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    Subject[PATCH v7 04/15] PCI: Add pci_find_vsec_capability() to find a specific VSEC
    Date
    Add pci_find_vsec_capability() to locate a Vendor-Specific Extended
    Capability with the specified VSEC ID.

    The Vendor-Specific Extended Capability (VSEC) allows one or more
    proprietary capabilities defined by the vendor which aren't standard
    or shared between vendors.

    Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
    ---
    drivers/pci/pci.c | 30 ++++++++++++++++++++++++++++++
    include/linux/pci.h | 1 +
    2 files changed, 31 insertions(+)

    diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
    index b9fecc2..aef217c 100644
    --- a/drivers/pci/pci.c
    +++ b/drivers/pci/pci.c
    @@ -693,6 +693,36 @@ u8 pci_find_ht_capability(struct pci_dev *dev, int ht_cap)
    EXPORT_SYMBOL_GPL(pci_find_ht_capability);

    /**
    + * pci_find_vsec_capability - Find a vendor-specific extended capability
    + * @dev: PCI device to query
    + * @vendor: Vendor ID for which capability is defined
    + * @cap: Vendor-specific capability ID
    + *
    + * If @dev has Vendor ID @vendor, search for a VSEC capability with
    + * VSEC ID @cap. If found, return the capability offset in
    + * config space; otherwise return 0.
    + */
    +u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap)
    +{
    + u16 vsec = 0;
    + u32 header;
    +
    + if (vendor != dev->vendor)
    + return 0;
    +
    + while ((vsec = pci_find_next_ext_capability(dev, vsec,
    + PCI_EXT_CAP_ID_VNDR))) {
    + if (pci_read_config_dword(dev, vsec + PCI_VNDR_HEADER,
    + &header) == PCIBIOS_SUCCESSFUL &&
    + PCI_VNDR_HEADER_ID(header) == cap)
    + return vsec;
    + }
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
    +
    +/**
    * pci_find_parent_resource - return resource region of parent bus of given
    * region
    * @dev: PCI device structure contains resources to be searched
    diff --git a/include/linux/pci.h b/include/linux/pci.h
    index b32126d..814f814 100644
    --- a/include/linux/pci.h
    +++ b/include/linux/pci.h
    @@ -1077,6 +1077,7 @@ u8 pci_find_next_ht_capability(struct pci_dev *dev, u8 pos, int ht_cap);
    u16 pci_find_ext_capability(struct pci_dev *dev, int cap);
    u16 pci_find_next_ext_capability(struct pci_dev *dev, u16 pos, int cap);
    struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
    +u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap);

    u64 pci_get_dsn(struct pci_dev *dev);

    --
    2.7.4
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