xref: /optee_os/core/kernel/dt_driver.c (revision bbbb5d00109b7e2767a26bf854ac1c6daa27eba7)
1 // SPDX-License-Identifier: BSD-2-Clause
2 /*
3  * Copyright (c) 2021, Linaro Limited
4  * Copyright (c) 2021, Bootlin
5  * Copyright (c) 2021, Linaro Limited
6  * Copyright (c) 2021, STMicroelectronics
7  */
8 
9 #include <assert.h>
10 #include <config.h>
11 #include <initcall.h>
12 #include <kernel/boot.h>
13 #include <kernel/dt.h>
14 #include <kernel/dt_driver.h>
15 #include <libfdt.h>
16 #include <malloc.h>
17 #include <sys/queue.h>
18 #include <tee_api_defines_extensions.h>
19 #include <tee_api_types.h>
20 
21 /*
22  * struct dt_driver_probe - Node instance in secure FDT to probe a driver for
23  *
24  * @link: List hook
25  * @nodeoffset: Node offset of device referenced in the FDT
26  * @type: One of DT_DRIVER_* or DT_DRIVER_NOTYPE.
27  * @deferrals: Driver probe deferrals count
28  * @dt_drv: Matching driver to probe if found or NULL
29  * @dm: Matching reference if applicable or NULL
30  */
31 struct dt_driver_probe {
32 	int nodeoffset;
33 	enum dt_driver_type type;
34 	unsigned int deferrals;
35 	const struct dt_driver *dt_drv;
36 	const struct dt_device_match *dm;
37 	TAILQ_ENTRY(dt_driver_probe) link;
38 };
39 
40 /*
41  * struct dt_driver_provider - DT related info on probed device
42  *
43  * Saves information on the probed device so that device
44  * drivers can get resources from DT phandle and related arguments.
45  *
46  * @nodeoffset: Node offset of device referenced in the FDT
47  * @type: One of DT_DRIVER_* or DT_DRIVER_NOTYPE.
48  * @provider_cells: Cells count in the FDT used by the driver's references
49  * @get_of_device: Function to get driver's device ref from phandle data
50  * @priv_data: Driver private data passed as @get_of_device argument
51  * @link: Reference in DT driver providers list
52  */
53 struct dt_driver_provider {
54 	int nodeoffset;
55 	enum dt_driver_type type;
56 	unsigned int provider_cells;
57 	uint32_t phandle;
58 	get_of_device_func get_of_device;
59 	void *priv_data;
60 	SLIST_ENTRY(dt_driver_provider) link;
61 };
62 
63 /*
64  * Device driver providers are able to provide a driver specific instance
65  * related to device phandle arguments found in the secure embedded FDT.
66  */
67 static SLIST_HEAD(, dt_driver_provider) dt_driver_provider_list =
68 	SLIST_HEAD_INITIALIZER(dt_driver_provider_list);
69 
70 /* FDT nodes for which a matching driver is to be probed */
71 static TAILQ_HEAD(dt_driver_probe_head, dt_driver_probe) dt_driver_probe_list =
72 	TAILQ_HEAD_INITIALIZER(dt_driver_probe_list);
73 
74 /* FDT nodes for which a matching driver has been successfully probed */
75 static TAILQ_HEAD(, dt_driver_probe) dt_driver_ready_list =
76 	TAILQ_HEAD_INITIALIZER(dt_driver_ready_list);
77 
78 /* List of the nodes for which a compatible driver but reported a failure */
79 static TAILQ_HEAD(, dt_driver_probe) dt_driver_failed_list =
80 	TAILQ_HEAD_INITIALIZER(dt_driver_failed_list);
81 
82 /* Flag enabled when a new node (possibly typed) is added in the probe list */
83 static bool added_node;
84 
85 /* Resolve drivers dependencies on core crypto layer */
86 static bool tee_crypt_is_ready;
87 
88 void dt_driver_crypt_init_complete(void)
89 {
90 	assert(!tee_crypt_is_ready);
91 	tee_crypt_is_ready = true;
92 }
93 
94 TEE_Result dt_driver_get_crypto(void)
95 {
96 	if (tee_crypt_is_ready)
97 		return TEE_SUCCESS;
98 	else
99 		return TEE_ERROR_DEFER_DRIVER_INIT;
100 }
101 
102 static void assert_type_is_valid(enum dt_driver_type type)
103 {
104 	switch (type) {
105 	case DT_DRIVER_NOTYPE:
106 	case DT_DRIVER_CLK:
107 	case DT_DRIVER_RSTCTRL:
108 	case DT_DRIVER_UART:
109 		return;
110 	default:
111 		assert(0);
112 	}
113 }
114 
115 /*
116  * Driver provider registering API functions
117  */
118 
119 TEE_Result dt_driver_register_provider(const void *fdt, int nodeoffset,
120 				       get_of_device_func get_of_device,
121 				       void *priv, enum dt_driver_type type)
122 {
123 	struct dt_driver_provider *prv = NULL;
124 	int provider_cells = 0;
125 	uint32_t phandle = 0;
126 
127 	assert_type_is_valid(type);
128 
129 	provider_cells = fdt_get_dt_driver_cells(fdt, nodeoffset, type);
130 	if (provider_cells < 0) {
131 		DMSG("Failed to find provider cells: %d", provider_cells);
132 		return TEE_ERROR_GENERIC;
133 	}
134 
135 	phandle = fdt_get_phandle(fdt, nodeoffset);
136 	if (phandle == (uint32_t)-1) {
137 		DMSG("Failed to find provide phandle");
138 		return TEE_ERROR_GENERIC;
139 	}
140 
141 	prv = calloc(1, sizeof(*prv));
142 	if (!prv)
143 		return TEE_ERROR_OUT_OF_MEMORY;
144 
145 	prv->nodeoffset = nodeoffset;
146 	prv->type = type;
147 	prv->provider_cells = provider_cells;
148 	prv->phandle = phandle;
149 	prv->get_of_device = get_of_device;
150 	prv->priv_data = priv;
151 
152 	SLIST_INSERT_HEAD(&dt_driver_provider_list, prv, link);
153 
154 	return TEE_SUCCESS;
155 }
156 
157 /*
158  * Helper functions for dt_drivers querying driver provider information
159  */
160 
161 int fdt_get_dt_driver_cells(const void *fdt, int nodeoffset,
162 			    enum dt_driver_type type)
163 {
164 	const char *cells_name = NULL;
165 	const fdt32_t *c = NULL;
166 	int len = 0;
167 
168 	switch (type) {
169 	case DT_DRIVER_CLK:
170 		cells_name = "#clock-cells";
171 		break;
172 	case DT_DRIVER_RSTCTRL:
173 		cells_name = "#reset-cells";
174 		break;
175 	default:
176 		panic();
177 	}
178 
179 	c = fdt_getprop(fdt, nodeoffset, cells_name, &len);
180 	if (!c)
181 		return len;
182 
183 	if (len != sizeof(*c))
184 		return -FDT_ERR_BADNCELLS;
185 
186 	return fdt32_to_cpu(*c);
187 }
188 
189 unsigned int dt_driver_provider_cells(struct dt_driver_provider *prv)
190 {
191 	return prv->provider_cells;
192 }
193 
194 struct dt_driver_provider *
195 dt_driver_get_provider_by_node(int nodeoffset, enum dt_driver_type type)
196 {
197 	struct dt_driver_provider *prv = NULL;
198 
199 	SLIST_FOREACH(prv, &dt_driver_provider_list, link)
200 		if (prv->nodeoffset == nodeoffset && prv->type == type)
201 			return prv;
202 
203 	return NULL;
204 }
205 
206 struct dt_driver_provider *
207 dt_driver_get_provider_by_phandle(uint32_t phandle, enum dt_driver_type type)
208 {
209 	struct dt_driver_provider *prv = NULL;
210 
211 	SLIST_FOREACH(prv, &dt_driver_provider_list, link)
212 		if (prv->phandle == phandle && prv->type == type)
213 			return prv;
214 
215 	return NULL;
216 }
217 
218 static void *device_from_provider_prop(struct dt_driver_provider *prv,
219 				       const void *fdt, int phandle_node,
220 				       const uint32_t *prop, TEE_Result *res)
221 {
222 	struct dt_driver_phandle_args *pargs = NULL;
223 	unsigned int n = 0;
224 	void *device = NULL;
225 
226 	pargs = calloc(1, prv->provider_cells * sizeof(uint32_t *) +
227 		       sizeof(*pargs));
228 	if (!pargs) {
229 		*res = TEE_ERROR_OUT_OF_MEMORY;
230 		return NULL;
231 	}
232 
233 	pargs->fdt = fdt;
234 	pargs->phandle_node = phandle_node;
235 	pargs->args_count = prv->provider_cells;
236 	for (n = 0; n < prv->provider_cells; n++)
237 		pargs->args[n] = fdt32_to_cpu(prop[n + 1]);
238 
239 	device = prv->get_of_device(pargs, prv->priv_data, res);
240 
241 	free(pargs);
242 
243 	return device;
244 }
245 
246 void *dt_driver_device_from_node_idx_prop(const char *prop_name,
247 					  const void *fdt, int nodeoffset,
248 					  unsigned int prop_idx,
249 					  enum dt_driver_type type,
250 					  TEE_Result *res)
251 {
252 	int len = 0;
253 	int idx = 0;
254 	int idx32 = 0;
255 	int prv_cells = 0;
256 	int phandle_node = -1;
257 	uint32_t phandle = 0;
258 	const uint32_t *prop = NULL;
259 	struct dt_driver_provider *prv = NULL;
260 
261 	prop = fdt_getprop(fdt, nodeoffset, prop_name, &len);
262 	if (!prop) {
263 		DMSG("Property %s missing in node %s", prop_name,
264 		     fdt_get_name(fdt, nodeoffset, NULL));
265 		*res = TEE_ERROR_ITEM_NOT_FOUND;
266 		return NULL;
267 	}
268 
269 	while (idx < len) {
270 		idx32 = idx / sizeof(uint32_t);
271 		phandle = fdt32_to_cpu(prop[idx32]);
272 		if (!phandle) {
273 			if (!prop_idx)
274 				break;
275 			idx += sizeof(phandle);
276 			prop_idx--;
277 			continue;
278 		}
279 
280 		prv = dt_driver_get_provider_by_phandle(phandle, type);
281 		if (!prv) {
282 			/* No provider registered yet */
283 			*res = TEE_ERROR_DEFER_DRIVER_INIT;
284 			return NULL;
285 		}
286 
287 		prv_cells = dt_driver_provider_cells(prv);
288 		if (prop_idx) {
289 			prop_idx--;
290 			idx += sizeof(phandle) + prv_cells * sizeof(uint32_t);
291 			continue;
292 		}
293 
294 		return device_from_provider_prop(prv, fdt, phandle_node,
295 						 prop + idx32, res);
296 	}
297 
298 	*res = TEE_ERROR_ITEM_NOT_FOUND;
299 	return NULL;
300 }
301 
302 static void __maybe_unused print_probe_list(const void *fdt __maybe_unused)
303 {
304 	struct dt_driver_probe *elt = NULL;
305 	unsigned int count = 0;
306 
307 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
308 		count++;
309 
310 	DMSG("Probe list: %u elements", count);
311 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
312 		DMSG("|- Driver %s probes on node %s",
313 		     elt->dt_drv->name,
314 		     fdt_get_name(fdt, elt->nodeoffset, NULL));
315 
316 	DMSG("`- Probe list end");
317 
318 	count = 0;
319 	TAILQ_FOREACH(elt, &dt_driver_failed_list, link)
320 		count++;
321 
322 	DMSG("Failed list: %u elements", count);
323 	TAILQ_FOREACH(elt, &dt_driver_failed_list, link)
324 		EMSG("|- Driver %s on node %s failed", elt->dt_drv->name,
325 		     fdt_get_name(fdt, elt->nodeoffset, NULL));
326 
327 	DMSG("`- Failed list end");
328 }
329 
330 /*
331  * Probe element: push to ready list if succeeds, push to probe list if probe
332  * if deferred, panic with an error trace otherwise.
333  */
334 static TEE_Result probe_driver_node(const void *fdt,
335 				    struct dt_driver_probe *elt)
336 {
337 	TEE_Result res = TEE_ERROR_GENERIC;
338 	const char __maybe_unused *drv_name = NULL;
339 	const char __maybe_unused *node_name = NULL;
340 
341 	node_name = fdt_get_name(fdt, elt->nodeoffset, NULL);
342 	drv_name = elt->dt_drv->name;
343 
344 	if (!elt->dt_drv->probe) {
345 		DMSG("No probe operator for driver %s, skipped", drv_name);
346 		return TEE_SUCCESS;
347 	}
348 
349 	FMSG("Probing %s on node %s", drv_name, node_name);
350 
351 	res = elt->dt_drv->probe(fdt, elt->nodeoffset, elt->dm->compat_data);
352 	switch (res) {
353 	case TEE_SUCCESS:
354 		TAILQ_INSERT_HEAD(&dt_driver_ready_list, elt, link);
355 
356 		DMSG("element: %s on node %s initialized", drv_name, node_name);
357 		break;
358 	case TEE_ERROR_DEFER_DRIVER_INIT:
359 		elt->deferrals++;
360 		TAILQ_INSERT_TAIL(&dt_driver_probe_list, elt, link);
361 
362 		DMSG("element: %s on node %s deferred %u time(s)", drv_name,
363 		     node_name, elt->deferrals);
364 		break;
365 	case TEE_ERROR_NODE_DISABLED:
366 		DMSG("element: %s on node %s is disabled", drv_name, node_name);
367 		break;
368 	default:
369 		TAILQ_INSERT_HEAD(&dt_driver_failed_list, elt, link);
370 
371 		EMSG("Failed to probe %s on node %s: %#"PRIx32,
372 		     drv_name, node_name, res);
373 		break;
374 	}
375 
376 	return res;
377 }
378 
379 static TEE_Result alloc_elt_and_probe(const void *fdt, int node,
380 				      const struct dt_driver *dt_drv,
381 				      const struct dt_device_match *dm)
382 {
383 	struct dt_driver_probe *elt = NULL;
384 
385 	/* Will be freed when lists are released */
386 	elt = calloc(1, sizeof(*elt));
387 	if (!elt)
388 		return TEE_ERROR_OUT_OF_MEMORY;
389 
390 	elt->nodeoffset = node;
391 	elt->dt_drv = dt_drv;
392 	elt->dm = dm;
393 	elt->type = dt_drv->type;
394 
395 	return probe_driver_node(fdt, elt);
396 }
397 
398 /* Lookup a compatible driver, possibly of a specific @type, for the FDT node */
399 static TEE_Result probe_device_by_compat(const void *fdt, int node,
400 					 const char *compat,
401 					 enum dt_driver_type type)
402 {
403 	const struct dt_driver *drv = NULL;
404 	const struct dt_device_match *dm = NULL;
405 
406 	for_each_dt_driver(drv) {
407 		if (drv->type != type)
408 			continue;
409 
410 		for (dm = drv->match_table; dm && dm->compatible; dm++)
411 			if (strcmp(dm->compatible, compat) == 0)
412 				return alloc_elt_and_probe(fdt, node, drv, dm);
413 	}
414 
415 	return TEE_ERROR_ITEM_NOT_FOUND;
416 }
417 
418 /*
419  * Lookup the best matching compatible driver, possibly of a specific @type,
420  * for the FDT node.
421  */
422 TEE_Result dt_driver_probe_device_by_node(const void *fdt, int nodeoffset,
423 					  enum dt_driver_type type)
424 {
425 	int idx = 0;
426 	int len = 0;
427 	int count = 0;
428 	const char *compat = NULL;
429 	TEE_Result res = TEE_ERROR_GENERIC;
430 
431 	assert_type_is_valid(type);
432 
433 	count = fdt_stringlist_count(fdt, nodeoffset, "compatible");
434 	if (count < 0)
435 		return TEE_ERROR_ITEM_NOT_FOUND;
436 
437 	for (idx = 0; idx < count; idx++) {
438 		compat = fdt_stringlist_get(fdt, nodeoffset, "compatible",
439 					    idx, &len);
440 		if (!compat)
441 			return TEE_ERROR_GENERIC;
442 
443 		res = probe_device_by_compat(fdt, nodeoffset, compat, type);
444 
445 		if (res != TEE_ERROR_ITEM_NOT_FOUND)
446 			return res;
447 	}
448 
449 	return TEE_ERROR_ITEM_NOT_FOUND;
450 }
451 
452 static TEE_Result process_probe_list(const void *fdt)
453 {
454 	struct dt_driver_probe *elt = NULL;
455 	struct dt_driver_probe *prev = NULL;
456 	static unsigned int __maybe_unused loop_count;
457 	static unsigned int __maybe_unused deferral_loop_count;
458 	bool __maybe_unused one_deferred = false;
459 	bool one_probed_ok = false;
460 
461 	do {
462 		loop_count++;
463 		FMSG("Probe loop %u after %u for deferral(s)", loop_count,
464 		     deferral_loop_count);
465 
466 		/* Hack here for TRACE_DEBUG messages on probe list elements */
467 		if (TRACE_LEVEL >= TRACE_FLOW)
468 			print_probe_list(fdt);
469 
470 		if (TAILQ_EMPTY(&dt_driver_probe_list))
471 			return TEE_SUCCESS;
472 
473 		/*
474 		 * Probe from current end to top. Deferred probed node are
475 		 * pushed back after current tail for the next probe round.
476 		 * Reset probe result flags and see status after probe round.
477 		 */
478 		one_deferred = false;
479 		one_probed_ok = false;
480 		added_node = false;
481 
482 		TAILQ_FOREACH_REVERSE_SAFE(elt, &dt_driver_probe_list,
483 					   dt_driver_probe_head, link, prev) {
484 			TAILQ_REMOVE(&dt_driver_probe_list, elt, link);
485 
486 			switch (probe_driver_node(fdt, elt)) {
487 			case TEE_SUCCESS:
488 				one_probed_ok = true;
489 				break;
490 			case TEE_ERROR_DEFER_DRIVER_INIT:
491 				one_deferred = true;
492 				break;
493 			default:
494 				break;
495 			}
496 		}
497 
498 		if (one_deferred)
499 			deferral_loop_count++;
500 
501 	} while (added_node || one_probed_ok);
502 
503 	DMSG("Unresolved dependencies after %u rounds, %u deferred",
504 	     loop_count, deferral_loop_count);
505 
506 	if (one_deferred)
507 		return TEE_ERROR_DEFER_DRIVER_INIT;
508 	else
509 		return TEE_ERROR_GENERIC;
510 }
511 
512 static int driver_probe_compare(struct dt_driver_probe *candidate,
513 				struct dt_driver_probe *elt)
514 {
515 	if (candidate->nodeoffset != elt->nodeoffset ||
516 	    candidate->type != elt->type)
517 		return 1;
518 
519 	assert(elt->dt_drv == candidate->dt_drv);
520 	return 0;
521 }
522 
523 /*
524  * Return TEE_SUCCESS if compatible found
525  *	  TEE_ERROR_OUT_OF_MEMORY if heap is exhausted
526  */
527 static TEE_Result add_node_to_probe(const void *fdt, int node,
528 				    const struct dt_driver *dt_drv,
529 				    const struct dt_device_match *dm)
530 {
531 	const char __maybe_unused *node_name = fdt_get_name(fdt, node, NULL);
532 	const char __maybe_unused *drv_name = dt_drv->name;
533 	struct dt_driver_probe *elt = NULL;
534 	struct dt_driver_probe elt_new = {
535 		.dm = dm,
536 		.dt_drv = dt_drv,
537 		.nodeoffset = node,
538 		.type = dt_drv->type,
539 	};
540 
541 	/* If node/type found in probe list or ready list, nothing to do */
542 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
543 		if (!driver_probe_compare(&elt_new, elt))
544 			return TEE_SUCCESS;
545 
546 	TAILQ_FOREACH(elt, &dt_driver_ready_list, link)
547 		if (!driver_probe_compare(&elt_new, elt))
548 			return TEE_SUCCESS;
549 
550 	elt = malloc(sizeof(*elt));
551 	if (!elt)
552 		return TEE_ERROR_OUT_OF_MEMORY;
553 
554 	DMSG("element: %s on node %s", node_name, drv_name);
555 
556 	memcpy(elt, &elt_new, sizeof(*elt));
557 
558 	added_node = true;
559 
560 	TAILQ_INSERT_TAIL(&dt_driver_probe_list, elt, link);
561 
562 	/* Hack here for TRACE_DEBUG messages on current probe list elements */
563 	if (TRACE_LEVEL >= TRACE_FLOW)
564 		print_probe_list(fdt);
565 
566 	return TEE_SUCCESS;
567 }
568 
569 /*
570  * Add a node to the probe list if a dt_driver matches target compatible.
571  *
572  * If @type is DT_DRIVER_ANY, probe list can hold only 1 driver to probe for
573  * the node. A node may probe several drivers if have a unique driver type.
574  *
575  * Return TEE_SUCCESS if compatible found
576  *	  TEE_ERROR_ITEM_NOT_FOUND if no matching driver
577  *	  TEE_ERROR_OUT_OF_MEMORY if heap is exhausted
578  */
579 static TEE_Result add_probe_node_by_compat(const void *fdt, int node,
580 					   const char *compat)
581 {
582 	TEE_Result res = TEE_ERROR_ITEM_NOT_FOUND;
583 	const struct dt_driver *dt_drv = NULL;
584 	const struct dt_device_match *dm = NULL;
585 	uint32_t found_types = 0;
586 
587 	for_each_dt_driver(dt_drv) {
588 		for (dm = dt_drv->match_table; dm && dm->compatible; dm++) {
589 			if (strcmp(dm->compatible, compat) == 0) {
590 				assert(dt_drv->type < 32);
591 
592 				res = add_node_to_probe(fdt, node, dt_drv, dm);
593 				if (res)
594 					return res;
595 
596 				if (found_types & BIT(dt_drv->type)) {
597 					EMSG("Driver %s multi hit on type %u",
598 					     dt_drv->name, dt_drv->type);
599 					panic();
600 				}
601 				found_types |= BIT(dt_drv->type);
602 
603 				/* Matching found for this driver, try next */
604 				break;
605 			}
606 		}
607 	}
608 
609 	return res;
610 }
611 
612 /*
613  * Add the node to the probe list if matching compatible drivers are found.
614  * Follow node's compatible property list ordering to find matching driver.
615  */
616 TEE_Result dt_driver_maybe_add_probe_node(const void *fdt, int node)
617 {
618 	int idx = 0;
619 	int len = 0;
620 	int count = 0;
621 	const char *compat = NULL;
622 	TEE_Result res = TEE_ERROR_GENERIC;
623 
624 	if (_fdt_get_status(fdt, node) == DT_STATUS_DISABLED)
625 		return TEE_SUCCESS;
626 
627 	count = fdt_stringlist_count(fdt, node, "compatible");
628 	if (count < 0)
629 		return TEE_SUCCESS;
630 
631 	for (idx = 0; idx < count; idx++) {
632 		compat = fdt_stringlist_get(fdt, node, "compatible", idx, &len);
633 		assert(compat && len > 0);
634 
635 		res = add_probe_node_by_compat(fdt, node, compat);
636 
637 		/* Stop lookup if something was found */
638 		if (res != TEE_ERROR_ITEM_NOT_FOUND)
639 			return res;
640 	}
641 
642 	return TEE_SUCCESS;
643 }
644 
645 static void parse_node(const void *fdt, int node)
646 {
647 	TEE_Result __maybe_unused res = TEE_ERROR_GENERIC;
648 	int subnode = 0;
649 
650 	fdt_for_each_subnode(subnode, fdt, node) {
651 		res = dt_driver_maybe_add_probe_node(fdt, subnode);
652 		if (res) {
653 			EMSG("Failed on node %s with %#"PRIx32,
654 			     fdt_get_name(fdt, subnode, NULL), res);
655 			panic();
656 		}
657 
658 		/*
659 		 * Rescursively parse the FDT, skipping disabled nodes.
660 		 * FDT is expected reliable and core shall have sufficient
661 		 * stack depth to possibly parse all DT nodes.
662 		 */
663 		if (IS_ENABLED(CFG_DRIVERS_DT_RECURSIVE_PROBE)) {
664 			if (_fdt_get_status(fdt, subnode) == DT_STATUS_DISABLED)
665 				continue;
666 
667 			parse_node(fdt, subnode);
668 		}
669 	}
670 }
671 
672 /*
673  * Parse FDT for nodes and save in probe list the node for which a dt_driver
674  * matches node's compatible property.
675  */
676 static TEE_Result probe_dt_drivers_early(void)
677 {
678 	TEE_Result res = TEE_ERROR_GENERIC;
679 	const void *fdt = NULL;
680 
681 	fdt = get_secure_dt();
682 	if (!fdt)
683 		return TEE_SUCCESS;
684 
685 	parse_node(fdt, fdt_path_offset(fdt, "/"));
686 
687 	res = process_probe_list(fdt);
688 	if (res == TEE_ERROR_DEFER_DRIVER_INIT) {
689 		DMSG("Deferred drivers probing");
690 		print_probe_list(fdt);
691 		res = TEE_SUCCESS;
692 	}
693 
694 	return res;
695 }
696 
697 static TEE_Result probe_dt_drivers(void)
698 {
699 	TEE_Result res = TEE_ERROR_GENERIC;
700 	const void *fdt = NULL;
701 
702 	fdt = get_secure_dt();
703 	if (!fdt)
704 		return TEE_SUCCESS;
705 
706 	res = process_probe_list(fdt);
707 	if (res || !TAILQ_EMPTY(&dt_driver_failed_list)) {
708 		EMSG("Probe sequence result: %#"PRIx32, res);
709 		print_probe_list(fdt);
710 	}
711 	if (res)
712 		panic();
713 
714 	return TEE_SUCCESS;
715 }
716 
717 early_init_late(probe_dt_drivers_early);
718 driver_init(probe_dt_drivers);
719 
720 static TEE_Result release_probe_lists(void)
721 {
722 	struct dt_driver_probe *elt = NULL;
723 	struct dt_driver_probe *next = NULL;
724 	struct dt_driver_provider *prov = NULL;
725 	struct dt_driver_provider *next_prov = NULL;
726 	const void *fdt = NULL;
727 
728 	fdt = get_secure_dt();
729 	if (!fdt)
730 		return TEE_SUCCESS;
731 
732 	assert(fdt && TAILQ_EMPTY(&dt_driver_probe_list));
733 
734 	TAILQ_FOREACH_SAFE(elt, &dt_driver_ready_list, link, next)
735 		free(elt);
736 
737 	TAILQ_FOREACH_SAFE(elt, &dt_driver_failed_list, link, next)
738 	       free(elt);
739 
740 	SLIST_FOREACH_SAFE(prov, &dt_driver_provider_list, link, next_prov)
741 	       free(prov);
742 
743 	return TEE_SUCCESS;
744 }
745 
746 release_init_resource(release_probe_lists);
747 
748 /*
749  * Simple bus support: handy to parse subnodes
750  */
751 static TEE_Result simple_bus_probe(const void *fdt, int node,
752 				   const void *compat_data __unused)
753 {
754 	TEE_Result res = TEE_ERROR_GENERIC;
755 	int subnode = 0;
756 
757 	fdt_for_each_subnode(subnode, fdt, node) {
758 		res = dt_driver_maybe_add_probe_node(fdt, subnode);
759 		if (res) {
760 			EMSG("Failed on node %s with %#"PRIx32,
761 			     fdt_get_name(fdt, subnode, NULL), res);
762 			panic();
763 		}
764 	}
765 
766 	return TEE_SUCCESS;
767 }
768 
769 static const struct dt_device_match simple_bus_match_table[] = {
770 	{ .compatible = "simple-bus" },
771 	{ }
772 };
773 
774 DEFINE_DT_DRIVER(simple_bus_dt_driver) = {
775 	.name = "simple-bus",
776 	.match_table = simple_bus_match_table,
777 	.probe = simple_bus_probe,
778 };
779