3 files changed, 114 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d0182bed7acc..01e4cab2e5cb 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1887,6 +1887,98 @@ void pci_disable_ido(struct pci_dev *dev, unsigned long type)
 }
 EXPORT_SYMBOL(pci_disable_ido);
 
+/**
+ * pci_enable_obff - enable optimized buffer flush/fill
+ * @dev: PCI device
+ * @type: type of signaling to use
+ *
+ * Try to enable @type OBFF signaling on @dev.  It will try using WAKE#
+ * signaling if possible, falling back to message signaling only if
+ * WAKE# isn't supported.  @type should indicate whether the PCIe link
+ * be brought out of L0s or L1 to send the message.  It should be either
+ * %PCI_EXP_OBFF_SIGNAL_ALWAYS or %PCI_OBFF_SIGNAL_L0.
+ *
+ * If your device can benefit from receiving all messages, even at the
+ * power cost of bringing the link back up from a low power state, use
+ * %PCI_EXP_OBFF_SIGNAL_ALWAYS.  Otherwise, use %PCI_OBFF_SIGNAL_L0 (the
+ * preferred type).
+ *
+ * RETURNS:
+ * Zero on success, appropriate error number on failure.
+ */
+int pci_enable_obff(struct pci_dev *dev, enum pci_obff_signal_type type)
+{
+        int pos;
+        u32 cap;
+        u16 ctrl;
+        int ret;
+
+        if (!pci_is_pcie(dev))
+                return -ENOTSUPP;
+
+        pos = pci_pcie_cap(dev);
+        if (!pos)
+                return -ENOTSUPP;
+
+        pci_read_config_dword(dev, pos + PCI_EXP_DEVCAP2, &cap);
+        if (!(cap & PCI_EXP_OBFF_MASK))
+                return -ENOTSUPP; /* no OBFF support at all */
+
+        /* Make sure the topology supports OBFF as well */
+        if (dev->bus) {
+                ret = pci_enable_obff(dev->bus->self, type);
+                if (ret)
+                        return ret;
+        }
+
+        pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);
+        if (cap & PCI_EXP_OBFF_WAKE)
+                ctrl |= PCI_EXP_OBFF_WAKE_EN;
+        else {
+                switch (type) {
+                case PCI_EXP_OBFF_SIGNAL_L0:
+                        if (!(ctrl & PCI_EXP_OBFF_WAKE_EN))
+                                ctrl |= PCI_EXP_OBFF_MSGA_EN;
+                        break;
+                case PCI_EXP_OBFF_SIGNAL_ALWAYS:
+                        ctrl &= ~PCI_EXP_OBFF_WAKE_EN;
+                        ctrl |= PCI_EXP_OBFF_MSGB_EN;
+                        break;
+                default:
+                        WARN(1, "bad OBFF signal type\n");
+                        return -ENOTSUPP;
+                }
+        }
+        pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);
+
+        return 0;
+}
+EXPORT_SYMBOL(pci_enable_obff);
+
+/**
+ * pci_disable_obff - disable optimized buffer flush/fill
+ * @dev: PCI device
+ *
+ * Disable OBFF on @dev.
+ */
+void pci_disable_obff(struct pci_dev *dev)
+{
+        int pos;
+        u16 ctrl;
+
+        if (!pci_is_pcie(dev))
+                return;
+
+        pos = pci_pcie_cap(dev);
+        if (!pos)
+                return;
+
+        pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);
+        ctrl &= ~PCI_EXP_OBFF_WAKE_EN;
+        pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);
+}
+EXPORT_SYMBOL(pci_disable_obff);
+
 static int pci_acs_enable;
 
 /**
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 551ddcb5f940..45a035cccd93 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -833,6 +833,13 @@ static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state,
 void pci_enable_ido(struct pci_dev *dev, unsigned long type);
 void pci_disable_ido(struct pci_dev *dev, unsigned long type);
 
+enum pci_obff_signal_type {
+        PCI_EXP_OBFF_SIGNAL_L0,
+        PCI_EXP_OBFF_SIGNAL_ALWAYS,
+};
+int pci_enable_obff(struct pci_dev *dev, enum pci_obff_signal_type);
+void pci_disable_obff(struct pci_dev *dev);
+
 /* For use by arch with custom probe code */
 void set_pcie_port_type(struct pci_dev *pdev);
 void set_pcie_hotplug_bridge(struct pci_dev *pdev);
@@ -1220,6 +1227,15 @@ static inline void pci_disable_ido(struct pci_dev *dev, unsigned long type)
 {
 }
 
+static inline int pci_enable_obff(struct pci_dev *dev, unsigned long type)
+{
+        return 0;
+}
+
+static inline void pci_disable_obff(struct pci_dev *dev)
+{
+}
+
 static inline int pci_request_regions(struct pci_dev *dev, const char *res_name)
 {
         return -EIO;
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index d9acf9b99814..aa420261843d 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -508,10 +508,16 @@
 #define PCI_EXP_RTSTA_PENDING   0x20000 /* PME pending */
 #define PCI_EXP_DEVCAP2         36      /* Device Capabilities 2 */
 #define  PCI_EXP_DEVCAP2_ARI    0x20    /* Alternative Routing-ID */
+#define  PCI_EXP_OBFF_MASK      0xc0000 /* OBFF support mechanism */
+#define  PCI_EXP_OBFF_MSG       0x40000 /* New message signaling */
+#define  PCI_EXP_OBFF_WAKE      0x80000 /* Re-use WAKE# for OBFF */
 #define PCI_EXP_DEVCTL2         40      /* Device Control 2 */
 #define  PCI_EXP_DEVCTL2_ARI    0x20    /* Alternative Routing-ID */
 #define  PCI_EXP_IDO_REQ_EN     0x100   /* ID-based ordering request enable */
 #define  PCI_EXP_IDO_CMP_EN     0x200   /* ID-based ordering completion enable */
+#define  PCI_EXP_OBFF_MSGA_EN   0x2000  /* OBFF enable with Message type A */
+#define  PCI_EXP_OBFF_MSGB_EN   0x4000  /* OBFF enable with Message type B */
+#define  PCI_EXP_OBFF_WAKE_EN   0x6000  /* OBFF using WAKE# signaling */
 #define PCI_EXP_LNKCTL2         48      /* Link Control 2 */
 #define PCI_EXP_SLTCTL2         56      /* Slot Control 2 */