--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -445,3 +445,205 @@ void pci_unblock_user_cfg_access(struct pci_dev *dev)
 	raw_spin_unlock_irqrestore(&pci_lock, flags);
 }
 EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);
+
+static inline int pcie_cap_version(const struct pci_dev *dev)
+{
+	return dev->pcie_flags_reg & PCI_EXP_FLAGS_VERS;
+}
+
+static inline bool pcie_cap_has_devctl(const struct pci_dev *dev)
+{
+	return true;
+}
+
+static inline bool pcie_cap_has_lnkctl(const struct pci_dev *dev)
+{
+	int type = pci_pcie_type(dev);
+
+	return pcie_cap_version(dev) > 1 ||
+	       type == PCI_EXP_TYPE_ROOT_PORT ||
+	       type == PCI_EXP_TYPE_ENDPOINT ||
+	       type == PCI_EXP_TYPE_LEG_END;
+}
+
+static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)
+{
+	int type = pci_pcie_type(dev);
+
+	return pcie_cap_version(dev) > 1 ||
+	       type == PCI_EXP_TYPE_ROOT_PORT ||
+	       (type == PCI_EXP_TYPE_DOWNSTREAM &&
+		dev->pcie_flags_reg & PCI_EXP_FLAGS_SLOT);
+}
+
+static inline bool pcie_cap_has_rtctl(const struct pci_dev *dev)
+{
+	int type = pci_pcie_type(dev);
+
+	return pcie_cap_version(dev) > 1 ||
+	       type == PCI_EXP_TYPE_ROOT_PORT ||
+	       type == PCI_EXP_TYPE_RC_EC;
+}
+
+static bool pcie_capability_reg_implemented(struct pci_dev *dev, int pos)
+{
+	if (!pci_is_pcie(dev))
+		return false;
+
+	switch (pos) {
+	case PCI_EXP_FLAGS_TYPE:
+		return true;
+	case PCI_EXP_DEVCAP:
+	case PCI_EXP_DEVCTL:
+	case PCI_EXP_DEVSTA:
+		return pcie_cap_has_devctl(dev);
+	case PCI_EXP_LNKCAP:
+	case PCI_EXP_LNKCTL:
+	case PCI_EXP_LNKSTA:
+		return pcie_cap_has_lnkctl(dev);
+	case PCI_EXP_SLTCAP:
+	case PCI_EXP_SLTCTL:
+	case PCI_EXP_SLTSTA:
+		return pcie_cap_has_sltctl(dev);
+	case PCI_EXP_RTCTL:
+	case PCI_EXP_RTCAP:
+	case PCI_EXP_RTSTA:
+		return pcie_cap_has_rtctl(dev);
+	case PCI_EXP_DEVCAP2:
+	case PCI_EXP_DEVCTL2:
+	case PCI_EXP_LNKCAP2:
+	case PCI_EXP_LNKCTL2:
+	case PCI_EXP_LNKSTA2:
+		return pcie_cap_version(dev) > 1;
+	default:
+		return false;
+	}
+}
+
+/*
+ * Note that these accessor functions are only for the "PCI Express
+ * Capability" (see PCIe spec r3.0, sec 7.8).  They do not apply to the
+ * other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
+ */
+int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val)
+{
+	int ret;
+
+	*val = 0;
+	if (pos & 1)
+		return -EINVAL;
+
+	if (pcie_capability_reg_implemented(dev, pos)) {
+		ret = pci_read_config_word(dev, pci_pcie_cap(dev) + pos, val);
+		/*
+		 * Reset *val to 0 if pci_read_config_word() fails, it may
+		 * have been written as 0xFFFF if hardware error happens
+		 * during pci_read_config_word().
+		 */
+		if (ret)
+			*val = 0;
+		return ret;
+	}
+
+	/*
+	 * For Functions that do not implement the Slot Capabilities,
+	 * Slot Status, and Slot Control registers, these spaces must
+	 * be hardwired to 0b, with the exception of the Presence Detect
+	 * State bit in the Slot Status register of Downstream Ports,
+	 * which must be hardwired to 1b.  (PCIe Base Spec 3.0, sec 7.8)
+	 */
+	if (pci_is_pcie(dev) && pos == PCI_EXP_SLTSTA &&
+		 pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM) {
+		*val = PCI_EXP_SLTSTA_PDS;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(pcie_capability_read_word);
+
+int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val)
+{
+	int ret;
+
+	*val = 0;
+	if (pos & 3)
+		return -EINVAL;
+
+	if (pcie_capability_reg_implemented(dev, pos)) {
+		ret = pci_read_config_dword(dev, pci_pcie_cap(dev) + pos, val);
+		/*
+		 * Reset *val to 0 if pci_read_config_dword() fails, it may
+		 * have been written as 0xFFFFFFFF if hardware error happens
+		 * during pci_read_config_dword().
+		 */
+		if (ret)
+			*val = 0;
+		return ret;
+	}
+
+	if (pci_is_pcie(dev) && pos == PCI_EXP_SLTCTL &&
+		 pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM) {
+		*val = PCI_EXP_SLTSTA_PDS;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(pcie_capability_read_dword);
+
+int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val)
+{
+	if (pos & 1)
+		return -EINVAL;
+
+	if (!pcie_capability_reg_implemented(dev, pos))
+		return 0;
+
+	return pci_write_config_word(dev, pci_pcie_cap(dev) + pos, val);
+}
+EXPORT_SYMBOL(pcie_capability_write_word);
+
+int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val)
+{
+	if (pos & 3)
+		return -EINVAL;
+
+	if (!pcie_capability_reg_implemented(dev, pos))
+		return 0;
+
+	return pci_write_config_dword(dev, pci_pcie_cap(dev) + pos, val);
+}
+EXPORT_SYMBOL(pcie_capability_write_dword);
+
+int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
+				       u16 clear, u16 set)
+{
+	int ret;
+	u16 val;
+
+	ret = pcie_capability_read_word(dev, pos, &val);
+	if (!ret) {
+		val &= ~clear;
+		val |= set;
+		ret = pcie_capability_write_word(dev, pos, val);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(pcie_capability_clear_and_set_word);
+
+int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
+					u32 clear, u32 set)
+{
+	int ret;
+	u32 val;
+
+	ret = pcie_capability_read_dword(dev, pos, &val);
+	if (!ret) {
+		val &= ~clear;
+		val |= set;
+		ret = pcie_capability_write_dword(dev, pos, val);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(pcie_capability_clear_and_set_dword);
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index e3efb43..b99d888 100644
