3 files changed, 47 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 553ca6657955..4db261e13e69 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1299,6 +1299,38 @@ void pci_pm_init(struct pci_dev *dev)
         }
 }
 
+/**
+ * pci_enable_ari - enable ARI forwarding if hardware support it
+ * @dev: the PCI device
+ */
+void pci_enable_ari(struct pci_dev *dev)
+{
+        int pos;
+        u32 cap;
+        u16 ctrl;
+
+        if (!dev->is_pcie)
+                return;
+
+        if (dev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
+            dev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
+                return;
+
+        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+        if (!pos)
+                return;
+
+        pci_read_config_dword(dev, pos + PCI_EXP_DEVCAP2, &cap);
+        if (!(cap & PCI_EXP_DEVCAP2_ARI))
+                return;
+
+        pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);
+        ctrl |= PCI_EXP_DEVCTL2_ARI;
+        pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);
+
+        dev->ari_enabled = 1;
+}
+
 int
 pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge)
 {
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 601abdc8dd9f..39684c1415c5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -151,4 +151,16 @@ struct pci_slot_attribute {
 };
 #define to_pci_slot_attr(s) container_of(s, struct pci_slot_attribute, attr)
 
+extern void pci_enable_ari(struct pci_dev *dev);
+/**
+ * pci_ari_enabled - query ARI forwarding status
+ * @dev: the PCI device
+ *
+ * Returns 1 if ARI forwarding is enabled, or 0 if not enabled;
+ */
+static inline int pci_ari_enabled(struct pci_dev *dev)
+{
+        return dev->ari_enabled;
+}
+
 #endif /* DRIVERS_PCI_H */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8c158b9abd41..3141e8deeac4 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1025,6 +1025,9 @@ static void pci_init_capabilities(struct pci_dev *dev)
 
         /* Vital Product Data */
         pci_vpd_pci22_init(dev);
+
+        /* Alternative Routing-ID Forwarding */
+        pci_enable_ari(dev);
 }
 
 void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)