Re: [PATCH] Preliminary MPIC MSI backend

From: Segher Boessenkool
Date: Sat Sep 30 2006 - 04:43:40 EST

A pretty hackish MPIC backend, just enough to flesh out the design.
Based on code from Segher.

It's pretty alright, and very hackish ;-) I'll sign off on it,
but some comments...

Signed-off-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>

+static int msi_mpic_check(struct pci_dev *pdev, int num,
+ struct msix_entry *entries, int type)
+ /* The irq allocator needs more work to support MSI-X/multi-MSI */
+ if (type == PCI_CAP_ID_MSIX || num != 1)
+ return 1;

I never tested any MSI-X, so maybe keep MSI-X disabled completely
for now?

+static int msi_mpic_alloc(struct pci_dev *pdev, int num,
+ struct msix_entry *entries, int type)
+ irq_hw_number_t hwirq;
+ unsigned int virq;
+ /* We need a smarter allocator for MSI-X/multi-MSI */
+ hwirq = irq_map[pdev->irq].hwirq;
+ hwirq += 100;

Yep, that's the main problem with this code. A sanity check to
make sure the number isn't >= 120 would be good, too.

+ set_irq_type(virq, IRQ_TYPE_EDGE_RISING);

I also had some code to show MSI IRQs as "MSI" instead of "EDGE"
in /proc/interrupts, maybe you want to add a generic version of
that? Or maybe you have, and I judt didn't see it.

+static int msi_mpic_setup_msi_msg(struct pci_dev *pdev,
+ struct msix_entry *entry, struct msi_msg *msg, int type)
+ msg->address_lo = 0xfee00000; /* XXX What is this value? */
+ msg->address_hi = 0;
+ msg->data = pdev->irq | 0x8000;

Lose the | 0x8000 part, that was an old experiment to work around
U3/U4 MPIC brokenness (and it didn't work).

+static int msi_mpic_init(void)
+ /* XXX Do this in mpic_init ? */
+ pr_debug("mpic_msi_init: Registering MPIC MSI ops.\n");
+ ppc_md.get_msi_ops = mpic_get_msi_ops;

It's best to do this in the platform code I think.


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