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>

3 files changed, 36 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 0bc27e059019..6011d064e89d 100644
--- a/drivers/pci/pci.c
+++ b/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;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 33ed8e0aba1e..709eaa4fee51 100644
--- a/drivers/pci/pci.h
+++ b/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 */
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index f70f4e23225c..86c9177a6c6c 100644
--- a/drivers/pci/quirks.c
+++ b/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