PCI/portdrv: Factor out Interrupt Message Number lookup

Factor out Interrupt Message Number lookup from the MSI/MSI-X interrupt
setup.  One side effect is that we only have to check once to see if we
have enough vectors for all the services.  No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 62 insertions, 48 deletions

diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index accd16082348..102f5c5fcfe0 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -43,6 +43,53 @@ static void release_pcie_device(struct device *dev)
         kfree(to_pcie_device(dev));
 }
 
+/*
+ * Fill in *pme, *aer, *dpc with the relevant Interrupt Message Numbers if
+ * services are enabled in "mask".  Return the number of MSI/MSI-X vectors
+ * required to accommodate the largest Message Number.
+ */
+static int pcie_message_numbers(struct pci_dev *dev, int mask,
+                                u32 *pme, u32 *aer, u32 *dpc)
+{
+        u32 nvec = 0, pos, reg32;
+        u16 reg16;
+
+        /*
+         * The Interrupt Message Number indicates which vector is used, i.e.,
+         * the MSI-X table entry or the MSI offset between the base Message
+         * Data and the generated interrupt message.  See PCIe r3.1, sec
+         * 7.8.2, 7.10.10, 7.31.2.
+         */
+
+        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
+                pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
+                *pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
+                nvec = *pme + 1;
+        }
+
+        if (mask & PCIE_PORT_SERVICE_AER) {
+                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
+                if (pos) {
+                        pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS,
+                                              &reg32);
+                        *aer = (reg32 & PCI_ERR_ROOT_AER_IRQ) >> 27;
+                        nvec = max(nvec, *aer + 1);
+                }
+        }
+
+        if (mask & PCIE_PORT_SERVICE_DPC) {
+                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC);
+                if (pos) {
+                        pci_read_config_word(dev, pos + PCI_EXP_DPC_CAP,
+                                             &reg16);
+                        *dpc = reg16 & PCI_EXP_DPC_IRQ;
+                        nvec = max(nvec, *dpc + 1);
+                }
+        }
+
+        return nvec;
+}
+
 /**
  * pcie_port_enable_irq_vec - try to set up MSI-X or MSI as interrupt mode
  * for given port
@@ -54,7 +101,8 @@ static void release_pcie_device(struct device *dev)
  */
 static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
 {
-        int nr_entries, entry, nvec = 0;
+        int nr_entries, nvec;
+        u32 pme = 0, aer = 0, dpc = 0;
 
         /* Allocate the maximum possible number of MSI/MSI-X vectors */
         nr_entries = pci_alloc_irq_vectors(dev, 1, PCIE_PORT_MAX_MSI_ENTRIES,
@@ -62,54 +110,24 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
         if (nr_entries < 0)
                 return nr_entries;
 
-        /*
-         * The Interrupt Message Number indicates which vector is used, i.e.,
-         * the MSI-X table entry or the MSI offset between the base Message
-         * Data and the generated interrupt message.  See PCIe r3.1, sec
-         * 7.8.2, 7.10.10, 7.31.2.
-         */
-        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
-                u16 reg16;
-
-                pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
-                entry = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
-                if (entry >= nr_entries)
-                        goto out_free_irqs;
-
-                /* PME and hotplug share an MSI/MSI-X vector */
-                irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pci_irq_vector(dev, entry);
-                irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pci_irq_vector(dev, entry);
-
-                nvec = max(nvec, entry + 1);
+        /* See how many and which Interrupt Message Numbers we actually use */
+        nvec = pcie_message_numbers(dev, mask, &pme, &aer, &dpc);
+        if (nvec > nr_entries) {
+                pci_free_irq_vectors(dev);
+                return -EIO;
         }
 
-        if (mask & PCIE_PORT_SERVICE_AER) {
-                u32 reg32, pos;
-
-                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
-                pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &reg32);
-                entry = (reg32 & PCI_ERR_ROOT_AER_IRQ) >> 27;
-                if (entry >= nr_entries)
-                        goto out_free_irqs;
-
-                irqs[PCIE_PORT_SERVICE_AER_SHIFT] = pci_irq_vector(dev, entry);
-
-                nvec = max(nvec, entry + 1);
+        /* PME and hotplug share an MSI/MSI-X vector */
+        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
+                irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pci_irq_vector(dev, pme);
+                irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pci_irq_vector(dev, pme);
         }
 
-        if (mask & PCIE_PORT_SERVICE_DPC) {
-                u16 reg16, pos;
-
-                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC);
-                pci_read_config_word(dev, pos + PCI_EXP_DPC_CAP, &reg16);
-                entry = reg16 & PCI_EXP_DPC_IRQ;
-                if (entry >= nr_entries)
-                        goto out_free_irqs;
-
-                irqs[PCIE_PORT_SERVICE_DPC_SHIFT] = pci_irq_vector(dev, entry);
+        if (mask & PCIE_PORT_SERVICE_AER)
+                irqs[PCIE_PORT_SERVICE_AER_SHIFT] = pci_irq_vector(dev, aer);
 
-                nvec = max(nvec, entry + 1);
-        }
+        if (mask & PCIE_PORT_SERVICE_DPC)
+                irqs[PCIE_PORT_SERVICE_DPC_SHIFT] = pci_irq_vector(dev, dpc);
 
         /* If we allocated more than we need, free them and allocate fewer */
         if (nvec != nr_entries) {
@@ -122,10 +140,6 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
         }
 
         return 0;
-
-out_free_irqs:
-        pci_free_irq_vectors(dev);
-        return -EIO;
 }
 
 /**