xref: /freebsd/sys/dev/usb/controller/xhci_pci.c (revision 234351604252cec485992cb7f5e76aa98c0a4380)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2010-2022 Hans Petter Selasky
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/stdint.h>
29 #include <sys/stddef.h>
30 #include <sys/param.h>
31 #include <sys/queue.h>
32 #include <sys/types.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 #include <sys/bus.h>
36 #include <sys/module.h>
37 #include <sys/lock.h>
38 #include <sys/mutex.h>
39 #include <sys/condvar.h>
40 #include <sys/sysctl.h>
41 #include <sys/sx.h>
42 #include <sys/unistd.h>
43 #include <sys/callout.h>
44 #include <sys/malloc.h>
45 #include <sys/priv.h>
46 
47 #include <dev/usb/usb.h>
48 #include <dev/usb/usbdi.h>
49 
50 #include <dev/usb/usb_core.h>
51 #include <dev/usb/usb_busdma.h>
52 #include <dev/usb/usb_process.h>
53 #include <dev/usb/usb_util.h>
54 
55 #include <dev/usb/usb_controller.h>
56 #include <dev/usb/usb_bus.h>
57 #include <dev/usb/usb_pci.h>
58 #include <dev/usb/controller/xhci.h>
59 #include <dev/usb/controller/xhcireg.h>
60 #include "usb_if.h"
61 
62 #define	PCI_XHCI_VENDORID_AMD		0x1022
63 #define	PCI_XHCI_VENDORID_INTEL		0x8086
64 #define	PCI_XHCI_VENDORID_VMWARE	0x15ad
65 #define	PCI_XHCI_VENDORID_ZHAOXIN	0x1d17
66 
67 static device_probe_t xhci_pci_probe;
68 static device_detach_t xhci_pci_detach;
69 static usb_take_controller_t xhci_pci_take_controller;
70 
71 static device_method_t xhci_device_methods[] = {
72 	/* device interface */
73 	DEVMETHOD(device_probe, xhci_pci_probe),
74 	DEVMETHOD(device_attach, xhci_pci_attach),
75 	DEVMETHOD(device_detach, xhci_pci_detach),
76 	DEVMETHOD(device_suspend, bus_generic_suspend),
77 	DEVMETHOD(device_resume, bus_generic_resume),
78 	DEVMETHOD(device_shutdown, bus_generic_shutdown),
79 	DEVMETHOD(usb_take_controller, xhci_pci_take_controller),
80 
81 	DEVMETHOD_END
82 };
83 
84 DEFINE_CLASS_0(xhci, xhci_pci_driver, xhci_device_methods,
85     sizeof(struct xhci_softc));
86 
87 DRIVER_MODULE(xhci, pci, xhci_pci_driver, NULL, NULL);
88 MODULE_DEPEND(xhci, usb, 1, 1, 1);
89 
90 static const char *
xhci_pci_match(device_t self)91 xhci_pci_match(device_t self)
92 {
93 	uint32_t device_id = pci_get_devid(self);
94 
95 	switch (device_id) {
96 	case 0x145c1022:
97 		return ("AMD KERNCZ USB 3.0 controller");
98 	case 0x148c1022:
99 		return ("AMD Starship USB 3.0 controller");
100 	case 0x149c1022:
101 		return ("AMD Matisse USB 3.0 controller");
102 	case 0x15b61022:
103 	case 0x15b71022:
104 		return ("AMD Raphael/Granite Ridge USB 3.1 controller");
105 	case 0x15b81022:
106 		return ("AMD Raphael/Granite Ridge USB 2.0 controller");
107 	case 0x15e01022:
108 	case 0x15e11022:
109 		return ("AMD Raven USB 3.1 controller");
110 	case 0x43ba1022:
111 		return ("AMD X399 USB 3.0 controller");
112 	case 0x43b91022: /* X370 */
113 	case 0x43bb1022: /* B350 */
114 		return ("AMD 300 Series USB 3.1 controller");
115 	case 0x43d51022:
116 		return ("AMD 400 Series USB 3.1 controller");
117 	case 0x43f71022:
118 		return ("AMD 600 Series USB 3.2 controller");
119 	case 0x78121022:
120 	case 0x78141022:
121 	case 0x79141022:
122 		return ("AMD FCH USB 3.0 controller");
123 
124 	case 0x077815ad:
125 	case 0x077915ad:
126 		return ("VMware USB 3.0 controller");
127 
128 	case 0x145f1d94:
129 		return ("Hygon USB 3.0 controller");
130 
131 	case 0x01941033:
132 		return ("NEC uPD720200 USB 3.0 controller");
133 	case 0x00151912:
134 		return ("NEC uPD720202 USB 3.0 controller");
135 
136 	case 0x10001b73:
137 		return ("Fresco Logic FL1000G USB 3.0 controller");
138 	case 0x10091b73:
139 		return ("Fresco Logic FL1009 USB 3.0 controller");
140 	case 0x11001b73:
141 		return ("Fresco Logic FL1100 USB 3.0 controller");
142 
143 	case 0x10421b21:
144 		return ("ASMedia ASM1042 USB 3.0 controller");
145 	case 0x11421b21:
146 		return ("ASMedia ASM1042A USB 3.0 controller");
147 	case 0x13431b21:
148 		return ("ASMedia ASM1143 USB 3.1 controller");
149 	case 0x32421b21:
150 		return ("ASMedia ASM3242 USB 3.2 controller");
151 
152 	case 0x0b278086:
153 		return ("Intel Goshen Ridge Thunderbolt 4 USB controller");
154 	case 0x0f358086:
155 		return ("Intel BayTrail USB 3.0 controller");
156 	case 0x11388086:
157 		return ("Intel Maple Ridge Thunderbolt 4 USB controller");
158 	case 0x15c18086:
159 	case 0x15d48086:
160 	case 0x15db8086:
161 		return ("Intel Alpine Ridge Thunderbolt 3 USB controller");
162 	case 0x15e98086:
163 	case 0x15ec8086:
164 	case 0x15f08086:
165 		return ("Intel Titan Ridge Thunderbolt 3 USB controller");
166 	case 0x19d08086:
167 		return ("Intel Denverton USB 3.0 controller");
168 	case 0x9c318086:
169 	case 0x1e318086:
170 		return ("Intel Panther Point USB 3.0 controller");
171 	case 0x22b58086:
172 		return ("Intel Braswell USB 3.0 controller");
173 	case 0x31a88086:
174 		return ("Intel Gemini Lake USB 3.0 controller");
175 	case 0x34ed8086:
176 		return ("Intel Ice Lake-LP USB 3.1 controller");
177 	case 0x43ed8086:
178 		return ("Intel Tiger Lake-H USB 3.2 controller");
179 	case 0x461e8086:
180 		return ("Intel Alder Lake-P Thunderbolt 4 USB controller");
181 	case 0x4b7d8086:
182 		return ("Intel Elkhart Lake USB 3.1 controller");
183 	case 0x51ed8086:
184 	case 0x54ed8086:
185 	case 0x5fed8086:
186 		return ("Intel Alder Lake USB 3.2 controller");
187 	case 0x5aa88086:
188 		return ("Intel Apollo Lake USB 3.0 controller");
189 	case 0x7ae08086:
190 		return ("Intel Alder Lake USB 3.2 controller");
191 	case 0x8a138086:
192 		return ("Intel Ice Lake Thunderbolt 3 USB controller");
193 	case 0x8c318086:
194 		return ("Intel Lynx Point USB 3.0 controller");
195 	case 0x8cb18086:
196 		return ("Intel Wildcat Point USB 3.0 controller");
197 	case 0x8d318086:
198 		return ("Intel Wellsburg USB 3.0 controller");
199 	case 0x9a138086:
200 		return ("Intel Tiger Lake-LP Thunderbolt 4 USB controller");
201 	case 0x9a178086:
202 		return ("Intel Tiger Lake-H Thunderbolt 4 USB controller");
203 	case 0x9cb18086:
204 		return ("Broadwell Integrated PCH-LP chipset USB 3.0 controller");
205 	case 0x9d2f8086:
206 		return ("Intel Sunrise Point-LP USB 3.0 controller");
207 	case 0xa0ed8086:
208 		return ("Intel Tiger Lake-LP USB 3.2 controller");
209 	case 0xa12f8086:
210 		return ("Intel Sunrise Point USB 3.0 controller");
211 	case 0xa1af8086:
212 		return ("Intel Lewisburg USB 3.0 controller");
213 	case 0xa2af8086:
214 		return ("Intel Union Point USB 3.0 controller");
215 	case 0xa36d8086:
216 		return ("Intel Cannon Lake USB 3.1 controller");
217 
218 	case 0xa01b177d:
219 		return ("Cavium ThunderX USB 3.0 controller");
220 
221 	case 0x1ada10de:
222 		return ("NVIDIA TU106 USB 3.1 controller");
223 
224 	case 0x92021d17:
225 		return ("Zhaoxin ZX-100 USB 3.0 controller");
226 	case 0x92031d17:
227 		return ("Zhaoxin ZX-200 USB 3.0 controller");
228 	case 0x92041d17:
229 		return ("Zhaoxin ZX-E USB 3.0 controller");
230 
231 	default:
232 		break;
233 	}
234 
235 	if ((pci_get_class(self) == PCIC_SERIALBUS)
236 	    && (pci_get_subclass(self) == PCIS_SERIALBUS_USB)
237 	    && (pci_get_progif(self) == PCIP_SERIALBUS_USB_XHCI)) {
238 		return ("XHCI (generic) USB 3.0 controller");
239 	}
240 	return (NULL);			/* dunno */
241 }
242 
243 static int
xhci_pci_probe(device_t self)244 xhci_pci_probe(device_t self)
245 {
246 	const char *desc = xhci_pci_match(self);
247 
248 	if (desc) {
249 		device_set_desc(self, desc);
250 		return (BUS_PROBE_DEFAULT);
251 	} else {
252 		return (ENXIO);
253 	}
254 }
255 
256 static int xhci_use_msi = 1;
257 TUNABLE_INT("hw.usb.xhci.msi", &xhci_use_msi);
258 static int xhci_use_msix = 1;
259 TUNABLE_INT("hw.usb.xhci.msix", &xhci_use_msix);
260 
261 static void
xhci_interrupt_poll(void * _sc)262 xhci_interrupt_poll(void *_sc)
263 {
264 	struct xhci_softc *sc = _sc;
265 	USB_BUS_UNLOCK(&sc->sc_bus);
266 	xhci_interrupt(sc);
267 	USB_BUS_LOCK(&sc->sc_bus);
268 	usb_callout_reset(&sc->sc_callout, 1, (void *)&xhci_interrupt_poll, sc);
269 }
270 
271 static int
xhci_pci_port_route(device_t self,uint32_t set,uint32_t clear)272 xhci_pci_port_route(device_t self, uint32_t set, uint32_t clear)
273 {
274 	uint32_t temp;
275 	uint32_t usb3_mask;
276 	uint32_t usb2_mask;
277 
278 	temp = pci_read_config(self, PCI_XHCI_INTEL_USB3_PSSEN, 4) |
279 	    pci_read_config(self, PCI_XHCI_INTEL_XUSB2PR, 4);
280 
281 	temp |= set;
282 	temp &= ~clear;
283 
284 	/* Don't set bits which the hardware doesn't support */
285 	usb3_mask = pci_read_config(self, PCI_XHCI_INTEL_USB3PRM, 4);
286 	usb2_mask = pci_read_config(self, PCI_XHCI_INTEL_USB2PRM, 4);
287 
288 	pci_write_config(self, PCI_XHCI_INTEL_USB3_PSSEN, temp & usb3_mask, 4);
289 	pci_write_config(self, PCI_XHCI_INTEL_XUSB2PR, temp & usb2_mask, 4);
290 
291 	device_printf(self, "Port routing mask set to 0x%08x\n", temp);
292 
293 	return (0);
294 }
295 
296 int
xhci_pci_attach(device_t self)297 xhci_pci_attach(device_t self)
298 {
299 	struct xhci_softc *sc = device_get_softc(self);
300 	int count, err, msix_table, rid;
301 	uint8_t usemsi = 1;
302 	uint8_t usedma32 = 0;
303 
304 	rid = PCI_XHCI_CBMEM;
305 	sc->sc_io_res = bus_alloc_resource_any(self, SYS_RES_MEMORY, &rid,
306 	    RF_ACTIVE);
307 	if (!sc->sc_io_res) {
308 		device_printf(self, "Could not map memory\n");
309 		return (ENOMEM);
310 	}
311 	sc->sc_io_tag = rman_get_bustag(sc->sc_io_res);
312 	sc->sc_io_hdl = rman_get_bushandle(sc->sc_io_res);
313 	sc->sc_io_size = rman_get_size(sc->sc_io_res);
314 
315 	switch (pci_get_devid(self)) {
316 	case 0x10091b73:	/* Fresco Logic FL1009 USB3.0 xHCI Controller */
317 	case 0x8241104c:	/* TUSB73x0 USB3.0 xHCI Controller */
318 		sc->sc_no_deconfigure = 1;
319 		break;
320 	case 0x01941033:	/* NEC uPD720200 USB 3.0 controller */
321 	case 0x00141912:	/* NEC uPD720201 USB 3.0 controller */
322 		/* Don't use 64-bit DMA on these controllers. */
323 		usedma32 = 1;
324 		break;
325 	case 0x10001b73:	/* FL1000G */
326 		/* Fresco Logic host doesn't support MSI. */
327 		usemsi = 0;
328 		break;
329 	case 0x0f358086:	/* BayTrail */
330 	case 0x9c318086:	/* Panther Point */
331 	case 0x1e318086:	/* Panther Point */
332 	case 0x8c318086:	/* Lynx Point */
333 	case 0x8cb18086:	/* Wildcat Point */
334 	case 0x9cb18086:	/* Broadwell Mobile Integrated */
335 		/*
336 		 * On Intel chipsets, reroute ports from EHCI to XHCI
337 		 * controller and use a different IMOD value.
338 		 */
339 		sc->sc_port_route = &xhci_pci_port_route;
340 		sc->sc_imod_default = XHCI_IMOD_DEFAULT_LP;
341 		sc->sc_ctlstep = 1;
342 		break;
343 	default:
344 		break;
345 	}
346 
347 	if (xhci_init(sc, self, usedma32)) {
348 		device_printf(self, "Could not initialize softc\n");
349 		bus_release_resource(self, SYS_RES_MEMORY, PCI_XHCI_CBMEM,
350 		    sc->sc_io_res);
351 		return (ENXIO);
352 	}
353 
354 	pci_enable_busmaster(self);
355 
356 	usb_callout_init_mtx(&sc->sc_callout, &sc->sc_bus.bus_mtx, 0);
357 
358 	rid = 0;
359 	if (xhci_use_msix && (msix_table = pci_msix_table_bar(self)) >= 0) {
360 		if (msix_table == PCI_XHCI_CBMEM) {
361 			sc->sc_msix_res = sc->sc_io_res;
362 		} else {
363 			sc->sc_msix_res = bus_alloc_resource_any(self,
364 			    SYS_RES_MEMORY, &msix_table, RF_ACTIVE);
365 			if (sc->sc_msix_res == NULL) {
366 				/* May not be enabled */
367 				device_printf(self,
368 				    "Unable to map MSI-X table\n");
369 			}
370 		}
371 		if (sc->sc_msix_res != NULL) {
372 			count = 1;
373 			if (pci_alloc_msix(self, &count) == 0) {
374 				if (bootverbose)
375 					device_printf(self, "MSI-X enabled\n");
376 				rid = 1;
377 			} else {
378 				if (sc->sc_msix_res != sc->sc_io_res) {
379 					bus_release_resource(self,
380 					    SYS_RES_MEMORY,
381 					    msix_table, sc->sc_msix_res);
382 				}
383 				sc->sc_msix_res = NULL;
384 			}
385 		}
386 	}
387 	if (rid == 0 && xhci_use_msi && usemsi) {
388 		count = 1;
389 		if (pci_alloc_msi(self, &count) == 0) {
390 			if (bootverbose)
391 				device_printf(self, "MSI enabled\n");
392 			rid = 1;
393 		}
394 	}
395 	sc->sc_irq_res = bus_alloc_resource_any(self, SYS_RES_IRQ, &rid,
396 	    RF_ACTIVE | (rid != 0 ? 0 : RF_SHAREABLE));
397 	if (sc->sc_irq_res == NULL) {
398 		pci_release_msi(self);
399 		device_printf(self, "Could not allocate IRQ\n");
400 		/* goto error; FALLTHROUGH - use polling */
401 	}
402 	sc->sc_bus.bdev = device_add_child(self, "usbus", DEVICE_UNIT_ANY);
403 	if (sc->sc_bus.bdev == NULL) {
404 		device_printf(self, "Could not add USB device\n");
405 		goto error;
406 	}
407 	device_set_ivars(sc->sc_bus.bdev, &sc->sc_bus);
408 
409 	switch (pci_get_vendor(self)) {
410 	case PCI_XHCI_VENDORID_AMD:
411 		strlcpy(sc->sc_vendor, "AMD", sizeof(sc->sc_vendor));
412 		break;
413 	case PCI_XHCI_VENDORID_INTEL:
414 		strlcpy(sc->sc_vendor, "Intel", sizeof(sc->sc_vendor));
415 		break;
416 	case PCI_XHCI_VENDORID_VMWARE:
417 		strlcpy(sc->sc_vendor, "VMware", sizeof(sc->sc_vendor));
418 		break;
419 	case PCI_XHCI_VENDORID_ZHAOXIN:
420 		strlcpy(sc->sc_vendor, "Zhaoxin", sizeof(sc->sc_vendor));
421 		break;
422 	default:
423 		if (bootverbose)
424 			device_printf(self, "(New XHCI DeviceId=0x%08x)\n",
425 			    pci_get_devid(self));
426 		snprintf(sc->sc_vendor, sizeof(sc->sc_vendor),
427 		    "(0x%04x)", pci_get_vendor(self));
428 		break;
429 	}
430 
431 	if (sc->sc_irq_res != NULL && xhci_use_polling() == 0) {
432 		err = bus_setup_intr(self, sc->sc_irq_res, INTR_TYPE_BIO | INTR_MPSAFE,
433 		    NULL, (driver_intr_t *)xhci_interrupt, sc, &sc->sc_intr_hdl);
434 		if (err != 0) {
435 			bus_release_resource(self, SYS_RES_IRQ,
436 			    rman_get_rid(sc->sc_irq_res), sc->sc_irq_res);
437 			sc->sc_irq_res = NULL;
438 			pci_release_msi(self);
439 			device_printf(self, "Could not setup IRQ, err=%d\n", err);
440 			sc->sc_intr_hdl = NULL;
441 		}
442 	}
443 	if (sc->sc_irq_res == NULL || sc->sc_intr_hdl == NULL) {
444 		if (xhci_use_polling() != 0) {
445 			device_printf(self, "Interrupt polling at %dHz\n", hz);
446 			USB_BUS_LOCK(&sc->sc_bus);
447 			xhci_interrupt_poll(sc);
448 			USB_BUS_UNLOCK(&sc->sc_bus);
449 		} else
450 			goto error;
451 	}
452 
453 	xhci_pci_take_controller(self);
454 
455 	err = xhci_halt_controller(sc);
456 
457 	if (err == 0)
458 		err = xhci_start_controller(sc);
459 
460 	if (err == 0)
461 		err = device_probe_and_attach(sc->sc_bus.bdev);
462 
463 	if (err) {
464 		device_printf(self, "XHCI halt/start/probe failed err=%d\n", err);
465 		goto error;
466 	}
467 	return (0);
468 
469 error:
470 	xhci_pci_detach(self);
471 	return (ENXIO);
472 }
473 
474 static int
xhci_pci_detach(device_t self)475 xhci_pci_detach(device_t self)
476 {
477 	struct xhci_softc *sc = device_get_softc(self);
478 	int error;
479 
480 	/* during module unload there are lots of children leftover */
481 	error = bus_generic_detach(self);
482 	if (error != 0)
483 		return (error);
484 
485 	usb_callout_drain(&sc->sc_callout);
486 	xhci_halt_controller(sc);
487 	xhci_reset_controller(sc);
488 
489 	pci_disable_busmaster(self);
490 
491 	if (sc->sc_irq_res && sc->sc_intr_hdl) {
492 		bus_teardown_intr(self, sc->sc_irq_res, sc->sc_intr_hdl);
493 		sc->sc_intr_hdl = NULL;
494 	}
495 	if (sc->sc_irq_res) {
496 		bus_release_resource(self, SYS_RES_IRQ,
497 		    rman_get_rid(sc->sc_irq_res), sc->sc_irq_res);
498 		sc->sc_irq_res = NULL;
499 		pci_release_msi(self);
500 	}
501 	if (sc->sc_msix_res != NULL && sc->sc_msix_res != sc->sc_io_res) {
502 		bus_release_resource(self, SYS_RES_MEMORY,
503 		    rman_get_rid(sc->sc_msix_res), sc->sc_msix_res);
504 		sc->sc_msix_res = NULL;
505 	}
506 	if (sc->sc_io_res) {
507 		bus_release_resource(self, SYS_RES_MEMORY, PCI_XHCI_CBMEM,
508 		    sc->sc_io_res);
509 		sc->sc_io_res = NULL;
510 	}
511 
512 	xhci_uninit(sc);
513 
514 	return (0);
515 }
516 
517 static int
xhci_pci_take_controller(device_t self)518 xhci_pci_take_controller(device_t self)
519 {
520 	struct xhci_softc *sc = device_get_softc(self);
521 	uint32_t cparams;
522 	uint32_t eecp;
523 	uint32_t eec;
524 	uint16_t to;
525 	uint8_t bios_sem;
526 
527 	cparams = XREAD4(sc, capa, XHCI_HCCPARAMS1);
528 
529 	eec = -1;
530 
531 	/* Synchronise with the BIOS if it owns the controller. */
532 	for (eecp = XHCI_HCS0_XECP(cparams) << 2; eecp != 0 && XHCI_XECP_NEXT(eec);
533 	    eecp += XHCI_XECP_NEXT(eec) << 2) {
534 		eec = XREAD4(sc, capa, eecp);
535 
536 		if (XHCI_XECP_ID(eec) != XHCI_ID_USB_LEGACY)
537 			continue;
538 		bios_sem = XREAD1(sc, capa, eecp +
539 		    XHCI_XECP_BIOS_SEM);
540 		if (bios_sem == 0)
541 			continue;
542 		device_printf(sc->sc_bus.bdev, "waiting for BIOS "
543 		    "to give up control\n");
544 		XWRITE1(sc, capa, eecp +
545 		    XHCI_XECP_OS_SEM, 1);
546 		to = 500;
547 		while (1) {
548 			bios_sem = XREAD1(sc, capa, eecp +
549 			    XHCI_XECP_BIOS_SEM);
550 			if (bios_sem == 0)
551 				break;
552 
553 			if (--to == 0) {
554 				device_printf(sc->sc_bus.bdev,
555 				    "timed out waiting for BIOS\n");
556 				break;
557 			}
558 			usb_pause_mtx(NULL, hz / 100);	/* wait 10ms */
559 		}
560 	}
561 	return (0);
562 }
563