From: Ben Widawsky <ben.widaw...@intel.com>
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....@linux.intel.com>
Cc: Jonathan Cameron <jonathan.came...@huawei.com>
Cc: Bjorn Helgaas <bhelg...@google.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: linux-...@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Andrew Donnellan <a...@linux.ibm.com>
Cc: Lu Baolu <baolu...@linux.intel.com>
Reviewed-by: Frederic Barrat <fbar...@linux.ibm.com>
Signed-off-by: Ben Widawsky <ben.widaw...@intel.com>
Reviewed-by: Andrew Donnellan <a...@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelg...@google.com>
Tested-by: Kan Liang <kan.li...@linux.intel.com>
Signed-off-by: Kan Liang <kan.li...@linux.intel.com>
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
drivers/pci/pci.c | 32 ++++++++++++++++++++++++++++++++
include/linux/pci.h | 1 +
2 files changed, 33 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ce2ab62b64cf..94ac86ff28b0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -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
diff --git a/include/linux/pci.h b/include/linux/pci.h
index cd8aa6fce204..c93ccfa4571b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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);
