3 files changed, 48 insertions, 2 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b821a62958fd..e8ccf6c0f08a 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3998,6 +3998,49 @@ int pcie_set_mps(struct pci_dev *dev, int mps)
 }
 
 /**
+ * pcie_get_minimum_link - determine minimum link settings of a PCI device
+ * @dev: PCI device to query
+ * @speed: storage for minimum speed
+ * @width: storage for minimum width
+ *
+ * This function will walk up the PCI device chain and determine the minimum
+ * link width and speed of the device.
+ */
+int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
+                          enum pcie_link_width *width)
+{
+        int ret;
+
+        *speed = PCI_SPEED_UNKNOWN;
+        *width = PCIE_LNK_WIDTH_UNKNOWN;
+
+        while (dev) {
+                u16 lnksta;
+                enum pci_bus_speed next_speed;
+                enum pcie_link_width next_width;
+
+                ret = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
+                if (ret)
+                        return ret;
+
+                next_speed = pcie_link_speed[lnksta & PCI_EXP_LNKSTA_CLS];
+                next_width = (lnksta & PCI_EXP_LNKSTA_NLW) >>
+                        PCI_EXP_LNKSTA_NLW_SHIFT;
+
+                if (next_speed < *speed)
+                        *speed = next_speed;
+
+                if (next_width < *width)
+                        *width = next_width;
+
+                dev = dev->bus->self;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(pcie_get_minimum_link);
+
+/**
  * pci_select_bars - Make BAR mask from the type of resource
  * @dev: the PCI device for which BAR mask is made
  * @flags: resource type mask to be selected
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 816c297f170c..8a00c063d7bc 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -6,6 +6,9 @@
 #define PCI_CFG_SPACE_SIZE      256
 #define PCI_CFG_SPACE_EXP_SIZE  4096
 
+extern const unsigned char pcix_bus_speed[];
+extern const unsigned char pcie_link_speed[];
+
 /* Functions internal to the PCI core code */
 
 int pci_create_sysfs_dev_files(struct pci_dev *pdev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index eeb50bd62402..4f9cc93c3b59 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -518,7 +518,7 @@ static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
         return bridge;
 }
 
-static unsigned char pcix_bus_speed[] = {
+const unsigned char pcix_bus_speed[] = {
         PCI_SPEED_UNKNOWN,              /* 0 */
         PCI_SPEED_66MHz_PCIX,           /* 1 */
         PCI_SPEED_100MHz_PCIX,          /* 2 */
@@ -537,7 +537,7 @@ static unsigned char pcix_bus_speed[] = {
         PCI_SPEED_133MHz_PCIX_533       /* F */
 };
 
-static unsigned char pcie_link_speed[] = {
+const unsigned char pcie_link_speed[] = {
         PCI_SPEED_UNKNOWN,              /* 0 */
         PCIE_SPEED_2_5GT,               /* 1 */
         PCIE_SPEED_5_0GT,               /* 2 */