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>

drivers/pci/pci.c

@@ -2284,6 +2284,21 @@ static int pci_parent_bus_reset(struct pci_dev *dev, int probe)
 	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 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
 		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;

drivers/pci/pci.h

@@ -313,4 +313,12 @@ static inline int pci_resource_alignment(struct pci_dev *dev,
 
 extern void pci_enable_acs(struct pci_dev *dev);
 
+struct pci_dev_reset_methods {
+	u16 vendor;
+	u16 device;
+	int (*reset)(struct pci_dev *dev, int probe);
+};
+
+extern struct pci_dev_reset_methods pci_dev_reset_methods[];
+
 #endif /* DRIVERS_PCI_H */

drivers/pci/quirks.c

@@ -2636,6 +2636,15 @@ static int __init pci_apply_final_quirks(void)
 }
 
 fs_initcall_sync(pci_apply_final_quirks);
+
+/*
+ * Followings are device-specific reset methods which can be used to
+ * reset a single function if other methods (e.g. FLR, PM D0->D3) are
+ * not available.
+ */
+struct pci_dev_reset_methods pci_dev_reset_methods[] = {
+	{ 0 }
+};
 #else
 void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev) {}
 #endif