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PCI: Add pcie_get_speed_cap() to find max supported link speed

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Add pcie_get_speed_cap() to find the max link speed supported by a device.
Change max_link_speed_show() to use pcie_get_speed_cap().

Signed-off-by: Tal Gilboa <talgi@mellanox.com>
[bhelgaas: return speed directly instead of error and *speed, don't export
outside drivers/pci]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
This commit is contained in:
Tal Gilboa
2018-03-30 07:44:05 -05:00
committed by Bjorn Helgaas
parent 1acfb9b7ee
commit 6cf57be0f7
3 changed files with 56 additions and 26 deletions
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44
drivers/pci/pci.c
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@@ -5146,6 +5146,50 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
}
EXPORT_SYMBOL(pcie_get_minimum_link);
/**
* pcie_get_speed_cap - query for the PCI device's link speed capability
* @dev: PCI device to query
*
* Query the PCI device speed capability. Return the maximum link speed
* supported by the device.
*/
enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
{
u32 lnkcap2, lnkcap;
/*
* PCIe r4.0 sec 7.5.3.18 recommends using the Supported Link
* Speeds Vector in Link Capabilities 2 when supported, falling
* back to Max Link Speed in Link Capabilities otherwise.
*/
pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2);
if (lnkcap2) { /* PCIe r3.0-compliant */
if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_16_0GB)
return PCIE_SPEED_16_0GT;
else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB)
return PCIE_SPEED_8_0GT;
else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB)
return PCIE_SPEED_5_0GT;
else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB)
return PCIE_SPEED_2_5GT;
return PCI_SPEED_UNKNOWN;
}
pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
if (lnkcap) {
if (lnkcap & PCI_EXP_LNKCAP_SLS_16_0GB)
return PCIE_SPEED_16_0GT;
else if (lnkcap & PCI_EXP_LNKCAP_SLS_8_0GB)
return PCIE_SPEED_8_0GT;
else if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB)
return PCIE_SPEED_5_0GT;
else if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB)
return PCIE_SPEED_2_5GT;
}
return PCI_SPEED_UNKNOWN;
}
/**
* pci_select_bars - Make BAR mask from the type of resource
* @dev: the PCI device for which BAR mask is made