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 (file)
--- 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 601abdc..39684c1 100644 (file)
--- 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 8c158b9..3141e8d 100644 (file)
--- 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 0080056..7e9a1f0 100644 (file)
--- 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 450684f..eb6686b 100644 (file)
--- 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 */