PCI: Allow PCIe Capability link-related register access for switches

Every PCIe device has a link, except Root Complex Integrated Endpoints
and Root Complex Event Collectors.  Previously we didn't give access
to PCIe capability link-related registers for Upstream Ports, Downstream
Ports, and Bridges, so attempts to read PCI_EXP_LNKCTL incorrectly
returned zero.  See PCIe spec r3.0, sec 7.8 and 1.3.2.3.

Reference: http://lkml.kernel.org/r/979A8436335E3744ADCD3A9F2A2B68A52AD136BE@SJEXCHMB10.corp.ad.broadcom.com
Reported-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-By: Jiang Liu <jiang.liu@huawei.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 1cc23661f79b..e26c3bd9aca4 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -485,9 +485,13 @@ static inline bool pcie_cap_has_lnkctl(const struct pci_dev *dev)
         int type = pci_pcie_type(dev);
 
         return pcie_cap_version(dev) > 1 ||
-               type == PCI_EXP_TYPE_ROOT_PORT ||
                type == PCI_EXP_TYPE_ENDPOINT ||
-               type == PCI_EXP_TYPE_LEG_END;
+               type == PCI_EXP_TYPE_LEG_END ||
+               type == PCI_EXP_TYPE_ROOT_PORT ||
+               type == PCI_EXP_TYPE_UPSTREAM ||
+               type == PCI_EXP_TYPE_DOWNSTREAM ||
+               type == PCI_EXP_TYPE_PCI_BRIDGE ||
+               type == PCI_EXP_TYPE_PCIE_BRIDGE;
 }
 
 static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)