Commit ee122037 authored by Ben Widawsky's avatar Ben Widawsky Committed by Dan Williams
Browse files

PCI: Add pci_find_dvsec_capability to find designated VSEC 



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: default avatarFrederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: default avatarBen Widawsky <ben.widawsky@intel.com>
Reviewed-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Tested-by: default avatarKan Liang <kan.liang@linux.intel.com>
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163379787943.692348.6814373487017444007.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 85afc317

drivers/pci/pci.c

+32 −0
Original line number Diff line number Diff line
@@ -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

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -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);