1 files changed, 50 insertions, 15 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 766bb13bb0a3..985df63aa59f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -278,6 +278,38 @@ int pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap)
 }
 
 /**
+ * pci_pcie_cap2 - query for devices' PCI_CAP_ID_EXP v2 capability structure
+ * @dev: PCI device to check
+ *
+ * Like pci_pcie_cap() but also checks that the PCIe capability version is
+ * >= 2.  Note that v1 capability structures could be sparse in that not
+ * all register fields were required.  v2 requires the entire structure to
+ * be present size wise, while still allowing for non-implemented registers
+ * to exist but they must be hardwired to 0.
+ *
+ * Due to the differences in the versions of capability structures, one
+ * must be careful not to try and access non-existant registers that may
+ * exist in early versions - v1 - of Express devices.
+ *
+ * Returns the offset of the PCIe capability structure as long as the
+ * capability version is >= 2; otherwise 0 is returned.
+ */
+static int pci_pcie_cap2(struct pci_dev *dev)
+{
+	u16 flags;
+	int pos;
+
+	pos = pci_pcie_cap(dev);
+	if (pos) {
+		pci_read_config_word(dev, pos + PCI_EXP_FLAGS, &flags);
+		if ((flags & PCI_EXP_FLAGS_VERS) < 2)
+			pos = 0;
+	}
+
+	return pos;
+}
+
+/**
  * pci_find_ext_capability - Find an extended capability
  * @dev: PCI device to query
  * @cap: capability code
@@ -1983,7 +2015,7 @@ void pci_enable_ari(struct pci_dev *dev)
 {
 	int pos;
 	u32 cap;
-	u16 flags, ctrl;
+	u16 ctrl;
 	struct pci_dev *bridge;
 
 	if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn)
@@ -1997,15 +2029,11 @@ void pci_enable_ari(struct pci_dev *dev)
 	if (!bridge)
 		return;
 
-	pos = pci_pcie_cap(bridge);
+	/* ARI is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(bridge);
 	if (!pos)
 		return;
 
-	/* ARI is a PCIe v2 feature */
-	pci_read_config_word(bridge, pos + PCI_EXP_FLAGS, &flags);
-	if ((flags & PCI_EXP_FLAGS_VERS) < 2)
-		return;
-
 	pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap);
 	if (!(cap & PCI_EXP_DEVCAP2_ARI))
 		return;
@@ -2018,7 +2046,7 @@ void pci_enable_ari(struct pci_dev *dev)
 }
 
 /**
- * pci_enable_ido - enable ID-based ordering on a device
+ * pci_enable_ido - enable ID-based Ordering on a device
  * @dev: the PCI device
  * @type: which types of IDO to enable
  *
@@ -2031,7 +2059,8 @@ void pci_enable_ido(struct pci_dev *dev, unsigned long type)
 	int pos;
 	u16 ctrl;
 
-	pos = pci_pcie_cap(dev);
+	/* ID-based Ordering is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return;
 
@@ -2054,7 +2083,8 @@ void pci_disable_ido(struct pci_dev *dev, unsigned long type)
 	int pos;
 	u16 ctrl;
 
-	pos = pci_pcie_cap(dev);
+	/* ID-based Ordering is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return;
 
@@ -2093,7 +2123,8 @@ int pci_enable_obff(struct pci_dev *dev, enum pci_obff_signal_type type)
 	u16 ctrl;
 	int ret;
 
-	pos = pci_pcie_cap(dev);
+	/* OBFF is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return -ENOTSUPP;
 
@@ -2143,7 +2174,8 @@ void pci_disable_obff(struct pci_dev *dev)
 	int pos;
 	u16 ctrl;
 
-	pos = pci_pcie_cap(dev);
+	/* OBFF is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return;
 
@@ -2165,7 +2197,8 @@ static bool pci_ltr_supported(struct pci_dev *dev)
 	int pos;
 	u32 cap;
 
-	pos = pci_pcie_cap(dev);
+	/* LTR is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return false;
 
@@ -2193,7 +2226,8 @@ int pci_enable_ltr(struct pci_dev *dev)
 	if (!pci_ltr_supported(dev))
 		return -ENOTSUPP;
 
-	pos = pci_pcie_cap(dev);
+	/* LTR is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return -ENOTSUPP;
 
@@ -2228,7 +2262,8 @@ void pci_disable_ltr(struct pci_dev *dev)
 	if (!pci_ltr_supported(dev))
 		return;
 
-	pos = pci_pcie_cap(dev);
+	/* LTR is a PCIe cap v2 feature */
+	pos = pci_pcie_cap2(dev);
 	if (!pos)
 		return;