[PATCH v9 8/8] ABI: sysfs-bus-pci: add documentation for p2pmem allocate

[Logan Gunthorpe]

Add documentation for the p2pmem/allocate binary file which allows
for allocating p2pmem buffers in userspace for passing to drivers
that support them. (Currently only O_DIRECT to NVMe devices.)

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-bus-pci | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 6fc2c2efe8ab..dca5e032b4fa 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -171,7 +171,7 @@ Description:
 		binary file containing the Vital Product Data for the
 		device.  It should follow the VPD format defined in
 		PCI Specification 2.1 or 2.2, but users should consider
-		that some devices may have incorrectly formatted data.  
+		that some devices may have incorrectly formatted data.
 		If the underlying VPD has a writable section then the
 		corresponding section of this file will be writable.
 
@@ -407,6 +407,16 @@ Description:
 	        file contains a '1' if the memory has been published for
 		use outside the driver that owns the device.
 
+What:		/sys/bus/pci/devices/.../p2pmem/allocate
+Date:		August 2022
+Contact:	Logan Gunthorpe <logang@xxxxxxxxxxxx>
+Description:
+		Thes attribute allows mapping p2pmem into userspace. For
+		each mmap() call on this file, the kernel will allocate
+		a chunk of Peer-to-Peer memory for use in Peer-to-Peer
+		transactions. This memory can be used in O_DIRECT calls
+		to NVMe backed files for Peer-to-Peer copies.
+
 What:		/sys/bus/pci/devices/.../link/clkpm
 		/sys/bus/pci/devices/.../link/l0s_aspm
 		/sys/bus/pci/devices/.../link/l1_aspm
-- 
2.30.2