xref: /openbmc/linux/drivers/acpi/acpica/evregion.c (revision 5f32c314)
1 /******************************************************************************
2  *
3  * Module Name: evregion - Operation Region support
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2013, Intel Corp.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions, and the following disclaimer,
16  *    without modification.
17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18  *    substantially similar to the "NO WARRANTY" disclaimer below
19  *    ("Disclaimer") and any redistribution must be conditioned upon
20  *    including a substantially similar Disclaimer requirement for further
21  *    binary redistribution.
22  * 3. Neither the names of the above-listed copyright holders nor the names
23  *    of any contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * Alternatively, this software may be distributed under the terms of the
27  * GNU General Public License ("GPL") version 2 as published by the Free
28  * Software Foundation.
29  *
30  * NO WARRANTY
31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41  * POSSIBILITY OF SUCH DAMAGES.
42  */
43 
44 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "acevents.h"
47 #include "acnamesp.h"
48 #include "acinterp.h"
49 
50 #define _COMPONENT          ACPI_EVENTS
51 ACPI_MODULE_NAME("evregion")
52 
53 extern u8 acpi_gbl_default_address_spaces[];
54 
55 /* Local prototypes */
56 
57 static void
58 acpi_ev_orphan_ec_reg_method(struct acpi_namespace_node *ec_device_node);
59 
60 static acpi_status
61 acpi_ev_reg_run(acpi_handle obj_handle,
62 		u32 level, void *context, void **return_value);
63 
64 /*******************************************************************************
65  *
66  * FUNCTION:    acpi_ev_initialize_op_regions
67  *
68  * PARAMETERS:  None
69  *
70  * RETURN:      Status
71  *
72  * DESCRIPTION: Execute _REG methods for all Operation Regions that have
73  *              an installed default region handler.
74  *
75  ******************************************************************************/
76 
77 acpi_status acpi_ev_initialize_op_regions(void)
78 {
79 	acpi_status status;
80 	u32 i;
81 
82 	ACPI_FUNCTION_TRACE(ev_initialize_op_regions);
83 
84 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
85 	if (ACPI_FAILURE(status)) {
86 		return_ACPI_STATUS(status);
87 	}
88 
89 	/* Run the _REG methods for op_regions in each default address space */
90 
91 	for (i = 0; i < ACPI_NUM_DEFAULT_SPACES; i++) {
92 		/*
93 		 * Make sure the installed handler is the DEFAULT handler. If not the
94 		 * default, the _REG methods will have already been run (when the
95 		 * handler was installed)
96 		 */
97 		if (acpi_ev_has_default_handler(acpi_gbl_root_node,
98 						acpi_gbl_default_address_spaces
99 						[i])) {
100 			status =
101 			    acpi_ev_execute_reg_methods(acpi_gbl_root_node,
102 							acpi_gbl_default_address_spaces
103 							[i]);
104 		}
105 	}
106 
107 	acpi_gbl_reg_methods_executed = TRUE;
108 
109 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
110 	return_ACPI_STATUS(status);
111 }
112 
113 /*******************************************************************************
114  *
115  * FUNCTION:    acpi_ev_address_space_dispatch
116  *
117  * PARAMETERS:  region_obj          - Internal region object
118  *              field_obj           - Corresponding field. Can be NULL.
119  *              function            - Read or Write operation
120  *              region_offset       - Where in the region to read or write
121  *              bit_width           - Field width in bits (8, 16, 32, or 64)
122  *              value               - Pointer to in or out value, must be
123  *                                    a full 64-bit integer
124  *
125  * RETURN:      Status
126  *
127  * DESCRIPTION: Dispatch an address space or operation region access to
128  *              a previously installed handler.
129  *
130  ******************************************************************************/
131 
132 acpi_status
133 acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
134 			       union acpi_operand_object *field_obj,
135 			       u32 function,
136 			       u32 region_offset, u32 bit_width, u64 *value)
137 {
138 	acpi_status status;
139 	acpi_adr_space_handler handler;
140 	acpi_adr_space_setup region_setup;
141 	union acpi_operand_object *handler_desc;
142 	union acpi_operand_object *region_obj2;
143 	void *region_context = NULL;
144 	struct acpi_connection_info *context;
145 
146 	ACPI_FUNCTION_TRACE(ev_address_space_dispatch);
147 
148 	region_obj2 = acpi_ns_get_secondary_object(region_obj);
149 	if (!region_obj2) {
150 		return_ACPI_STATUS(AE_NOT_EXIST);
151 	}
152 
153 	/* Ensure that there is a handler associated with this region */
154 
155 	handler_desc = region_obj->region.handler;
156 	if (!handler_desc) {
157 		ACPI_ERROR((AE_INFO,
158 			    "No handler for Region [%4.4s] (%p) [%s]",
159 			    acpi_ut_get_node_name(region_obj->region.node),
160 			    region_obj,
161 			    acpi_ut_get_region_name(region_obj->region.
162 						    space_id)));
163 
164 		return_ACPI_STATUS(AE_NOT_EXIST);
165 	}
166 
167 	context = handler_desc->address_space.context;
168 
169 	/*
170 	 * It may be the case that the region has never been initialized.
171 	 * Some types of regions require special init code
172 	 */
173 	if (!(region_obj->region.flags & AOPOBJ_SETUP_COMPLETE)) {
174 
175 		/* This region has not been initialized yet, do it */
176 
177 		region_setup = handler_desc->address_space.setup;
178 		if (!region_setup) {
179 
180 			/* No initialization routine, exit with error */
181 
182 			ACPI_ERROR((AE_INFO,
183 				    "No init routine for region(%p) [%s]",
184 				    region_obj,
185 				    acpi_ut_get_region_name(region_obj->region.
186 							    space_id)));
187 			return_ACPI_STATUS(AE_NOT_EXIST);
188 		}
189 
190 		/*
191 		 * We must exit the interpreter because the region setup will
192 		 * potentially execute control methods (for example, the _REG method
193 		 * for this region)
194 		 */
195 		acpi_ex_exit_interpreter();
196 
197 		status = region_setup(region_obj, ACPI_REGION_ACTIVATE,
198 				      context, &region_context);
199 
200 		/* Re-enter the interpreter */
201 
202 		acpi_ex_enter_interpreter();
203 
204 		/* Check for failure of the Region Setup */
205 
206 		if (ACPI_FAILURE(status)) {
207 			ACPI_EXCEPTION((AE_INFO, status,
208 					"During region initialization: [%s]",
209 					acpi_ut_get_region_name(region_obj->
210 								region.
211 								space_id)));
212 			return_ACPI_STATUS(status);
213 		}
214 
215 		/* Region initialization may have been completed by region_setup */
216 
217 		if (!(region_obj->region.flags & AOPOBJ_SETUP_COMPLETE)) {
218 			region_obj->region.flags |= AOPOBJ_SETUP_COMPLETE;
219 
220 			/*
221 			 * Save the returned context for use in all accesses to
222 			 * the handler for this particular region
223 			 */
224 			if (!(region_obj2->extra.region_context)) {
225 				region_obj2->extra.region_context =
226 				    region_context;
227 			}
228 		}
229 	}
230 
231 	/* We have everything we need, we can invoke the address space handler */
232 
233 	handler = handler_desc->address_space.handler;
234 
235 	ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
236 			  "Handler %p (@%p) Address %8.8X%8.8X [%s]\n",
237 			  &region_obj->region.handler->address_space, handler,
238 			  ACPI_FORMAT_NATIVE_UINT(region_obj->region.address +
239 						  region_offset),
240 			  acpi_ut_get_region_name(region_obj->region.
241 						  space_id)));
242 
243 	/*
244 	 * Special handling for generic_serial_bus and general_purpose_io:
245 	 * There are three extra parameters that must be passed to the
246 	 * handler via the context:
247 	 *   1) Connection buffer, a resource template from Connection() op.
248 	 *   2) Length of the above buffer.
249 	 *   3) Actual access length from the access_as() op.
250 	 */
251 	if (((region_obj->region.space_id == ACPI_ADR_SPACE_GSBUS) ||
252 	     (region_obj->region.space_id == ACPI_ADR_SPACE_GPIO)) &&
253 	    context && field_obj) {
254 
255 		/* Get the Connection (resource_template) buffer */
256 
257 		context->connection = field_obj->field.resource_buffer;
258 		context->length = field_obj->field.resource_length;
259 		context->access_length = field_obj->field.access_length;
260 	}
261 
262 	if (!(handler_desc->address_space.handler_flags &
263 	      ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) {
264 		/*
265 		 * For handlers other than the default (supplied) handlers, we must
266 		 * exit the interpreter because the handler *might* block -- we don't
267 		 * know what it will do, so we can't hold the lock on the intepreter.
268 		 */
269 		acpi_ex_exit_interpreter();
270 	}
271 
272 	/* Call the handler */
273 
274 	status = handler(function,
275 			 (region_obj->region.address + region_offset),
276 			 bit_width, value, context,
277 			 region_obj2->extra.region_context);
278 
279 	if (ACPI_FAILURE(status)) {
280 		ACPI_EXCEPTION((AE_INFO, status, "Returned by Handler for [%s]",
281 				acpi_ut_get_region_name(region_obj->region.
282 							space_id)));
283 	}
284 
285 	if (!(handler_desc->address_space.handler_flags &
286 	      ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) {
287 		/*
288 		 * We just returned from a non-default handler, we must re-enter the
289 		 * interpreter
290 		 */
291 		acpi_ex_enter_interpreter();
292 	}
293 
294 	return_ACPI_STATUS(status);
295 }
296 
297 /*******************************************************************************
298  *
299  * FUNCTION:    acpi_ev_detach_region
300  *
301  * PARAMETERS:  region_obj          - Region Object
302  *              acpi_ns_is_locked   - Namespace Region Already Locked?
303  *
304  * RETURN:      None
305  *
306  * DESCRIPTION: Break the association between the handler and the region
307  *              this is a two way association.
308  *
309  ******************************************************************************/
310 
311 void
312 acpi_ev_detach_region(union acpi_operand_object *region_obj,
313 		      u8 acpi_ns_is_locked)
314 {
315 	union acpi_operand_object *handler_obj;
316 	union acpi_operand_object *obj_desc;
317 	union acpi_operand_object **last_obj_ptr;
318 	acpi_adr_space_setup region_setup;
319 	void **region_context;
320 	union acpi_operand_object *region_obj2;
321 	acpi_status status;
322 
323 	ACPI_FUNCTION_TRACE(ev_detach_region);
324 
325 	region_obj2 = acpi_ns_get_secondary_object(region_obj);
326 	if (!region_obj2) {
327 		return_VOID;
328 	}
329 	region_context = &region_obj2->extra.region_context;
330 
331 	/* Get the address handler from the region object */
332 
333 	handler_obj = region_obj->region.handler;
334 	if (!handler_obj) {
335 
336 		/* This region has no handler, all done */
337 
338 		return_VOID;
339 	}
340 
341 	/* Find this region in the handler's list */
342 
343 	obj_desc = handler_obj->address_space.region_list;
344 	last_obj_ptr = &handler_obj->address_space.region_list;
345 
346 	while (obj_desc) {
347 
348 		/* Is this the correct Region? */
349 
350 		if (obj_desc == region_obj) {
351 			ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
352 					  "Removing Region %p from address handler %p\n",
353 					  region_obj, handler_obj));
354 
355 			/* This is it, remove it from the handler's list */
356 
357 			*last_obj_ptr = obj_desc->region.next;
358 			obj_desc->region.next = NULL;	/* Must clear field */
359 
360 			if (acpi_ns_is_locked) {
361 				status =
362 				    acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
363 				if (ACPI_FAILURE(status)) {
364 					return_VOID;
365 				}
366 			}
367 
368 			/* Now stop region accesses by executing the _REG method */
369 
370 			status =
371 			    acpi_ev_execute_reg_method(region_obj,
372 						       ACPI_REG_DISCONNECT);
373 			if (ACPI_FAILURE(status)) {
374 				ACPI_EXCEPTION((AE_INFO, status,
375 						"from region _REG, [%s]",
376 						acpi_ut_get_region_name
377 						(region_obj->region.space_id)));
378 			}
379 
380 			if (acpi_ns_is_locked) {
381 				status =
382 				    acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
383 				if (ACPI_FAILURE(status)) {
384 					return_VOID;
385 				}
386 			}
387 
388 			/*
389 			 * If the region has been activated, call the setup handler with
390 			 * the deactivate notification
391 			 */
392 			if (region_obj->region.flags & AOPOBJ_SETUP_COMPLETE) {
393 				region_setup = handler_obj->address_space.setup;
394 				status =
395 				    region_setup(region_obj,
396 						 ACPI_REGION_DEACTIVATE,
397 						 handler_obj->address_space.
398 						 context, region_context);
399 
400 				/*
401 				 * region_context should have been released by the deactivate
402 				 * operation. We don't need access to it anymore here.
403 				 */
404 				if (region_context) {
405 					*region_context = NULL;
406 				}
407 
408 				/* Init routine may fail, Just ignore errors */
409 
410 				if (ACPI_FAILURE(status)) {
411 					ACPI_EXCEPTION((AE_INFO, status,
412 							"from region handler - deactivate, [%s]",
413 							acpi_ut_get_region_name
414 							(region_obj->region.
415 							 space_id)));
416 				}
417 
418 				region_obj->region.flags &=
419 				    ~(AOPOBJ_SETUP_COMPLETE);
420 			}
421 
422 			/*
423 			 * Remove handler reference in the region
424 			 *
425 			 * NOTE: this doesn't mean that the region goes away, the region
426 			 * is just inaccessible as indicated to the _REG method
427 			 *
428 			 * If the region is on the handler's list, this must be the
429 			 * region's handler
430 			 */
431 			region_obj->region.handler = NULL;
432 			acpi_ut_remove_reference(handler_obj);
433 
434 			return_VOID;
435 		}
436 
437 		/* Walk the linked list of handlers */
438 
439 		last_obj_ptr = &obj_desc->region.next;
440 		obj_desc = obj_desc->region.next;
441 	}
442 
443 	/* If we get here, the region was not in the handler's region list */
444 
445 	ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
446 			  "Cannot remove region %p from address handler %p\n",
447 			  region_obj, handler_obj));
448 
449 	return_VOID;
450 }
451 
452 /*******************************************************************************
453  *
454  * FUNCTION:    acpi_ev_attach_region
455  *
456  * PARAMETERS:  handler_obj         - Handler Object
457  *              region_obj          - Region Object
458  *              acpi_ns_is_locked   - Namespace Region Already Locked?
459  *
460  * RETURN:      None
461  *
462  * DESCRIPTION: Create the association between the handler and the region
463  *              this is a two way association.
464  *
465  ******************************************************************************/
466 
467 acpi_status
468 acpi_ev_attach_region(union acpi_operand_object *handler_obj,
469 		      union acpi_operand_object *region_obj,
470 		      u8 acpi_ns_is_locked)
471 {
472 
473 	ACPI_FUNCTION_TRACE(ev_attach_region);
474 
475 	ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
476 			  "Adding Region [%4.4s] %p to address handler %p [%s]\n",
477 			  acpi_ut_get_node_name(region_obj->region.node),
478 			  region_obj, handler_obj,
479 			  acpi_ut_get_region_name(region_obj->region.
480 						  space_id)));
481 
482 	/* Link this region to the front of the handler's list */
483 
484 	region_obj->region.next = handler_obj->address_space.region_list;
485 	handler_obj->address_space.region_list = region_obj;
486 
487 	/* Install the region's handler */
488 
489 	if (region_obj->region.handler) {
490 		return_ACPI_STATUS(AE_ALREADY_EXISTS);
491 	}
492 
493 	region_obj->region.handler = handler_obj;
494 	acpi_ut_add_reference(handler_obj);
495 
496 	return_ACPI_STATUS(AE_OK);
497 }
498 
499 /*******************************************************************************
500  *
501  * FUNCTION:    acpi_ev_execute_reg_method
502  *
503  * PARAMETERS:  region_obj          - Region object
504  *              function            - Passed to _REG: On (1) or Off (0)
505  *
506  * RETURN:      Status
507  *
508  * DESCRIPTION: Execute _REG method for a region
509  *
510  ******************************************************************************/
511 
512 acpi_status
513 acpi_ev_execute_reg_method(union acpi_operand_object *region_obj, u32 function)
514 {
515 	struct acpi_evaluate_info *info;
516 	union acpi_operand_object *args[3];
517 	union acpi_operand_object *region_obj2;
518 	acpi_status status;
519 
520 	ACPI_FUNCTION_TRACE(ev_execute_reg_method);
521 
522 	region_obj2 = acpi_ns_get_secondary_object(region_obj);
523 	if (!region_obj2) {
524 		return_ACPI_STATUS(AE_NOT_EXIST);
525 	}
526 
527 	if (region_obj2->extra.method_REG == NULL) {
528 		return_ACPI_STATUS(AE_OK);
529 	}
530 
531 	/* Allocate and initialize the evaluation information block */
532 
533 	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
534 	if (!info) {
535 		return_ACPI_STATUS(AE_NO_MEMORY);
536 	}
537 
538 	info->prefix_node = region_obj2->extra.method_REG;
539 	info->relative_pathname = NULL;
540 	info->parameters = args;
541 	info->flags = ACPI_IGNORE_RETURN_VALUE;
542 
543 	/*
544 	 * The _REG method has two arguments:
545 	 *
546 	 * arg0 - Integer:
547 	 *  Operation region space ID Same value as region_obj->Region.space_id
548 	 *
549 	 * arg1 - Integer:
550 	 *  connection status 1 for connecting the handler, 0 for disconnecting
551 	 *  the handler (Passed as a parameter)
552 	 */
553 	args[0] =
554 	    acpi_ut_create_integer_object((u64)region_obj->region.space_id);
555 	if (!args[0]) {
556 		status = AE_NO_MEMORY;
557 		goto cleanup1;
558 	}
559 
560 	args[1] = acpi_ut_create_integer_object((u64)function);
561 	if (!args[1]) {
562 		status = AE_NO_MEMORY;
563 		goto cleanup2;
564 	}
565 
566 	args[2] = NULL;		/* Terminate list */
567 
568 	/* Execute the method, no return value */
569 
570 	ACPI_DEBUG_EXEC(acpi_ut_display_init_pathname
571 			(ACPI_TYPE_METHOD, info->prefix_node, NULL));
572 
573 	status = acpi_ns_evaluate(info);
574 	acpi_ut_remove_reference(args[1]);
575 
576 cleanup2:
577 	acpi_ut_remove_reference(args[0]);
578 
579 cleanup1:
580 	ACPI_FREE(info);
581 	return_ACPI_STATUS(status);
582 }
583 
584 /*******************************************************************************
585  *
586  * FUNCTION:    acpi_ev_execute_reg_methods
587  *
588  * PARAMETERS:  node            - Namespace node for the device
589  *              space_id        - The address space ID
590  *
591  * RETURN:      Status
592  *
593  * DESCRIPTION: Run all _REG methods for the input Space ID;
594  *              Note: assumes namespace is locked, or system init time.
595  *
596  ******************************************************************************/
597 
598 acpi_status
599 acpi_ev_execute_reg_methods(struct acpi_namespace_node *node,
600 			    acpi_adr_space_type space_id)
601 {
602 	acpi_status status;
603 
604 	ACPI_FUNCTION_TRACE(ev_execute_reg_methods);
605 
606 	/*
607 	 * Run all _REG methods for all Operation Regions for this space ID. This
608 	 * is a separate walk in order to handle any interdependencies between
609 	 * regions and _REG methods. (i.e. handlers must be installed for all
610 	 * regions of this Space ID before we can run any _REG methods)
611 	 */
612 	status = acpi_ns_walk_namespace(ACPI_TYPE_ANY, node, ACPI_UINT32_MAX,
613 					ACPI_NS_WALK_UNLOCK, acpi_ev_reg_run,
614 					NULL, &space_id, NULL);
615 
616 	/* Special case for EC: handle "orphan" _REG methods with no region */
617 
618 	if (space_id == ACPI_ADR_SPACE_EC) {
619 		acpi_ev_orphan_ec_reg_method(node);
620 	}
621 
622 	return_ACPI_STATUS(status);
623 }
624 
625 /*******************************************************************************
626  *
627  * FUNCTION:    acpi_ev_reg_run
628  *
629  * PARAMETERS:  walk_namespace callback
630  *
631  * DESCRIPTION: Run _REG method for region objects of the requested spaceID
632  *
633  ******************************************************************************/
634 
635 static acpi_status
636 acpi_ev_reg_run(acpi_handle obj_handle,
637 		u32 level, void *context, void **return_value)
638 {
639 	union acpi_operand_object *obj_desc;
640 	struct acpi_namespace_node *node;
641 	acpi_adr_space_type space_id;
642 	acpi_status status;
643 
644 	space_id = *ACPI_CAST_PTR(acpi_adr_space_type, context);
645 
646 	/* Convert and validate the device handle */
647 
648 	node = acpi_ns_validate_handle(obj_handle);
649 	if (!node) {
650 		return (AE_BAD_PARAMETER);
651 	}
652 
653 	/*
654 	 * We only care about regions.and objects that are allowed to have address
655 	 * space handlers
656 	 */
657 	if ((node->type != ACPI_TYPE_REGION) && (node != acpi_gbl_root_node)) {
658 		return (AE_OK);
659 	}
660 
661 	/* Check for an existing internal object */
662 
663 	obj_desc = acpi_ns_get_attached_object(node);
664 	if (!obj_desc) {
665 
666 		/* No object, just exit */
667 
668 		return (AE_OK);
669 	}
670 
671 	/* Object is a Region */
672 
673 	if (obj_desc->region.space_id != space_id) {
674 
675 		/* This region is for a different address space, just ignore it */
676 
677 		return (AE_OK);
678 	}
679 
680 	status = acpi_ev_execute_reg_method(obj_desc, ACPI_REG_CONNECT);
681 	return (status);
682 }
683 
684 /*******************************************************************************
685  *
686  * FUNCTION:    acpi_ev_orphan_ec_reg_method
687  *
688  * PARAMETERS:  ec_device_node      - Namespace node for an EC device
689  *
690  * RETURN:      None
691  *
692  * DESCRIPTION: Execute an "orphan" _REG method that appears under the EC
693  *              device. This is a _REG method that has no corresponding region
694  *              within the EC device scope. The orphan _REG method appears to
695  *              have been enabled by the description of the ECDT in the ACPI
696  *              specification: "The availability of the region space can be
697  *              detected by providing a _REG method object underneath the
698  *              Embedded Controller device."
699  *
700  *              To quickly access the EC device, we use the ec_device_node used
701  *              during EC handler installation. Otherwise, we would need to
702  *              perform a time consuming namespace walk, executing _HID
703  *              methods to find the EC device.
704  *
705  *  MUTEX:      Assumes the namespace is locked
706  *
707  ******************************************************************************/
708 
709 static void
710 acpi_ev_orphan_ec_reg_method(struct acpi_namespace_node *ec_device_node)
711 {
712 	acpi_handle reg_method;
713 	struct acpi_namespace_node *next_node;
714 	acpi_status status;
715 	struct acpi_object_list args;
716 	union acpi_object objects[2];
717 
718 	ACPI_FUNCTION_TRACE(ev_orphan_ec_reg_method);
719 
720 	if (!ec_device_node) {
721 		return_VOID;
722 	}
723 
724 	/* Namespace is currently locked, must release */
725 
726 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
727 
728 	/* Get a handle to a _REG method immediately under the EC device */
729 
730 	status = acpi_get_handle(ec_device_node, METHOD_NAME__REG, &reg_method);
731 	if (ACPI_FAILURE(status)) {
732 		goto exit;	/* There is no _REG method present */
733 	}
734 
735 	/*
736 	 * Execute the _REG method only if there is no Operation Region in
737 	 * this scope with the Embedded Controller space ID. Otherwise, it
738 	 * will already have been executed. Note, this allows for Regions
739 	 * with other space IDs to be present; but the code below will then
740 	 * execute the _REG method with the embedded_control space_ID argument.
741 	 */
742 	next_node = acpi_ns_get_next_node(ec_device_node, NULL);
743 	while (next_node) {
744 		if ((next_node->type == ACPI_TYPE_REGION) &&
745 		    (next_node->object) &&
746 		    (next_node->object->region.space_id == ACPI_ADR_SPACE_EC)) {
747 			goto exit;	/* Do not execute the _REG */
748 		}
749 
750 		next_node = acpi_ns_get_next_node(ec_device_node, next_node);
751 	}
752 
753 	/* Evaluate the _REG(embedded_control,Connect) method */
754 
755 	args.count = 2;
756 	args.pointer = objects;
757 	objects[0].type = ACPI_TYPE_INTEGER;
758 	objects[0].integer.value = ACPI_ADR_SPACE_EC;
759 	objects[1].type = ACPI_TYPE_INTEGER;
760 	objects[1].integer.value = ACPI_REG_CONNECT;
761 
762 	status = acpi_evaluate_object(reg_method, NULL, &args, NULL);
763 
764 exit:
765 	/* We ignore all errors from above, don't care */
766 
767 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
768 	return_VOID;
769 }
770