xref: /optee_os/core/kernel/dt_driver.c (revision 750c544ca5b1d498d11b2a16fdfe30411f6ea6ce)
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 	case DT_DRIVER_GPIO:
110 	case DT_DRIVER_I2C:
111 		return;
112 	default:
113 		assert(0);
114 	}
115 }
116 
117 /*
118  * Driver provider registering API functions
119  */
120 
121 TEE_Result dt_driver_register_provider(const void *fdt, int nodeoffset,
122 				       get_of_device_func get_of_device,
123 				       void *priv, enum dt_driver_type type)
124 {
125 	struct dt_driver_provider *prv = NULL;
126 	int provider_cells = 0;
127 	uint32_t phandle = 0;
128 
129 	assert_type_is_valid(type);
130 
131 	provider_cells = fdt_get_dt_driver_cells(fdt, nodeoffset, type);
132 	if (provider_cells < 0) {
133 		DMSG("Failed to find provider cells: %d", provider_cells);
134 		return TEE_ERROR_GENERIC;
135 	}
136 
137 	phandle = fdt_get_phandle(fdt, nodeoffset);
138 	if (phandle == (uint32_t)-1) {
139 		DMSG("Failed to find provide phandle");
140 		return TEE_ERROR_GENERIC;
141 	}
142 
143 	prv = calloc(1, sizeof(*prv));
144 	if (!prv)
145 		return TEE_ERROR_OUT_OF_MEMORY;
146 
147 	prv->nodeoffset = nodeoffset;
148 	prv->type = type;
149 	prv->provider_cells = provider_cells;
150 	prv->phandle = phandle;
151 	prv->get_of_device = get_of_device;
152 	prv->priv_data = priv;
153 
154 	SLIST_INSERT_HEAD(&dt_driver_provider_list, prv, link);
155 
156 	return TEE_SUCCESS;
157 }
158 
159 /*
160  * Helper functions for dt_drivers querying driver provider information
161  */
162 
163 int fdt_get_dt_driver_cells(const void *fdt, int nodeoffset,
164 			    enum dt_driver_type type)
165 {
166 	const char *cells_name = NULL;
167 	const fdt32_t *c = NULL;
168 	int len = 0;
169 
170 	switch (type) {
171 	case DT_DRIVER_CLK:
172 		cells_name = "#clock-cells";
173 		break;
174 	case DT_DRIVER_RSTCTRL:
175 		cells_name = "#reset-cells";
176 		break;
177 	case DT_DRIVER_GPIO:
178 		cells_name = "#gpio-cells";
179 		break;
180 	case DT_DRIVER_I2C:
181 		return 0;
182 	default:
183 		panic();
184 	}
185 
186 	c = fdt_getprop(fdt, nodeoffset, cells_name, &len);
187 	if (!c)
188 		return len;
189 
190 	if (len != sizeof(*c))
191 		return -FDT_ERR_BADNCELLS;
192 
193 	return fdt32_to_cpu(*c);
194 }
195 
196 unsigned int dt_driver_provider_cells(struct dt_driver_provider *prv)
197 {
198 	return prv->provider_cells;
199 }
200 
201 struct dt_driver_provider *
202 dt_driver_get_provider_by_node(int nodeoffset, enum dt_driver_type type)
203 {
204 	struct dt_driver_provider *prv = NULL;
205 
206 	SLIST_FOREACH(prv, &dt_driver_provider_list, link)
207 		if (prv->nodeoffset == nodeoffset && prv->type == type)
208 			return prv;
209 
210 	return NULL;
211 }
212 
213 struct dt_driver_provider *
214 dt_driver_get_provider_by_phandle(uint32_t phandle, enum dt_driver_type type)
215 {
216 	struct dt_driver_provider *prv = NULL;
217 
218 	SLIST_FOREACH(prv, &dt_driver_provider_list, link)
219 		if (prv->phandle == phandle && prv->type == type)
220 			return prv;
221 
222 	return NULL;
223 }
224 
225 static void *device_from_provider_prop(struct dt_driver_provider *prv,
226 				       const void *fdt, int phandle_node,
227 				       const uint32_t *prop, TEE_Result *res)
228 {
229 	struct dt_driver_phandle_args *pargs = NULL;
230 	unsigned int n = 0;
231 	void *device = NULL;
232 
233 	pargs = calloc(1, prv->provider_cells * sizeof(uint32_t *) +
234 		       sizeof(*pargs));
235 	if (!pargs) {
236 		*res = TEE_ERROR_OUT_OF_MEMORY;
237 		return NULL;
238 	}
239 
240 	pargs->fdt = fdt;
241 	pargs->phandle_node = phandle_node;
242 	pargs->args_count = prv->provider_cells;
243 	for (n = 0; n < prv->provider_cells; n++)
244 		pargs->args[n] = fdt32_to_cpu(prop[n + 1]);
245 
246 	device = prv->get_of_device(pargs, prv->priv_data, res);
247 
248 	free(pargs);
249 
250 	return device;
251 }
252 
253 void *dt_driver_device_from_parent(const void *fdt, int nodeoffset,
254 				   enum dt_driver_type type, TEE_Result *res)
255 {
256 	int parent = -1;
257 	struct dt_driver_provider *prv = NULL;
258 
259 	assert(fdt == get_secure_dt());
260 
261 	parent = fdt_parent_offset(fdt, nodeoffset);
262 	if (parent < 0) {
263 		*res =  TEE_ERROR_GENERIC;
264 		return NULL;
265 	}
266 
267 	prv = dt_driver_get_provider_by_node(parent, type);
268 	if (!prv) {
269 		/* No provider registered yet */
270 		*res = TEE_ERROR_DEFER_DRIVER_INIT;
271 		return NULL;
272 	}
273 
274 	return device_from_provider_prop(prv, fdt, nodeoffset, NULL, res);
275 }
276 
277 void *dt_driver_device_from_node_idx_prop(const char *prop_name,
278 					  const void *fdt, int nodeoffset,
279 					  unsigned int prop_idx,
280 					  enum dt_driver_type type,
281 					  TEE_Result *res)
282 {
283 	int len = 0;
284 	int idx = 0;
285 	int idx32 = 0;
286 	int prv_cells = 0;
287 	int phandle_node = -1;
288 	uint32_t phandle = 0;
289 	const uint32_t *prop = NULL;
290 	struct dt_driver_provider *prv = NULL;
291 
292 	prop = fdt_getprop(fdt, nodeoffset, prop_name, &len);
293 	if (!prop) {
294 		DMSG("Property %s missing in node %s", prop_name,
295 		     fdt_get_name(fdt, nodeoffset, NULL));
296 		*res = TEE_ERROR_ITEM_NOT_FOUND;
297 		return NULL;
298 	}
299 
300 	while (idx < len) {
301 		idx32 = idx / sizeof(uint32_t);
302 		phandle = fdt32_to_cpu(prop[idx32]);
303 		if (!phandle) {
304 			if (!prop_idx)
305 				break;
306 			idx += sizeof(phandle);
307 			prop_idx--;
308 			continue;
309 		}
310 
311 		prv = dt_driver_get_provider_by_phandle(phandle, type);
312 		if (!prv) {
313 			/* No provider registered yet */
314 			*res = TEE_ERROR_DEFER_DRIVER_INIT;
315 			return NULL;
316 		}
317 
318 		prv_cells = dt_driver_provider_cells(prv);
319 		if (prop_idx) {
320 			prop_idx--;
321 			idx += sizeof(phandle) + prv_cells * sizeof(uint32_t);
322 			continue;
323 		}
324 
325 		return device_from_provider_prop(prv, fdt, phandle_node,
326 						 prop + idx32, res);
327 	}
328 
329 	*res = TEE_ERROR_ITEM_NOT_FOUND;
330 	return NULL;
331 }
332 
333 static void __maybe_unused print_probe_list(const void *fdt __maybe_unused)
334 {
335 	struct dt_driver_probe *elt = NULL;
336 	unsigned int count = 0;
337 
338 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
339 		count++;
340 
341 	DMSG("Probe list: %u elements", count);
342 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
343 		DMSG("|- Driver %s probes on node %s",
344 		     elt->dt_drv->name,
345 		     fdt_get_name(fdt, elt->nodeoffset, NULL));
346 
347 	DMSG("`- Probe list end");
348 
349 	count = 0;
350 	TAILQ_FOREACH(elt, &dt_driver_failed_list, link)
351 		count++;
352 
353 	DMSG("Failed list: %u elements", count);
354 	TAILQ_FOREACH(elt, &dt_driver_failed_list, link)
355 		EMSG("|- Driver %s on node %s failed", elt->dt_drv->name,
356 		     fdt_get_name(fdt, elt->nodeoffset, NULL));
357 
358 	DMSG("`- Failed list end");
359 }
360 
361 /*
362  * Probe element: push to ready list if succeeds, push to probe list if probe
363  * if deferred, panic with an error trace otherwise.
364  */
365 static TEE_Result probe_driver_node(const void *fdt,
366 				    struct dt_driver_probe *elt)
367 {
368 	TEE_Result res = TEE_ERROR_GENERIC;
369 	const char __maybe_unused *drv_name = NULL;
370 	const char __maybe_unused *node_name = NULL;
371 
372 	node_name = fdt_get_name(fdt, elt->nodeoffset, NULL);
373 	drv_name = elt->dt_drv->name;
374 
375 	if (!elt->dt_drv->probe) {
376 		DMSG("No probe operator for driver %s, skipped", drv_name);
377 		return TEE_SUCCESS;
378 	}
379 
380 	FMSG("Probing %s on node %s", drv_name, node_name);
381 
382 	res = elt->dt_drv->probe(fdt, elt->nodeoffset, elt->dm->compat_data);
383 	switch (res) {
384 	case TEE_SUCCESS:
385 		TAILQ_INSERT_HEAD(&dt_driver_ready_list, elt, link);
386 
387 		DMSG("element: %s on node %s initialized", drv_name, node_name);
388 		break;
389 	case TEE_ERROR_DEFER_DRIVER_INIT:
390 		elt->deferrals++;
391 		TAILQ_INSERT_TAIL(&dt_driver_probe_list, elt, link);
392 
393 		DMSG("element: %s on node %s deferred %u time(s)", drv_name,
394 		     node_name, elt->deferrals);
395 		break;
396 	case TEE_ERROR_NODE_DISABLED:
397 		DMSG("element: %s on node %s is disabled", drv_name, node_name);
398 		break;
399 	default:
400 		TAILQ_INSERT_HEAD(&dt_driver_failed_list, elt, link);
401 
402 		EMSG("Failed to probe %s on node %s: %#"PRIx32,
403 		     drv_name, node_name, res);
404 		break;
405 	}
406 
407 	return res;
408 }
409 
410 static TEE_Result alloc_elt_and_probe(const void *fdt, int node,
411 				      const struct dt_driver *dt_drv,
412 				      const struct dt_device_match *dm)
413 {
414 	struct dt_driver_probe *elt = NULL;
415 
416 	/* Will be freed when lists are released */
417 	elt = calloc(1, sizeof(*elt));
418 	if (!elt)
419 		return TEE_ERROR_OUT_OF_MEMORY;
420 
421 	elt->nodeoffset = node;
422 	elt->dt_drv = dt_drv;
423 	elt->dm = dm;
424 	elt->type = dt_drv->type;
425 
426 	return probe_driver_node(fdt, elt);
427 }
428 
429 /* Lookup a compatible driver, possibly of a specific @type, for the FDT node */
430 static TEE_Result probe_device_by_compat(const void *fdt, int node,
431 					 const char *compat,
432 					 enum dt_driver_type type)
433 {
434 	const struct dt_driver *drv = NULL;
435 	const struct dt_device_match *dm = NULL;
436 
437 	for_each_dt_driver(drv) {
438 		if (drv->type != type)
439 			continue;
440 
441 		for (dm = drv->match_table; dm && dm->compatible; dm++)
442 			if (strcmp(dm->compatible, compat) == 0)
443 				return alloc_elt_and_probe(fdt, node, drv, dm);
444 	}
445 
446 	return TEE_ERROR_ITEM_NOT_FOUND;
447 }
448 
449 /*
450  * Lookup the best matching compatible driver, possibly of a specific @type,
451  * for the FDT node.
452  */
453 TEE_Result dt_driver_probe_device_by_node(const void *fdt, int nodeoffset,
454 					  enum dt_driver_type type)
455 {
456 	int idx = 0;
457 	int len = 0;
458 	int count = 0;
459 	const char *compat = NULL;
460 	TEE_Result res = TEE_ERROR_GENERIC;
461 
462 	assert_type_is_valid(type);
463 
464 	count = fdt_stringlist_count(fdt, nodeoffset, "compatible");
465 	if (count < 0)
466 		return TEE_ERROR_ITEM_NOT_FOUND;
467 
468 	for (idx = 0; idx < count; idx++) {
469 		compat = fdt_stringlist_get(fdt, nodeoffset, "compatible",
470 					    idx, &len);
471 		if (!compat)
472 			return TEE_ERROR_GENERIC;
473 
474 		res = probe_device_by_compat(fdt, nodeoffset, compat, type);
475 
476 		if (res != TEE_ERROR_ITEM_NOT_FOUND)
477 			return res;
478 	}
479 
480 	return TEE_ERROR_ITEM_NOT_FOUND;
481 }
482 
483 static TEE_Result process_probe_list(const void *fdt)
484 {
485 	struct dt_driver_probe *elt = NULL;
486 	struct dt_driver_probe *prev = NULL;
487 	static unsigned int __maybe_unused loop_count;
488 	static unsigned int __maybe_unused deferral_loop_count;
489 	bool __maybe_unused one_deferred = false;
490 	bool one_probed_ok = false;
491 
492 	do {
493 		loop_count++;
494 		FMSG("Probe loop %u after %u for deferral(s)", loop_count,
495 		     deferral_loop_count);
496 
497 		/* Hack here for TRACE_DEBUG messages on probe list elements */
498 		if (TRACE_LEVEL >= TRACE_FLOW)
499 			print_probe_list(fdt);
500 
501 		if (TAILQ_EMPTY(&dt_driver_probe_list))
502 			return TEE_SUCCESS;
503 
504 		/*
505 		 * Probe from current end to top. Deferred probed node are
506 		 * pushed back after current tail for the next probe round.
507 		 * Reset probe result flags and see status after probe round.
508 		 */
509 		one_deferred = false;
510 		one_probed_ok = false;
511 		added_node = false;
512 
513 		TAILQ_FOREACH_REVERSE_SAFE(elt, &dt_driver_probe_list,
514 					   dt_driver_probe_head, link, prev) {
515 			TAILQ_REMOVE(&dt_driver_probe_list, elt, link);
516 
517 			switch (probe_driver_node(fdt, elt)) {
518 			case TEE_SUCCESS:
519 				one_probed_ok = true;
520 				break;
521 			case TEE_ERROR_DEFER_DRIVER_INIT:
522 				one_deferred = true;
523 				break;
524 			default:
525 				break;
526 			}
527 		}
528 
529 		if (one_deferred)
530 			deferral_loop_count++;
531 
532 	} while (added_node || one_probed_ok);
533 
534 	DMSG("Unresolved dependencies after %u rounds, %u deferred",
535 	     loop_count, deferral_loop_count);
536 
537 	if (one_deferred)
538 		return TEE_ERROR_DEFER_DRIVER_INIT;
539 	else
540 		return TEE_ERROR_GENERIC;
541 }
542 
543 static int driver_probe_compare(struct dt_driver_probe *candidate,
544 				struct dt_driver_probe *elt)
545 {
546 	if (candidate->nodeoffset != elt->nodeoffset ||
547 	    candidate->type != elt->type)
548 		return 1;
549 
550 	assert(elt->dt_drv == candidate->dt_drv);
551 	return 0;
552 }
553 
554 /*
555  * Return TEE_SUCCESS if compatible found
556  *	  TEE_ERROR_OUT_OF_MEMORY if heap is exhausted
557  */
558 static TEE_Result add_node_to_probe(const void *fdt, int node,
559 				    const struct dt_driver *dt_drv,
560 				    const struct dt_device_match *dm)
561 {
562 	const char __maybe_unused *node_name = fdt_get_name(fdt, node, NULL);
563 	const char __maybe_unused *drv_name = dt_drv->name;
564 	struct dt_driver_probe *elt = NULL;
565 	struct dt_driver_probe elt_new = {
566 		.dm = dm,
567 		.dt_drv = dt_drv,
568 		.nodeoffset = node,
569 		.type = dt_drv->type,
570 	};
571 
572 	/* If node/type found in probe list or ready list, nothing to do */
573 	TAILQ_FOREACH(elt, &dt_driver_probe_list, link)
574 		if (!driver_probe_compare(&elt_new, elt))
575 			return TEE_SUCCESS;
576 
577 	TAILQ_FOREACH(elt, &dt_driver_ready_list, link)
578 		if (!driver_probe_compare(&elt_new, elt))
579 			return TEE_SUCCESS;
580 
581 	elt = malloc(sizeof(*elt));
582 	if (!elt)
583 		return TEE_ERROR_OUT_OF_MEMORY;
584 
585 	DMSG("element: %s on node %s", node_name, drv_name);
586 
587 	memcpy(elt, &elt_new, sizeof(*elt));
588 
589 	added_node = true;
590 
591 	TAILQ_INSERT_TAIL(&dt_driver_probe_list, elt, link);
592 
593 	/* Hack here for TRACE_DEBUG messages on current probe list elements */
594 	if (TRACE_LEVEL >= TRACE_FLOW)
595 		print_probe_list(fdt);
596 
597 	return TEE_SUCCESS;
598 }
599 
600 /*
601  * Add a node to the probe list if a dt_driver matches target compatible.
602  *
603  * If @type is DT_DRIVER_ANY, probe list can hold only 1 driver to probe for
604  * the node. A node may probe several drivers if have a unique driver type.
605  *
606  * Return TEE_SUCCESS if compatible found
607  *	  TEE_ERROR_ITEM_NOT_FOUND if no matching driver
608  *	  TEE_ERROR_OUT_OF_MEMORY if heap is exhausted
609  */
610 static TEE_Result add_probe_node_by_compat(const void *fdt, int node,
611 					   const char *compat)
612 {
613 	TEE_Result res = TEE_ERROR_ITEM_NOT_FOUND;
614 	const struct dt_driver *dt_drv = NULL;
615 	const struct dt_device_match *dm = NULL;
616 	uint32_t found_types = 0;
617 
618 	for_each_dt_driver(dt_drv) {
619 		for (dm = dt_drv->match_table; dm && dm->compatible; dm++) {
620 			if (strcmp(dm->compatible, compat) == 0) {
621 				assert(dt_drv->type < 32);
622 
623 				res = add_node_to_probe(fdt, node, dt_drv, dm);
624 				if (res)
625 					return res;
626 
627 				if (found_types & BIT(dt_drv->type)) {
628 					EMSG("Driver %s multi hit on type %u",
629 					     dt_drv->name, dt_drv->type);
630 					panic();
631 				}
632 				found_types |= BIT(dt_drv->type);
633 
634 				/* Matching found for this driver, try next */
635 				break;
636 			}
637 		}
638 	}
639 
640 	return res;
641 }
642 
643 /*
644  * Add the node to the probe list if matching compatible drivers are found.
645  * Follow node's compatible property list ordering to find matching driver.
646  */
647 TEE_Result dt_driver_maybe_add_probe_node(const void *fdt, int node)
648 {
649 	int idx = 0;
650 	int len = 0;
651 	int count = 0;
652 	const char *compat = NULL;
653 	TEE_Result res = TEE_ERROR_GENERIC;
654 
655 	if (fdt_get_status(fdt, node) == DT_STATUS_DISABLED)
656 		return TEE_SUCCESS;
657 
658 	count = fdt_stringlist_count(fdt, node, "compatible");
659 	if (count < 0)
660 		return TEE_SUCCESS;
661 
662 	for (idx = 0; idx < count; idx++) {
663 		compat = fdt_stringlist_get(fdt, node, "compatible", idx, &len);
664 		assert(compat && len > 0);
665 
666 		res = add_probe_node_by_compat(fdt, node, compat);
667 
668 		/* Stop lookup if something was found */
669 		if (res != TEE_ERROR_ITEM_NOT_FOUND)
670 			return res;
671 	}
672 
673 	return TEE_SUCCESS;
674 }
675 
676 static void parse_node(const void *fdt, int node)
677 {
678 	TEE_Result __maybe_unused res = TEE_ERROR_GENERIC;
679 	int subnode = 0;
680 
681 	fdt_for_each_subnode(subnode, fdt, node) {
682 		res = dt_driver_maybe_add_probe_node(fdt, subnode);
683 		if (res) {
684 			EMSG("Failed on node %s with %#"PRIx32,
685 			     fdt_get_name(fdt, subnode, NULL), res);
686 			panic();
687 		}
688 
689 		/*
690 		 * Rescursively parse the FDT, skipping disabled nodes.
691 		 * FDT is expected reliable and core shall have sufficient
692 		 * stack depth to possibly parse all DT nodes.
693 		 */
694 		if (IS_ENABLED(CFG_DRIVERS_DT_RECURSIVE_PROBE)) {
695 			if (fdt_get_status(fdt, subnode) == DT_STATUS_DISABLED)
696 				continue;
697 
698 			parse_node(fdt, subnode);
699 		}
700 	}
701 }
702 
703 /*
704  * Parse FDT for nodes and save in probe list the node for which a dt_driver
705  * matches node's compatible property.
706  */
707 static TEE_Result probe_dt_drivers_early(void)
708 {
709 	TEE_Result res = TEE_ERROR_GENERIC;
710 	const void *fdt = NULL;
711 
712 	fdt = get_secure_dt();
713 	if (!fdt)
714 		return TEE_SUCCESS;
715 
716 	parse_node(fdt, fdt_path_offset(fdt, "/"));
717 
718 	res = process_probe_list(fdt);
719 	if (res == TEE_ERROR_DEFER_DRIVER_INIT) {
720 		DMSG("Deferred drivers probing");
721 		print_probe_list(fdt);
722 		res = TEE_SUCCESS;
723 	}
724 
725 	return res;
726 }
727 
728 static TEE_Result probe_dt_drivers(void)
729 {
730 	TEE_Result res = TEE_ERROR_GENERIC;
731 	const void *fdt = NULL;
732 
733 	fdt = get_secure_dt();
734 	if (!fdt)
735 		return TEE_SUCCESS;
736 
737 	res = process_probe_list(fdt);
738 	if (res || !TAILQ_EMPTY(&dt_driver_failed_list)) {
739 		EMSG("Probe sequence result: %#"PRIx32, res);
740 		print_probe_list(fdt);
741 	}
742 	if (res)
743 		panic();
744 
745 	return TEE_SUCCESS;
746 }
747 
748 early_init_late(probe_dt_drivers_early);
749 driver_init(probe_dt_drivers);
750 
751 static TEE_Result release_probe_lists(void)
752 {
753 	struct dt_driver_probe *elt = NULL;
754 	struct dt_driver_probe *next = NULL;
755 	struct dt_driver_provider *prov = NULL;
756 	struct dt_driver_provider *next_prov = NULL;
757 	const void *fdt = NULL;
758 
759 	fdt = get_secure_dt();
760 	if (!fdt)
761 		return TEE_SUCCESS;
762 
763 	assert(fdt && TAILQ_EMPTY(&dt_driver_probe_list));
764 
765 	TAILQ_FOREACH_SAFE(elt, &dt_driver_ready_list, link, next)
766 		free(elt);
767 
768 	TAILQ_FOREACH_SAFE(elt, &dt_driver_failed_list, link, next)
769 	       free(elt);
770 
771 	SLIST_FOREACH_SAFE(prov, &dt_driver_provider_list, link, next_prov)
772 	       free(prov);
773 
774 	return TEE_SUCCESS;
775 }
776 
777 release_init_resource(release_probe_lists);
778 
779 /*
780  * Simple bus support: handy to parse subnodes
781  */
782 static TEE_Result simple_bus_probe(const void *fdt, int node,
783 				   const void *compat_data __unused)
784 {
785 	TEE_Result res = TEE_ERROR_GENERIC;
786 	int subnode = 0;
787 
788 	fdt_for_each_subnode(subnode, fdt, node) {
789 		res = dt_driver_maybe_add_probe_node(fdt, subnode);
790 		if (res) {
791 			EMSG("Failed on node %s with %#"PRIx32,
792 			     fdt_get_name(fdt, subnode, NULL), res);
793 			panic();
794 		}
795 	}
796 
797 	return TEE_SUCCESS;
798 }
799 
800 static const struct dt_device_match simple_bus_match_table[] = {
801 	{ .compatible = "simple-bus" },
802 	{ }
803 };
804 
805 DEFINE_DT_DRIVER(simple_bus_dt_driver) = {
806 	.name = "simple-bus",
807 	.match_table = simple_bus_match_table,
808 	.probe = simple_bus_probe,
809 };
810