diff options
Diffstat (limited to 'src/device')
| -rw-r--r-- | src/device/pciexp_device.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/device/pciexp_device.c b/src/device/pciexp_device.c index ea0ec1a39b..bc4012503a 100644 --- a/src/device/pciexp_device.c +++ b/src/device/pciexp_device.c @@ -55,6 +55,35 @@ unsigned int pciexp_find_extended_cap(const struct device *dev, unsigned int cap return pciexp_get_ext_cap_offset(dev, cap, next_cap_offset); } +/* + * Search for a vendor-specific extended capability, + * with the vendor-specific ID `cap`. + * + * Returns the offset of the vendor-specific header, + * i.e. the offset of the extended capability + 4, + * or 0 if none is found. + * + * A new search is started with `offset == 0`. + * To continue a search, the prior return value + * should be passed as `offset`. + */ +unsigned int pciexp_find_ext_vendor_cap(const struct device *dev, unsigned int cap, + unsigned int offset) +{ + /* Reconstruct capability offset from vendor-specific header offset. */ + if (offset >= 4) + offset -= 4; + + for (;;) { + offset = pciexp_find_extended_cap(dev, PCI_EXT_CAP_ID_VNDR, offset); + if (!offset) + return 0; + + const unsigned int vndr_cap = pci_read_config32(dev, offset + 4); + if ((vndr_cap & 0xffff) == cap) + return offset + 4; + } +} /* * Re-train a PCIe link |