diff options
Diffstat (limited to 'Documentation/usb')
| -rw-r--r-- | Documentation/usb/functionfs-desc.rst | 39 | ||||
| -rw-r--r-- | Documentation/usb/functionfs.rst | 38 | ||||
| -rw-r--r-- | Documentation/usb/gadget-testing.rst | 27 | ||||
| -rw-r--r-- | Documentation/usb/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/usb/usbip_protocol.rst | 12 |
5 files changed, 111 insertions, 6 deletions
diff --git a/Documentation/usb/functionfs-desc.rst b/Documentation/usb/functionfs-desc.rst new file mode 100644 index 000000000000..39649774da54 --- /dev/null +++ b/Documentation/usb/functionfs-desc.rst @@ -0,0 +1,39 @@ +====================== +FunctionFS Descriptors +====================== + +Some of the descriptors that can be written to the FFS gadget are +described below. Device and configuration descriptors are handled +by the composite gadget and are not written by the user to the +FFS gadget. + +Descriptors are written to the "ep0" file in the FFS gadget +following the descriptor header. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: descriptors + +Interface Descriptors +--------------------- + +Standard USB interface descriptors may be written. The class/subclass of the +most recent interface descriptor determines what type of class-specific +descriptors are accepted. + +Class-Specific Descriptors +-------------------------- + +Class-specific descriptors are accepted only for the class/subclass of the +most recent interface descriptor. The following are some of the +class-specific descriptors that are supported. + +DFU Functional Descriptor +~~~~~~~~~~~~~~~~~~~~~~~~~ + +When the interface class is USB_CLASS_APP_SPEC and the interface subclass +is USB_SUBCLASS_DFU, a DFU functional descriptor can be provided. +The DFU functional descriptor is a described in the USB specification for +Device Firmware Upgrade (DFU), version 1.1 as of this writing. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: usb_dfu_functional_descriptor diff --git a/Documentation/usb/functionfs.rst b/Documentation/usb/functionfs.rst index a3054bea38f3..f7487b0d8057 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 @@ -22,6 +25,8 @@ interface numbers starting from zero). The FunctionFS changes them as needed also handling situation when numbers differ in different configurations. +For more information about FunctionFS descriptors see :doc:`functionfs-desc` + When descriptors and strings are written "ep#" files appear (one for each declared endpoint) which handle communication on a single endpoint. Again, FunctionFS takes care of the real @@ -66,3 +71,36 @@ 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. diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst index 077dfac7ed98..bf555c2270f5 100644 --- a/Documentation/usb/gadget-testing.rst +++ b/Documentation/usb/gadget-testing.rst @@ -206,6 +206,14 @@ the standard procedure for using FunctionFS (mount it, run the userspace process which implements the function proper). The gadget should be enabled by writing a suitable string to usb_gadget/<gadget>/UDC. +The FFS function provides just one attribute in its function directory: + + ready + +The attribute is read-only and signals if the function is ready (1) to be +used, E.G. if userspace has written descriptors and strings to ep0, so +the gadget can be enabled. + Testing the FFS function ------------------------ @@ -757,6 +765,17 @@ The uac2 function provides these attributes in its function directory: req_number the number of pre-allocated request for both capture and playback function_name name of the interface + if_ctrl_name topology control name + clksrc_in_name input clock name + clksrc_out_name output clock name + p_it_name playback input terminal name + p_it_ch_name playback input first channel name + p_ot_name playback output terminal name + p_fu_vol_name playback function unit name + c_it_name capture input terminal name + c_it_ch_name capture input first channel name + c_ot_name capture output terminal name + c_fu_vol_name capture functional unit name c_terminal_type code of the capture terminal type p_terminal_type code of the playback terminal type ================ ==================================================== @@ -949,6 +968,14 @@ The uac1 function provides these attributes in its function directory: req_number the number of pre-allocated requests for both capture and playback function_name name of the interface + p_it_name playback input terminal name + p_it_ch_name playback channels name + p_ot_name playback output terminal name + p_fu_vol_name playback mute/volume functional unit name + c_it_name capture input terminal name + c_it_ch_name capture channels name + c_ot_name capture output terminal name + c_fu_vol_name capture mute/volume functional unit name ================ ==================================================== The attributes have sane default values. diff --git a/Documentation/usb/index.rst b/Documentation/usb/index.rst index 27955dad95e1..826492c813ac 100644 --- a/Documentation/usb/index.rst +++ b/Documentation/usb/index.rst @@ -11,6 +11,7 @@ USB support dwc3 ehci functionfs + functionfs-desc gadget_configfs gadget_hid gadget_multi diff --git a/Documentation/usb/usbip_protocol.rst b/Documentation/usb/usbip_protocol.rst index adc158967cc6..3da1df3d94f5 100644 --- a/Documentation/usb/usbip_protocol.rst +++ b/Documentation/usb/usbip_protocol.rst @@ -285,17 +285,17 @@ OP_REP_IMPORT: +-----------+--------+------------+---------------------------------------------------+ | 0x138 | 2 | | bcdDevice | +-----------+--------+------------+---------------------------------------------------+ -| 0x139 | 1 | | bDeviceClass | +| 0x13A | 1 | | bDeviceClass | +-----------+--------+------------+---------------------------------------------------+ -| 0x13A | 1 | | bDeviceSubClass | +| 0x13B | 1 | | bDeviceSubClass | +-----------+--------+------------+---------------------------------------------------+ -| 0x13B | 1 | | bDeviceProtocol | +| 0x13C | 1 | | bDeviceProtocol | +-----------+--------+------------+---------------------------------------------------+ -| 0x13C | 1 | | bConfigurationValue | +| 0x13D | 1 | | bConfigurationValue | +-----------+--------+------------+---------------------------------------------------+ -| 0x13D | 1 | | bNumConfigurations | +| 0x13E | 1 | | bNumConfigurations | +-----------+--------+------------+---------------------------------------------------+ -| 0x13E | 1 | | bNumInterfaces | +| 0x13F | 1 | | bNumInterfaces | +-----------+--------+------------+---------------------------------------------------+ The following four commands have a common basic header called |