s390/pci: Refactor arch_setup_msi_irqs()

Factor out adapter interrupt allocation from arch_setup_msi_irqs() in
preparation for enabling registration of multiple MSIs. Code movement
only, no change of functionality intended.
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/pci/pci_irq.c

@@ -268,33 +268,20 @@ static void zpci_floating_irq_handler(struct airq_struct *airq,
 	}
 }
 
-int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
+static int __alloc_airq(struct zpci_dev *zdev, int msi_vecs,
+			unsigned long *bit)
 {
-	struct zpci_dev *zdev = to_zpci(pdev);
-	unsigned int hwirq, msi_vecs, cpu;
-	unsigned long bit;
-	struct msi_desc *msi;
-	struct msi_msg msg;
-	int cpu_addr;
-	int rc, irq;
-
-	zdev->aisb = -1UL;
-	zdev->msi_first_bit = -1U;
-	if (type == PCI_CAP_ID_MSI && nvec > 1)
-		return 1;
-	msi_vecs = min_t(unsigned int, nvec, zdev->max_msi);
-
 	if (irq_delivery == DIRECTED) {
 		/* Allocate cpu vector bits */
-		bit = airq_iv_alloc(zpci_ibv[0], msi_vecs);
-		if (bit == -1UL)
+		*bit = airq_iv_alloc(zpci_ibv[0], msi_vecs);
+		if (*bit == -1UL)
 			return -EIO;
 	} else {
 		/* Allocate adapter summary indicator bit */
-		bit = airq_iv_alloc_bit(zpci_sbv);
-		if (bit == -1UL)
+		*bit = airq_iv_alloc_bit(zpci_sbv);
+		if (*bit == -1UL)
 			return -EIO;
-		zdev->aisb = bit;
+		zdev->aisb = *bit;
 
 		/* Create adapter interrupt vector */
 		zdev->aibv = airq_iv_create(msi_vecs, AIRQ_IV_DATA | AIRQ_IV_BITLOCK, NULL);
@@ -302,10 +289,33 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 			return -ENOMEM;
 
 		/* Wire up shortcut pointer */
-		zpci_ibv[bit] = zdev->aibv;
+		zpci_ibv[*bit] = zdev->aibv;
 		/* Each function has its own interrupt vector */
-		bit = 0;
+		*bit = 0;
 	}
+	return 0;
+}
+
+int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
+{
+	struct zpci_dev *zdev = to_zpci(pdev);
+	unsigned int hwirq, msi_vecs, cpu;
+	struct msi_desc *msi;
+	struct msi_msg msg;
+	unsigned long bit;
+	int cpu_addr;
+	int rc, irq;
+
+	zdev->aisb = -1UL;
+	zdev->msi_first_bit = -1U;
+
+	if (type == PCI_CAP_ID_MSI && nvec > 1)
+		return 1;
+	msi_vecs = min_t(unsigned int, nvec, zdev->max_msi);
+
+	rc = __alloc_airq(zdev, msi_vecs, &bit);
+	if (rc < 0)
+		return rc;
 
 	/* Request MSI interrupts */
 	hwirq = bit;