3 files changed, 48 insertions, 2 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e37fea6e178d..c71e78c46705 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3579,6 +3579,49 @@ 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 d1182c4a754e..948d1a033a22 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 46ada5c098eb..496c5b082d42 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -513,7 +513,7 @@ 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 */
@@ -532,7 +532,7 @@ 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 */