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path: root/drivers/pci/pci.c
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Diffstat (limited to 'drivers/pci/pci.c')
-rw-r--r--drivers/pci/pci.c43
1 files changed, 43 insertions, 0 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