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>

2 files changed, 45 insertions, 19 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 88362f1bd9cf..c71e8e4c7168 100644
--- 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 931e013f1db5..494627ae021f 100644
--- 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);