1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * dfu.c -- DFU back-end routines
4  *
5  * Copyright (C) 2012 Samsung Electronics
6  * author: Lukasz Majewski <l.majewski@samsung.com>
7  */
8 
9 #include <common.h>
10 #include <env.h>
11 #include <errno.h>
12 #include <log.h>
13 #include <malloc.h>
14 #include <mmc.h>
15 #include <fat.h>
16 #include <dfu.h>
17 #include <hash.h>
18 #include <linux/list.h>
19 #include <linux/compiler.h>
20 
21 LIST_HEAD(dfu_list);
22 static int dfu_alt_num;
23 static int alt_num_cnt;
24 static struct hash_algo *dfu_hash_algo;
25 #ifdef CONFIG_DFU_TIMEOUT
26 static unsigned long dfu_timeout = 0;
27 #endif
28 
29 bool dfu_reinit_needed = false;
30 
31 /*
32  * The purpose of the dfu_flush_callback() function is to
33  * provide callback for dfu user
34  */
dfu_flush_callback(struct dfu_entity * dfu)35 __weak void dfu_flush_callback(struct dfu_entity *dfu)
36 {
37 }
38 
39 /*
40  * The purpose of the dfu_initiated_callback() function is to
41  * provide callback for dfu user
42  */
dfu_initiated_callback(struct dfu_entity * dfu)43 __weak void dfu_initiated_callback(struct dfu_entity *dfu)
44 {
45 }
46 
47 /*
48  * The purpose of the dfu_error_callback() function is to
49  * provide callback for dfu user
50  */
dfu_error_callback(struct dfu_entity * dfu,const char * msg)51 __weak void dfu_error_callback(struct dfu_entity *dfu, const char *msg)
52 {
53 }
54 
55 /*
56  * The purpose of the dfu_usb_get_reset() function is to
57  * provide information if after USB_DETACH request
58  * being sent the dfu-util performed reset of USB
59  * bus.
60  *
61  * Described behaviour is the only way to distinct if
62  * user has typed -e (detach) or -R (reset) when invoking
63  * dfu-util command.
64  *
65  */
dfu_usb_get_reset(void)66 __weak bool dfu_usb_get_reset(void)
67 {
68 #ifdef CONFIG_SPL_DFU_NO_RESET
69 	return false;
70 #else
71 	return true;
72 #endif
73 }
74 
75 #ifdef CONFIG_DFU_TIMEOUT
dfu_set_timeout(unsigned long timeout)76 void dfu_set_timeout(unsigned long timeout)
77 {
78 	dfu_timeout = timeout;
79 }
80 
dfu_get_timeout(void)81 unsigned long dfu_get_timeout(void)
82 {
83 	return dfu_timeout;
84 }
85 #endif
86 
dfu_find_alt_num(const char * s)87 static int dfu_find_alt_num(const char *s)
88 {
89 	int i = 0;
90 
91 	for (; *s; s++)
92 		if (*s == ';')
93 			i++;
94 
95 	return ++i;
96 }
97 
98 /*
99  * treat dfu_alt_info with several interface information
100  * to allow DFU on several device with one command,
101  * the string format is
102  * interface devstring'='alternate list (';' separated)
103  * and each interface separated by '&'
104  */
dfu_config_interfaces(char * env)105 int dfu_config_interfaces(char *env)
106 {
107 	struct dfu_entity *dfu;
108 	char *s, *i, *d, *a, *part;
109 	int ret = -EINVAL;
110 	int n = 1;
111 
112 	s = env;
113 	for (; *s; s++) {
114 		if (*s == ';')
115 			n++;
116 		if (*s == '&')
117 			n++;
118 	}
119 	ret = dfu_alt_init(n, &dfu);
120 	if (ret)
121 		return ret;
122 
123 	s = env;
124 	while (s) {
125 		ret = -EINVAL;
126 		i = strsep(&s, " ");
127 		if (!i)
128 			break;
129 		d = strsep(&s, "=");
130 		if (!d)
131 			break;
132 		a = strsep(&s, "&");
133 		if (!a)
134 			a = s;
135 		do {
136 			part = strsep(&a, ";");
137 			ret = dfu_alt_add(dfu, i, d, part);
138 			if (ret)
139 				return ret;
140 		} while (a);
141 	}
142 
143 	return ret;
144 }
145 
dfu_init_env_entities(char * interface,char * devstr)146 int dfu_init_env_entities(char *interface, char *devstr)
147 {
148 	const char *str_env;
149 	char *env_bkp;
150 	int ret = 0;
151 
152 	dfu_reinit_needed = false;
153 
154 #ifdef CONFIG_SET_DFU_ALT_INFO
155 	set_dfu_alt_info(interface, devstr);
156 #endif
157 	str_env = env_get("dfu_alt_info");
158 	if (!str_env) {
159 		pr_err("\"dfu_alt_info\" env variable not defined!\n");
160 		return -EINVAL;
161 	}
162 
163 	env_bkp = strdup(str_env);
164 	if (!interface && !devstr)
165 		ret = dfu_config_interfaces(env_bkp);
166 	else
167 		ret = dfu_config_entities(env_bkp, interface, devstr);
168 
169 	if (ret) {
170 		pr_err("DFU entities configuration failed!\n");
171 		pr_err("(partition table does not match dfu_alt_info?)\n");
172 		goto done;
173 	}
174 
175 done:
176 	free(env_bkp);
177 	return ret;
178 }
179 
180 static unsigned char *dfu_buf;
181 static unsigned long dfu_buf_size;
182 static enum dfu_device_type dfu_buf_device_type;
183 
dfu_free_buf(void)184 unsigned char *dfu_free_buf(void)
185 {
186 	free(dfu_buf);
187 	dfu_buf = NULL;
188 	return dfu_buf;
189 }
190 
dfu_get_buf_size(void)191 unsigned long dfu_get_buf_size(void)
192 {
193 	return dfu_buf_size;
194 }
195 
dfu_get_buf(struct dfu_entity * dfu)196 unsigned char *dfu_get_buf(struct dfu_entity *dfu)
197 {
198 	char *s;
199 
200 	/* manage several entity with several contraint */
201 	if (dfu_buf && dfu->dev_type != dfu_buf_device_type)
202 		dfu_free_buf();
203 
204 	if (dfu_buf != NULL)
205 		return dfu_buf;
206 
207 	s = env_get("dfu_bufsiz");
208 	if (s)
209 		dfu_buf_size = (unsigned long)simple_strtol(s, NULL, 0);
210 
211 	if (!s || !dfu_buf_size)
212 		dfu_buf_size = CONFIG_SYS_DFU_DATA_BUF_SIZE;
213 
214 	if (dfu->max_buf_size && dfu_buf_size > dfu->max_buf_size)
215 		dfu_buf_size = dfu->max_buf_size;
216 
217 	dfu_buf = memalign(CONFIG_SYS_CACHELINE_SIZE, dfu_buf_size);
218 	if (dfu_buf == NULL)
219 		printf("%s: Could not memalign 0x%lx bytes\n",
220 		       __func__, dfu_buf_size);
221 
222 	dfu_buf_device_type = dfu->dev_type;
223 	return dfu_buf;
224 }
225 
dfu_get_hash_algo(void)226 static char *dfu_get_hash_algo(void)
227 {
228 	char *s;
229 
230 	s = env_get("dfu_hash_algo");
231 	if (!s)
232 		return NULL;
233 
234 	if (!strcmp(s, "crc32")) {
235 		debug("%s: DFU hash method: %s\n", __func__, s);
236 		return s;
237 	}
238 
239 	pr_err("DFU hash method: %s not supported!\n", s);
240 	return NULL;
241 }
242 
dfu_write_buffer_drain(struct dfu_entity * dfu)243 static int dfu_write_buffer_drain(struct dfu_entity *dfu)
244 {
245 	long w_size;
246 	int ret;
247 
248 	/* flush size? */
249 	w_size = dfu->i_buf - dfu->i_buf_start;
250 	if (w_size == 0)
251 		return 0;
252 
253 	if (dfu_hash_algo)
254 		dfu_hash_algo->hash_update(dfu_hash_algo, &dfu->crc,
255 					   dfu->i_buf_start, w_size, 0);
256 
257 	ret = dfu->write_medium(dfu, dfu->offset, dfu->i_buf_start, &w_size);
258 	if (ret)
259 		debug("%s: Write error!\n", __func__);
260 
261 	/* point back */
262 	dfu->i_buf = dfu->i_buf_start;
263 
264 	/* update offset */
265 	dfu->offset += w_size;
266 
267 	puts("#");
268 
269 	return ret;
270 }
271 
dfu_transaction_cleanup(struct dfu_entity * dfu)272 void dfu_transaction_cleanup(struct dfu_entity *dfu)
273 {
274 	/* clear everything */
275 	dfu->crc = 0;
276 	dfu->offset = 0;
277 	dfu->i_blk_seq_num = 0;
278 	dfu->i_buf_start = dfu_get_buf(dfu);
279 	dfu->i_buf_end = dfu->i_buf_start;
280 	dfu->i_buf = dfu->i_buf_start;
281 	dfu->r_left = 0;
282 	dfu->b_left = 0;
283 	dfu->bad_skip = 0;
284 
285 	dfu->inited = 0;
286 }
287 
dfu_transaction_initiate(struct dfu_entity * dfu,bool read)288 int dfu_transaction_initiate(struct dfu_entity *dfu, bool read)
289 {
290 	int ret = 0;
291 
292 	if (dfu->inited)
293 		return 0;
294 
295 	dfu_transaction_cleanup(dfu);
296 
297 	if (dfu->i_buf_start == NULL)
298 		return -ENOMEM;
299 
300 	dfu->i_buf_end = dfu->i_buf_start + dfu_get_buf_size();
301 
302 	if (read) {
303 		ret = dfu->get_medium_size(dfu, &dfu->r_left);
304 		if (ret < 0)
305 			return ret;
306 		debug("%s: %s %lld [B]\n", __func__, dfu->name, dfu->r_left);
307 	}
308 
309 	dfu->inited = 1;
310 	dfu_initiated_callback(dfu);
311 
312 	return 0;
313 }
314 
dfu_flush(struct dfu_entity * dfu,void * buf,int size,int blk_seq_num)315 int dfu_flush(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
316 {
317 	int ret = 0;
318 
319 	ret = dfu_write_buffer_drain(dfu);
320 	if (ret)
321 		return ret;
322 
323 	if (dfu->flush_medium)
324 		ret = dfu->flush_medium(dfu);
325 
326 	if (dfu_hash_algo)
327 		printf("\nDFU complete %s: 0x%08x\n", dfu_hash_algo->name,
328 		       dfu->crc);
329 
330 	dfu_flush_callback(dfu);
331 
332 	dfu_transaction_cleanup(dfu);
333 
334 	return ret;
335 }
336 
dfu_write(struct dfu_entity * dfu,void * buf,int size,int blk_seq_num)337 int dfu_write(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
338 {
339 	int ret;
340 
341 	debug("%s: name: %s buf: 0x%p size: 0x%x p_num: 0x%x offset: 0x%llx bufoffset: 0x%lx\n",
342 	      __func__, dfu->name, buf, size, blk_seq_num, dfu->offset,
343 	      (unsigned long)(dfu->i_buf - dfu->i_buf_start));
344 
345 	ret = dfu_transaction_initiate(dfu, false);
346 	if (ret < 0)
347 		return ret;
348 
349 	if (dfu->i_blk_seq_num != blk_seq_num) {
350 		printf("%s: Wrong sequence number! [%d] [%d]\n",
351 		       __func__, dfu->i_blk_seq_num, blk_seq_num);
352 		dfu_transaction_cleanup(dfu);
353 		dfu_error_callback(dfu, "Wrong sequence number");
354 		return -1;
355 	}
356 
357 	/* DFU 1.1 standard says:
358 	 * The wBlockNum field is a block sequence number. It increments each
359 	 * time a block is transferred, wrapping to zero from 65,535. It is used
360 	 * to provide useful context to the DFU loader in the device."
361 	 *
362 	 * This means that it's a 16 bit counter that roll-overs at
363 	 * 0xffff -> 0x0000. By having a typical 4K transfer block
364 	 * we roll-over at exactly 256MB. Not very fun to debug.
365 	 *
366 	 * Handling rollover, and having an inited variable,
367 	 * makes things work.
368 	 */
369 
370 	/* handle rollover */
371 	dfu->i_blk_seq_num = (dfu->i_blk_seq_num + 1) & 0xffff;
372 
373 	/* flush buffer if overflow */
374 	if ((dfu->i_buf + size) > dfu->i_buf_end) {
375 		ret = dfu_write_buffer_drain(dfu);
376 		if (ret) {
377 			dfu_transaction_cleanup(dfu);
378 			dfu_error_callback(dfu, "DFU write error");
379 			return ret;
380 		}
381 	}
382 
383 	/* we should be in buffer now (if not then size too large) */
384 	if ((dfu->i_buf + size) > dfu->i_buf_end) {
385 		pr_err("Buffer overflow! (0x%p + 0x%x > 0x%p)\n", dfu->i_buf,
386 		      size, dfu->i_buf_end);
387 		dfu_transaction_cleanup(dfu);
388 		dfu_error_callback(dfu, "Buffer overflow");
389 		return -1;
390 	}
391 
392 	memcpy(dfu->i_buf, buf, size);
393 	dfu->i_buf += size;
394 
395 	/* if end or if buffer full flush */
396 	if (size == 0 || (dfu->i_buf + size) > dfu->i_buf_end) {
397 		ret = dfu_write_buffer_drain(dfu);
398 		if (ret) {
399 			dfu_transaction_cleanup(dfu);
400 			dfu_error_callback(dfu, "DFU write error");
401 			return ret;
402 		}
403 	}
404 
405 	return 0;
406 }
407 
dfu_read_buffer_fill(struct dfu_entity * dfu,void * buf,int size)408 static int dfu_read_buffer_fill(struct dfu_entity *dfu, void *buf, int size)
409 {
410 	long chunk;
411 	int ret, readn;
412 
413 	readn = 0;
414 	while (size > 0) {
415 		/* get chunk that can be read */
416 		chunk = min((long)size, dfu->b_left);
417 		/* consume */
418 		if (chunk > 0) {
419 			memcpy(buf, dfu->i_buf, chunk);
420 			if (dfu_hash_algo)
421 				dfu_hash_algo->hash_update(dfu_hash_algo,
422 							   &dfu->crc, buf,
423 							   chunk, 0);
424 
425 			dfu->i_buf += chunk;
426 			dfu->b_left -= chunk;
427 			size -= chunk;
428 			buf += chunk;
429 			readn += chunk;
430 		}
431 
432 		/* all done */
433 		if (size > 0) {
434 			/* no more to read */
435 			if (dfu->r_left == 0)
436 				break;
437 
438 			dfu->i_buf = dfu->i_buf_start;
439 			dfu->b_left = dfu->i_buf_end - dfu->i_buf_start;
440 
441 			/* got to read, but buffer is empty */
442 			if (dfu->b_left > dfu->r_left)
443 				dfu->b_left = dfu->r_left;
444 			ret = dfu->read_medium(dfu, dfu->offset, dfu->i_buf,
445 					&dfu->b_left);
446 			if (ret != 0) {
447 				debug("%s: Read error!\n", __func__);
448 				return ret;
449 			}
450 			if (dfu->b_left == 0)
451 				break;
452 			dfu->offset += dfu->b_left;
453 			dfu->r_left -= dfu->b_left;
454 
455 			puts("#");
456 		}
457 	}
458 
459 	return readn;
460 }
461 
dfu_read(struct dfu_entity * dfu,void * buf,int size,int blk_seq_num)462 int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
463 {
464 	int ret = 0;
465 
466 	debug("%s: name: %s buf: 0x%p size: 0x%x p_num: 0x%x i_buf: 0x%p\n",
467 	       __func__, dfu->name, buf, size, blk_seq_num, dfu->i_buf);
468 
469 	ret = dfu_transaction_initiate(dfu, true);
470 	if (ret < 0)
471 		return ret;
472 
473 	if (dfu->i_blk_seq_num != blk_seq_num) {
474 		printf("%s: Wrong sequence number! [%d] [%d]\n",
475 		       __func__, dfu->i_blk_seq_num, blk_seq_num);
476 		return -1;
477 	}
478 	/* handle rollover */
479 	dfu->i_blk_seq_num = (dfu->i_blk_seq_num + 1) & 0xffff;
480 
481 	ret = dfu_read_buffer_fill(dfu, buf, size);
482 	if (ret < 0) {
483 		printf("%s: Failed to fill buffer\n", __func__);
484 		return -1;
485 	}
486 
487 	if (ret < size) {
488 		if (dfu_hash_algo)
489 			debug("%s: %s %s: 0x%x\n", __func__, dfu->name,
490 			      dfu_hash_algo->name, dfu->crc);
491 		puts("\nUPLOAD ... done\nCtrl+C to exit ...\n");
492 
493 		dfu_transaction_cleanup(dfu);
494 	}
495 
496 	return ret;
497 }
498 
dfu_fill_entity(struct dfu_entity * dfu,char * s,int alt,char * interface,char * devstr)499 static int dfu_fill_entity(struct dfu_entity *dfu, char *s, int alt,
500 			   char *interface, char *devstr)
501 {
502 	char *st;
503 
504 	debug("%s: %s interface: %s dev: %s\n", __func__, s, interface, devstr);
505 	st = strsep(&s, " ");
506 	strcpy(dfu->name, st);
507 
508 	dfu->alt = alt;
509 	dfu->max_buf_size = 0;
510 	dfu->free_entity = NULL;
511 
512 	/* Specific for mmc device */
513 	if (strcmp(interface, "mmc") == 0) {
514 		if (dfu_fill_entity_mmc(dfu, devstr, s))
515 			return -1;
516 	} else if (strcmp(interface, "mtd") == 0) {
517 		if (dfu_fill_entity_mtd(dfu, devstr, s))
518 			return -1;
519 	} else if (strcmp(interface, "nand") == 0) {
520 		if (dfu_fill_entity_nand(dfu, devstr, s))
521 			return -1;
522 	} else if (strcmp(interface, "ram") == 0) {
523 		if (dfu_fill_entity_ram(dfu, devstr, s))
524 			return -1;
525 	} else if (strcmp(interface, "sf") == 0) {
526 		if (dfu_fill_entity_sf(dfu, devstr, s))
527 			return -1;
528 	} else if (strcmp(interface, "virt") == 0) {
529 		if (dfu_fill_entity_virt(dfu, devstr, s))
530 			return -1;
531 	} else {
532 		printf("%s: Device %s not (yet) supported!\n",
533 		       __func__,  interface);
534 		return -1;
535 	}
536 	dfu_get_buf(dfu);
537 
538 	return 0;
539 }
540 
dfu_free_entities(void)541 void dfu_free_entities(void)
542 {
543 	struct dfu_entity *dfu, *p, *t = NULL;
544 
545 	dfu_free_buf();
546 	list_for_each_entry_safe_reverse(dfu, p, &dfu_list, list) {
547 		list_del(&dfu->list);
548 		if (dfu->free_entity)
549 			dfu->free_entity(dfu);
550 		t = dfu;
551 	}
552 	if (t)
553 		free(t);
554 	INIT_LIST_HEAD(&dfu_list);
555 
556 	alt_num_cnt = 0;
557 }
558 
dfu_alt_init(int num,struct dfu_entity ** dfu)559 int dfu_alt_init(int num, struct dfu_entity **dfu)
560 {
561 	char *s;
562 	int ret;
563 
564 	dfu_alt_num = num;
565 	debug("%s: dfu_alt_num=%d\n", __func__, dfu_alt_num);
566 
567 	dfu_hash_algo = NULL;
568 	s = dfu_get_hash_algo();
569 	if (s) {
570 		ret = hash_lookup_algo(s, &dfu_hash_algo);
571 		if (ret)
572 			pr_err("Hash algorithm %s not supported\n", s);
573 	}
574 
575 	*dfu = calloc(sizeof(struct dfu_entity), dfu_alt_num);
576 	if (!*dfu)
577 		return -1;
578 
579 	return 0;
580 }
581 
dfu_alt_add(struct dfu_entity * dfu,char * interface,char * devstr,char * s)582 int dfu_alt_add(struct dfu_entity *dfu, char *interface, char *devstr, char *s)
583 {
584 	struct dfu_entity *p_dfu;
585 	int ret;
586 
587 	if (alt_num_cnt >= dfu_alt_num)
588 		return -1;
589 
590 	p_dfu = &dfu[alt_num_cnt];
591 	ret = dfu_fill_entity(p_dfu, s, alt_num_cnt, interface, devstr);
592 	if (ret)
593 		return -1;
594 
595 	list_add_tail(&p_dfu->list, &dfu_list);
596 	alt_num_cnt++;
597 
598 	return 0;
599 }
600 
dfu_config_entities(char * env,char * interface,char * devstr)601 int dfu_config_entities(char *env, char *interface, char *devstr)
602 {
603 	struct dfu_entity *dfu;
604 	int i, ret;
605 	char *s;
606 
607 	ret = dfu_alt_init(dfu_find_alt_num(env), &dfu);
608 	if (ret)
609 		return -1;
610 
611 	for (i = 0; i < dfu_alt_num; i++) {
612 		s = strsep(&env, ";");
613 		ret = dfu_alt_add(dfu, interface, devstr, s);
614 		if (ret) {
615 			/* We will free "dfu" in dfu_free_entities() */
616 			return -1;
617 		}
618 	}
619 
620 	return 0;
621 }
622 
dfu_get_dev_type(enum dfu_device_type t)623 const char *dfu_get_dev_type(enum dfu_device_type t)
624 {
625 	const char *const dev_t[] = {NULL, "eMMC", "OneNAND", "NAND", "RAM",
626 				     "SF", "MTD", "VIRT"};
627 	return dev_t[t];
628 }
629 
dfu_get_layout(enum dfu_layout l)630 const char *dfu_get_layout(enum dfu_layout l)
631 {
632 	const char *const dfu_layout[] = {NULL, "RAW_ADDR", "FAT", "EXT2",
633 					  "EXT3", "EXT4", "RAM_ADDR", "SKIP",
634 					  "SCRIPT" };
635 	return dfu_layout[l];
636 }
637 
dfu_show_entities(void)638 void dfu_show_entities(void)
639 {
640 	struct dfu_entity *dfu;
641 
642 	puts("DFU alt settings list:\n");
643 
644 	list_for_each_entry(dfu, &dfu_list, list) {
645 		printf("dev: %s alt: %d name: %s layout: %s\n",
646 		       dfu_get_dev_type(dfu->dev_type), dfu->alt,
647 		       dfu->name, dfu_get_layout(dfu->layout));
648 	}
649 }
650 
dfu_get_alt_number(void)651 int dfu_get_alt_number(void)
652 {
653 	return dfu_alt_num;
654 }
655 
dfu_get_entity(int alt)656 struct dfu_entity *dfu_get_entity(int alt)
657 {
658 	struct dfu_entity *dfu;
659 
660 	list_for_each_entry(dfu, &dfu_list, list) {
661 		if (dfu->alt == alt)
662 			return dfu;
663 	}
664 
665 	return NULL;
666 }
667 
dfu_get_alt(char * name)668 int dfu_get_alt(char *name)
669 {
670 	struct dfu_entity *dfu;
671 	char *str;
672 
673 	list_for_each_entry(dfu, &dfu_list, list) {
674 		if (dfu->name[0] != '/') {
675 			if (!strncmp(dfu->name, name, strlen(dfu->name)))
676 				return dfu->alt;
677 		} else {
678 			/*
679 			 * One must also consider absolute path
680 			 * (/boot/bin/uImage) available at dfu->name when
681 			 * compared "plain" file name (uImage)
682 			 *
683 			 * It is the case for e.g. thor gadget where lthor SW
684 			 * sends only the file name, so only the very last part
685 			 * of path must be checked for equality
686 			 */
687 
688 			str = strstr(dfu->name, name);
689 			if (!str)
690 				continue;
691 
692 			/*
693 			 * Check if matching substring is the last element of
694 			 * dfu->name (uImage)
695 			 */
696 			if (strlen(dfu->name) ==
697 			    ((str - dfu->name) + strlen(name)))
698 				return dfu->alt;
699 		}
700 	}
701 
702 	return -ENODEV;
703 }
704 
dfu_write_from_mem_addr(struct dfu_entity * dfu,void * buf,int size)705 int dfu_write_from_mem_addr(struct dfu_entity *dfu, void *buf, int size)
706 {
707 	unsigned long dfu_buf_size, write, left = size;
708 	int i, ret = 0;
709 	void *dp = buf;
710 
711 	/*
712 	 * Here we must call dfu_get_buf(dfu) first to be sure that dfu_buf_size
713 	 * has been properly initialized - e.g. if "dfu_bufsiz" has been taken
714 	 * into account.
715 	 */
716 	dfu_get_buf(dfu);
717 	dfu_buf_size = dfu_get_buf_size();
718 	debug("%s: dfu buf size: %lu\n", __func__, dfu_buf_size);
719 
720 	for (i = 0; left > 0; i++) {
721 		write = min(dfu_buf_size, left);
722 
723 		debug("%s: dp: 0x%p left: %lu write: %lu\n", __func__,
724 		      dp, left, write);
725 		ret = dfu_write(dfu, dp, write, i);
726 		if (ret) {
727 			pr_err("DFU write failed\n");
728 			return ret;
729 		}
730 
731 		dp += write;
732 		left -= write;
733 	}
734 
735 	ret = dfu_flush(dfu, NULL, 0, i);
736 	if (ret)
737 		pr_err("DFU flush failed!");
738 
739 	return ret;
740 }
741