MSI: Give archs the option to allocate all MSI/Xs at once.

This patch introduces an optional function, arch_setup_msi_irqs(),
(note the plural) which gives an arch the opportunity to do per-device
setup for MSI/X and then allocate all the requested MSI/Xs at once.

If that's not required by the arch, the default version simply calls
arch_setup_msi_irq() for each MSI irq required.

arch_setup_msi_irqs() is passed a pdev, attached to the pdev is a list
of msi_descs with irq == 0, it is up to the arch to connect these up to
an irq (via set_irq_msi()) or return an error. For convenience the number
of vectors and the type are passed also.

All msi_descs with irq != 0 are considered allocated, and the arch
teardown routine will be called on them when necessary.

The existing semantics of pci_enable_msix() are that if the requested
number of irqs can not be allocated, the maximum number that _could_ be
allocated is returned. To support that, we define that in case of an
error from arch_setup_msi_irqs(), the number of msi_descs with irq != 0
are considered allocated, and are counted toward the "max that could be
allocated".

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 88362f1..c71e8e4 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -334,13 +334,15 @@ static int msi_capability_init(struct pci_dev *dev)
                        msi_mask_bits_reg(pos, is_64bit_address(control)),
                        maskbits);
        }
+       list_add(&entry->list, &dev->msi_list);
+
        /* Configure MSI capability structure */
-       ret = arch_setup_msi_irq(dev, entry);
+       ret = arch_setup_msi_irqs(dev, 1, PCI_CAP_ID_MSI);
        if (ret) {
+               list_del(&entry->list);
                kfree(entry);
                return ret;
        }
-       list_add(&entry->list, &dev->msi_list);
 
        /* Set MSI enabled bits  */
        pci_intx(dev, 0);               /* disable intx */
@@ -365,7 +367,7 @@ static int msix_capability_init(struct pci_dev *dev,
                                struct msix_entry *entries, int nvec)
 {
        struct msi_desc *entry;
-       int irq, pos, i, j, nr_entries, ret;
+       int pos, i, j, nr_entries, ret;
        unsigned long phys_addr;
        u32 table_offset;
        u16 control;
@@ -404,30 +406,33 @@ static int msix_capability_init(struct pci_dev *dev,
                entry->dev = dev;
                entry->mask_base = base;
 
-               /* Configure MSI-X capability structure */
-               ret = arch_setup_msi_irq(dev, entry);
-               if (ret) {
-                       kfree(entry);
-                       break;
-               }
-               entries[i].vector = entry->irq;
                list_add(&entry->list, &dev->msi_list);
        }
-       if (i != nvec) {
-               int avail = i - 1;
-               i--;
-               for (; i >= 0; i--) {
-                       irq = (entries + i)->vector;
-                       msi_free_irq(dev, irq);
-                       (entries + i)->vector = 0;
+
+       ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
+       if (ret) {
+               int avail = 0;
+               list_for_each_entry(entry, &dev->msi_list, list) {
+                       if (entry->irq != 0) {
+                               avail++;
+                               msi_free_irq(dev, entry->irq);
+                       }
                }
+
                /* If we had some success report the number of irqs
                 * we succeeded in setting up.
                 */
-               if (avail <= 0)
-                       avail = -EBUSY;
+               if (avail == 0)
+                       avail = ret;
                return avail;
        }
+
+       i = 0;
+       list_for_each_entry(entry, &dev->msi_list, list) {
+               entries[i].vector = entry->irq;
+               set_irq_msi(entry->irq, entry);
+               i++;
+       }
        /* Set MSI-X enabled bits */
        pci_intx(dev, 0);               /* disable intx */
        msix_set_enable(dev, 1);
@@ -694,3 +699,23 @@ arch_msi_check_device(struct pci_dev* dev, int nvec, int type)
        return 0;
 }
 
+int __attribute__ ((weak))
+arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *entry)
+{
+       return 0;
+}
+
+int __attribute__ ((weak))
+arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
+{
+       struct msi_desc *entry;
+       int ret;
+
+       list_for_each_entry(entry, &dev->msi_list, list) {
+               ret = arch_setup_msi_irq(dev, entry);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 931e013..494627a 100644 (file)
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -41,6 +41,7 @@ struct msi_desc {
  */
 int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc);
 void arch_teardown_msi_irq(unsigned int irq);
+extern int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
 extern int arch_msi_check_device(struct pci_dev* dev, int nvec, int type);