1 # SPDX-License-Identifier: GPL-2.0
3 # USB Gadget support on a system involves
4 # (a) a peripheral controller, and
5 # (b) the gadget driver using it.
7 # NOTE: Gadget support ** DOES NOT ** depend on host-side CONFIG_USB !!
9 # - Host systems (like PCs) need CONFIG_USB (with "A" jacks).
10 # - Peripherals (like PDAs) need CONFIG_USB_GADGET (with "B" jacks).
11 # - Some systems have both kinds of controllers.
13 # With help from a special transceiver and a "Mini-AB" jack, systems with
14 # both kinds of controller can also support "USB On-the-Go" (CONFIG_USB_OTG).
18 tristate "USB Gadget Support"
22 USB is a host/device protocol, organized with one host (such as a
23 PC) controlling up to 127 peripheral devices.
24 The USB hardware is asymmetric, which makes it easier to set up:
25 you can't connect a "to-the-host" connector to a peripheral.
27 Linux can run in the host, or in the peripheral. In both cases
28 you need a low level bus controller driver, and some software
29 talking to it. Peripheral controllers are often discrete silicon,
30 or are integrated with the CPU in a microcontroller. The more
31 familiar host side controllers have names like "EHCI", "OHCI",
32 or "UHCI", and are usually integrated into southbridges on PC
35 Enable this configuration option if you want to run Linux inside
36 a USB peripheral device. Configure one hardware driver for your
37 peripheral/device side bus controller, and a "gadget driver" for
38 your peripheral protocol. (If you use modular gadget drivers,
39 you may configure more than one.)
41 If in doubt, say "N" and don't enable these drivers; most people
42 don't have this kind of hardware (except maybe inside Linux PDAs).
44 For more information, see <http://www.linux-usb.org/gadget> and
45 the kernel documentation for this API.
49 config USB_GADGET_DEBUG
50 bool "Debugging messages (DEVELOPMENT)"
51 depends on DEBUG_KERNEL
53 Many controller and gadget drivers will print some debugging
54 messages if you use this option to ask for those messages.
56 Avoid enabling these messages, even if you're actively
57 debugging such a driver. Many drivers will emit so many
58 messages that the driver timings are affected, which will
59 either create new failure modes or remove the one you're
60 trying to track down. Never enable these messages for a
63 config USB_GADGET_VERBOSE
64 bool "Verbose debugging Messages (DEVELOPMENT)"
65 depends on USB_GADGET_DEBUG
67 Many controller and gadget drivers will print verbose debugging
68 messages if you use this option to ask for those messages.
70 Avoid enabling these messages, even if you're actively
71 debugging such a driver. Many drivers will emit so many
72 messages that the driver timings are affected, which will
73 either create new failure modes or remove the one you're
74 trying to track down. Never enable these messages for a
77 config USB_GADGET_DEBUG_FILES
78 bool "Debugging information files (DEVELOPMENT)"
81 Some of the drivers in the "gadget" framework can expose
82 debugging information in files such as /proc/driver/udc
83 (for a peripheral controller). The information in these
84 files may help when you're troubleshooting or bringing up a
85 driver on a new board. Enable these files by choosing "Y"
86 here. If in doubt, or to conserve kernel memory, say "N".
88 config USB_GADGET_DEBUG_FS
89 bool "Debugging information files in debugfs (DEVELOPMENT)"
92 Some of the drivers in the "gadget" framework can expose
93 debugging information in files under /sys/kernel/debug/.
94 The information in these files may help when you're
95 troubleshooting or bringing up a driver on a new board.
96 Enable these files by choosing "Y" here. If in doubt, or
97 to conserve kernel memory, say "N".
99 config USB_GADGET_VBUS_DRAW
100 int "Maximum VBUS Power usage (2-500 mA)"
104 Some devices need to draw power from USB when they are
105 configured, perhaps to operate circuitry or to recharge
106 batteries. This is in addition to any local power supply,
107 such as an AC adapter or batteries.
109 Enter the maximum power your device draws through USB, in
110 milliAmperes. The permitted range of values is 2 - 500 mA;
111 0 mA would be legal, but can make some hosts misbehave.
113 This value will be used except for system-specific gadget
114 drivers that have more specific information.
116 config USB_GADGET_STORAGE_NUM_BUFFERS
117 int "Number of storage pipeline buffers"
121 Usually 2 buffers are enough to establish a good buffering
122 pipeline. The number may be increased in order to compensate
123 for a bursty VFS behaviour. For instance there may be CPU wake up
124 latencies that makes the VFS to appear bursty in a system with
125 an CPU on-demand governor. Especially if DMA is doing IO to
126 offload the CPU. In this case the CPU will go into power
127 save often and spin up occasionally to move data within VFS.
128 If selecting USB_GADGET_DEBUG_FILES this value may be set by
129 a module parameter as well.
132 config U_SERIAL_CONSOLE
133 bool "Serial gadget console support"
134 depends on USB_U_SERIAL
136 It supports the serial gadget can be used as a console.
138 source "drivers/usb/gadget/udc/Kconfig"
144 # composite based drivers
145 config USB_LIBCOMPOSITE
148 depends on USB_GADGET
189 config USB_F_MASS_STORAGE
198 config USB_F_UAC1_LEGACY
219 # this first set of drivers all depend on bulk-capable hardware.
222 tristate "USB Gadget functions configurable through configfs"
223 select USB_LIBCOMPOSITE
225 A Linux USB "gadget" can be set up through configfs.
226 If this is the case, the USB functions (which from the host's
227 perspective are seen as interfaces) and configurations are
228 specified simply by creating appropriate directories in configfs.
229 Associating functions with configurations is done by creating
230 appropriate symbolic links.
231 For more information see Documentation/usb/gadget_configfs.rst.
233 config USB_CONFIGFS_SERIAL
234 bool "Generic serial bulk in/out"
235 depends on USB_CONFIGFS
240 The function talks to the Linux-USB generic serial driver.
242 config USB_CONFIGFS_ACM
243 bool "Abstract Control Model (CDC ACM)"
244 depends on USB_CONFIGFS
249 ACM serial link. This function can be used to interoperate with
250 MS-Windows hosts or with the Linux-USB "cdc-acm" driver.
252 config USB_CONFIGFS_OBEX
253 bool "Object Exchange Model (CDC OBEX)"
254 depends on USB_CONFIGFS
259 You will need a user space OBEX server talking to /dev/ttyGS*,
260 since the kernel itself doesn't implement the OBEX protocol.
262 config USB_CONFIGFS_NCM
263 bool "Network Control Model (CDC NCM)"
264 depends on USB_CONFIGFS
270 NCM is an advanced protocol for Ethernet encapsulation, allows
271 grouping of several ethernet frames into one USB transfer and
272 different alignment possibilities.
274 config USB_CONFIGFS_ECM
275 bool "Ethernet Control Model (CDC ECM)"
276 depends on USB_CONFIGFS
281 The "Communication Device Class" (CDC) Ethernet Control Model.
282 That protocol is often avoided with pure Ethernet adapters, in
283 favor of simpler vendor-specific hardware, but is widely
284 supported by firmware for smart network devices.
286 config USB_CONFIGFS_ECM_SUBSET
287 bool "Ethernet Control Model (CDC ECM) subset"
288 depends on USB_CONFIGFS
293 On hardware that can't implement the full protocol,
294 a simple CDC subset is used, placing fewer demands on USB.
296 config USB_CONFIGFS_RNDIS
298 depends on USB_CONFIGFS
303 Microsoft Windows XP bundles the "Remote NDIS" (RNDIS) protocol,
304 and Microsoft provides redistributable binary RNDIS drivers for
305 older versions of Windows.
307 To make MS-Windows work with this, use Documentation/usb/linux.inf
308 as the "driver info file". For versions of MS-Windows older than
309 XP, you'll need to download drivers from Microsoft's website; a URL
310 is given in comments found in that info file.
312 config USB_CONFIGFS_EEM
313 bool "Ethernet Emulation Model (EEM)"
314 depends on USB_CONFIGFS
320 CDC EEM is a newer USB standard that is somewhat simpler than CDC ECM
321 and therefore can be supported by more hardware. Technically ECM and
322 EEM are designed for different applications. The ECM model extends
323 the network interface to the target (e.g. a USB cable modem), and the
324 EEM model is for mobile devices to communicate with hosts using
325 ethernet over USB. For Linux gadgets, however, the interface with
326 the host is the same (a usbX device), so the differences are minimal.
328 config USB_CONFIGFS_PHONET
329 bool "Phonet protocol"
330 depends on USB_CONFIGFS
336 The Phonet protocol implementation for USB device.
338 config USB_CONFIGFS_MASS_STORAGE
340 depends on USB_CONFIGFS
342 select USB_F_MASS_STORAGE
344 The Mass Storage Gadget acts as a USB Mass Storage disk drive.
345 As its storage repository it can use a regular file or a block
346 device (in much the same way as the "loop" device driver),
347 specified as a module parameter or sysfs option.
349 config USB_CONFIGFS_F_LB_SS
350 bool "Loopback and sourcesink function (for testing)"
351 depends on USB_CONFIGFS
354 Loopback function loops back a configurable number of transfers.
355 Sourcesink function either sinks and sources bulk data.
356 It also implements control requests, for "chapter 9" conformance.
357 Make this be the first driver you try using on top of any new
358 USB peripheral controller driver. Then you can use host-side
359 test software, like the "usbtest" driver, to put your hardware
360 and its driver through a basic set of functional tests.
362 config USB_CONFIGFS_F_FS
363 bool "Function filesystem (FunctionFS)"
364 depends on USB_CONFIGFS
367 The Function Filesystem (FunctionFS) lets one create USB
368 composite functions in user space in the same way GadgetFS
369 lets one create USB gadgets in user space. This allows creation
370 of composite gadgets such that some of the functions are
371 implemented in kernel space (for instance Ethernet, serial or
372 mass storage) and other are implemented in user space.
374 config USB_CONFIGFS_F_UAC1
375 bool "Audio Class 1.0"
376 depends on USB_CONFIGFS
378 select USB_LIBCOMPOSITE
383 This Audio function implements 1 AudioControl interface,
384 1 AudioStreaming Interface each for USB-OUT and USB-IN.
385 This driver doesn't expect any real Audio codec to be present
386 on the device - the audio streams are simply sinked to and
387 sourced from a virtual ALSA sound card created. The user-space
388 application may choose to do whatever it wants with the data
389 received from the USB Host and choose to provide whatever it
390 wants as audio data to the USB Host.
392 config USB_CONFIGFS_F_UAC1_LEGACY
393 bool "Audio Class 1.0 (legacy implementation)"
394 depends on USB_CONFIGFS
396 select USB_LIBCOMPOSITE
398 select USB_F_UAC1_LEGACY
400 This Audio function implements 1 AudioControl interface,
401 1 AudioStreaming Interface each for USB-OUT and USB-IN.
402 This is a legacy driver and requires a real Audio codec
403 to be present on the device.
405 config USB_CONFIGFS_F_UAC2
406 bool "Audio Class 2.0"
407 depends on USB_CONFIGFS
409 select USB_LIBCOMPOSITE
414 This Audio function is compatible with USB Audio Class
415 specification 2.0. It implements 1 AudioControl interface,
416 1 AudioStreaming Interface each for USB-OUT and USB-IN.
417 This driver doesn't expect any real Audio codec to be present
418 on the device - the audio streams are simply sinked to and
419 sourced from a virtual ALSA sound card created. The user-space
420 application may choose to do whatever it wants with the data
421 received from the USB Host and choose to provide whatever it
422 wants as audio data to the USB Host.
424 config USB_CONFIGFS_F_MIDI
426 depends on USB_CONFIGFS
428 select USB_LIBCOMPOSITE
432 The MIDI Function acts as a USB Audio device, with one MIDI
433 input and one MIDI output. These MIDI jacks appear as
434 a sound "card" in the ALSA sound system. Other MIDI
435 connections can then be made on the gadget system, using
436 ALSA's aconnect utility etc.
438 config USB_CONFIGFS_F_HID
440 depends on USB_CONFIGFS
443 The HID function driver provides generic emulation of USB
444 Human Interface Devices (HID).
446 For more information, see Documentation/usb/gadget_hid.rst.
448 config USB_CONFIGFS_F_UVC
449 bool "USB Webcam function"
450 depends on USB_CONFIGFS
451 depends on VIDEO_V4L2
453 select VIDEOBUF2_VMALLOC
456 The Webcam function acts as a composite USB Audio and Video Class
457 device. It provides a userspace API to process UVC control requests
458 and stream video data to the host.
460 config USB_CONFIGFS_F_PRINTER
461 bool "Printer function"
463 depends on USB_CONFIGFS
465 The Printer function channels data between the USB host and a
466 userspace program driving the print engine. The user space
467 program reads and writes the device file /dev/g_printer<X> to
468 receive or send printer data. It can use ioctl calls to
469 the device file to get or set printer status.
471 For more information, see Documentation/usb/gadget_printer.rst
472 which includes sample code for accessing the device file.
474 config USB_CONFIGFS_F_TCM
475 bool "USB Gadget Target Fabric"
476 depends on TARGET_CORE
477 depends on USB_CONFIGFS
478 select USB_LIBCOMPOSITE
481 This fabric is a USB gadget component. Two USB protocols are
482 supported that is BBB or BOT (Bulk Only Transport) and UAS
483 (USB Attached SCSI). BOT is advertised on alternative
484 interface 0 (primary) and UAS is on alternative interface 1.
485 Both protocols can work on USB2.0 and USB3.0.
486 UAS utilizes the USB 3.0 feature called streams support.
488 source "drivers/usb/gadget/legacy/Kconfig"