• Jiang Liu's avatar
    PCI: Add accessors for PCI Express Capability · 8c0d3a02
    Jiang Liu authored
    The PCI Express Capability (PCIe spec r3.0, sec 7.8) comes in two
    versions, v1 and v2.  In v1 Capability structures (PCIe spec r1.0 and
    r1.1), some fields are optional, so the structure size depends on the
    device type.
    
    This patch adds functions to access this capability so drivers don't
    have to be aware of the differences between v1 and v2.  Note that these
    new functions apply only to the "PCI Express Capability," not to any of
    the other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
    
    Function pcie_capability_read_word/dword() reads the PCIe Capabilities
    register and returns the value in the reference parameter "val".  If
    the PCIe Capabilities register is not implemented on the PCIe device,
    "val" is set to 0.
    
    Function pcie_capability_write_word/dword() writes the value to the
    specified PCIe Capability register.
    
    Function pcie_capability_clear_and_set_word/dword() sets and/or clears bits
    of a PCIe Capability register.
    
    [bhelgaas: changelog, drop "pci_" prefixes, don't export
    pcie_capability_reg_implemented()]
    Signed-off-by: 's avatarJiang Liu <jiang.liu@huawei.com>
    Signed-off-by: 's avatarYijing Wang <wangyijing@huawei.com>
    Signed-off-by: 's avatarBjorn Helgaas <bhelgaas@google.com>
    8c0d3a02
access.c 16 KB