PCI: support Secondary Bus Reset

PCI-to-PCI Bridge 1.2 specifies that the Secondary Bus Reset bit can
force the assertion of RST# on the secondary interface, which can be
used to reset all devices including subordinates under this bus. This
can be used to reset a function if this function is the only device
under this bus.

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2e58acc..c56a4a0 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2162,6 +2162,33 @@ 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)
+{
+       u16 ctrl;
+       struct pci_dev *pdev;
+
+       if (dev->subordinate)
+               return -ENOTTY;
+
+       list_for_each_entry(pdev, &dev->bus->devices, bus_list)
+               if (pdev != dev)
+                       return -ENOTTY;
+
+       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);
+
+       return 0;
+}
+
 static int pci_dev_reset(struct pci_dev *dev, int probe)
 {
        int rc;
@@ -2183,6 +2210,10 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
                goto done;
 
        rc = pci_pm_reset(dev, probe);
+       if (rc != -ENOTTY)
+               goto done;
+
+       rc = pci_parent_bus_reset(dev, probe);
 done:
        if (!probe) {
                up(&dev->dev.sem);