCF8);
>>> outl(chipset_irq_map, 0xCFC);My main question with this block of code is
>>> what the two outl() calls are for. It looks like pciAddr gets the address
>>> of the 0x5c steering register, and chipset_irq_map sets the right bits to
>>> set all 4 PIRQ lines. But I'd expect to see the chipset_irq_map written to
>>> pciAddr.
>>>
>>> As an alternative, Kenji Noguchi used this code block to set the registers
>>> in a CS5530 system he's working on (posted 5-May-2007):
>>> device_t pdev;
>>> //CS5530A
>>> pdev = dev_find_slot(0, (0x12 << 3) + 0);
>>> pci_write_config8(pdev, 0x5c, 0xab);
>>> pci_write_config8(pdev, 0x5d, 0x09);
>>>
>>>
>>> This block makes more sense to me. Obviously the register values could be
>>> set by
>>> #defines, but it looks simpler to me.
>>>
>>> Bottom line is, before I implement IRQ steering for my CS5530 system, I
>>> want to understand what the first code block is doing, and if (or why) it's
>>> preferable over the 2nd code block. Any guidance is appreciated.
>>>
>>> thanks,
>>> Jonathan
>>
>>
>> outl(pciAddr & ~3, 0xCF8);
>> outl(chipset_irq_map, 0xCFC)
>>
>> is basically the same as
>>
>> pci_write_config8(pdev, 0x5c, 0xab);
>> pci_write_config8(pdev, 0x5d, 0x09);
>>
>>
>> CFC/CF8 is the PCI config space.
>
> Ahhh... thanks Marc, that was the clarification I needed.
>
> With that in mind, that block of code should work directly with the CS5530
> after defining CHIPSET_DEV_NUM appropriately. What about '0x80000000', is
> that a common base address applicable to all CS553x systems?
>
> thanks,
> Jonathan
DEV_NUM should be a constant for the 5530. It is always hooked up on the
same IDSEL. The 0x80000000 is standard for all i/o based PCI config
accesses. It indicates that it is a config access and not just a normal
PCI i/o access.
Marc
Marc,
I've implemented the CS5536-style IRQ steering register code from above in my
CS5530 system. This is what I'm using:
/* Set up chipset IRQ steering. */
pciAddr = 0x80000000 | (0x12 << 11) | 0x5C;
chipset_irq_map = (PIRQD << 12 | PIRQC << 8 | PIRQB << 4 | PIRQA);
printk_debug("%s(%08X, %04X)\n", __FUNCTION__, pciAddr,
chipset_irq_map);
outl(pciAddr & ~3, 0xCF8);
outl(chipset_irq_map, 0xCFC);
However, it doesn't seem to have worked entirely. If it had worked, I assume I
should be able to boot a standard Linux kernel and have IRQs worked for the
devices in the PIRQ table. Instead, these devices don't work, unless I boot a
kernel with the CS5530 IRQ router patch.
In the LB output, you get this from write_pirq_routing_table():
write_pirq_routing_table(8000905C, 99BA)
...which I think is right. It doesn't seem like there's much that could be
wrong here. Are the the steering bits reversed maybe? The high 8 bits are for
PIRQD and C, so that would screw things up if they were written to 0x5C, which
is the INTB/INTA register. Is there a reliable way to see the settings of the
steering bits from a running system?
thanks,
Jonathan
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