xref: /freebsd/sys/arm/broadcom/bcm2835/bcm2835_mbox.c (revision fdafd315ad0d0f28a11b9fb4476a9ab059c62b92)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2012 Oleksandr Tymoshenko <gonzo@freebsd.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/bus.h>
32 #include <sys/kernel.h>
33 #include <sys/lock.h>
34 #include <sys/module.h>
35 #include <sys/mutex.h>
36 #include <sys/sx.h>
37 #include <sys/rman.h>
38 #include <machine/bus.h>
39 
40 #include <dev/ofw/ofw_bus.h>
41 #include <dev/ofw/ofw_bus_subr.h>
42 
43 #include <arm/broadcom/bcm2835/bcm2835_firmware.h>
44 #include <arm/broadcom/bcm2835/bcm2835_mbox.h>
45 #include <arm/broadcom/bcm2835/bcm2835_mbox_prop.h>
46 #include <arm/broadcom/bcm2835/bcm2835_vcbus.h>
47 
48 #include "mbox_if.h"
49 
50 #define	REG_READ	0x00
51 #define	REG_POL		0x10
52 #define	REG_SENDER	0x14
53 #define	REG_STATUS	0x18
54 #define		STATUS_FULL	0x80000000
55 #define		STATUS_EMPTY	0x40000000
56 #define	REG_CONFIG	0x1C
57 #define		CONFIG_DATA_IRQ	0x00000001
58 #define	REG_WRITE	0x20 /* This is Mailbox 1 address */
59 
60 #define	MBOX_MSG(chan, data)	(((data) & ~0xf) | ((chan) & 0xf))
61 #define	MBOX_CHAN(msg)		((msg) & 0xf)
62 #define	MBOX_DATA(msg)		((msg) & ~0xf)
63 
64 #define	MBOX_LOCK(sc)	do {	\
65 	mtx_lock(&(sc)->lock);	\
66 } while(0)
67 
68 #define	MBOX_UNLOCK(sc)	do {		\
69 	mtx_unlock(&(sc)->lock);	\
70 } while(0)
71 
72 #ifdef  DEBUG
73 #define dprintf(fmt, args...) printf(fmt, ##args)
74 #else
75 #define dprintf(fmt, args...)
76 #endif
77 
78 struct bcm_mbox_softc {
79 	struct mtx		lock;
80 	struct resource *	mem_res;
81 	struct resource *	irq_res;
82 	void*			intr_hl;
83 	bus_space_tag_t		bst;
84 	bus_space_handle_t	bsh;
85 	int			msg[BCM2835_MBOX_CHANS];
86 	int			have_message[BCM2835_MBOX_CHANS];
87 	struct sx		property_chan_lock;
88 };
89 
90 #define	mbox_read_4(sc, reg)		\
91     bus_space_read_4((sc)->bst, (sc)->bsh, reg)
92 #define	mbox_write_4(sc, reg, val)		\
93     bus_space_write_4((sc)->bst, (sc)->bsh, reg, val)
94 
95 static struct ofw_compat_data compat_data[] = {
96 	{"broadcom,bcm2835-mbox",	1},
97 	{"brcm,bcm2835-mbox",		1},
98 	{NULL,				0}
99 };
100 
101 static int
bcm_mbox_read_msg(struct bcm_mbox_softc * sc,int * ochan)102 bcm_mbox_read_msg(struct bcm_mbox_softc *sc, int *ochan)
103 {
104 #ifdef DEBUG
105 	uint32_t data;
106 #endif
107 	uint32_t msg;
108 	int chan;
109 
110 	msg = mbox_read_4(sc, REG_READ);
111 	dprintf("bcm_mbox_intr: raw data %08x\n", msg);
112 	chan = MBOX_CHAN(msg);
113 #ifdef DEBUG
114 	data = MBOX_DATA(msg);
115 #endif
116 	if (sc->msg[chan]) {
117 		printf("bcm_mbox_intr: channel %d oveflow\n", chan);
118 		return (1);
119 	}
120 	dprintf("bcm_mbox_intr: chan %d, data %08x\n", chan, data);
121 	sc->msg[chan] = msg;
122 
123 	if (ochan != NULL)
124 		*ochan = chan;
125 
126 	return (0);
127 }
128 
129 static void
bcm_mbox_intr(void * arg)130 bcm_mbox_intr(void *arg)
131 {
132 	struct bcm_mbox_softc *sc = arg;
133 	int chan;
134 
135 	MBOX_LOCK(sc);
136 	while (!(mbox_read_4(sc, REG_STATUS) & STATUS_EMPTY))
137 		if (bcm_mbox_read_msg(sc, &chan) == 0) {
138 			sc->have_message[chan] = 1;
139 			wakeup(&sc->have_message[chan]);
140 		}
141 	MBOX_UNLOCK(sc);
142 }
143 
144 static int
bcm_mbox_probe(device_t dev)145 bcm_mbox_probe(device_t dev)
146 {
147 
148 	if (!ofw_bus_status_okay(dev))
149 		return (ENXIO);
150 
151 	if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
152 		return (ENXIO);
153 
154 	device_set_desc(dev, "BCM2835 VideoCore Mailbox");
155 
156 	return (BUS_PROBE_DEFAULT);
157 }
158 
159 static int
bcm_mbox_attach(device_t dev)160 bcm_mbox_attach(device_t dev)
161 {
162 	struct bcm_mbox_softc *sc = device_get_softc(dev);
163 	int i;
164 	int rid = 0;
165 
166 	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
167 	if (sc->mem_res == NULL) {
168 		device_printf(dev, "could not allocate memory resource\n");
169 		return (ENXIO);
170 	}
171 
172 	sc->bst = rman_get_bustag(sc->mem_res);
173 	sc->bsh = rman_get_bushandle(sc->mem_res);
174 
175 	rid = 0;
176 	sc->irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid, RF_ACTIVE);
177 	if (sc->irq_res == NULL) {
178 		device_printf(dev, "could not allocate interrupt resource\n");
179 		return (ENXIO);
180 	}
181 
182 	/* Setup and enable the timer */
183 	if (bus_setup_intr(dev, sc->irq_res, INTR_MPSAFE | INTR_TYPE_MISC,
184 	    NULL, bcm_mbox_intr, sc, &sc->intr_hl) != 0) {
185 		bus_release_resource(dev, SYS_RES_IRQ, rid, sc->irq_res);
186 		device_printf(dev, "Unable to setup the clock irq handler.\n");
187 		return (ENXIO);
188 	}
189 
190 	mtx_init(&sc->lock, "vcio mbox", NULL, MTX_DEF);
191 	for (i = 0; i < BCM2835_MBOX_CHANS; i++) {
192 		sc->msg[i] = 0;
193 		sc->have_message[i] = 0;
194 	}
195 
196 	sx_init(&sc->property_chan_lock, "mboxprop");
197 
198 	/* Read all pending messages */
199 	while ((mbox_read_4(sc, REG_STATUS) & STATUS_EMPTY) == 0)
200 		(void)mbox_read_4(sc, REG_READ);
201 
202 	mbox_write_4(sc, REG_CONFIG, CONFIG_DATA_IRQ);
203 
204 	return (0);
205 }
206 
207 /*
208  * Mailbox API
209  */
210 static int
bcm_mbox_write(device_t dev,int chan,uint32_t data)211 bcm_mbox_write(device_t dev, int chan, uint32_t data)
212 {
213 	int limit = 1000;
214 	struct bcm_mbox_softc *sc = device_get_softc(dev);
215 
216 	dprintf("bcm_mbox_write: chan %d, data %08x\n", chan, data);
217 	MBOX_LOCK(sc);
218 	sc->have_message[chan] = 0;
219 	while ((mbox_read_4(sc, REG_STATUS) & STATUS_FULL) && --limit)
220 		DELAY(5);
221 	if (limit == 0) {
222 		printf("bcm_mbox_write: STATUS_FULL stuck");
223 		MBOX_UNLOCK(sc);
224 		return (EAGAIN);
225 	}
226 	mbox_write_4(sc, REG_WRITE, MBOX_MSG(chan, data));
227 	MBOX_UNLOCK(sc);
228 
229 	return (0);
230 }
231 
232 static int
bcm_mbox_read(device_t dev,int chan,uint32_t * data)233 bcm_mbox_read(device_t dev, int chan, uint32_t *data)
234 {
235 	struct bcm_mbox_softc *sc = device_get_softc(dev);
236 	int err, read_chan;
237 
238 	dprintf("bcm_mbox_read: chan %d\n", chan);
239 
240 	err = 0;
241 	MBOX_LOCK(sc);
242 	if (!cold) {
243 		if (sc->have_message[chan] == 0) {
244 			if (mtx_sleep(&sc->have_message[chan], &sc->lock, 0,
245 			    "mbox", 10*hz) != 0) {
246 				device_printf(dev, "timeout waiting for message on chan %d\n", chan);
247 				err = ETIMEDOUT;
248 			}
249 		}
250 	} else {
251 		do {
252 			/* Wait for a message */
253 			while ((mbox_read_4(sc, REG_STATUS) & STATUS_EMPTY))
254 				;
255 			/* Read the message */
256 			if (bcm_mbox_read_msg(sc, &read_chan) != 0) {
257 				err = EINVAL;
258 				goto out;
259 			}
260 		} while (read_chan != chan);
261 	}
262 	/*
263 	 *  get data from intr handler, the same channel is never coming
264 	 *  because of holding sc lock.
265 	 */
266 	*data = MBOX_DATA(sc->msg[chan]);
267 	sc->msg[chan] = 0;
268 	sc->have_message[chan] = 0;
269 out:
270 	MBOX_UNLOCK(sc);
271 	dprintf("bcm_mbox_read: chan %d, data %08x\n", chan, *data);
272 
273 	return (err);
274 }
275 
276 static device_method_t bcm_mbox_methods[] = {
277 	DEVMETHOD(device_probe,		bcm_mbox_probe),
278 	DEVMETHOD(device_attach,	bcm_mbox_attach),
279 
280 	DEVMETHOD(mbox_read,		bcm_mbox_read),
281 	DEVMETHOD(mbox_write,		bcm_mbox_write),
282 
283 	DEVMETHOD_END
284 };
285 
286 static driver_t bcm_mbox_driver = {
287 	"mbox",
288 	bcm_mbox_methods,
289 	sizeof(struct bcm_mbox_softc),
290 };
291 
292 EARLY_DRIVER_MODULE(mbox, simplebus, bcm_mbox_driver, 0, 0,
293     BUS_PASS_INTERRUPT + BUS_PASS_ORDER_LAST);
294 
295 static void
bcm2835_mbox_dma_cb(void * arg,bus_dma_segment_t * segs,int nseg,int err)296 bcm2835_mbox_dma_cb(void *arg, bus_dma_segment_t *segs, int nseg, int err)
297 {
298 	bus_addr_t *addr;
299 
300 	if (err)
301 		return;
302 	addr = (bus_addr_t *)arg;
303 	*addr = ARMC_TO_VCBUS(segs[0].ds_addr);
304 }
305 
306 static void *
bcm2835_mbox_init_dma(device_t dev,size_t len,bus_dma_tag_t * tag,bus_dmamap_t * map,bus_addr_t * phys)307 bcm2835_mbox_init_dma(device_t dev, size_t len, bus_dma_tag_t *tag,
308     bus_dmamap_t *map, bus_addr_t *phys)
309 {
310 	void *buf;
311 	int err;
312 
313 	err = bus_dma_tag_create(bus_get_dma_tag(dev), 16, 0,
314 	    bcm283x_dmabus_peripheral_lowaddr(), BUS_SPACE_MAXADDR, NULL, NULL,
315 	    len, 1, len, 0, NULL, NULL, tag);
316 	if (err != 0) {
317 		device_printf(dev, "can't create DMA tag\n");
318 		return (NULL);
319 	}
320 
321 	err = bus_dmamem_alloc(*tag, &buf, 0, map);
322 	if (err != 0) {
323 		bus_dma_tag_destroy(*tag);
324 		device_printf(dev, "can't allocate dmamem\n");
325 		return (NULL);
326 	}
327 
328 	err = bus_dmamap_load(*tag, *map, buf, len, bcm2835_mbox_dma_cb,
329 	    phys, 0);
330 	if (err != 0) {
331 		bus_dmamem_free(*tag, buf, *map);
332 		bus_dma_tag_destroy(*tag);
333 		device_printf(dev, "can't load DMA map\n");
334 		return (NULL);
335 	}
336 
337 	return (buf);
338 }
339 
340 static int
bcm2835_mbox_err(device_t dev,bus_addr_t msg_phys,uint32_t resp_phys,struct bcm2835_mbox_hdr * msg,size_t len)341 bcm2835_mbox_err(device_t dev, bus_addr_t msg_phys, uint32_t resp_phys,
342 	struct bcm2835_mbox_hdr *msg, size_t len)
343 {
344 	int idx;
345 	struct bcm2835_mbox_tag_hdr *tag;
346 	uint8_t *last;
347 
348 	if ((uint32_t)msg_phys != resp_phys) {
349 		device_printf(dev, "response channel mismatch\n");
350 		return (EIO);
351 	}
352 	if (msg->code != BCM2835_MBOX_CODE_RESP_SUCCESS) {
353 		device_printf(dev, "mbox response error\n");
354 		return (EIO);
355 	}
356 
357 	/* Loop until the end tag. */
358 	tag = (struct bcm2835_mbox_tag_hdr *)(msg + 1);
359 	last = (uint8_t *)msg + len;
360 	for (idx = 0; tag->tag != 0; idx++) {
361 		/*
362 		 * When setting the GPIO config or state the firmware doesn't
363 		 * set tag->val_len correctly.
364 		 */
365 		if ((tag->tag == BCM2835_FIRMWARE_TAG_SET_GPIO_CONFIG ||
366 		     tag->tag == BCM2835_FIRMWARE_TAG_SET_GPIO_STATE) &&
367 		    tag->val_len == 0) {
368 			tag->val_len = BCM2835_MBOX_TAG_VAL_LEN_RESPONSE |
369 			    tag->val_buf_size;
370 		}
371 		if ((tag->val_len & BCM2835_MBOX_TAG_VAL_LEN_RESPONSE) == 0) {
372 			device_printf(dev, "tag %d response error\n", idx);
373 			return (EIO);
374 		}
375 		/* Clear the response bit. */
376 		tag->val_len &= ~BCM2835_MBOX_TAG_VAL_LEN_RESPONSE;
377 
378 		/* Next tag. */
379 		tag = (struct bcm2835_mbox_tag_hdr *)((uint8_t *)tag +
380 		    sizeof(*tag) + tag->val_buf_size);
381 
382 		if ((uint8_t *)tag > last) {
383 			device_printf(dev, "mbox buffer size error\n");
384 			return (EIO);
385 		}
386 	}
387 
388 	return (0);
389 }
390 
391 int
bcm2835_mbox_property(void * msg,size_t msg_size)392 bcm2835_mbox_property(void *msg, size_t msg_size)
393 {
394 	struct bcm_mbox_softc *sc;
395 	bus_dma_tag_t msg_tag;
396 	bus_dmamap_t msg_map;
397 	bus_addr_t msg_phys;
398 	char *buf;
399 	uint32_t reg;
400 	device_t mbox;
401 	int err;
402 
403 	/* get mbox device */
404 	mbox = devclass_get_device(devclass_find("mbox"), 0);
405 	if (mbox == NULL)
406 		return (ENXIO);
407 
408 	sc = device_get_softc(mbox);
409 	sx_xlock(&sc->property_chan_lock);
410 
411 	/* Allocate memory for the message */
412 	buf = bcm2835_mbox_init_dma(mbox, msg_size, &msg_tag, &msg_map,
413 	    &msg_phys);
414 	if (buf == NULL) {
415 		err = ENOMEM;
416 		goto out;
417 	}
418 
419 	memcpy(buf, msg, msg_size);
420 
421 	bus_dmamap_sync(msg_tag, msg_map,
422 	    BUS_DMASYNC_PREWRITE);
423 
424 	MBOX_WRITE(mbox, BCM2835_MBOX_CHAN_PROP, (uint32_t)msg_phys);
425 	MBOX_READ(mbox, BCM2835_MBOX_CHAN_PROP, &reg);
426 
427 	bus_dmamap_sync(msg_tag, msg_map,
428 	    BUS_DMASYNC_PREREAD);
429 
430 	memcpy(msg, buf, msg_size);
431 
432 	err = bcm2835_mbox_err(mbox, msg_phys, reg,
433 	    (struct bcm2835_mbox_hdr *)msg, msg_size);
434 
435 	bus_dmamap_unload(msg_tag, msg_map);
436 	bus_dmamem_free(msg_tag, buf, msg_map);
437 	bus_dma_tag_destroy(msg_tag);
438 out:
439 	sx_xunlock(&sc->property_chan_lock);
440 	return (err);
441 }
442 
443 int
bcm2835_mbox_set_power_state(uint32_t device_id,boolean_t on)444 bcm2835_mbox_set_power_state(uint32_t device_id, boolean_t on)
445 {
446 	struct msg_set_power_state msg;
447 	int err;
448 
449 	memset(&msg, 0, sizeof(msg));
450 	msg.hdr.buf_size = sizeof(msg);
451 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
452 	msg.tag_hdr.tag = BCM2835_MBOX_TAG_SET_POWER_STATE;
453 	msg.tag_hdr.val_buf_size = sizeof(msg.body);
454 	msg.tag_hdr.val_len = sizeof(msg.body.req);
455 	msg.body.req.device_id = device_id;
456 	msg.body.req.state = (on ? BCM2835_MBOX_POWER_ON : 0) |
457 	    BCM2835_MBOX_POWER_WAIT;
458 	msg.end_tag = 0;
459 
460 	err = bcm2835_mbox_property(&msg, sizeof(msg));
461 
462 	return (err);
463 }
464 
465 int
bcm2835_mbox_notify_xhci_reset(uint32_t pci_dev_addr)466 bcm2835_mbox_notify_xhci_reset(uint32_t pci_dev_addr)
467 {
468 	struct msg_notify_xhci_reset msg;
469 	int err;
470 
471 	memset(&msg, 0, sizeof(msg));
472 	msg.hdr.buf_size = sizeof(msg);
473 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
474 	msg.tag_hdr.tag = BCM2835_MBOX_TAG_NOTIFY_XHCI_RESET;
475 	msg.tag_hdr.val_buf_size = sizeof(msg.body);
476 	msg.tag_hdr.val_len = sizeof(msg.body.req);
477 	msg.body.req.pci_device_addr = pci_dev_addr;
478 	msg.end_tag = 0;
479 
480 	err = bcm2835_mbox_property(&msg, sizeof(msg));
481 
482 	return (err);
483 }
484 
485 int
bcm2835_mbox_get_clock_rate(uint32_t clock_id,uint32_t * hz)486 bcm2835_mbox_get_clock_rate(uint32_t clock_id, uint32_t *hz)
487 {
488 	struct msg_get_clock_rate msg;
489 	int err;
490 
491 	memset(&msg, 0, sizeof(msg));
492 	msg.hdr.buf_size = sizeof(msg);
493 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
494 	msg.tag_hdr.tag = BCM2835_MBOX_TAG_GET_CLOCK_RATE;
495 	msg.tag_hdr.val_buf_size = sizeof(msg.body);
496 	msg.tag_hdr.val_len = sizeof(msg.body.req);
497 	msg.body.req.clock_id = clock_id;
498 	msg.end_tag = 0;
499 
500 	err = bcm2835_mbox_property(&msg, sizeof(msg));
501 	*hz = msg.body.resp.rate_hz;
502 
503 	return (err);
504 }
505 
506 int
bcm2835_mbox_fb_get_w_h(struct bcm2835_fb_config * fb)507 bcm2835_mbox_fb_get_w_h(struct bcm2835_fb_config *fb)
508 {
509 	int err;
510 	struct msg_fb_get_w_h msg;
511 
512 	memset(&msg, 0, sizeof(msg));
513 	msg.hdr.buf_size = sizeof(msg);
514 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
515 	BCM2835_MBOX_INIT_TAG(&msg.physical_w_h, GET_PHYSICAL_W_H);
516 	msg.physical_w_h.tag_hdr.val_len = 0;
517 	msg.end_tag = 0;
518 
519 	err = bcm2835_mbox_property(&msg, sizeof(msg));
520 	if (err == 0) {
521 		fb->xres = msg.physical_w_h.body.resp.width;
522 		fb->yres = msg.physical_w_h.body.resp.height;
523 	}
524 
525 	return (err);
526 }
527 
528 int
bcm2835_mbox_fb_get_bpp(struct bcm2835_fb_config * fb)529 bcm2835_mbox_fb_get_bpp(struct bcm2835_fb_config *fb)
530 {
531 	int err;
532 	struct msg_fb_get_bpp msg;
533 
534 	memset(&msg, 0, sizeof(msg));
535 	msg.hdr.buf_size = sizeof(msg);
536 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
537 	BCM2835_MBOX_INIT_TAG(&msg.bpp, GET_DEPTH);
538 	msg.bpp.tag_hdr.val_len = 0;
539 	msg.end_tag = 0;
540 
541 	err = bcm2835_mbox_property(&msg, sizeof(msg));
542 	if (err == 0)
543 		fb->bpp = msg.bpp.body.resp.bpp;
544 
545 	return (err);
546 }
547 
548 int
bcm2835_mbox_fb_init(struct bcm2835_fb_config * fb)549 bcm2835_mbox_fb_init(struct bcm2835_fb_config *fb)
550 {
551 	int err;
552 	struct msg_fb_setup msg;
553 
554 	memset(&msg, 0, sizeof(msg));
555 	msg.hdr.buf_size = sizeof(msg);
556 	msg.hdr.code = BCM2835_MBOX_CODE_REQ;
557 	BCM2835_MBOX_INIT_TAG(&msg.physical_w_h, SET_PHYSICAL_W_H);
558 	msg.physical_w_h.body.req.width = fb->xres;
559 	msg.physical_w_h.body.req.height = fb->yres;
560 	BCM2835_MBOX_INIT_TAG(&msg.virtual_w_h, SET_VIRTUAL_W_H);
561 	msg.virtual_w_h.body.req.width = fb->vxres;
562 	msg.virtual_w_h.body.req.height = fb->vyres;
563 	BCM2835_MBOX_INIT_TAG(&msg.offset, SET_VIRTUAL_OFFSET);
564 	msg.offset.body.req.x = fb->xoffset;
565 	msg.offset.body.req.y = fb->yoffset;
566 	BCM2835_MBOX_INIT_TAG(&msg.depth, SET_DEPTH);
567 	msg.depth.body.req.bpp = fb->bpp;
568 	BCM2835_MBOX_INIT_TAG(&msg.alpha, SET_ALPHA_MODE);
569 	msg.alpha.body.req.alpha = BCM2835_MBOX_ALPHA_MODE_IGNORED;
570 	BCM2835_MBOX_INIT_TAG(&msg.buffer, ALLOCATE_BUFFER);
571 	msg.buffer.body.req.alignment = PAGE_SIZE;
572 	BCM2835_MBOX_INIT_TAG(&msg.pitch, GET_PITCH);
573 	msg.end_tag = 0;
574 
575 	err = bcm2835_mbox_property(&msg, sizeof(msg));
576 	if (err == 0) {
577 		fb->xres = msg.physical_w_h.body.resp.width;
578 		fb->yres = msg.physical_w_h.body.resp.height;
579 		fb->vxres = msg.virtual_w_h.body.resp.width;
580 		fb->vyres = msg.virtual_w_h.body.resp.height;
581 		fb->xoffset = msg.offset.body.resp.x;
582 		fb->yoffset = msg.offset.body.resp.y;
583 		fb->pitch = msg.pitch.body.resp.pitch;
584 		fb->base = VCBUS_TO_ARMC(msg.buffer.body.resp.fb_address);
585 		fb->size = msg.buffer.body.resp.fb_size;
586 	}
587 
588 	return (err);
589 }
590