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;