PCI: support device-specific reset methods

Add a new type of quirk for resetting devices at pci_dev_reset time.
This is necessary to handle device with nonstandard reset procedures,
especially useful for guest drivers.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 0bc27e0..6011d06 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2284,6 +2284,21 @@
 	return 0;
 }
 
+static int pci_dev_specific_reset(struct pci_dev *dev, int probe)
+{
+	struct pci_dev_reset_methods *i;
+
+	for (i = pci_dev_reset_methods; i->reset; i++) {
+		if ((i->vendor == dev->vendor ||
+		     i->vendor == (u16)PCI_ANY_ID) &&
+		    (i->device == dev->device ||
+		     i->device == (u16)PCI_ANY_ID))
+			return i->reset(dev, probe);
+	}
+
+	return -ENOTTY;
+}
+
 static int pci_dev_reset(struct pci_dev *dev, int probe)
 {
 	int rc;
@@ -2296,6 +2311,10 @@
 		down(&dev->dev.sem);
 	}
 
+	rc = pci_dev_specific_reset(dev, probe);
+	if (rc != -ENOTTY)
+		goto done;
+
 	rc = pcie_flr(dev, probe);
 	if (rc != -ENOTTY)
 		goto done;