1 # SPDX-License-Identifier: GPL-2.0
3 # USB Host Controller Drivers
5 comment "USB Host Controller Drivers"
8 tristate "Cypress C67x00 HCD support"
11 The Cypress C67x00 (EZ-Host/EZ-OTG) chips are dual-role
12 host/peripheral/OTG USB controllers.
14 Enable this option to support this chip in host controller mode.
17 To compile this driver as a module, choose M here: the
18 module will be called c67x00.
21 tristate "xHCI HCD (USB 3.0) support"
22 depends on HAS_DMA && HAS_IOMEM
24 The eXtensible Host Controller Interface (xHCI) is standard for USB 3.0
25 "SuperSpeed" host controller hardware.
27 To compile this driver as a module, choose M here: the
28 module will be called xhci-hcd.
31 config USB_XHCI_DBGCAP
32 bool "xHCI support for debug capability"
35 Say 'Y' to enable the support for the xHCI debug capability. Make
36 sure that your xHCI host supports the extended debug capability and
37 you want a TTY serial device based on the xHCI debug capability
38 before enabling this option. If unsure, say 'N'.
43 depends on USB_XHCI_PCI_RENESAS || !USB_XHCI_PCI_RENESAS
46 config USB_XHCI_PCI_RENESAS
47 tristate "Support for additional Renesas xHCI controller with firmware"
49 Say 'Y' to enable the support for the Renesas xHCI controller with
50 firmware. Make sure you have the firmware for the device and
51 installed on your system for this device to work.
54 config USB_XHCI_PLATFORM
55 tristate "Generic xHCI driver for a platform device"
57 Adds an xHCI host driver for a generic platform device, which
58 provides a memory space and an irq.
59 It is also a prerequisite for platform specific drivers that
60 implement some extra quirks.
65 tristate "xHCI support for HiSilicon STB SoCs"
66 depends on USB_XHCI_PLATFORM && (ARCH_HISI || COMPILE_TEST)
68 Say 'Y' to enable the support for the xHCI host controller
69 found in HiSilicon STB SoCs.
72 tristate "xHCI support for MediaTek SoCs"
74 depends on (MIPS && SOC_MT7621) || ARCH_MEDIATEK || COMPILE_TEST
76 Say 'Y' to enable the support for the xHCI host controller
77 found in MediaTek SoCs.
81 tristate "xHCI support for Marvell Armada 375/38x/37xx"
82 select USB_XHCI_PLATFORM
84 depends on ARCH_MVEBU || COMPILE_TEST
86 Say 'Y' to enable the support for the xHCI host controller
87 found in Marvell Armada 375/38x/37xx ARM SOCs.
90 tristate "xHCI support for Renesas R-Car SoCs"
91 depends on USB_XHCI_PLATFORM
92 depends on ARCH_RENESAS || COMPILE_TEST
95 Say 'Y' to enable the support for the xHCI host controller
96 found in Renesas R-Car ARM SoCs.
99 bool "xHCI support for Renesas RZ/V2M SoC"
100 depends on USB_XHCI_RCAR
101 depends on ARCH_R9A09G011 || COMPILE_TEST
102 depends on USB_RZV2M_USB3DRD=y || (USB_RZV2M_USB3DRD=USB_XHCI_RCAR)
104 Say 'Y' to enable the support for the xHCI host controller
105 found in Renesas RZ/V2M SoC.
107 config USB_XHCI_TEGRA
108 tristate "xHCI support for NVIDIA Tegra SoCs"
109 depends on PHY_TEGRA_XUSB
110 depends on RESET_CONTROLLER
113 Say 'Y' to enable the support for the xHCI host controller
114 found in NVIDIA Tegra124 and later SoCs.
118 config USB_EHCI_BRCMSTB
122 tristate "Broadcom STB USB support"
123 depends on (ARCH_BRCMSTB && PHY_BRCM_USB) || COMPILE_TEST
124 select USB_OHCI_HCD_PLATFORM if USB_OHCI_HCD
125 select USB_EHCI_BRCMSTB if USB_EHCI_HCD
126 select USB_XHCI_PLATFORM if USB_XHCI_HCD
128 Enables support for XHCI, EHCI and OHCI host controllers
129 found in Broadcom STB SoC's.
131 To compile these drivers as modules, choose M here: the
132 modules will be called ohci-platform.ko, ehci-brcm.ko and
135 Disabling this will keep the controllers and corresponding
139 tristate "EHCI HCD (USB 2.0) support"
140 depends on HAS_DMA && HAS_IOMEM
142 The Enhanced Host Controller Interface (EHCI) is standard for USB 2.0
143 "high speed" (480 Mbit/sec, 60 Mbyte/sec) host controller hardware.
144 If your USB host controller supports USB 2.0, you will likely want to
145 configure this Host Controller Driver.
147 EHCI controllers are packaged with "companion" host controllers (OHCI
148 or UHCI) to handle USB 1.1 devices connected to root hub ports. Ports
149 will connect to EHCI if the device is high speed, otherwise they
150 connect to a companion controller. If you configure EHCI, you should
151 probably configure the OHCI (for NEC and some other vendors) USB Host
152 Controller Driver or UHCI (for Via motherboards) Host Controller
155 You may want to read <file:Documentation/usb/ehci.rst>.
157 To compile this driver as a module, choose M here: the
158 module will be called ehci-hcd.
160 config USB_EHCI_ROOT_HUB_TT
161 bool "Root Hub Transaction Translators"
162 depends on USB_EHCI_HCD
164 Some EHCI chips have vendor-specific extensions to integrate
165 transaction translators, so that no OHCI or UHCI companion
166 controller is needed. It's safe to say "y" even if your
167 controller doesn't support this feature.
169 This supports the EHCI implementation that's originally
170 from ARC, and has since changed hands a few times.
172 config USB_EHCI_TT_NEWSCHED
173 bool "Improved Transaction Translator scheduling"
174 depends on USB_EHCI_HCD
177 This changes the periodic scheduling code to fill more of the low
178 and full speed bandwidth available from the Transaction Translator
179 (TT) in USB 2.0 hubs. Without this, only one transfer will be
180 issued in each microframe, significantly reducing the number of
181 periodic low/fullspeed transfers possible.
183 If you have multiple periodic low/fullspeed devices connected to a
184 highspeed USB hub which is connected to a highspeed USB Host
185 Controller, and some of those devices will not work correctly
186 (possibly due to "ENOSPC" or "-28" errors), say Y. Conversely, if
187 you have only one such device and it doesn't work, you could try
199 config XPS_USB_HCD_XILINX
200 bool "Use Xilinx usb host EHCI controller core"
201 depends on (PPC32 || MICROBLAZE)
202 select USB_EHCI_BIG_ENDIAN_DESC
203 select USB_EHCI_BIG_ENDIAN_MMIO
205 Xilinx xps USB host controller core is EHCI compliant and has
206 transaction translator built-in. It can be configured to either
207 support both high speed and full speed devices, or high speed
211 tristate "Support for Freescale on-chip EHCI USB controller"
212 select USB_EHCI_ROOT_HUB_TT
214 Variation of ARC USB block used in some Freescale chips.
216 config USB_EHCI_HCD_NPCM7XX
217 tristate "Support for Nuvoton NPCM on-chip EHCI USB controller"
218 depends on (USB_EHCI_HCD && ARCH_NPCM) || COMPILE_TEST
219 default y if (USB_EHCI_HCD && ARCH_NPCM)
221 Enables support for the on-chip EHCI controller on
224 config USB_EHCI_HCD_OMAP
225 tristate "EHCI support for OMAP3 and later chips"
226 depends on ARCH_OMAP || COMPILE_TEST
227 depends on NOP_USB_XCEIV
230 Enables support for the on-chip EHCI controller on
231 OMAP3 and later chips.
233 config USB_EHCI_HCD_ORION
234 tristate "Support for Marvell EBU on-chip EHCI USB controller"
235 depends on USB_EHCI_HCD && (PLAT_ORION || ARCH_MVEBU || COMPILE_TEST)
236 default y if (PLAT_ORION || ARCH_MVEBU)
238 Enables support for the on-chip EHCI controller on Marvell's
239 embedded ARM SoCs, including Orion, Kirkwood, Dove, Armada XP,
240 Armada 370. This is different from the EHCI implementation
241 on Marvell's mobile PXA and MMP SoC, see "EHCI support for
242 Marvell PXA/MMP USB controller" for those.
244 config USB_EHCI_HCD_SPEAR
245 tristate "Support for ST SPEAr on-chip EHCI USB controller"
246 depends on USB_EHCI_HCD && (PLAT_SPEAR || COMPILE_TEST)
247 default y if PLAT_SPEAR
249 Enables support for the on-chip EHCI controller on
252 config USB_EHCI_HCD_STI
253 tristate "Support for ST STiHxxx on-chip EHCI USB controller"
254 depends on (ARCH_STI || COMPILE_TEST) && OF
256 select USB_EHCI_HCD_PLATFORM
258 Enable support for the on-chip EHCI controller found on
259 STMicroelectronics consumer electronics SoC's.
261 config USB_EHCI_HCD_AT91
262 tristate "Support for Atmel on-chip EHCI USB controller"
263 depends on USB_EHCI_HCD && (ARCH_AT91 || COMPILE_TEST)
264 default y if ARCH_AT91
266 Enables support for the on-chip EHCI controller on
269 config USB_EHCI_TEGRA
270 tristate "NVIDIA Tegra HCD support"
271 depends on ARCH_TEGRA
273 select USB_CHIPIDEA_HOST
274 select USB_CHIPIDEA_TEGRA
277 This option is deprecated now and the driver was removed, use
278 USB_CHIPIDEA_TEGRA instead.
280 Enable support for the internal USB Host Controllers
281 found in NVIDIA Tegra SoCs. The controllers are EHCI compliant.
283 config USB_EHCI_HCD_PPC_OF
284 bool "EHCI support for PPC USB controller on OF platform bus"
288 Enables support for the USB controller present on the PowerPC
289 OpenFirmware platform bus.
292 bool "EHCI support for SuperH USB controller"
293 depends on SUPERH || COMPILE_TEST
295 Enables support for the on-chip EHCI controller on the SuperH.
296 If you use the PCI EHCI controller, this option is not necessary.
298 config USB_EHCI_EXYNOS
299 tristate "EHCI support for Samsung S5P/Exynos SoC Series"
300 depends on ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
302 Enable support for the Samsung S5Pv210 and Exynos SOC's on-chip EHCI
306 tristate "EHCI support for Marvell PXA/MMP USB controller"
307 depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST
308 select USB_EHCI_ROOT_HUB_TT
310 Enables support for Marvell (including PXA and MMP series) on-chip
311 USB SPH and OTG controller. SPH is a single port host, and it can
312 only be EHCI host. OTG is controller that can switch to host mode.
313 Note that this driver will not work on Marvell's other EHCI
314 controller used by the EBU-type SoCs including Orion, Kirkwood,
315 Dova, Armada 370 and Armada XP. See "Support for Marvell EBU
316 on-chip EHCI USB controller" for those.
318 config USB_OCTEON_HCD
319 tristate "Cavium Networks Octeon USB support"
320 depends on CAVIUM_OCTEON_SOC && USB
322 This driver supports USB host controller on some Cavium
323 Networks' products in the Octeon family.
325 To compile this driver as a module, choose M here. The module
326 will be called octeon-hcd.
328 config USB_EHCI_HCD_PLATFORM
329 tristate "Generic EHCI driver for a platform device"
331 Adds an EHCI host driver for a generic platform device, which
332 provides a memory space and an irq.
336 config USB_OCTEON_EHCI
337 bool "Octeon on-chip EHCI support (DEPRECATED)"
338 depends on CAVIUM_OCTEON_SOC
339 select USB_EHCI_BIG_ENDIAN_MMIO if CPU_BIG_ENDIAN
340 select USB_EHCI_HCD_PLATFORM
342 This option is deprecated now and the driver was removed, use
343 USB_EHCI_HCD_PLATFORM instead.
345 Enable support for the Octeon II SOC's on-chip EHCI
346 controller. It is needed for high-speed (480Mbit/sec)
347 USB 2.0 device support. All CN6XXX based chips with USB are
352 config USB_OXU210HP_HCD
353 tristate "OXU210HP HCD support"
356 The OXU210HP is an USB host/OTG/device controller. Enable this
357 option if your board has this chip. If unsure, say N.
359 This driver does not support isochronous transfers and doesn't
360 implement OTG nor USB device controllers.
362 To compile this driver as a module, choose M here: the
363 module will be called oxu210hp-hcd.
365 config USB_ISP116X_HCD
366 tristate "ISP116X HCD support"
369 The ISP1160 and ISP1161 chips are USB host controllers. Enable this
370 option if your board has this chip. If unsure, say N.
372 This driver does not support isochronous transfers.
374 To compile this driver as a module, choose M here: the
375 module will be called isp116x-hcd.
377 config USB_ISP1362_HCD
378 tristate "ISP1362 HCD support"
379 depends on HAS_IOPORT
380 depends on COMPILE_TEST # nothing uses this
382 Supports the Philips ISP1362 chip as a host controller
384 This driver does not support isochronous transfers.
386 To compile this driver as a module, choose M here: the
387 module will be called isp1362-hcd.
389 config USB_MAX3421_HCD
390 tristate "MAX3421 HCD (USB-over-SPI) support"
391 depends on USB && SPI
393 The Maxim MAX3421E chip supports standard USB 2.0-compliant
394 full-speed devices either in host or peripheral mode. This
395 driver supports the host-mode of the MAX3421E only.
397 To compile this driver as a module, choose M here: the module will
398 be called max3421-hcd.
401 tristate "OHCI HCD (USB 1.1) support"
402 depends on HAS_DMA && HAS_IOMEM
404 The Open Host Controller Interface (OHCI) is a standard for accessing
405 USB 1.1 host controller hardware. It does more in hardware than Intel's
406 UHCI specification. If your USB host controller follows the OHCI spec,
407 say Y. On most non-x86 systems, and on x86 hardware that's not using a
408 USB controller from Intel or VIA, this is appropriate. If your host
409 controller doesn't use PCI, this is probably appropriate. For a PCI
410 based system where you're not sure, the "lspci -v" entry will list the
411 right "prog-if" for your USB controller(s): EHCI, OHCI, or UHCI.
413 To compile this driver as a module, choose M here: the
414 module will be called ohci-hcd.
418 config USB_OHCI_HCD_OMAP1
419 tristate "OHCI support for OMAP1/2 chips"
420 depends on ARCH_OMAP1
423 Enables support for the OHCI controller on OMAP1/2 chips.
425 config USB_OHCI_HCD_SPEAR
426 tristate "Support for ST SPEAr on-chip OHCI USB controller"
427 depends on USB_OHCI_HCD && (PLAT_SPEAR || COMPILE_TEST)
428 default y if PLAT_SPEAR
430 Enables support for the on-chip OHCI controller on
433 config USB_OHCI_HCD_STI
434 tristate "Support for ST STiHxxx on-chip OHCI USB controller"
435 depends on (ARCH_STI || COMPILE_TEST) && OF
437 select USB_OHCI_HCD_PLATFORM
439 Enable support for the on-chip OHCI controller found on
440 STMicroelectronics consumer electronics SoC's.
442 config USB_OHCI_HCD_S3C2410
443 tristate "OHCI support for Samsung S3C64xx SoC series"
444 depends on USB_OHCI_HCD && (ARCH_S3C64XX || COMPILE_TEST)
447 Enables support for the on-chip OHCI controller on
450 config USB_OHCI_HCD_LPC32XX
451 tristate "Support for LPC on-chip OHCI USB controller"
452 depends on USB_OHCI_HCD
453 depends on ARCH_LPC32XX || COMPILE_TEST
454 depends on USB_ISP1301
457 Enables support for the on-chip OHCI controller on
460 config USB_OHCI_HCD_PXA27X
461 tristate "Support for PXA27X/PXA3XX on-chip OHCI USB controller"
462 depends on USB_OHCI_HCD && (PXA27x || PXA3xx)
465 Enables support for the on-chip OHCI controller on
468 config USB_OHCI_HCD_AT91
469 tristate "Support for Atmel on-chip OHCI USB controller"
470 depends on USB_OHCI_HCD && (ARCH_AT91 || COMPILE_TEST) && OF
471 default y if ARCH_AT91
473 Enables support for the on-chip OHCI controller on
476 config USB_OHCI_HCD_OMAP3
477 tristate "OHCI support for OMAP3 and later chips"
478 depends on ARCH_OMAP3 || ARCH_OMAP4 || SOC_OMAP5 || COMPILE_TEST
479 select USB_OHCI_HCD_PLATFORM
480 default y if ARCH_OMAP3 || ARCH_OMAP4 || SOC_OMAP5
482 This option is deprecated now and the driver was removed, use
483 USB_OHCI_HCD_PLATFORM instead.
485 Enables support for the on-chip OHCI controller on
486 OMAP3 and later chips.
488 config USB_OHCI_HCD_DAVINCI
489 tristate "OHCI support for TI DaVinci DA8xx"
490 depends on ARCH_DAVINCI_DA8XX || COMPILE_TEST
491 depends on USB_OHCI_HCD
493 default y if ARCH_DAVINCI_DA8XX
495 Enables support for the DaVinci DA8xx integrated OHCI
496 controller. This driver cannot currently be a loadable
497 module because it lacks a proper PHY abstraction.
499 config USB_OHCI_HCD_PPC_OF_BE
500 bool "OHCI support for OF platform bus (big endian)"
502 select USB_OHCI_BIG_ENDIAN_DESC
503 select USB_OHCI_BIG_ENDIAN_MMIO
505 Enables support for big-endian USB controllers present on the
506 OpenFirmware platform bus.
508 config USB_OHCI_HCD_PPC_OF_LE
509 bool "OHCI support for OF platform bus (little endian)"
511 select USB_OHCI_LITTLE_ENDIAN
513 Enables support for little-endian USB controllers present on the
514 OpenFirmware platform bus.
516 config USB_OHCI_HCD_PPC_OF
519 default USB_OHCI_HCD_PPC_OF_BE || USB_OHCI_HCD_PPC_OF_LE
521 config USB_OHCI_HCD_PCI
522 tristate "OHCI support for PCI-bus USB controllers"
525 select USB_OHCI_LITTLE_ENDIAN
527 Enables support for PCI-bus plug-in USB controller cards.
530 config USB_OHCI_HCD_SSB
531 bool "OHCI support for Broadcom SSB OHCI core (DEPRECATED)"
532 depends on (SSB = y || SSB = USB_OHCI_HCD)
534 select USB_OHCI_HCD_PLATFORM
536 This option is deprecated now and the driver was removed, use
537 USB_HCD_SSB and USB_OHCI_HCD_PLATFORM instead.
539 Support for the Sonics Silicon Backplane (SSB) attached
540 Broadcom USB OHCI core.
542 This device is present in some embedded devices with
543 Broadcom based SSB bus.
547 config USB_OHCI_EXYNOS
548 tristate "OHCI support for Samsung S5P/Exynos SoC Series"
549 depends on ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
551 Enable support for the Samsung S5Pv210 and Exynos SOC's on-chip OHCI
554 config USB_OHCI_HCD_PLATFORM
555 tristate "Generic OHCI driver for a platform device"
557 Adds an OHCI host driver for a generic platform device, which
558 provides a memory space and an irq.
562 config USB_OCTEON_OHCI
563 bool "Octeon on-chip OHCI support (DEPRECATED)"
564 depends on CAVIUM_OCTEON_SOC
565 default USB_OCTEON_EHCI
566 select USB_OHCI_BIG_ENDIAN_MMIO if CPU_BIG_ENDIAN
567 select USB_OHCI_LITTLE_ENDIAN
568 select USB_OHCI_HCD_PLATFORM
570 This option is deprecated now and the driver was removed, use
571 USB_OHCI_HCD_PLATFORM instead.
573 Enable support for the Octeon II SOC's on-chip OHCI
574 controller. It is needed for low-speed USB 1.0 device
575 support. All CN6XXX based chips with USB are supported.
580 tristate "UHCI HCD (most Intel and VIA) support"
581 depends on (USB_PCI && HAS_IOPORT) || USB_UHCI_SUPPORT_NON_PCI_HC
583 The Universal Host Controller Interface is a standard by Intel for
584 accessing the USB hardware in the PC (which is also called the USB
585 host controller). If your USB host controller conforms to this
586 standard, you may want to say Y, but see below. All recent boards
587 with Intel PCI chipsets (like intel 430TX, 440FX, 440LX, 440BX,
588 i810, i820) conform to this standard. Also all VIA PCI chipsets
589 (like VIA VP2, VP3, MVP3, Apollo Pro, Apollo Pro II or Apollo Pro
590 133) and LEON/GRLIB SoCs with the GRUSBHC controller.
593 To compile this driver as a module, choose M here: the
594 module will be called uhci-hcd.
596 config USB_UHCI_SUPPORT_NON_PCI_HC
598 default y if (SPARC_LEON || USB_UHCI_PLATFORM)
600 config USB_UHCI_PLATFORM
602 default y if (ARCH_VT8500 || ARCH_ASPEED)
604 config USB_UHCI_ASPEED
606 default y if ARCH_ASPEED
609 tristate "Freescale QE USB Host Controller support"
610 depends on OF_GPIO && QE_GPIO && QUICC_ENGINE
614 This driver enables support for Freescale QE USB Host Controller
615 (as found on MPC8360 and MPC8323 processors), the driver supports
616 Full and Low Speed USB.
619 bool "Freescale QE USB Host Controller debug support"
620 depends on USB_FHCI_HCD && DEBUG_FS
622 Say "y" to see some FHCI debug information and statistics
626 tristate "SL811HS HCD support"
629 The SL811HS is a single-port USB controller that supports either
630 host side or peripheral side roles. Enable this option if your
631 board has this chip, and you want to use it as a host controller.
634 To compile this driver as a module, choose M here: the
635 module will be called sl811-hcd.
637 config USB_SL811_HCD_ISO
638 bool "partial ISO support"
639 depends on USB_SL811_HCD
641 The driver doesn't support iso_frame_desc (yet), but for some simple
642 devices that just queue one ISO frame per URB, then ISO transfers
643 "should" work using the normal urb status fields.
648 tristate "CF/PCMCIA support for SL811HS HCD"
649 depends on USB_SL811_HCD && PCMCIA
651 Wraps a PCMCIA driver around the SL811HS HCD, supporting the RATOC
652 REX-CFU1U CF card (often used with PDAs). If unsure, say N.
654 To compile this driver as a module, choose M here: the
655 module will be called "sl811_cs".
657 config USB_R8A66597_HCD
658 tristate "R8A66597 HCD support"
661 The R8A66597 is a USB 2.0 host and peripheral controller.
663 Enable this option if your board has this chip, and you want
664 to use it as a host controller. If unsure, say N.
666 To compile this driver as a module, choose M here: the
667 module will be called r8a66597-hcd.
669 config USB_RENESAS_USBHS_HCD
670 tristate "Renesas USBHS HCD support"
671 depends on USB_RENESAS_USBHS
673 The Renesas USBHS is a USB 2.0 host and peripheral controller.
675 Enable this option if your board has this chip, and you want
676 to use it as a host controller. If unsure, say N.
678 To compile this driver as a module, choose M here: the
679 module will be called renesas-usbhs.
682 tristate "BCMA usb host driver"
684 select USB_OHCI_HCD_PLATFORM if USB_OHCI_HCD
685 select USB_EHCI_HCD_PLATFORM if USB_EHCI_HCD
687 Enable support for the EHCI and OCHI host controller on an bcma bus.
688 It converts the bcma driver into two platform device drivers
694 tristate "SSB usb host driver"
696 select USB_OHCI_HCD_PLATFORM if USB_OHCI_HCD
697 select USB_EHCI_HCD_PLATFORM if USB_EHCI_HCD
699 Enable support for the EHCI and OCHI host controller on an bcma bus.
700 It converts the bcma driver into two platform device drivers
705 config USB_HCD_TEST_MODE
706 bool "HCD test mode support"
708 Say 'Y' to enable additional software test modes that may be
709 supported by the host controller drivers.
711 One such test mode is the Embedded High-speed Host Electrical Test
712 (EHSET) for EHCI host controller hardware, specifically the "Single
713 Step Set Feature" test. Typically this will be enabled for On-the-Go
714 or embedded hosts that need to undergo USB-IF compliance testing with
715 the aid of special testing hardware. In the future, this may expand
716 to include other tests that require support from a HCD driver.
718 This option is of interest only to developers who need to validate
719 their USB hardware designs. It is not needed for normal use. If
723 tristate "Xen usb virtual host driver"
725 select XEN_XENBUS_FRONTEND
727 The Xen usb virtual host driver serves as a frontend driver enabling
728 a Xen guest system to access USB Devices passed through to the guest
729 by the Xen host (usually Dom0).
730 Only needed if the kernel is running in a Xen guest and generic
731 access to a USB device is needed.