PCI: Add pci_find_vsec_capability() to find a specific VSEC

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>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/d89506834fb11c6fa0bd5d515c0dd55b13ac6958.1613674948.git.gustavo.pimentel@synopsys.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 16a17215f633ddc40d87faa4329bdfb20a7e2ed5..97c0f2ec922b9791e6881b7b53937d67626b6998 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -692,6 +692,36 @@ 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

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 86c799c97b7796665524666dc4a73f12ab81cbb3..59e731a2d1f8c94d2ea66fe988063a118dd99233 100644 (file)
--- 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);