PCI/MSI: Add internal msix_clear_and_set_ctrl() function

Add msix_clear_and_set_ctrl() simplify code.  No functional change.

[bhelgaas: fix whitespace]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/msi.c

@@ -149,15 +149,14 @@ static void msi_set_enable(struct pci_dev *dev, int enable)
 	pci_write_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, control);
 }
 
-static void msix_set_enable(struct pci_dev *dev, int enable)
+static void msix_clear_and_set_ctrl(struct pci_dev *dev, u16 clear, u16 set)
 {
-	u16 control;
+	u16 ctrl;
 
-	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
-	control &= ~PCI_MSIX_FLAGS_ENABLE;
-	if (enable)
-		control |= PCI_MSIX_FLAGS_ENABLE;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &ctrl);
+	ctrl &= ~clear;
+	ctrl |= set;
+	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, ctrl);
 }
 
 static inline __attribute_const__ u32 msi_mask(unsigned x)
@@ -469,26 +468,23 @@ static void __pci_restore_msi_state(struct pci_dev *dev)
 static void __pci_restore_msix_state(struct pci_dev *dev)
 {
 	struct msi_desc *entry;
-	u16 control;
 
 	if (!dev->msix_enabled)
 		return;
 	BUG_ON(list_empty(&dev->msi_list));
 	entry = list_first_entry(&dev->msi_list, struct msi_desc, list);
-	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
 
 	/* route the table */
 	pci_intx_for_msi(dev, 0);
-	control |= PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	msix_clear_and_set_ctrl(dev, 0,
+				PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL);
 
 	arch_restore_msi_irqs(dev);
 	list_for_each_entry(entry, &dev->msi_list, list) {
 		msix_mask_irq(entry, entry->masked);
 	}
 
-	control &= ~PCI_MSIX_FLAGS_MASKALL;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 }
 
 void pci_restore_msi_state(struct pci_dev *dev)
@@ -743,12 +739,10 @@ static int msix_capability_init(struct pci_dev *dev,
 	u16 control;
 	void __iomem *base;
 
-	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
-
 	/* Ensure MSI-X is disabled while it is set up */
-	control &= ~PCI_MSIX_FLAGS_ENABLE;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
 
+	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
 	/* Request & Map MSI-X table region */
 	base = msix_map_region(dev, msix_table_size(control));
 	if (!base)
@@ -767,8 +761,8 @@ static int msix_capability_init(struct pci_dev *dev,
 	 * MSI-X registers.  We need to mask all the vectors to prevent
 	 * interrupts coming in before they're fully set up.
 	 */
-	control |= PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	msix_clear_and_set_ctrl(dev, 0,
+				PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE);
 
 	msix_program_entries(dev, entries);
 
@@ -780,8 +774,7 @@ static int msix_capability_init(struct pci_dev *dev,
 	pci_intx_for_msi(dev, 0);
 	dev->msix_enabled = 1;
 
-	control &= ~PCI_MSIX_FLAGS_MASKALL;
-	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, control);
+	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 
 	return 0;
 
@@ -1001,7 +994,7 @@ void pci_msix_shutdown(struct pci_dev *dev)
 		arch_msix_mask_irq(entry, 1);
 	}
 
-	msix_set_enable(dev, 0);
+	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
 	pci_intx_for_msi(dev, 1);
 	dev->msix_enabled = 0;
 }
@@ -1065,7 +1058,7 @@ void pci_msi_init_pci_dev(struct pci_dev *dev)
 
 	dev->msix_cap = pci_find_capability(dev, PCI_CAP_ID_MSIX);
 	if (dev->msix_cap)
-		msix_set_enable(dev, 0);
+		msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
 }
 
 /**