xref: /freebsd/sys/i386/pci/pci_cfgreg.c (revision 93e779a26c651610ac6e7986d67ecc9ed2cadcbf)
1 /*-
2  * Copyright (c) 1997, Stefan Esser <se@freebsd.org>
3  * Copyright (c) 2000, Michael Smith <msmith@freebsd.org>
4  * Copyright (c) 2000, BSDi
5  * Copyright (c) 2004, Scott Long <scottl@freebsd.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice unmodified, this list of conditions, and the following
13  *    disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include "opt_xbox.h"
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/bus.h>
38 #include <sys/lock.h>
39 #include <sys/kernel.h>
40 #include <sys/mutex.h>
41 #include <sys/malloc.h>
42 #include <sys/queue.h>
43 #include <sys/sysctl.h>
44 #include <dev/pci/pcivar.h>
45 #include <dev/pci/pcireg.h>
46 #include <machine/pci_cfgreg.h>
47 #include <machine/pc/bios.h>
48 
49 #include <vm/vm.h>
50 #include <vm/vm_param.h>
51 #include <vm/vm_kern.h>
52 #include <vm/vm_extern.h>
53 #include <vm/pmap.h>
54 #include <machine/pmap.h>
55 
56 #ifdef XBOX
57 #include <machine/xbox.h>
58 #endif
59 
60 #define PRVERB(a) do {							\
61 	if (bootverbose)						\
62 		printf a ;						\
63 } while(0)
64 
65 #define PCIE_CACHE 8
66 struct pcie_cfg_elem {
67 	TAILQ_ENTRY(pcie_cfg_elem)	elem;
68 	vm_offset_t	vapage;
69 	vm_paddr_t	papage;
70 };
71 
72 enum {
73 	CFGMECH_NONE = 0,
74 	CFGMECH_1,
75 	CFGMECH_2,
76 	CFGMECH_PCIE,
77 };
78 
79 SYSCTL_DECL(_hw_pci);
80 
81 static TAILQ_HEAD(pcie_cfg_list, pcie_cfg_elem) pcie_list[MAXCPU];
82 static uint64_t pcie_base;
83 static int pcie_minbus, pcie_maxbus;
84 static uint32_t pcie_badslots;
85 static int cfgmech;
86 static int devmax;
87 static struct mtx pcicfg_mtx;
88 static int mcfg_enable = 1;
89 SYSCTL_INT(_hw_pci, OID_AUTO, mcfg, CTLFLAG_RDTUN, &mcfg_enable, 0,
90     "Enable support for PCI-e memory mapped config access");
91 
92 static uint32_t	pci_docfgregread(int bus, int slot, int func, int reg,
93 		    int bytes);
94 static int	pcireg_cfgread(int bus, int slot, int func, int reg, int bytes);
95 static void	pcireg_cfgwrite(int bus, int slot, int func, int reg, int data, int bytes);
96 static int	pcireg_cfgopen(void);
97 static int	pciereg_cfgread(int bus, unsigned slot, unsigned func,
98 		    unsigned reg, unsigned bytes);
99 static void	pciereg_cfgwrite(int bus, unsigned slot, unsigned func,
100 		    unsigned reg, int data, unsigned bytes);
101 
102 /*
103  * Some BIOS writers seem to want to ignore the spec and put
104  * 0 in the intline rather than 255 to indicate none.  Some use
105  * numbers in the range 128-254 to indicate something strange and
106  * apparently undocumented anywhere.  Assume these are completely bogus
107  * and map them to 255, which means "none".
108  */
109 static __inline int
110 pci_i386_map_intline(int line)
111 {
112 	if (line == 0 || line >= 128)
113 		return (PCI_INVALID_IRQ);
114 	return (line);
115 }
116 
117 static u_int16_t
118 pcibios_get_version(void)
119 {
120 	struct bios_regs args;
121 
122 	if (PCIbios.ventry == 0) {
123 		PRVERB(("pcibios: No call entry point\n"));
124 		return (0);
125 	}
126 	args.eax = PCIBIOS_BIOS_PRESENT;
127 	if (bios32(&args, PCIbios.ventry, GSEL(GCODE_SEL, SEL_KPL))) {
128 		PRVERB(("pcibios: BIOS_PRESENT call failed\n"));
129 		return (0);
130 	}
131 	if (args.edx != 0x20494350) {
132 		PRVERB(("pcibios: BIOS_PRESENT didn't return 'PCI ' in edx\n"));
133 		return (0);
134 	}
135 	return (args.ebx & 0xffff);
136 }
137 
138 /*
139  * Initialise access to PCI configuration space
140  */
141 int
142 pci_cfgregopen(void)
143 {
144 	static int		opened = 0;
145 	uint64_t		pciebar;
146 	u_int16_t		vid, did;
147 	u_int16_t		v;
148 
149 	if (opened)
150 		return (1);
151 
152 	if (cfgmech == CFGMECH_NONE && pcireg_cfgopen() == 0)
153 		return (0);
154 
155 	v = pcibios_get_version();
156 	if (v > 0)
157 		PRVERB(("pcibios: BIOS version %x.%02x\n", (v & 0xff00) >> 8,
158 		    v & 0xff));
159 	mtx_init(&pcicfg_mtx, "pcicfg", NULL, MTX_SPIN);
160 	opened = 1;
161 
162 	/* $PIR requires PCI BIOS 2.10 or greater. */
163 	if (v >= 0x0210)
164 		pci_pir_open();
165 
166 	if (cfgmech == CFGMECH_PCIE)
167 		return (1);
168 
169 	/*
170 	 * Grope around in the PCI config space to see if this is a
171 	 * chipset that is capable of doing memory-mapped config cycles.
172 	 * This also implies that it can do PCIe extended config cycles.
173 	 */
174 
175 	/* Check for supported chipsets */
176 	vid = pci_cfgregread(0, 0, 0, PCIR_VENDOR, 2);
177 	did = pci_cfgregread(0, 0, 0, PCIR_DEVICE, 2);
178 	switch (vid) {
179 	case 0x8086:
180 		switch (did) {
181 		case 0x3590:
182 		case 0x3592:
183 			/* Intel 7520 or 7320 */
184 			pciebar = pci_cfgregread(0, 0, 0, 0xce, 2) << 16;
185 			pcie_cfgregopen(pciebar, 0, 255);
186 			break;
187 		case 0x2580:
188 		case 0x2584:
189 		case 0x2590:
190 			/* Intel 915, 925, or 915GM */
191 			pciebar = pci_cfgregread(0, 0, 0, 0x48, 4);
192 			pcie_cfgregopen(pciebar, 0, 255);
193 			break;
194 		}
195 	}
196 
197 	return(1);
198 }
199 
200 static uint32_t
201 pci_docfgregread(int bus, int slot, int func, int reg, int bytes)
202 {
203 
204 	if (cfgmech == CFGMECH_PCIE &&
205 	    (bus >= pcie_minbus && bus <= pcie_maxbus) &&
206 	    (bus != 0 || !(1 << slot & pcie_badslots)))
207 		return (pciereg_cfgread(bus, slot, func, reg, bytes));
208 	else
209 		return (pcireg_cfgread(bus, slot, func, reg, bytes));
210 }
211 
212 /*
213  * Read configuration space register
214  */
215 u_int32_t
216 pci_cfgregread(int bus, int slot, int func, int reg, int bytes)
217 {
218 	uint32_t line;
219 
220 	/*
221 	 * Some BIOS writers seem to want to ignore the spec and put
222 	 * 0 in the intline rather than 255 to indicate none.  The rest of
223 	 * the code uses 255 as an invalid IRQ.
224 	 */
225 	if (reg == PCIR_INTLINE && bytes == 1) {
226 		line = pci_docfgregread(bus, slot, func, PCIR_INTLINE, 1);
227 		return (pci_i386_map_intline(line));
228 	}
229 	return (pci_docfgregread(bus, slot, func, reg, bytes));
230 }
231 
232 /*
233  * Write configuration space register
234  */
235 void
236 pci_cfgregwrite(int bus, int slot, int func, int reg, u_int32_t data, int bytes)
237 {
238 
239 	if (cfgmech == CFGMECH_PCIE &&
240 	    (bus >= pcie_minbus && bus <= pcie_maxbus) &&
241 	    (bus != 0 || !(1 << slot & pcie_badslots)))
242 		pciereg_cfgwrite(bus, slot, func, reg, data, bytes);
243 	else
244 		pcireg_cfgwrite(bus, slot, func, reg, data, bytes);
245 }
246 
247 /*
248  * Configuration space access using direct register operations
249  */
250 
251 /* enable configuration space accesses and return data port address */
252 static int
253 pci_cfgenable(unsigned bus, unsigned slot, unsigned func, int reg, int bytes)
254 {
255 	int dataport = 0;
256 
257 #ifdef XBOX
258 	if (arch_i386_is_xbox) {
259 		/*
260 		 * The Xbox MCPX chipset is a derivative of the nForce 1
261 		 * chipset. It almost has the same bus layout; some devices
262 		 * cannot be used, because they have been removed.
263 		 */
264 
265 		/*
266 		 * Devices 00:00.1 and 00:00.2 used to be memory controllers on
267 		 * the nForce chipset, but on the Xbox, using them will lockup
268 		 * the chipset.
269 		 */
270 		if (bus == 0 && slot == 0 && (func == 1 || func == 2))
271 			return dataport;
272 
273 		/*
274 		 * Bus 1 only contains a VGA controller at 01:00.0. When you try
275 		 * to probe beyond that device, you only get garbage, which
276 		 * could cause lockups.
277 		 */
278 		if (bus == 1 && (slot != 0 || func != 0))
279 			return dataport;
280 
281 		/*
282 		 * Bus 2 used to contain the AGP controller, but the Xbox MCPX
283 		 * doesn't have one. Probing it can cause lockups.
284 		 */
285 		if (bus >= 2)
286 			return dataport;
287 	}
288 #endif
289 
290 	if (bus <= PCI_BUSMAX
291 	    && slot < devmax
292 	    && func <= PCI_FUNCMAX
293 	    && (unsigned)reg <= PCI_REGMAX
294 	    && bytes != 3
295 	    && (unsigned)bytes <= 4
296 	    && (reg & (bytes - 1)) == 0) {
297 		switch (cfgmech) {
298 		case CFGMECH_PCIE:
299 		case CFGMECH_1:
300 			outl(CONF1_ADDR_PORT, (1U << 31)
301 			    | (bus << 16) | (slot << 11)
302 			    | (func << 8) | (reg & ~0x03));
303 			dataport = CONF1_DATA_PORT + (reg & 0x03);
304 			break;
305 		case CFGMECH_2:
306 			outb(CONF2_ENABLE_PORT, 0xf0 | (func << 1));
307 			outb(CONF2_FORWARD_PORT, bus);
308 			dataport = 0xc000 | (slot << 8) | reg;
309 			break;
310 		}
311 	}
312 	return (dataport);
313 }
314 
315 /* disable configuration space accesses */
316 static void
317 pci_cfgdisable(void)
318 {
319 	switch (cfgmech) {
320 	case CFGMECH_PCIE:
321 	case CFGMECH_1:
322 		/*
323 		 * Do nothing for the config mechanism 1 case.
324 		 * Writing a 0 to the address port can apparently
325 		 * confuse some bridges and cause spurious
326 		 * access failures.
327 		 */
328 		break;
329 	case CFGMECH_2:
330 		outb(CONF2_ENABLE_PORT, 0);
331 		break;
332 	}
333 }
334 
335 static int
336 pcireg_cfgread(int bus, int slot, int func, int reg, int bytes)
337 {
338 	int data = -1;
339 	int port;
340 
341 	mtx_lock_spin(&pcicfg_mtx);
342 	port = pci_cfgenable(bus, slot, func, reg, bytes);
343 	if (port != 0) {
344 		switch (bytes) {
345 		case 1:
346 			data = inb(port);
347 			break;
348 		case 2:
349 			data = inw(port);
350 			break;
351 		case 4:
352 			data = inl(port);
353 			break;
354 		}
355 		pci_cfgdisable();
356 	}
357 	mtx_unlock_spin(&pcicfg_mtx);
358 	return (data);
359 }
360 
361 static void
362 pcireg_cfgwrite(int bus, int slot, int func, int reg, int data, int bytes)
363 {
364 	int port;
365 
366 	mtx_lock_spin(&pcicfg_mtx);
367 	port = pci_cfgenable(bus, slot, func, reg, bytes);
368 	if (port != 0) {
369 		switch (bytes) {
370 		case 1:
371 			outb(port, data);
372 			break;
373 		case 2:
374 			outw(port, data);
375 			break;
376 		case 4:
377 			outl(port, data);
378 			break;
379 		}
380 		pci_cfgdisable();
381 	}
382 	mtx_unlock_spin(&pcicfg_mtx);
383 }
384 
385 /* check whether the configuration mechanism has been correctly identified */
386 static int
387 pci_cfgcheck(int maxdev)
388 {
389 	uint32_t id, class;
390 	uint8_t header;
391 	uint8_t device;
392 	int port;
393 
394 	if (bootverbose)
395 		printf("pci_cfgcheck:\tdevice ");
396 
397 	for (device = 0; device < maxdev; device++) {
398 		if (bootverbose)
399 			printf("%d ", device);
400 
401 		port = pci_cfgenable(0, device, 0, 0, 4);
402 		id = inl(port);
403 		if (id == 0 || id == 0xffffffff)
404 			continue;
405 
406 		port = pci_cfgenable(0, device, 0, 8, 4);
407 		class = inl(port) >> 8;
408 		if (bootverbose)
409 			printf("[class=%06x] ", class);
410 		if (class == 0 || (class & 0xf870ff) != 0)
411 			continue;
412 
413 		port = pci_cfgenable(0, device, 0, 14, 1);
414 		header = inb(port);
415 		if (bootverbose)
416 			printf("[hdr=%02x] ", header);
417 		if ((header & 0x7e) != 0)
418 			continue;
419 
420 		if (bootverbose)
421 			printf("is there (id=%08x)\n", id);
422 
423 		pci_cfgdisable();
424 		return (1);
425 	}
426 	if (bootverbose)
427 		printf("-- nothing found\n");
428 
429 	pci_cfgdisable();
430 	return (0);
431 }
432 
433 static int
434 pcireg_cfgopen(void)
435 {
436 	uint32_t mode1res, oldval1;
437 	uint8_t mode2res, oldval2;
438 
439 	/* Check for type #1 first. */
440 	oldval1 = inl(CONF1_ADDR_PORT);
441 
442 	if (bootverbose) {
443 		printf("pci_open(1):\tmode 1 addr port (0x0cf8) is 0x%08x\n",
444 		    oldval1);
445 	}
446 
447 	cfgmech = CFGMECH_1;
448 	devmax = 32;
449 
450 	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK);
451 	DELAY(1);
452 	mode1res = inl(CONF1_ADDR_PORT);
453 	outl(CONF1_ADDR_PORT, oldval1);
454 
455 	if (bootverbose)
456 		printf("pci_open(1a):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
457 		    CONF1_ENABLE_CHK);
458 
459 	if (mode1res) {
460 		if (pci_cfgcheck(32))
461 			return (cfgmech);
462 	}
463 
464 	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK1);
465 	mode1res = inl(CONF1_ADDR_PORT);
466 	outl(CONF1_ADDR_PORT, oldval1);
467 
468 	if (bootverbose)
469 		printf("pci_open(1b):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
470 		    CONF1_ENABLE_CHK1);
471 
472 	if ((mode1res & CONF1_ENABLE_MSK1) == CONF1_ENABLE_RES1) {
473 		if (pci_cfgcheck(32))
474 			return (cfgmech);
475 	}
476 
477 	/* Type #1 didn't work, so try type #2. */
478 	oldval2 = inb(CONF2_ENABLE_PORT);
479 
480 	if (bootverbose) {
481 		printf("pci_open(2):\tmode 2 enable port (0x0cf8) is 0x%02x\n",
482 		    oldval2);
483 	}
484 
485 	if ((oldval2 & 0xf0) == 0) {
486 
487 		cfgmech = CFGMECH_2;
488 		devmax = 16;
489 
490 		outb(CONF2_ENABLE_PORT, CONF2_ENABLE_CHK);
491 		mode2res = inb(CONF2_ENABLE_PORT);
492 		outb(CONF2_ENABLE_PORT, oldval2);
493 
494 		if (bootverbose)
495 			printf("pci_open(2a):\tmode2res=0x%02x (0x%02x)\n",
496 			    mode2res, CONF2_ENABLE_CHK);
497 
498 		if (mode2res == CONF2_ENABLE_RES) {
499 			if (bootverbose)
500 				printf("pci_open(2a):\tnow trying mechanism 2\n");
501 
502 			if (pci_cfgcheck(16))
503 				return (cfgmech);
504 		}
505 	}
506 
507 	/* Nothing worked, so punt. */
508 	cfgmech = CFGMECH_NONE;
509 	devmax = 0;
510 	return (cfgmech);
511 }
512 
513 int
514 pcie_cfgregopen(uint64_t base, uint8_t minbus, uint8_t maxbus)
515 {
516 	struct pcie_cfg_list *pcielist;
517 	struct pcie_cfg_elem *pcie_array, *elem;
518 #ifdef SMP
519 	struct pcpu *pc;
520 #endif
521 	vm_offset_t va;
522 	uint32_t val1, val2;
523 	int i, slot;
524 
525 	if (!mcfg_enable)
526 		return (0);
527 
528 	if (minbus != 0)
529 		return (0);
530 
531 #ifndef PAE
532 	if (base >= 0x100000000) {
533 		if (bootverbose)
534 			printf(
535 	    "PCI: Memory Mapped PCI configuration area base 0x%jx too high\n",
536 			    (uintmax_t)base);
537 		return (0);
538 	}
539 #endif
540 
541 	if (bootverbose)
542 		printf("PCIe: Memory Mapped configuration base @ 0x%jx\n",
543 		    (uintmax_t)base);
544 
545 #ifdef SMP
546 	STAILQ_FOREACH(pc, &cpuhead, pc_allcpu)
547 #endif
548 	{
549 
550 		pcie_array = malloc(sizeof(struct pcie_cfg_elem) * PCIE_CACHE,
551 		    M_DEVBUF, M_NOWAIT);
552 		if (pcie_array == NULL)
553 			return (0);
554 
555 		va = kva_alloc(PCIE_CACHE * PAGE_SIZE);
556 		if (va == 0) {
557 			free(pcie_array, M_DEVBUF);
558 			return (0);
559 		}
560 
561 #ifdef SMP
562 		pcielist = &pcie_list[pc->pc_cpuid];
563 #else
564 		pcielist = &pcie_list[0];
565 #endif
566 		TAILQ_INIT(pcielist);
567 		for (i = 0; i < PCIE_CACHE; i++) {
568 			elem = &pcie_array[i];
569 			elem->vapage = va + (i * PAGE_SIZE);
570 			elem->papage = 0;
571 			TAILQ_INSERT_HEAD(pcielist, elem, elem);
572 		}
573 	}
574 
575 	pcie_base = base;
576 	pcie_minbus = minbus;
577 	pcie_maxbus = maxbus;
578 	cfgmech = CFGMECH_PCIE;
579 	devmax = 32;
580 
581 	/*
582 	 * On some AMD systems, some of the devices on bus 0 are
583 	 * inaccessible using memory-mapped PCI config access.  Walk
584 	 * bus 0 looking for such devices.  For these devices, we will
585 	 * fall back to using type 1 config access instead.
586 	 */
587 	if (pci_cfgregopen() != 0) {
588 		for (slot = 0; slot <= PCI_SLOTMAX; slot++) {
589 			val1 = pcireg_cfgread(0, slot, 0, 0, 4);
590 			if (val1 == 0xffffffff)
591 				continue;
592 
593 			val2 = pciereg_cfgread(0, slot, 0, 0, 4);
594 			if (val2 != val1)
595 				pcie_badslots |= (1 << slot);
596 		}
597 	}
598 
599 	return (1);
600 }
601 
602 #define PCIE_PADDR(base, reg, bus, slot, func)	\
603 	((base)				+	\
604 	((((bus) & 0xff) << 20)		|	\
605 	(((slot) & 0x1f) << 15)		|	\
606 	(((func) & 0x7) << 12)		|	\
607 	((reg) & 0xfff)))
608 
609 static __inline vm_offset_t
610 pciereg_findaddr(int bus, unsigned slot, unsigned func, unsigned reg)
611 {
612 	struct pcie_cfg_list *pcielist;
613 	struct pcie_cfg_elem *elem;
614 	vm_paddr_t pa, papage;
615 
616 	pa = PCIE_PADDR(pcie_base, reg, bus, slot, func);
617 	papage = pa & ~PAGE_MASK;
618 
619 	/*
620 	 * Find an element in the cache that matches the physical page desired,
621 	 * or create a new mapping from the least recently used element.
622 	 * A very simple LRU algorithm is used here, does it need to be more
623 	 * efficient?
624 	 */
625 	pcielist = &pcie_list[PCPU_GET(cpuid)];
626 	TAILQ_FOREACH(elem, pcielist, elem) {
627 		if (elem->papage == papage)
628 			break;
629 	}
630 
631 	if (elem == NULL) {
632 		elem = TAILQ_LAST(pcielist, pcie_cfg_list);
633 		if (elem->papage != 0) {
634 			pmap_kremove(elem->vapage);
635 			invlpg(elem->vapage);
636 		}
637 		pmap_kenter(elem->vapage, papage);
638 		elem->papage = papage;
639 	}
640 
641 	if (elem != TAILQ_FIRST(pcielist)) {
642 		TAILQ_REMOVE(pcielist, elem, elem);
643 		TAILQ_INSERT_HEAD(pcielist, elem, elem);
644 	}
645 	return (elem->vapage | (pa & PAGE_MASK));
646 }
647 
648 /*
649  * AMD BIOS And Kernel Developer's Guides for CPU families starting with 10h
650  * have a requirement that all accesses to the memory mapped PCI configuration
651  * space are done using AX class of registers.
652  * Since other vendors do not currently have any contradicting requirements
653  * the AMD access pattern is applied universally.
654  */
655 
656 static int
657 pciereg_cfgread(int bus, unsigned slot, unsigned func, unsigned reg,
658     unsigned bytes)
659 {
660 	vm_offset_t va;
661 	int data = -1;
662 
663 	if (bus < pcie_minbus || bus > pcie_maxbus || slot > PCI_SLOTMAX ||
664 	    func > PCI_FUNCMAX || reg > PCIE_REGMAX)
665 		return (-1);
666 
667 	critical_enter();
668 	va = pciereg_findaddr(bus, slot, func, reg);
669 
670 	switch (bytes) {
671 	case 4:
672 		__asm("movl %1, %0" : "=a" (data)
673 		    : "m" (*(volatile uint32_t *)va));
674 		break;
675 	case 2:
676 		__asm("movzwl %1, %0" : "=a" (data)
677 		    : "m" (*(volatile uint16_t *)va));
678 		break;
679 	case 1:
680 		__asm("movzbl %1, %0" : "=a" (data)
681 		    : "m" (*(volatile uint8_t *)va));
682 		break;
683 	}
684 
685 	critical_exit();
686 	return (data);
687 }
688 
689 static void
690 pciereg_cfgwrite(int bus, unsigned slot, unsigned func, unsigned reg, int data,
691     unsigned bytes)
692 {
693 	vm_offset_t va;
694 
695 	if (bus < pcie_minbus || bus > pcie_maxbus || slot > PCI_SLOTMAX ||
696 	    func > PCI_FUNCMAX || reg > PCIE_REGMAX)
697 		return;
698 
699 	critical_enter();
700 	va = pciereg_findaddr(bus, slot, func, reg);
701 
702 	switch (bytes) {
703 	case 4:
704 		__asm("movl %1, %0" : "=m" (*(volatile uint32_t *)va)
705 		    : "a" (data));
706 		break;
707 	case 2:
708 		__asm("movw %1, %0" : "=m" (*(volatile uint16_t *)va)
709 		    : "a" ((uint16_t)data));
710 		break;
711 	case 1:
712 		__asm("movb %1, %0" : "=m" (*(volatile uint8_t *)va)
713 		    : "a" ((uint8_t)data));
714 		break;
715 	}
716 
717 	critical_exit();
718 }
719