Merge tag 'usb-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB / Thunderbolt updates from Greg KH:
 "Here is the big set of USB and Thunderbolt changes for 6.9-rc1. Lots
  of tiny changes and forward progress to support new hardware and
  better support for existing devices. Included in here are:

   - Thunderbolt (i.e. USB4) updates for newer hardware and uses as more
     people start to use the hardware

   - default USB authentication mode Kconfig and documentation update to
     make it more obvious what is going on

   - USB typec updates and enhancements

   - usual dwc3 driver updates

   - usual xhci driver updates

   - function USB (i.e. gadget) driver updates and additions

   - new device ids for lots of drivers

   - loads of other small updates, full details in the shortlog

  All of these, including a "last minute regression fix" have been in
  linux-next with no reported issues"

* tag 'usb-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (185 commits)
  usb: usb-acpi: Fix oops due to freeing uninitialized pld pointer
  usb: gadget: net2272: Use irqflags in the call to net2272_probe_fin
  usb: gadget: tegra-xudc: Fix USB3 PHY retrieval logic
  phy: tegra: xusb: Add API to retrieve the port number of phy
  USB: gadget: pxa27x_udc: Remove unused of_gpio.h
  usb: gadget/snps_udc_plat: Remove unused of_gpio.h
  usb: ohci-pxa27x: Remove unused of_gpio.h
  usb: sl811-hcd: only defined function checkdone if QUIRK2 is defined
  usb: Clarify expected behavior of dev_bin_attrs_are_visible()
  xhci: Allow RPM on the USB controller (1022:43f7) by default
  usb: isp1760: remove SLAB_MEM_SPREAD flag usage
  usb: misc: onboard_hub: use pointer consistently in the probe function
  usb: gadget: fsl: Increase size of name buffer for endpoints
  usb: gadget: fsl: Add of device table to enable module autoloading
  usb: typec: tcpm: add support to set tcpc connector orientatition
  usb: typec: tcpci: add generic tcpci fallback compatible
  dt-bindings: usb: typec-tcpci: add tcpci fallback binding
  usb: gadget: fsl-udc: Replace custom log wrappers by dev_{err,warn,dbg,vdbg}
  usb: core: Set connect_type of ports based on DT node
  dt-bindings: usb: Add downstream facing ports to realtek binding
  ...

1 files changed, 36 insertions, 0 deletions

diff --git a/Documentation/usb/functionfs.rst b/Documentation/usb/functionfs.rst
index a3054bea38f3cd..d05a775bc45bc0 100644
--- a/Documentation/usb/functionfs.rst
+++ b/Documentation/usb/functionfs.rst
@@ -2,6 +2,9 @@
 How FunctionFS works
 ====================
 
+Overview
+========
+
 From kernel point of view it is just a composite function with some
 unique behaviour.  It may be added to an USB configuration only after
 the user space driver has registered by writing descriptors and
@@ -66,3 +69,36 @@ have been written to their ep0's.
 
 Conversely, the gadget is unregistered after the first USB function
 closes its endpoints.
+
+DMABUF interface
+================
+
+FunctionFS additionally supports a DMABUF based interface, where the
+userspace can attach DMABUF objects (externally created) to an endpoint,
+and subsequently use them for data transfers.
+
+A userspace application can then use this interface to share DMABUF
+objects between several interfaces, allowing it to transfer data in a
+zero-copy fashion, for instance between IIO and the USB stack.
+
+As part of this interface, three new IOCTLs have been added. These three
+IOCTLs have to be performed on a data endpoint (ie. not ep0). They are:
+
+  ``FUNCTIONFS_DMABUF_ATTACH(int)``
+    Attach the DMABUF object, identified by its file descriptor, to the
+    data endpoint. Returns zero on success, and a negative errno value
+    on error.
+
+  ``FUNCTIONFS_DMABUF_DETACH(int)``
+    Detach the given DMABUF object, identified by its file descriptor,
+    from the data endpoint. Returns zero on success, and a negative
+    errno value on error. Note that closing the endpoint's file
+    descriptor will automatically detach all attached DMABUFs.
+
+  ``FUNCTIONFS_DMABUF_TRANSFER(struct usb_ffs_dmabuf_transfer_req *)``
+    Enqueue the previously attached DMABUF to the transfer queue.
+    The argument is a structure that packs the DMABUF's file descriptor,
+    the size in bytes to transfer (which should generally correspond to
+    the size of the DMABUF), and a 'flags' field which is unused
+    for now. Returns zero on success, and a negative errno value on
+    error.