xref: /freebsd/sys/i386/pci/pci_cfgreg.c (revision 3fc36ee018bb836bd1796067cf4ef8683f166ebc)
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 
55 #ifdef XBOX
56 #include <machine/xbox.h>
57 #endif
58 
59 #define PRVERB(a) do {							\
60 	if (bootverbose)						\
61 		printf a ;						\
62 } while(0)
63 
64 #define PCIE_CACHE 8
65 struct pcie_cfg_elem {
66 	TAILQ_ENTRY(pcie_cfg_elem)	elem;
67 	vm_offset_t	vapage;
68 	vm_paddr_t	papage;
69 };
70 
71 enum {
72 	CFGMECH_NONE = 0,
73 	CFGMECH_1,
74 	CFGMECH_2,
75 	CFGMECH_PCIE,
76 };
77 
78 SYSCTL_DECL(_hw_pci);
79 
80 static TAILQ_HEAD(pcie_cfg_list, pcie_cfg_elem) pcie_list[MAXCPU];
81 static uint64_t pcie_base;
82 static int pcie_minbus, pcie_maxbus;
83 static uint32_t pcie_badslots;
84 static int cfgmech;
85 static int devmax;
86 static struct mtx pcicfg_mtx;
87 static int mcfg_enable = 1;
88 SYSCTL_INT(_hw_pci, OID_AUTO, mcfg, CTLFLAG_RDTUN, &mcfg_enable, 0,
89     "Enable support for PCI-e memory mapped config access");
90 
91 static uint32_t	pci_docfgregread(int bus, int slot, int func, int reg,
92 		    int bytes);
93 static int	pcireg_cfgread(int bus, int slot, int func, int reg, int bytes);
94 static void	pcireg_cfgwrite(int bus, int slot, int func, int reg, int data, int bytes);
95 static int	pcireg_cfgopen(void);
96 static int	pciereg_cfgread(int bus, unsigned slot, unsigned func,
97 		    unsigned reg, unsigned bytes);
98 static void	pciereg_cfgwrite(int bus, unsigned slot, unsigned func,
99 		    unsigned reg, int data, unsigned bytes);
100 
101 /*
102  * Some BIOS writers seem to want to ignore the spec and put
103  * 0 in the intline rather than 255 to indicate none.  Some use
104  * numbers in the range 128-254 to indicate something strange and
105  * apparently undocumented anywhere.  Assume these are completely bogus
106  * and map them to 255, which means "none".
107  */
108 static __inline int
109 pci_i386_map_intline(int line)
110 {
111 	if (line == 0 || line >= 128)
112 		return (PCI_INVALID_IRQ);
113 	return (line);
114 }
115 
116 static u_int16_t
117 pcibios_get_version(void)
118 {
119 	struct bios_regs args;
120 
121 	if (PCIbios.ventry == 0) {
122 		PRVERB(("pcibios: No call entry point\n"));
123 		return (0);
124 	}
125 	args.eax = PCIBIOS_BIOS_PRESENT;
126 	if (bios32(&args, PCIbios.ventry, GSEL(GCODE_SEL, SEL_KPL))) {
127 		PRVERB(("pcibios: BIOS_PRESENT call failed\n"));
128 		return (0);
129 	}
130 	if (args.edx != 0x20494350) {
131 		PRVERB(("pcibios: BIOS_PRESENT didn't return 'PCI ' in edx\n"));
132 		return (0);
133 	}
134 	return (args.ebx & 0xffff);
135 }
136 
137 /*
138  * Initialise access to PCI configuration space
139  */
140 int
141 pci_cfgregopen(void)
142 {
143 	static int		opened = 0;
144 	uint64_t		pciebar;
145 	u_int16_t		vid, did;
146 	u_int16_t		v;
147 
148 	if (opened)
149 		return (1);
150 
151 	if (cfgmech == CFGMECH_NONE && pcireg_cfgopen() == 0)
152 		return (0);
153 
154 	v = pcibios_get_version();
155 	if (v > 0)
156 		PRVERB(("pcibios: BIOS version %x.%02x\n", (v & 0xff00) >> 8,
157 		    v & 0xff));
158 	mtx_init(&pcicfg_mtx, "pcicfg", NULL, MTX_SPIN);
159 	opened = 1;
160 
161 	/* $PIR requires PCI BIOS 2.10 or greater. */
162 	if (v >= 0x0210)
163 		pci_pir_open();
164 
165 	if (cfgmech == CFGMECH_PCIE)
166 		return (1);
167 
168 	/*
169 	 * Grope around in the PCI config space to see if this is a
170 	 * chipset that is capable of doing memory-mapped config cycles.
171 	 * This also implies that it can do PCIe extended config cycles.
172 	 */
173 
174 	/* Check for supported chipsets */
175 	vid = pci_cfgregread(0, 0, 0, PCIR_VENDOR, 2);
176 	did = pci_cfgregread(0, 0, 0, PCIR_DEVICE, 2);
177 	switch (vid) {
178 	case 0x8086:
179 		switch (did) {
180 		case 0x3590:
181 		case 0x3592:
182 			/* Intel 7520 or 7320 */
183 			pciebar = pci_cfgregread(0, 0, 0, 0xce, 2) << 16;
184 			pcie_cfgregopen(pciebar, 0, 255);
185 			break;
186 		case 0x2580:
187 		case 0x2584:
188 		case 0x2590:
189 			/* Intel 915, 925, or 915GM */
190 			pciebar = pci_cfgregread(0, 0, 0, 0x48, 4);
191 			pcie_cfgregopen(pciebar, 0, 255);
192 			break;
193 		}
194 	}
195 
196 	return(1);
197 }
198 
199 static uint32_t
200 pci_docfgregread(int bus, int slot, int func, int reg, int bytes)
201 {
202 
203 	if (cfgmech == CFGMECH_PCIE &&
204 	    (bus >= pcie_minbus && bus <= pcie_maxbus) &&
205 	    (bus != 0 || !(1 << slot & pcie_badslots)))
206 		return (pciereg_cfgread(bus, slot, func, reg, bytes));
207 	else
208 		return (pcireg_cfgread(bus, slot, func, reg, bytes));
209 }
210 
211 /*
212  * Read configuration space register
213  */
214 u_int32_t
215 pci_cfgregread(int bus, int slot, int func, int reg, int bytes)
216 {
217 	uint32_t line;
218 
219 	/*
220 	 * Some BIOS writers seem to want to ignore the spec and put
221 	 * 0 in the intline rather than 255 to indicate none.  The rest of
222 	 * the code uses 255 as an invalid IRQ.
223 	 */
224 	if (reg == PCIR_INTLINE && bytes == 1) {
225 		line = pci_docfgregread(bus, slot, func, PCIR_INTLINE, 1);
226 		return (pci_i386_map_intline(line));
227 	}
228 	return (pci_docfgregread(bus, slot, func, reg, bytes));
229 }
230 
231 /*
232  * Write configuration space register
233  */
234 void
235 pci_cfgregwrite(int bus, int slot, int func, int reg, u_int32_t data, int bytes)
236 {
237 
238 	if (cfgmech == CFGMECH_PCIE &&
239 	    (bus >= pcie_minbus && bus <= pcie_maxbus) &&
240 	    (bus != 0 || !(1 << slot & pcie_badslots)))
241 		pciereg_cfgwrite(bus, slot, func, reg, data, bytes);
242 	else
243 		pcireg_cfgwrite(bus, slot, func, reg, data, bytes);
244 }
245 
246 /*
247  * Configuration space access using direct register operations
248  */
249 
250 /* enable configuration space accesses and return data port address */
251 static int
252 pci_cfgenable(unsigned bus, unsigned slot, unsigned func, int reg, int bytes)
253 {
254 	int dataport = 0;
255 
256 #ifdef XBOX
257 	if (arch_i386_is_xbox) {
258 		/*
259 		 * The Xbox MCPX chipset is a derivative of the nForce 1
260 		 * chipset. It almost has the same bus layout; some devices
261 		 * cannot be used, because they have been removed.
262 		 */
263 
264 		/*
265 		 * Devices 00:00.1 and 00:00.2 used to be memory controllers on
266 		 * the nForce chipset, but on the Xbox, using them will lockup
267 		 * the chipset.
268 		 */
269 		if (bus == 0 && slot == 0 && (func == 1 || func == 2))
270 			return dataport;
271 
272 		/*
273 		 * Bus 1 only contains a VGA controller at 01:00.0. When you try
274 		 * to probe beyond that device, you only get garbage, which
275 		 * could cause lockups.
276 		 */
277 		if (bus == 1 && (slot != 0 || func != 0))
278 			return dataport;
279 
280 		/*
281 		 * Bus 2 used to contain the AGP controller, but the Xbox MCPX
282 		 * doesn't have one. Probing it can cause lockups.
283 		 */
284 		if (bus >= 2)
285 			return dataport;
286 	}
287 #endif
288 
289 	if (bus <= PCI_BUSMAX
290 	    && slot < devmax
291 	    && func <= PCI_FUNCMAX
292 	    && (unsigned)reg <= PCI_REGMAX
293 	    && bytes != 3
294 	    && (unsigned)bytes <= 4
295 	    && (reg & (bytes - 1)) == 0) {
296 		switch (cfgmech) {
297 		case CFGMECH_PCIE:
298 		case CFGMECH_1:
299 			outl(CONF1_ADDR_PORT, (1U << 31)
300 			    | (bus << 16) | (slot << 11)
301 			    | (func << 8) | (reg & ~0x03));
302 			dataport = CONF1_DATA_PORT + (reg & 0x03);
303 			break;
304 		case CFGMECH_2:
305 			outb(CONF2_ENABLE_PORT, 0xf0 | (func << 1));
306 			outb(CONF2_FORWARD_PORT, bus);
307 			dataport = 0xc000 | (slot << 8) | reg;
308 			break;
309 		}
310 	}
311 	return (dataport);
312 }
313 
314 /* disable configuration space accesses */
315 static void
316 pci_cfgdisable(void)
317 {
318 	switch (cfgmech) {
319 	case CFGMECH_PCIE:
320 	case CFGMECH_1:
321 		/*
322 		 * Do nothing for the config mechanism 1 case.
323 		 * Writing a 0 to the address port can apparently
324 		 * confuse some bridges and cause spurious
325 		 * access failures.
326 		 */
327 		break;
328 	case CFGMECH_2:
329 		outb(CONF2_ENABLE_PORT, 0);
330 		break;
331 	}
332 }
333 
334 static int
335 pcireg_cfgread(int bus, int slot, int func, int reg, int bytes)
336 {
337 	int data = -1;
338 	int port;
339 
340 	mtx_lock_spin(&pcicfg_mtx);
341 	port = pci_cfgenable(bus, slot, func, reg, bytes);
342 	if (port != 0) {
343 		switch (bytes) {
344 		case 1:
345 			data = inb(port);
346 			break;
347 		case 2:
348 			data = inw(port);
349 			break;
350 		case 4:
351 			data = inl(port);
352 			break;
353 		}
354 		pci_cfgdisable();
355 	}
356 	mtx_unlock_spin(&pcicfg_mtx);
357 	return (data);
358 }
359 
360 static void
361 pcireg_cfgwrite(int bus, int slot, int func, int reg, int data, int bytes)
362 {
363 	int port;
364 
365 	mtx_lock_spin(&pcicfg_mtx);
366 	port = pci_cfgenable(bus, slot, func, reg, bytes);
367 	if (port != 0) {
368 		switch (bytes) {
369 		case 1:
370 			outb(port, data);
371 			break;
372 		case 2:
373 			outw(port, data);
374 			break;
375 		case 4:
376 			outl(port, data);
377 			break;
378 		}
379 		pci_cfgdisable();
380 	}
381 	mtx_unlock_spin(&pcicfg_mtx);
382 }
383 
384 /* check whether the configuration mechanism has been correctly identified */
385 static int
386 pci_cfgcheck(int maxdev)
387 {
388 	uint32_t id, class;
389 	uint8_t header;
390 	uint8_t device;
391 	int port;
392 
393 	if (bootverbose)
394 		printf("pci_cfgcheck:\tdevice ");
395 
396 	for (device = 0; device < maxdev; device++) {
397 		if (bootverbose)
398 			printf("%d ", device);
399 
400 		port = pci_cfgenable(0, device, 0, 0, 4);
401 		id = inl(port);
402 		if (id == 0 || id == 0xffffffff)
403 			continue;
404 
405 		port = pci_cfgenable(0, device, 0, 8, 4);
406 		class = inl(port) >> 8;
407 		if (bootverbose)
408 			printf("[class=%06x] ", class);
409 		if (class == 0 || (class & 0xf870ff) != 0)
410 			continue;
411 
412 		port = pci_cfgenable(0, device, 0, 14, 1);
413 		header = inb(port);
414 		if (bootverbose)
415 			printf("[hdr=%02x] ", header);
416 		if ((header & 0x7e) != 0)
417 			continue;
418 
419 		if (bootverbose)
420 			printf("is there (id=%08x)\n", id);
421 
422 		pci_cfgdisable();
423 		return (1);
424 	}
425 	if (bootverbose)
426 		printf("-- nothing found\n");
427 
428 	pci_cfgdisable();
429 	return (0);
430 }
431 
432 static int
433 pcireg_cfgopen(void)
434 {
435 	uint32_t mode1res, oldval1;
436 	uint8_t mode2res, oldval2;
437 
438 	/* Check for type #1 first. */
439 	oldval1 = inl(CONF1_ADDR_PORT);
440 
441 	if (bootverbose) {
442 		printf("pci_open(1):\tmode 1 addr port (0x0cf8) is 0x%08x\n",
443 		    oldval1);
444 	}
445 
446 	cfgmech = CFGMECH_1;
447 	devmax = 32;
448 
449 	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK);
450 	DELAY(1);
451 	mode1res = inl(CONF1_ADDR_PORT);
452 	outl(CONF1_ADDR_PORT, oldval1);
453 
454 	if (bootverbose)
455 		printf("pci_open(1a):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
456 		    CONF1_ENABLE_CHK);
457 
458 	if (mode1res) {
459 		if (pci_cfgcheck(32))
460 			return (cfgmech);
461 	}
462 
463 	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK1);
464 	mode1res = inl(CONF1_ADDR_PORT);
465 	outl(CONF1_ADDR_PORT, oldval1);
466 
467 	if (bootverbose)
468 		printf("pci_open(1b):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
469 		    CONF1_ENABLE_CHK1);
470 
471 	if ((mode1res & CONF1_ENABLE_MSK1) == CONF1_ENABLE_RES1) {
472 		if (pci_cfgcheck(32))
473 			return (cfgmech);
474 	}
475 
476 	/* Type #1 didn't work, so try type #2. */
477 	oldval2 = inb(CONF2_ENABLE_PORT);
478 
479 	if (bootverbose) {
480 		printf("pci_open(2):\tmode 2 enable port (0x0cf8) is 0x%02x\n",
481 		    oldval2);
482 	}
483 
484 	if ((oldval2 & 0xf0) == 0) {
485 
486 		cfgmech = CFGMECH_2;
487 		devmax = 16;
488 
489 		outb(CONF2_ENABLE_PORT, CONF2_ENABLE_CHK);
490 		mode2res = inb(CONF2_ENABLE_PORT);
491 		outb(CONF2_ENABLE_PORT, oldval2);
492 
493 		if (bootverbose)
494 			printf("pci_open(2a):\tmode2res=0x%02x (0x%02x)\n",
495 			    mode2res, CONF2_ENABLE_CHK);
496 
497 		if (mode2res == CONF2_ENABLE_RES) {
498 			if (bootverbose)
499 				printf("pci_open(2a):\tnow trying mechanism 2\n");
500 
501 			if (pci_cfgcheck(16))
502 				return (cfgmech);
503 		}
504 	}
505 
506 	/* Nothing worked, so punt. */
507 	cfgmech = CFGMECH_NONE;
508 	devmax = 0;
509 	return (cfgmech);
510 }
511 
512 int
513 pcie_cfgregopen(uint64_t base, uint8_t minbus, uint8_t maxbus)
514 {
515 	struct pcie_cfg_list *pcielist;
516 	struct pcie_cfg_elem *pcie_array, *elem;
517 #ifdef SMP
518 	struct pcpu *pc;
519 #endif
520 	vm_offset_t va;
521 	uint32_t val1, val2;
522 	int i, slot;
523 
524 	if (!mcfg_enable)
525 		return (0);
526 
527 	if (minbus != 0)
528 		return (0);
529 
530 #ifndef PAE
531 	if (base >= 0x100000000) {
532 		if (bootverbose)
533 			printf(
534 	    "PCI: Memory Mapped PCI configuration area base 0x%jx too high\n",
535 			    (uintmax_t)base);
536 		return (0);
537 	}
538 #endif
539 
540 	if (bootverbose)
541 		printf("PCIe: Memory Mapped configuration base @ 0x%jx\n",
542 		    (uintmax_t)base);
543 
544 #ifdef SMP
545 	STAILQ_FOREACH(pc, &cpuhead, pc_allcpu)
546 #endif
547 	{
548 
549 		pcie_array = malloc(sizeof(struct pcie_cfg_elem) * PCIE_CACHE,
550 		    M_DEVBUF, M_NOWAIT);
551 		if (pcie_array == NULL)
552 			return (0);
553 
554 		va = kva_alloc(PCIE_CACHE * PAGE_SIZE);
555 		if (va == 0) {
556 			free(pcie_array, M_DEVBUF);
557 			return (0);
558 		}
559 
560 #ifdef SMP
561 		pcielist = &pcie_list[pc->pc_cpuid];
562 #else
563 		pcielist = &pcie_list[0];
564 #endif
565 		TAILQ_INIT(pcielist);
566 		for (i = 0; i < PCIE_CACHE; i++) {
567 			elem = &pcie_array[i];
568 			elem->vapage = va + (i * PAGE_SIZE);
569 			elem->papage = 0;
570 			TAILQ_INSERT_HEAD(pcielist, elem, elem);
571 		}
572 	}
573 
574 	pcie_base = base;
575 	pcie_minbus = minbus;
576 	pcie_maxbus = maxbus;
577 	cfgmech = CFGMECH_PCIE;
578 	devmax = 32;
579 
580 	/*
581 	 * On some AMD systems, some of the devices on bus 0 are
582 	 * inaccessible using memory-mapped PCI config access.  Walk
583 	 * bus 0 looking for such devices.  For these devices, we will
584 	 * fall back to using type 1 config access instead.
585 	 */
586 	if (pci_cfgregopen() != 0) {
587 		for (slot = 0; slot <= PCI_SLOTMAX; slot++) {
588 			val1 = pcireg_cfgread(0, slot, 0, 0, 4);
589 			if (val1 == 0xffffffff)
590 				continue;
591 
592 			val2 = pciereg_cfgread(0, slot, 0, 0, 4);
593 			if (val2 != val1)
594 				pcie_badslots |= (1 << slot);
595 		}
596 	}
597 
598 	return (1);
599 }
600 
601 #define PCIE_PADDR(base, reg, bus, slot, func)	\
602 	((base)				+	\
603 	((((bus) & 0xff) << 20)		|	\
604 	(((slot) & 0x1f) << 15)		|	\
605 	(((func) & 0x7) << 12)		|	\
606 	((reg) & 0xfff)))
607 
608 static __inline vm_offset_t
609 pciereg_findaddr(int bus, unsigned slot, unsigned func, unsigned reg)
610 {
611 	struct pcie_cfg_list *pcielist;
612 	struct pcie_cfg_elem *elem;
613 	vm_paddr_t pa, papage;
614 
615 	pa = PCIE_PADDR(pcie_base, reg, bus, slot, func);
616 	papage = pa & ~PAGE_MASK;
617 
618 	/*
619 	 * Find an element in the cache that matches the physical page desired,
620 	 * or create a new mapping from the least recently used element.
621 	 * A very simple LRU algorithm is used here, does it need to be more
622 	 * efficient?
623 	 */
624 	pcielist = &pcie_list[PCPU_GET(cpuid)];
625 	TAILQ_FOREACH(elem, pcielist, elem) {
626 		if (elem->papage == papage)
627 			break;
628 	}
629 
630 	if (elem == NULL) {
631 		elem = TAILQ_LAST(pcielist, pcie_cfg_list);
632 		if (elem->papage != 0) {
633 			pmap_kremove(elem->vapage);
634 			invlpg(elem->vapage);
635 		}
636 		pmap_kenter(elem->vapage, papage);
637 		elem->papage = papage;
638 	}
639 
640 	if (elem != TAILQ_FIRST(pcielist)) {
641 		TAILQ_REMOVE(pcielist, elem, elem);
642 		TAILQ_INSERT_HEAD(pcielist, elem, elem);
643 	}
644 	return (elem->vapage | (pa & PAGE_MASK));
645 }
646 
647 /*
648  * AMD BIOS And Kernel Developer's Guides for CPU families starting with 10h
649  * have a requirement that all accesses to the memory mapped PCI configuration
650  * space are done using AX class of registers.
651  * Since other vendors do not currently have any contradicting requirements
652  * the AMD access pattern is applied universally.
653  */
654 
655 static int
656 pciereg_cfgread(int bus, unsigned slot, unsigned func, unsigned reg,
657     unsigned bytes)
658 {
659 	vm_offset_t va;
660 	int data = -1;
661 
662 	if (bus < pcie_minbus || bus > pcie_maxbus || slot > PCI_SLOTMAX ||
663 	    func > PCI_FUNCMAX || reg > PCIE_REGMAX)
664 		return (-1);
665 
666 	critical_enter();
667 	va = pciereg_findaddr(bus, slot, func, reg);
668 
669 	switch (bytes) {
670 	case 4:
671 		__asm("movl %1, %0" : "=a" (data)
672 		    : "m" (*(volatile uint32_t *)va));
673 		break;
674 	case 2:
675 		__asm("movzwl %1, %0" : "=a" (data)
676 		    : "m" (*(volatile uint16_t *)va));
677 		break;
678 	case 1:
679 		__asm("movzbl %1, %0" : "=a" (data)
680 		    : "m" (*(volatile uint8_t *)va));
681 		break;
682 	}
683 
684 	critical_exit();
685 	return (data);
686 }
687 
688 static void
689 pciereg_cfgwrite(int bus, unsigned slot, unsigned func, unsigned reg, int data,
690     unsigned bytes)
691 {
692 	vm_offset_t va;
693 
694 	if (bus < pcie_minbus || bus > pcie_maxbus || slot > PCI_SLOTMAX ||
695 	    func > PCI_FUNCMAX || reg > PCIE_REGMAX)
696 		return;
697 
698 	critical_enter();
699 	va = pciereg_findaddr(bus, slot, func, reg);
700 
701 	switch (bytes) {
702 	case 4:
703 		__asm("movl %1, %0" : "=m" (*(volatile uint32_t *)va)
704 		    : "a" (data));
705 		break;
706 	case 2:
707 		__asm("movw %1, %0" : "=m" (*(volatile uint16_t *)va)
708 		    : "a" ((uint16_t)data));
709 		break;
710 	case 1:
711 		__asm("movb %1, %0" : "=m" (*(volatile uint8_t *)va)
712 		    : "a" ((uint8_t)data));
713 		break;
714 	}
715 
716 	critical_exit();
717 }
718