diff options
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/pci.c | 43 |
1 files changed, 43 insertions, 0 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 |