xref: /openbsd-src/sys/dev/fdt/virtio_mmio.c (revision dcc91c2622318df8f66a9bca2d2864253df1bfc3)
1 /*	$OpenBSD: virtio_mmio.c,v 1.16 2024/08/27 19:01:11 sf Exp $	*/
2 /*	$NetBSD: virtio.c,v 1.3 2011/11/02 23:05:52 njoly Exp $	*/
3 
4 /*
5  * Copyright (c) 2014 Patrick Wildt <patrick@blueri.se>
6  * Copyright (c) 2012 Stefan Fritsch.
7  * Copyright (c) 2010 Minoura Makoto.
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34 #include <sys/device.h>
35 #include <sys/mutex.h>
36 
37 #include <dev/pv/virtioreg.h>
38 #include <dev/pv/virtiovar.h>
39 
40 #include <machine/fdt.h>
41 
42 #include <dev/ofw/fdt.h>
43 #include <dev/ofw/openfirm.h>
44 
45 #define VIRTIO_MMIO_MAGIC		('v' | 'i' << 8 | 'r' << 16 | 't' << 24)
46 
47 #define VIRTIO_MMIO_MAGIC_VALUE		0x000
48 #define VIRTIO_MMIO_VERSION		0x004
49 #define VIRTIO_MMIO_DEVICE_ID		0x008
50 #define VIRTIO_MMIO_VENDOR_ID		0x00c
51 #define VIRTIO_MMIO_HOST_FEATURES	0x010
52 #define VIRTIO_MMIO_HOST_FEATURES_SEL	0x014
53 #define VIRTIO_MMIO_GUEST_FEATURES	0x020
54 #define VIRTIO_MMIO_GUEST_FEATURES_SEL	0x024
55 #define VIRTIO_MMIO_GUEST_PAGE_SIZE	0x028
56 #define VIRTIO_MMIO_QUEUE_SEL		0x030
57 #define VIRTIO_MMIO_QUEUE_NUM_MAX	0x034
58 #define VIRTIO_MMIO_QUEUE_NUM		0x038
59 #define VIRTIO_MMIO_QUEUE_ALIGN		0x03c
60 #define VIRTIO_MMIO_QUEUE_PFN		0x040
61 #define VIRTIO_MMIO_QUEUE_READY		0x044
62 #define VIRTIO_MMIO_QUEUE_NOTIFY	0x050
63 #define VIRTIO_MMIO_INTERRUPT_STATUS	0x060
64 #define VIRTIO_MMIO_INTERRUPT_ACK	0x064
65 #define VIRTIO_MMIO_STATUS		0x070
66 #define VIRTIO_MMIO_QUEUE_DESC_LOW	0x080
67 #define VIRTIO_MMIO_QUEUE_DESC_HIGH	0x084
68 #define VIRTIO_MMIO_QUEUE_AVAIL_LOW	0x090
69 #define VIRTIO_MMIO_QUEUE_AVAIL_HIGH	0x094
70 #define VIRTIO_MMIO_QUEUE_USED_LOW	0x0a0
71 #define VIRTIO_MMIO_QUEUE_USED_HIGH	0x0a4
72 #define VIRTIO_MMIO_CONFIG		0x100
73 
74 #define VIRTIO_MMIO_INT_VRING		(1 << 0)
75 #define VIRTIO_MMIO_INT_CONFIG		(1 << 1)
76 
77 #define DEVNAME(sc) (sc)->sc_dev.dv_xname
78 
79 /*
80  * XXX: Before being used on big endian arches, the access to config registers
81  * XXX: needs to be reviewed/fixed. The non-device specific registers are
82  * XXX: PCI-endian while the device specific registers are native endian.
83  */
84 
85 int		virtio_mmio_match(struct device *, void *, void *);
86 void		virtio_mmio_attach(struct device *, struct device *, void *);
87 int		virtio_mmio_detach(struct device *, int);
88 
89 void		virtio_mmio_kick(struct virtio_softc *, uint16_t);
90 uint8_t		virtio_mmio_read_device_config_1(struct virtio_softc *, int);
91 uint16_t	virtio_mmio_read_device_config_2(struct virtio_softc *, int);
92 uint32_t	virtio_mmio_read_device_config_4(struct virtio_softc *, int);
93 uint64_t	virtio_mmio_read_device_config_8(struct virtio_softc *, int);
94 void		virtio_mmio_write_device_config_1(struct virtio_softc *, int, uint8_t);
95 void		virtio_mmio_write_device_config_2(struct virtio_softc *, int, uint16_t);
96 void		virtio_mmio_write_device_config_4(struct virtio_softc *, int, uint32_t);
97 void		virtio_mmio_write_device_config_8(struct virtio_softc *, int, uint64_t);
98 uint16_t	virtio_mmio_read_queue_size(struct virtio_softc *, uint16_t);
99 void		virtio_mmio_setup_queue(struct virtio_softc *, struct virtqueue *, uint64_t);
100 int		virtio_mmio_get_status(struct virtio_softc *);
101 void		virtio_mmio_set_status(struct virtio_softc *, int);
102 int		virtio_mmio_negotiate_features(struct virtio_softc *,
103     const struct virtio_feature_name *);
104 int		virtio_mmio_intr(void *);
105 
106 struct virtio_mmio_softc {
107 	struct virtio_softc	sc_sc;
108 
109 	bus_space_tag_t		sc_iot;
110 	bus_space_handle_t	sc_ioh;
111 	bus_size_t		sc_iosize;
112 	bus_dma_tag_t		sc_dmat;
113 
114 	void			*sc_ih;
115 
116 	int			sc_config_offset;
117 	uint32_t		sc_version;
118 };
119 
120 const struct cfattach virtio_mmio_ca = {
121 	sizeof(struct virtio_mmio_softc),
122 	virtio_mmio_match,
123 	virtio_mmio_attach,
124 	virtio_mmio_detach,
125 	NULL
126 };
127 
128 const struct cfattach virtio_mmio_fdt_ca = {
129 	sizeof(struct virtio_mmio_softc),
130 	NULL,
131 	virtio_mmio_attach,
132 	virtio_mmio_detach,
133 	NULL
134 };
135 
136 const struct virtio_ops virtio_mmio_ops = {
137 	virtio_mmio_kick,
138 	virtio_mmio_read_device_config_1,
139 	virtio_mmio_read_device_config_2,
140 	virtio_mmio_read_device_config_4,
141 	virtio_mmio_read_device_config_8,
142 	virtio_mmio_write_device_config_1,
143 	virtio_mmio_write_device_config_2,
144 	virtio_mmio_write_device_config_4,
145 	virtio_mmio_write_device_config_8,
146 	virtio_mmio_read_queue_size,
147 	virtio_mmio_setup_queue,
148 	virtio_mmio_get_status,
149 	virtio_mmio_set_status,
150 	virtio_mmio_negotiate_features,
151 	virtio_mmio_intr,
152 };
153 
154 uint16_t
155 virtio_mmio_read_queue_size(struct virtio_softc *vsc, uint16_t idx)
156 {
157 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
158 	bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_QUEUE_SEL, idx);
159 	return bus_space_read_4(sc->sc_iot, sc->sc_ioh,
160 	    VIRTIO_MMIO_QUEUE_NUM_MAX);
161 }
162 
163 void
164 virtio_mmio_setup_queue(struct virtio_softc *vsc, struct virtqueue *vq,
165     uint64_t addr)
166 {
167 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
168 	bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_QUEUE_SEL,
169 	    vq->vq_index);
170 	bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_QUEUE_NUM,
171 	    bus_space_read_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_QUEUE_NUM_MAX));
172 	if (sc->sc_version == 1) {
173 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
174 		    VIRTIO_MMIO_QUEUE_ALIGN, PAGE_SIZE);
175 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
176 		    VIRTIO_MMIO_QUEUE_PFN, addr / VIRTIO_PAGE_SIZE);
177 	} else {
178 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
179 		    VIRTIO_MMIO_QUEUE_DESC_LOW, addr);
180 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
181 		    VIRTIO_MMIO_QUEUE_DESC_HIGH, addr >> 32);
182 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
183 		    VIRTIO_MMIO_QUEUE_AVAIL_LOW,
184 		    addr + vq->vq_availoffset);
185 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
186 		    VIRTIO_MMIO_QUEUE_AVAIL_HIGH,
187 		    (addr + vq->vq_availoffset) >> 32);
188 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
189 		    VIRTIO_MMIO_QUEUE_USED_LOW,
190 		    addr + vq->vq_usedoffset);
191 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
192 		    VIRTIO_MMIO_QUEUE_USED_HIGH,
193 		    (addr + vq->vq_usedoffset) >> 32);
194 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
195 		    VIRTIO_MMIO_QUEUE_READY, 1);
196 	}
197 }
198 
199 int
200 virtio_mmio_get_status(struct virtio_softc *vsc)
201 {
202 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
203 
204 	return bus_space_read_4(sc->sc_iot, sc->sc_ioh,
205 	    VIRTIO_MMIO_STATUS);
206 }
207 
208 void
209 virtio_mmio_set_status(struct virtio_softc *vsc, int status)
210 {
211 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
212 	int old = 0;
213 
214 	if (status == 0) {
215 		bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_STATUS,
216 		    0);
217 		while (bus_space_read_4(sc->sc_iot, sc->sc_ioh,
218 		    VIRTIO_MMIO_STATUS) != 0) {
219 			CPU_BUSY_CYCLE();
220 		}
221 	} else  {
222 		old = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
223 		    VIRTIO_MMIO_STATUS);
224 		bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_STATUS,
225 		    status|old);
226 	}
227 }
228 
229 int
230 virtio_mmio_match(struct device *parent, void *cfdata, void *aux)
231 {
232 	struct fdt_attach_args *faa = aux;
233 
234 	return OF_is_compatible(faa->fa_node, "virtio,mmio");
235 }
236 
237 void
238 virtio_mmio_attach(struct device *parent, struct device *self, void *aux)
239 {
240 	struct fdt_attach_args *faa = aux;
241 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)self;
242 	struct virtio_softc *vsc = &sc->sc_sc;
243 	uint32_t id, magic;
244 	struct virtio_attach_args va = { 0 };
245 
246 	if (faa->fa_nreg < 1) {
247 		printf(": no register data\n");
248 		return;
249 	}
250 
251 	sc->sc_iosize = faa->fa_reg[0].size;
252 	sc->sc_iot = faa->fa_iot;
253 	sc->sc_dmat = faa->fa_dmat;
254 	if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr, faa->fa_reg[0].size,
255 	    0, &sc->sc_ioh))
256 		panic("%s: bus_space_map failed!", __func__);
257 
258 	magic = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
259 	    VIRTIO_MMIO_MAGIC_VALUE);
260 	if (magic != VIRTIO_MMIO_MAGIC) {
261 		printf(": wrong magic value 0x%08x; giving up\n", magic);
262 		return;
263 	}
264 
265 	sc->sc_version = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
266 	    VIRTIO_MMIO_VERSION);
267 	if (sc->sc_version < 1 || sc->sc_version > 2) {
268 		printf(": unknown version 0x%02x; giving up\n", sc->sc_version);
269 		return;
270 	}
271 
272 	id = bus_space_read_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_DEVICE_ID);
273 	printf(": Virtio %s Device", virtio_device_string(id));
274 
275 	printf("\n");
276 
277 	/* No device connected. */
278 	if (id == 0)
279 		return;
280 
281 	if (sc->sc_version == 1)
282 		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
283 		    VIRTIO_MMIO_GUEST_PAGE_SIZE, PAGE_SIZE);
284 
285 	vsc->sc_ops = &virtio_mmio_ops;
286 	vsc->sc_dmat = sc->sc_dmat;
287 	sc->sc_config_offset = VIRTIO_MMIO_CONFIG;
288 
289 	virtio_device_reset(vsc);
290 	virtio_mmio_set_status(vsc, VIRTIO_CONFIG_DEVICE_STATUS_ACK);
291 	virtio_mmio_set_status(vsc, VIRTIO_CONFIG_DEVICE_STATUS_DRIVER);
292 
293 	va.va_devid = id;
294 	va.va_nintr = 1;
295 	vsc->sc_child = NULL;
296 	config_found(self, &va, NULL);
297 	if (vsc->sc_child == NULL) {
298 		printf("%s: no matching child driver; not configured\n",
299 		    vsc->sc_dev.dv_xname);
300 		goto fail_1;
301 	}
302 	if (vsc->sc_child == VIRTIO_CHILD_ERROR) {
303 		printf("%s: virtio configuration failed\n",
304 		    vsc->sc_dev.dv_xname);
305 		goto fail_1;
306 	}
307 
308 	sc->sc_ih = fdt_intr_establish(faa->fa_node, vsc->sc_ipl,
309 	    virtio_mmio_intr, sc, vsc->sc_dev.dv_xname);
310 	if (sc->sc_ih == NULL) {
311 		printf("%s: couldn't establish interrupt\n",
312 		    vsc->sc_dev.dv_xname);
313 		goto fail_2;
314 	}
315 
316 	return;
317 
318 fail_2:
319 	config_detach(vsc->sc_child, 0);
320 fail_1:
321 	/* no mmio_mapreg_unmap() or mmio_intr_unmap() */
322 	virtio_set_status(vsc, VIRTIO_CONFIG_DEVICE_STATUS_FAILED);
323 }
324 
325 int
326 virtio_mmio_detach(struct device *self, int flags)
327 {
328 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)self;
329 	struct virtio_softc *vsc = &sc->sc_sc;
330 	int r;
331 
332 	if (vsc->sc_child != 0 && vsc->sc_child != VIRTIO_CHILD_ERROR) {
333 		r = config_detach(vsc->sc_child, flags);
334 		if (r)
335 			return r;
336 	}
337 	KASSERT(vsc->sc_child == 0 || vsc->sc_child == VIRTIO_CHILD_ERROR);
338 	KASSERT(vsc->sc_vqs == 0);
339 	fdt_intr_disestablish(sc->sc_ih);
340 	sc->sc_ih = 0;
341 	if (sc->sc_iosize)
342 		bus_space_unmap(sc->sc_iot, sc->sc_ioh, sc->sc_iosize);
343 	sc->sc_iosize = 0;
344 
345 	return 0;
346 }
347 
348 /*
349  * Feature negotiation.
350  * Prints available / negotiated features if guest_feature_names != NULL and
351  * VIRTIO_DEBUG is 1
352  */
353 int
354 virtio_mmio_negotiate_features(struct virtio_softc *vsc,
355     const struct virtio_feature_name *guest_feature_names)
356 {
357 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
358 	uint64_t host, neg;
359 
360 	vsc->sc_active_features = 0;
361 
362 	/*
363 	 * We enable indirect descriptors by default. They can be switched
364 	 * off by setting bit 1 in the driver flags, see config(8).
365 	 */
366 	if (!(vsc->sc_dev.dv_cfdata->cf_flags & VIRTIO_CF_NO_INDIRECT) &&
367 	    !(vsc->sc_child->dv_cfdata->cf_flags & VIRTIO_CF_NO_INDIRECT)) {
368 		vsc->sc_driver_features |= VIRTIO_F_RING_INDIRECT_DESC;
369 	} else if (guest_feature_names != NULL) {
370 		printf("RingIndirectDesc disabled by UKC\n");
371 	}
372 	/*
373 	 * The driver must add VIRTIO_F_RING_EVENT_IDX if it supports it.
374 	 * If it did, check if it is disabled by bit 2 in the driver flags.
375 	 */
376 	if ((vsc->sc_driver_features & VIRTIO_F_RING_EVENT_IDX) &&
377 	    ((vsc->sc_dev.dv_cfdata->cf_flags & VIRTIO_CF_NO_EVENT_IDX) ||
378 	    (vsc->sc_child->dv_cfdata->cf_flags & VIRTIO_CF_NO_EVENT_IDX))) {
379 		if (guest_feature_names != NULL)
380 			printf(" RingEventIdx disabled by UKC");
381 		vsc->sc_driver_features &= ~(VIRTIO_F_RING_EVENT_IDX);
382 	}
383 
384 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
385 	    VIRTIO_MMIO_HOST_FEATURES_SEL, 0);
386 	host = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
387 				VIRTIO_MMIO_HOST_FEATURES);
388 	neg = host & vsc->sc_driver_features;
389 #if VIRTIO_DEBUG
390 	if (guest_feature_names)
391 		virtio_log_features(host, neg, guest_feature_names);
392 #endif
393 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
394 	    VIRTIO_MMIO_GUEST_FEATURES_SEL, 0);
395 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
396 			  VIRTIO_MMIO_GUEST_FEATURES, neg);
397 	vsc->sc_active_features = neg;
398 	if (neg & VIRTIO_F_RING_INDIRECT_DESC)
399 		vsc->sc_indirect = 1;
400 	else
401 		vsc->sc_indirect = 0;
402 
403 	return 0;
404 }
405 
406 /*
407  * Device configuration registers.
408  */
409 uint8_t
410 virtio_mmio_read_device_config_1(struct virtio_softc *vsc, int index)
411 {
412 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
413 	return bus_space_read_1(sc->sc_iot, sc->sc_ioh,
414 				sc->sc_config_offset + index);
415 }
416 
417 uint16_t
418 virtio_mmio_read_device_config_2(struct virtio_softc *vsc, int index)
419 {
420 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
421 	return bus_space_read_2(sc->sc_iot, sc->sc_ioh,
422 				sc->sc_config_offset + index);
423 }
424 
425 uint32_t
426 virtio_mmio_read_device_config_4(struct virtio_softc *vsc, int index)
427 {
428 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
429 	return bus_space_read_4(sc->sc_iot, sc->sc_ioh,
430 				sc->sc_config_offset + index);
431 }
432 
433 uint64_t
434 virtio_mmio_read_device_config_8(struct virtio_softc *vsc, int index)
435 {
436 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
437 	uint64_t r;
438 
439 	r = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
440 			     sc->sc_config_offset + index + sizeof(uint32_t));
441 	r <<= 32;
442 	r += bus_space_read_4(sc->sc_iot, sc->sc_ioh,
443 			      sc->sc_config_offset + index);
444 	return r;
445 }
446 
447 void
448 virtio_mmio_write_device_config_1(struct virtio_softc *vsc,
449 			     int index, uint8_t value)
450 {
451 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
452 	bus_space_write_1(sc->sc_iot, sc->sc_ioh,
453 			  sc->sc_config_offset + index, value);
454 }
455 
456 void
457 virtio_mmio_write_device_config_2(struct virtio_softc *vsc,
458 			     int index, uint16_t value)
459 {
460 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
461 	bus_space_write_2(sc->sc_iot, sc->sc_ioh,
462 			  sc->sc_config_offset + index, value);
463 }
464 
465 void
466 virtio_mmio_write_device_config_4(struct virtio_softc *vsc,
467 			     int index, uint32_t value)
468 {
469 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
470 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
471 			  sc->sc_config_offset + index, value);
472 }
473 
474 void
475 virtio_mmio_write_device_config_8(struct virtio_softc *vsc,
476 			     int index, uint64_t value)
477 {
478 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
479 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
480 			  sc->sc_config_offset + index,
481 			  value & 0xffffffff);
482 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
483 			  sc->sc_config_offset + index + sizeof(uint32_t),
484 			  value >> 32);
485 }
486 
487 /*
488  * Interrupt handler.
489  */
490 int
491 virtio_mmio_intr(void *arg)
492 {
493 	struct virtio_mmio_softc *sc = arg;
494 	struct virtio_softc *vsc = &sc->sc_sc;
495 	int isr, r = 0;
496 
497 	/* check and ack the interrupt */
498 	isr = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
499 			       VIRTIO_MMIO_INTERRUPT_STATUS);
500 	bus_space_write_4(sc->sc_iot, sc->sc_ioh,
501 			  VIRTIO_MMIO_INTERRUPT_ACK, isr);
502 	if ((isr & VIRTIO_MMIO_INT_CONFIG) &&
503 	    (vsc->sc_config_change != NULL))
504 		r = (vsc->sc_config_change)(vsc);
505 	if ((isr & VIRTIO_MMIO_INT_VRING))
506 		r |= virtio_check_vqs(vsc);
507 
508 	return r;
509 }
510 
511 void
512 virtio_mmio_kick(struct virtio_softc *vsc, uint16_t idx)
513 {
514 	struct virtio_mmio_softc *sc = (struct virtio_mmio_softc *)vsc;
515 	bus_space_write_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_QUEUE_NOTIFY,
516 	    idx);
517 }
518