PCI: Add pci_reset_bridge_secondary_bus()

Move the secondary bus reset code from pci_parent_bus_reset() into its own
function.  Export it as we'll later be calling it from hotplug controllers
and elsewhere.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

2 files changed, 24 insertions, 9 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e37fea6e178d..d46860898e1f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3215,9 +3215,30 @@ static int pci_pm_reset(struct pci_dev *dev, int probe)
         return 0;
 }
 
-static int pci_parent_bus_reset(struct pci_dev *dev, int probe)
+/**
+ * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge.
+ * @dev: Bridge device
+ *
+ * Use the bridge control register to assert reset on the secondary bus.
+ * Devices on the secondary bus are left in power-on state.
+ */
+void pci_reset_bridge_secondary_bus(struct pci_dev *dev)
 {
         u16 ctrl;
+
+        pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &ctrl);
+        ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
+        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
+        msleep(100);
+
+        ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
+        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
+        msleep(100);
+}
+EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus);
+
+static int pci_parent_bus_reset(struct pci_dev *dev, int probe)
+{
         struct pci_dev *pdev;
 
         if (pci_is_root_bus(dev->bus) || dev->subordinate || !dev->bus->self)
@@ -3230,14 +3251,7 @@ static int pci_parent_bus_reset(struct pci_dev *dev, int probe)
         if (probe)
                 return 0;
 
-        pci_read_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, &ctrl);
-        ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
-        pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl);
-        msleep(100);
-
-        ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
-        pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl);
-        msleep(100);
+        pci_reset_bridge_secondary_bus(dev->bus->self);
 
         return 0;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0fd1f1582fa1..35c1bc4909f3 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -924,6 +924,7 @@ int pcie_set_mps(struct pci_dev *dev, int mps);
 int __pci_reset_function(struct pci_dev *dev);
 int __pci_reset_function_locked(struct pci_dev *dev);
 int pci_reset_function(struct pci_dev *dev);
+void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
 void pci_update_resource(struct pci_dev *dev, int resno);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);