5 files changed, 62 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)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 008005674b60..7e9a1f0715e6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -214,6 +214,7 @@ struct pci_dev {
         unsigned int    broken_parity_status:1; /* Device generates false positive parity */
         unsigned int    msi_enabled:1;
         unsigned int    msix_enabled:1;
+        unsigned int    ari_enabled:1;  /* ARI forwarding */
         unsigned int    is_managed:1;
         unsigned int    is_pcie:1;
         pci_dev_flags_t dev_flags;
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index 450684f7eaac..eb6686b88f9a 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -419,6 +419,10 @@
 #define  PCI_EXP_RTCTL_CRSSVE   0x10    /* CRS Software Visibility Enable */
 #define PCI_EXP_RTCAP           30      /* Root Capabilities */
 #define PCI_EXP_RTSTA           32      /* Root Status */
+#define PCI_EXP_DEVCAP2         36      /* Device Capabilities 2 */
+#define  PCI_EXP_DEVCAP2_ARI    0x20    /* Alternative Routing-ID */
+#define PCI_EXP_DEVCTL2         40      /* Device Control 2 */
+#define  PCI_EXP_DEVCTL2_ARI    0x20    /* Alternative Routing-ID */
 
 /* Extended Capabilities (PCI-X 2.0 and Express) */
 #define PCI_EXT_CAP_ID(header)          (header & 0x0000ffff)
@@ -429,6 +433,7 @@
 #define PCI_EXT_CAP_ID_VC       2
 #define PCI_EXT_CAP_ID_DSN      3
 #define PCI_EXT_CAP_ID_PWR      4
+#define PCI_EXT_CAP_ID_ARI      14
 
 /* Advanced Error Reporting */
 #define PCI_ERR_UNCOR_STATUS    4       /* Uncorrectable Error Status */
@@ -536,5 +541,14 @@
 #define HT_CAPTYPE_GEN3         0xD0    /* Generation 3 hypertransport configuration */
 #define HT_CAPTYPE_PM           0xE0    /* Hypertransport powermanagement configuration */
 
+/* Alternative Routing-ID Interpretation */
+#define PCI_ARI_CAP             0x04    /* ARI Capability Register */
+#define  PCI_ARI_CAP_MFVC       0x0001  /* MFVC Function Groups Capability */
+#define  PCI_ARI_CAP_ACS        0x0002  /* ACS Function Groups Capability */
+#define  PCI_ARI_CAP_NFN(x)     (((x) >> 8) & 0xff) /* Next Function Number */
+#define PCI_ARI_CTRL            0x06    /* ARI Control Register */
+#define  PCI_ARI_CTRL_MFVC      0x0001  /* MFVC Function Groups Enable */
+#define  PCI_ARI_CTRL_ACS       0x0002  /* ACS Function Groups Enable */
+#define  PCI_ARI_CTRL_FG(x)     (((x) >> 4) & 7) /* Function Group */
 
 #endif /* LINUX_PCI_REGS_H */