PCI: support PCIe ARI capability
This patch adds support for PCI Express Alternative Routing-ID
Interpretation (ARI) capability.
The ARI capability extends the Function Number field of the PCI Express
Endpoint by reusing the Device Number which is otherwise hardwired to 0.
With ARI, an Endpoint can have up to 256 functions.
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 553ca66..4db261e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1299,6 +1299,38 @@
}
}
+/**
+ * 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 601abdc8..39684c1 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -151,4 +151,16 @@
};
#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 8c158b9..3141e8d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1025,6 +1025,9 @@
/* 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)