[PATCH V2 1/4] PCI: Add DEV3 14-Bit Tag Requester register definitions

From: Vidya Sagar

Date: Tue Aug 11 2026 - 13:29:48 EST


The Device 3 Extended Capability advertises 14-Bit Tag Requester support
in bit 2 of the Device 3 Capabilities register and carries the matching
enable in bit 2 of the Device 3 Control register. Only the register
offsets and DEV3_STA.Segment Captured are defined today.

Add both 14-Bit Tag Requester bit definitions. There is deliberately no
completer counterpart: a completer reflects the Tag field of the request
it answers, so the spec defines a 14-Bit Tag Completer Supported bit but
no completer enable, and software has nothing to program there.

No functional change.

Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
---
V2:
* New patch as a result of splitting the V1 monolithic patch

include/uapi/linux/pci_regs.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index facaa324bd86..b2ba5c2642f0 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -1254,7 +1254,9 @@

/* Device 3 Extended Capability */
#define PCI_DEV3_CAP 0x04 /* Device 3 Capabilities Register */
+#define PCI_DEV3_CAP_14BIT_TAG_REQ 0x00000004 /* 14-Bit Tag Requester Supported */
#define PCI_DEV3_CTL 0x08 /* Device 3 Control Register */
+#define PCI_DEV3_CTL_14BIT_TAG_REQ_EN 0x00000004 /* 14-Bit Tag Requester Enable */
#define PCI_DEV3_STA 0x0c /* Device 3 Status Register */
#define PCI_DEV3_STA_SEGMENT 0x8 /* Segment Captured (end-to-end flit-mode detected) */

--
2.43.0