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PCI: Add pci_find_dvsec_capability to find designated VSEC

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Add pci_find_dvsec_capability to locate a Designated Vendor-Specific
Extended Capability with the specified Vendor ID and Capability ID.

The Designated Vendor-Specific Extended Capability (DVSEC) allows one or
more "vendor" specific capabilities that are not tied to the Vendor ID
of the PCI component. Where the DVSEC Vendor may be a standards body
like CXL.

Cc: David E. Box <david.e.box@linux.intel.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-pci@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Andrew Donnellan <ajd@linux.ibm.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163379787943.692348.6814373487017444007.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Ben Widawsky 2021-10-09 09:44:39 -07:00 committed by Dan Williams
parent 85afc3175a
commit ee12203746
2 changed files with 33 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
drivers/pci/pci.c
View file

@ -732,6 +732,38 @@ u16 pci_find_vsec_capability(struct pci_dev *dev, u16 vendor, int cap)
}
EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
/**
* pci_find_dvsec_capability - Find DVSEC for vendor
* @dev: PCI device to query
* @vendor: Vendor ID to match for the DVSEC
* @dvsec: Designated Vendor-specific capability ID
*
* If DVSEC has Vendor ID @vendor and DVSEC ID @dvsec return the capability
* offset in config space; otherwise return 0.
*/
u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec)
{
int pos;
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DVSEC);
if (!pos)
return 0;
while (pos) {
u16 v, id;
pci_read_config_word(dev, pos + PCI_DVSEC_HEADER1, &v);
pci_read_config_word(dev, pos + PCI_DVSEC_HEADER2, &id);
if (vendor == v && dvsec == id)
return pos;
pos = pci_find_next_ext_capability(dev, pos, PCI_EXT_CAP_ID_DVSEC);
}
return 0;
}
EXPORT_SYMBOL_GPL(pci_find_dvsec_capability);
/**
* pci_find_parent_resource - return resource region of parent bus of given
* region

1
include/linux/pci.h
View file

@ -1130,6 +1130,7 @@ 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);
u16 pci_find_dvsec_capability(struct pci_dev *dev, u16 vendor, u16 dvsec);
u64 pci_get_dsn(struct pci_dev *dev);