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>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2e58acc66a8c..c56a4a0355a8 100644
--- 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);