xref: /linux/drivers/acpi/sleep.c (revision 4eb7ae7a301d3586c3351e81d5c3cfe2304a1a6a)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * sleep.c - ACPI sleep support.
4  *
5  * Copyright (c) 2005 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
6  * Copyright (c) 2004 David Shaohua Li <shaohua.li@intel.com>
7  * Copyright (c) 2000-2003 Patrick Mochel
8  * Copyright (c) 2003 Open Source Development Lab
9  */
10 
11 #include <linux/delay.h>
12 #include <linux/irq.h>
13 #include <linux/dmi.h>
14 #include <linux/device.h>
15 #include <linux/interrupt.h>
16 #include <linux/suspend.h>
17 #include <linux/reboot.h>
18 #include <linux/acpi.h>
19 #include <linux/module.h>
20 #include <linux/syscore_ops.h>
21 #include <asm/io.h>
22 #include <trace/events/power.h>
23 
24 #include "internal.h"
25 #include "sleep.h"
26 
27 /*
28  * Some HW-full platforms do not have _S5, so they may need
29  * to leverage efi power off for a shutdown.
30  */
31 bool acpi_no_s5;
32 static u8 sleep_states[ACPI_S_STATE_COUNT];
33 
34 static void acpi_sleep_tts_switch(u32 acpi_state)
35 {
36 	acpi_status status;
37 
38 	status = acpi_execute_simple_method(NULL, "\\_TTS", acpi_state);
39 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
40 		/*
41 		 * OS can't evaluate the _TTS object correctly. Some warning
42 		 * message will be printed. But it won't break anything.
43 		 */
44 		printk(KERN_NOTICE "Failure in evaluating _TTS object\n");
45 	}
46 }
47 
48 static int tts_notify_reboot(struct notifier_block *this,
49 			unsigned long code, void *x)
50 {
51 	acpi_sleep_tts_switch(ACPI_STATE_S5);
52 	return NOTIFY_DONE;
53 }
54 
55 static struct notifier_block tts_notifier = {
56 	.notifier_call	= tts_notify_reboot,
57 	.next		= NULL,
58 	.priority	= 0,
59 };
60 
61 static int acpi_sleep_prepare(u32 acpi_state)
62 {
63 #ifdef CONFIG_ACPI_SLEEP
64 	/* do we have a wakeup address for S2 and S3? */
65 	if (acpi_state == ACPI_STATE_S3) {
66 		if (!acpi_wakeup_address)
67 			return -EFAULT;
68 		acpi_set_waking_vector(acpi_wakeup_address);
69 
70 	}
71 	ACPI_FLUSH_CPU_CACHE();
72 #endif
73 	printk(KERN_INFO PREFIX "Preparing to enter system sleep state S%d\n",
74 		acpi_state);
75 	acpi_enable_wakeup_devices(acpi_state);
76 	acpi_enter_sleep_state_prep(acpi_state);
77 	return 0;
78 }
79 
80 bool acpi_sleep_state_supported(u8 sleep_state)
81 {
82 	acpi_status status;
83 	u8 type_a, type_b;
84 
85 	status = acpi_get_sleep_type_data(sleep_state, &type_a, &type_b);
86 	return ACPI_SUCCESS(status) && (!acpi_gbl_reduced_hardware
87 		|| (acpi_gbl_FADT.sleep_control.address
88 			&& acpi_gbl_FADT.sleep_status.address));
89 }
90 
91 #ifdef CONFIG_ACPI_SLEEP
92 static bool sleep_no_lps0 __read_mostly;
93 module_param(sleep_no_lps0, bool, 0644);
94 MODULE_PARM_DESC(sleep_no_lps0, "Do not use the special LPS0 device interface");
95 
96 static u32 acpi_target_sleep_state = ACPI_STATE_S0;
97 
98 u32 acpi_target_system_state(void)
99 {
100 	return acpi_target_sleep_state;
101 }
102 EXPORT_SYMBOL_GPL(acpi_target_system_state);
103 
104 static bool pwr_btn_event_pending;
105 
106 /*
107  * The ACPI specification wants us to save NVS memory regions during hibernation
108  * and to restore them during the subsequent resume.  Windows does that also for
109  * suspend to RAM.  However, it is known that this mechanism does not work on
110  * all machines, so we allow the user to disable it with the help of the
111  * 'acpi_sleep=nonvs' kernel command line option.
112  */
113 static bool nvs_nosave;
114 
115 void __init acpi_nvs_nosave(void)
116 {
117 	nvs_nosave = true;
118 }
119 
120 /*
121  * The ACPI specification wants us to save NVS memory regions during hibernation
122  * but says nothing about saving NVS during S3.  Not all versions of Windows
123  * save NVS on S3 suspend either, and it is clear that not all systems need
124  * NVS to be saved at S3 time.  To improve suspend/resume time, allow the
125  * user to disable saving NVS on S3 if their system does not require it, but
126  * continue to save/restore NVS for S4 as specified.
127  */
128 static bool nvs_nosave_s3;
129 
130 void __init acpi_nvs_nosave_s3(void)
131 {
132 	nvs_nosave_s3 = true;
133 }
134 
135 static int __init init_nvs_save_s3(const struct dmi_system_id *d)
136 {
137 	nvs_nosave_s3 = false;
138 	return 0;
139 }
140 
141 /*
142  * ACPI 1.0 wants us to execute _PTS before suspending devices, so we allow the
143  * user to request that behavior by using the 'acpi_old_suspend_ordering'
144  * kernel command line option that causes the following variable to be set.
145  */
146 static bool old_suspend_ordering;
147 
148 void __init acpi_old_suspend_ordering(void)
149 {
150 	old_suspend_ordering = true;
151 }
152 
153 static int __init init_old_suspend_ordering(const struct dmi_system_id *d)
154 {
155 	acpi_old_suspend_ordering();
156 	return 0;
157 }
158 
159 static int __init init_nvs_nosave(const struct dmi_system_id *d)
160 {
161 	acpi_nvs_nosave();
162 	return 0;
163 }
164 
165 static bool acpi_sleep_default_s3;
166 
167 static int __init init_default_s3(const struct dmi_system_id *d)
168 {
169 	acpi_sleep_default_s3 = true;
170 	return 0;
171 }
172 
173 static const struct dmi_system_id acpisleep_dmi_table[] __initconst = {
174 	{
175 	.callback = init_old_suspend_ordering,
176 	.ident = "Abit KN9 (nForce4 variant)",
177 	.matches = {
178 		DMI_MATCH(DMI_BOARD_VENDOR, "http://www.abit.com.tw/"),
179 		DMI_MATCH(DMI_BOARD_NAME, "KN9 Series(NF-CK804)"),
180 		},
181 	},
182 	{
183 	.callback = init_old_suspend_ordering,
184 	.ident = "HP xw4600 Workstation",
185 	.matches = {
186 		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
187 		DMI_MATCH(DMI_PRODUCT_NAME, "HP xw4600 Workstation"),
188 		},
189 	},
190 	{
191 	.callback = init_old_suspend_ordering,
192 	.ident = "Asus Pundit P1-AH2 (M2N8L motherboard)",
193 	.matches = {
194 		DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTek Computer INC."),
195 		DMI_MATCH(DMI_BOARD_NAME, "M2N8L"),
196 		},
197 	},
198 	{
199 	.callback = init_old_suspend_ordering,
200 	.ident = "Panasonic CF51-2L",
201 	.matches = {
202 		DMI_MATCH(DMI_BOARD_VENDOR,
203 				"Matsushita Electric Industrial Co.,Ltd."),
204 		DMI_MATCH(DMI_BOARD_NAME, "CF51-2L"),
205 		},
206 	},
207 	{
208 	.callback = init_nvs_nosave,
209 	.ident = "Sony Vaio VGN-FW41E_H",
210 	.matches = {
211 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
212 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-FW41E_H"),
213 		},
214 	},
215 	{
216 	.callback = init_nvs_nosave,
217 	.ident = "Sony Vaio VGN-FW21E",
218 	.matches = {
219 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
220 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-FW21E"),
221 		},
222 	},
223 	{
224 	.callback = init_nvs_nosave,
225 	.ident = "Sony Vaio VGN-FW21M",
226 	.matches = {
227 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
228 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-FW21M"),
229 		},
230 	},
231 	{
232 	.callback = init_nvs_nosave,
233 	.ident = "Sony Vaio VPCEB17FX",
234 	.matches = {
235 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
236 		DMI_MATCH(DMI_PRODUCT_NAME, "VPCEB17FX"),
237 		},
238 	},
239 	{
240 	.callback = init_nvs_nosave,
241 	.ident = "Sony Vaio VGN-SR11M",
242 	.matches = {
243 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
244 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-SR11M"),
245 		},
246 	},
247 	{
248 	.callback = init_nvs_nosave,
249 	.ident = "Everex StepNote Series",
250 	.matches = {
251 		DMI_MATCH(DMI_SYS_VENDOR, "Everex Systems, Inc."),
252 		DMI_MATCH(DMI_PRODUCT_NAME, "Everex StepNote Series"),
253 		},
254 	},
255 	{
256 	.callback = init_nvs_nosave,
257 	.ident = "Sony Vaio VPCEB1Z1E",
258 	.matches = {
259 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
260 		DMI_MATCH(DMI_PRODUCT_NAME, "VPCEB1Z1E"),
261 		},
262 	},
263 	{
264 	.callback = init_nvs_nosave,
265 	.ident = "Sony Vaio VGN-NW130D",
266 	.matches = {
267 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
268 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-NW130D"),
269 		},
270 	},
271 	{
272 	.callback = init_nvs_nosave,
273 	.ident = "Sony Vaio VPCCW29FX",
274 	.matches = {
275 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
276 		DMI_MATCH(DMI_PRODUCT_NAME, "VPCCW29FX"),
277 		},
278 	},
279 	{
280 	.callback = init_nvs_nosave,
281 	.ident = "Averatec AV1020-ED2",
282 	.matches = {
283 		DMI_MATCH(DMI_SYS_VENDOR, "AVERATEC"),
284 		DMI_MATCH(DMI_PRODUCT_NAME, "1000 Series"),
285 		},
286 	},
287 	{
288 	.callback = init_old_suspend_ordering,
289 	.ident = "Asus A8N-SLI DELUXE",
290 	.matches = {
291 		DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
292 		DMI_MATCH(DMI_BOARD_NAME, "A8N-SLI DELUXE"),
293 		},
294 	},
295 	{
296 	.callback = init_old_suspend_ordering,
297 	.ident = "Asus A8N-SLI Premium",
298 	.matches = {
299 		DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
300 		DMI_MATCH(DMI_BOARD_NAME, "A8N-SLI Premium"),
301 		},
302 	},
303 	{
304 	.callback = init_nvs_nosave,
305 	.ident = "Sony Vaio VGN-SR26GN_P",
306 	.matches = {
307 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
308 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-SR26GN_P"),
309 		},
310 	},
311 	{
312 	.callback = init_nvs_nosave,
313 	.ident = "Sony Vaio VPCEB1S1E",
314 	.matches = {
315 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
316 		DMI_MATCH(DMI_PRODUCT_NAME, "VPCEB1S1E"),
317 		},
318 	},
319 	{
320 	.callback = init_nvs_nosave,
321 	.ident = "Sony Vaio VGN-FW520F",
322 	.matches = {
323 		DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
324 		DMI_MATCH(DMI_PRODUCT_NAME, "VGN-FW520F"),
325 		},
326 	},
327 	{
328 	.callback = init_nvs_nosave,
329 	.ident = "Asus K54C",
330 	.matches = {
331 		DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
332 		DMI_MATCH(DMI_PRODUCT_NAME, "K54C"),
333 		},
334 	},
335 	{
336 	.callback = init_nvs_nosave,
337 	.ident = "Asus K54HR",
338 	.matches = {
339 		DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
340 		DMI_MATCH(DMI_PRODUCT_NAME, "K54HR"),
341 		},
342 	},
343 	{
344 	.callback = init_nvs_save_s3,
345 	.ident = "Asus 1025C",
346 	.matches = {
347 		DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
348 		DMI_MATCH(DMI_PRODUCT_NAME, "1025C"),
349 		},
350 	},
351 	/*
352 	 * https://bugzilla.kernel.org/show_bug.cgi?id=189431
353 	 * Lenovo G50-45 is a platform later than 2012, but needs nvs memory
354 	 * saving during S3.
355 	 */
356 	{
357 	.callback = init_nvs_save_s3,
358 	.ident = "Lenovo G50-45",
359 	.matches = {
360 		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
361 		DMI_MATCH(DMI_PRODUCT_NAME, "80E3"),
362 		},
363 	},
364 	/*
365 	 * ThinkPad X1 Tablet(2016) cannot do suspend-to-idle using
366 	 * the Low Power S0 Idle firmware interface (see
367 	 * https://bugzilla.kernel.org/show_bug.cgi?id=199057).
368 	 */
369 	{
370 	.callback = init_default_s3,
371 	.ident = "ThinkPad X1 Tablet(2016)",
372 	.matches = {
373 		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
374 		DMI_MATCH(DMI_PRODUCT_NAME, "20GGA00L00"),
375 		},
376 	},
377 	{},
378 };
379 
380 static bool ignore_blacklist;
381 
382 void __init acpi_sleep_no_blacklist(void)
383 {
384 	ignore_blacklist = true;
385 }
386 
387 static void __init acpi_sleep_dmi_check(void)
388 {
389 	if (ignore_blacklist)
390 		return;
391 
392 	if (dmi_get_bios_year() >= 2012)
393 		acpi_nvs_nosave_s3();
394 
395 	dmi_check_system(acpisleep_dmi_table);
396 }
397 
398 /**
399  * acpi_pm_freeze - Disable the GPEs and suspend EC transactions.
400  */
401 static int acpi_pm_freeze(void)
402 {
403 	acpi_disable_all_gpes();
404 	acpi_os_wait_events_complete();
405 	acpi_ec_block_transactions();
406 	return 0;
407 }
408 
409 /**
410  * acpi_pre_suspend - Enable wakeup devices, "freeze" EC and save NVS.
411  */
412 static int acpi_pm_pre_suspend(void)
413 {
414 	acpi_pm_freeze();
415 	return suspend_nvs_save();
416 }
417 
418 /**
419  *	__acpi_pm_prepare - Prepare the platform to enter the target state.
420  *
421  *	If necessary, set the firmware waking vector and do arch-specific
422  *	nastiness to get the wakeup code to the waking vector.
423  */
424 static int __acpi_pm_prepare(void)
425 {
426 	int error = acpi_sleep_prepare(acpi_target_sleep_state);
427 	if (error)
428 		acpi_target_sleep_state = ACPI_STATE_S0;
429 
430 	return error;
431 }
432 
433 /**
434  *	acpi_pm_prepare - Prepare the platform to enter the target sleep
435  *		state and disable the GPEs.
436  */
437 static int acpi_pm_prepare(void)
438 {
439 	int error = __acpi_pm_prepare();
440 	if (!error)
441 		error = acpi_pm_pre_suspend();
442 
443 	return error;
444 }
445 
446 /**
447  *	acpi_pm_finish - Instruct the platform to leave a sleep state.
448  *
449  *	This is called after we wake back up (or if entering the sleep state
450  *	failed).
451  */
452 static void acpi_pm_finish(void)
453 {
454 	struct acpi_device *pwr_btn_adev;
455 	u32 acpi_state = acpi_target_sleep_state;
456 
457 	acpi_ec_unblock_transactions();
458 	suspend_nvs_free();
459 
460 	if (acpi_state == ACPI_STATE_S0)
461 		return;
462 
463 	printk(KERN_INFO PREFIX "Waking up from system sleep state S%d\n",
464 		acpi_state);
465 	acpi_disable_wakeup_devices(acpi_state);
466 	acpi_leave_sleep_state(acpi_state);
467 
468 	/* reset firmware waking vector */
469 	acpi_set_waking_vector(0);
470 
471 	acpi_target_sleep_state = ACPI_STATE_S0;
472 
473 	acpi_resume_power_resources();
474 
475 	/* If we were woken with the fixed power button, provide a small
476 	 * hint to userspace in the form of a wakeup event on the fixed power
477 	 * button device (if it can be found).
478 	 *
479 	 * We delay the event generation til now, as the PM layer requires
480 	 * timekeeping to be running before we generate events. */
481 	if (!pwr_btn_event_pending)
482 		return;
483 
484 	pwr_btn_event_pending = false;
485 	pwr_btn_adev = acpi_dev_get_first_match_dev(ACPI_BUTTON_HID_POWERF,
486 						    NULL, -1);
487 	if (pwr_btn_adev) {
488 		pm_wakeup_event(&pwr_btn_adev->dev, 0);
489 		acpi_dev_put(pwr_btn_adev);
490 	}
491 }
492 
493 /**
494  * acpi_pm_start - Start system PM transition.
495  */
496 static void acpi_pm_start(u32 acpi_state)
497 {
498 	acpi_target_sleep_state = acpi_state;
499 	acpi_sleep_tts_switch(acpi_target_sleep_state);
500 	acpi_scan_lock_acquire();
501 }
502 
503 /**
504  * acpi_pm_end - Finish up system PM transition.
505  */
506 static void acpi_pm_end(void)
507 {
508 	acpi_turn_off_unused_power_resources();
509 	acpi_scan_lock_release();
510 	/*
511 	 * This is necessary in case acpi_pm_finish() is not called during a
512 	 * failing transition to a sleep state.
513 	 */
514 	acpi_target_sleep_state = ACPI_STATE_S0;
515 	acpi_sleep_tts_switch(acpi_target_sleep_state);
516 }
517 #else /* !CONFIG_ACPI_SLEEP */
518 #define sleep_no_lps0	(1)
519 #define acpi_target_sleep_state	ACPI_STATE_S0
520 #define acpi_sleep_default_s3	(1)
521 static inline void acpi_sleep_dmi_check(void) {}
522 #endif /* CONFIG_ACPI_SLEEP */
523 
524 #ifdef CONFIG_SUSPEND
525 static u32 acpi_suspend_states[] = {
526 	[PM_SUSPEND_ON] = ACPI_STATE_S0,
527 	[PM_SUSPEND_STANDBY] = ACPI_STATE_S1,
528 	[PM_SUSPEND_MEM] = ACPI_STATE_S3,
529 	[PM_SUSPEND_MAX] = ACPI_STATE_S5
530 };
531 
532 /**
533  *	acpi_suspend_begin - Set the target system sleep state to the state
534  *		associated with given @pm_state, if supported.
535  */
536 static int acpi_suspend_begin(suspend_state_t pm_state)
537 {
538 	u32 acpi_state = acpi_suspend_states[pm_state];
539 	int error;
540 
541 	error = (nvs_nosave || nvs_nosave_s3) ? 0 : suspend_nvs_alloc();
542 	if (error)
543 		return error;
544 
545 	if (!sleep_states[acpi_state]) {
546 		pr_err("ACPI does not support sleep state S%u\n", acpi_state);
547 		return -ENOSYS;
548 	}
549 	if (acpi_state > ACPI_STATE_S1)
550 		pm_set_suspend_via_firmware();
551 
552 	acpi_pm_start(acpi_state);
553 	return 0;
554 }
555 
556 /**
557  *	acpi_suspend_enter - Actually enter a sleep state.
558  *	@pm_state: ignored
559  *
560  *	Flush caches and go to sleep. For STR we have to call arch-specific
561  *	assembly, which in turn call acpi_enter_sleep_state().
562  *	It's unfortunate, but it works. Please fix if you're feeling frisky.
563  */
564 static int acpi_suspend_enter(suspend_state_t pm_state)
565 {
566 	acpi_status status = AE_OK;
567 	u32 acpi_state = acpi_target_sleep_state;
568 	int error;
569 
570 	ACPI_FLUSH_CPU_CACHE();
571 
572 	trace_suspend_resume(TPS("acpi_suspend"), acpi_state, true);
573 	switch (acpi_state) {
574 	case ACPI_STATE_S1:
575 		barrier();
576 		status = acpi_enter_sleep_state(acpi_state);
577 		break;
578 
579 	case ACPI_STATE_S3:
580 		if (!acpi_suspend_lowlevel)
581 			return -ENOSYS;
582 		error = acpi_suspend_lowlevel();
583 		if (error)
584 			return error;
585 		pr_info(PREFIX "Low-level resume complete\n");
586 		pm_set_resume_via_firmware();
587 		break;
588 	}
589 	trace_suspend_resume(TPS("acpi_suspend"), acpi_state, false);
590 
591 	/* This violates the spec but is required for bug compatibility. */
592 	acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
593 
594 	/* Reprogram control registers */
595 	acpi_leave_sleep_state_prep(acpi_state);
596 
597 	/* ACPI 3.0 specs (P62) says that it's the responsibility
598 	 * of the OSPM to clear the status bit [ implying that the
599 	 * POWER_BUTTON event should not reach userspace ]
600 	 *
601 	 * However, we do generate a small hint for userspace in the form of
602 	 * a wakeup event. We flag this condition for now and generate the
603 	 * event later, as we're currently too early in resume to be able to
604 	 * generate wakeup events.
605 	 */
606 	if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
607 		acpi_event_status pwr_btn_status = ACPI_EVENT_FLAG_DISABLED;
608 
609 		acpi_get_event_status(ACPI_EVENT_POWER_BUTTON, &pwr_btn_status);
610 
611 		if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET) {
612 			acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
613 			/* Flag for later */
614 			pwr_btn_event_pending = true;
615 		}
616 	}
617 
618 	/*
619 	 * Disable and clear GPE status before interrupt is enabled. Some GPEs
620 	 * (like wakeup GPE) haven't handler, this can avoid such GPE misfire.
621 	 * acpi_leave_sleep_state will reenable specific GPEs later
622 	 */
623 	acpi_disable_all_gpes();
624 	/* Allow EC transactions to happen. */
625 	acpi_ec_unblock_transactions();
626 
627 	suspend_nvs_restore();
628 
629 	return ACPI_SUCCESS(status) ? 0 : -EFAULT;
630 }
631 
632 static int acpi_suspend_state_valid(suspend_state_t pm_state)
633 {
634 	u32 acpi_state;
635 
636 	switch (pm_state) {
637 	case PM_SUSPEND_ON:
638 	case PM_SUSPEND_STANDBY:
639 	case PM_SUSPEND_MEM:
640 		acpi_state = acpi_suspend_states[pm_state];
641 
642 		return sleep_states[acpi_state];
643 	default:
644 		return 0;
645 	}
646 }
647 
648 static const struct platform_suspend_ops acpi_suspend_ops = {
649 	.valid = acpi_suspend_state_valid,
650 	.begin = acpi_suspend_begin,
651 	.prepare_late = acpi_pm_prepare,
652 	.enter = acpi_suspend_enter,
653 	.wake = acpi_pm_finish,
654 	.end = acpi_pm_end,
655 };
656 
657 /**
658  *	acpi_suspend_begin_old - Set the target system sleep state to the
659  *		state associated with given @pm_state, if supported, and
660  *		execute the _PTS control method.  This function is used if the
661  *		pre-ACPI 2.0 suspend ordering has been requested.
662  */
663 static int acpi_suspend_begin_old(suspend_state_t pm_state)
664 {
665 	int error = acpi_suspend_begin(pm_state);
666 	if (!error)
667 		error = __acpi_pm_prepare();
668 
669 	return error;
670 }
671 
672 /*
673  * The following callbacks are used if the pre-ACPI 2.0 suspend ordering has
674  * been requested.
675  */
676 static const struct platform_suspend_ops acpi_suspend_ops_old = {
677 	.valid = acpi_suspend_state_valid,
678 	.begin = acpi_suspend_begin_old,
679 	.prepare_late = acpi_pm_pre_suspend,
680 	.enter = acpi_suspend_enter,
681 	.wake = acpi_pm_finish,
682 	.end = acpi_pm_end,
683 	.recover = acpi_pm_finish,
684 };
685 
686 static bool s2idle_wakeup;
687 
688 /*
689  * On platforms supporting the Low Power S0 Idle interface there is an ACPI
690  * device object with the PNP0D80 compatible device ID (System Power Management
691  * Controller) and a specific _DSM method under it.  That method, if present,
692  * can be used to indicate to the platform that the OS is transitioning into a
693  * low-power state in which certain types of activity are not desirable or that
694  * it is leaving such a state, which allows the platform to adjust its operation
695  * mode accordingly.
696  */
697 static const struct acpi_device_id lps0_device_ids[] = {
698 	{"PNP0D80", },
699 	{"", },
700 };
701 
702 #define ACPI_LPS0_DSM_UUID	"c4eb40a0-6cd2-11e2-bcfd-0800200c9a66"
703 
704 #define ACPI_LPS0_GET_DEVICE_CONSTRAINTS	1
705 #define ACPI_LPS0_SCREEN_OFF	3
706 #define ACPI_LPS0_SCREEN_ON	4
707 #define ACPI_LPS0_ENTRY		5
708 #define ACPI_LPS0_EXIT		6
709 
710 static acpi_handle lps0_device_handle;
711 static guid_t lps0_dsm_guid;
712 static char lps0_dsm_func_mask;
713 
714 /* Device constraint entry structure */
715 struct lpi_device_info {
716 	char *name;
717 	int enabled;
718 	union acpi_object *package;
719 };
720 
721 /* Constraint package structure */
722 struct lpi_device_constraint {
723 	int uid;
724 	int min_dstate;
725 	int function_states;
726 };
727 
728 struct lpi_constraints {
729 	acpi_handle handle;
730 	int min_dstate;
731 };
732 
733 static struct lpi_constraints *lpi_constraints_table;
734 static int lpi_constraints_table_size;
735 
736 static void lpi_device_get_constraints(void)
737 {
738 	union acpi_object *out_obj;
739 	int i;
740 
741 	out_obj = acpi_evaluate_dsm_typed(lps0_device_handle, &lps0_dsm_guid,
742 					  1, ACPI_LPS0_GET_DEVICE_CONSTRAINTS,
743 					  NULL, ACPI_TYPE_PACKAGE);
744 
745 	acpi_handle_debug(lps0_device_handle, "_DSM function 1 eval %s\n",
746 			  out_obj ? "successful" : "failed");
747 
748 	if (!out_obj)
749 		return;
750 
751 	lpi_constraints_table = kcalloc(out_obj->package.count,
752 					sizeof(*lpi_constraints_table),
753 					GFP_KERNEL);
754 	if (!lpi_constraints_table)
755 		goto free_acpi_buffer;
756 
757 	acpi_handle_debug(lps0_device_handle, "LPI: constraints list begin:\n");
758 
759 	for (i = 0; i < out_obj->package.count; i++) {
760 		struct lpi_constraints *constraint;
761 		acpi_status status;
762 		union acpi_object *package = &out_obj->package.elements[i];
763 		struct lpi_device_info info = { };
764 		int package_count = 0, j;
765 
766 		if (!package)
767 			continue;
768 
769 		for (j = 0; j < package->package.count; ++j) {
770 			union acpi_object *element =
771 					&(package->package.elements[j]);
772 
773 			switch (element->type) {
774 			case ACPI_TYPE_INTEGER:
775 				info.enabled = element->integer.value;
776 				break;
777 			case ACPI_TYPE_STRING:
778 				info.name = element->string.pointer;
779 				break;
780 			case ACPI_TYPE_PACKAGE:
781 				package_count = element->package.count;
782 				info.package = element->package.elements;
783 				break;
784 			}
785 		}
786 
787 		if (!info.enabled || !info.package || !info.name)
788 			continue;
789 
790 		constraint = &lpi_constraints_table[lpi_constraints_table_size];
791 
792 		status = acpi_get_handle(NULL, info.name, &constraint->handle);
793 		if (ACPI_FAILURE(status))
794 			continue;
795 
796 		acpi_handle_debug(lps0_device_handle,
797 				  "index:%d Name:%s\n", i, info.name);
798 
799 		constraint->min_dstate = -1;
800 
801 		for (j = 0; j < package_count; ++j) {
802 			union acpi_object *info_obj = &info.package[j];
803 			union acpi_object *cnstr_pkg;
804 			union acpi_object *obj;
805 			struct lpi_device_constraint dev_info;
806 
807 			switch (info_obj->type) {
808 			case ACPI_TYPE_INTEGER:
809 				/* version */
810 				break;
811 			case ACPI_TYPE_PACKAGE:
812 				if (info_obj->package.count < 2)
813 					break;
814 
815 				cnstr_pkg = info_obj->package.elements;
816 				obj = &cnstr_pkg[0];
817 				dev_info.uid = obj->integer.value;
818 				obj = &cnstr_pkg[1];
819 				dev_info.min_dstate = obj->integer.value;
820 
821 				acpi_handle_debug(lps0_device_handle,
822 					"uid:%d min_dstate:%s\n",
823 					dev_info.uid,
824 					acpi_power_state_string(dev_info.min_dstate));
825 
826 				constraint->min_dstate = dev_info.min_dstate;
827 				break;
828 			}
829 		}
830 
831 		if (constraint->min_dstate < 0) {
832 			acpi_handle_debug(lps0_device_handle,
833 					  "Incomplete constraint defined\n");
834 			continue;
835 		}
836 
837 		lpi_constraints_table_size++;
838 	}
839 
840 	acpi_handle_debug(lps0_device_handle, "LPI: constraints list end\n");
841 
842 free_acpi_buffer:
843 	ACPI_FREE(out_obj);
844 }
845 
846 static void lpi_check_constraints(void)
847 {
848 	int i;
849 
850 	for (i = 0; i < lpi_constraints_table_size; ++i) {
851 		acpi_handle handle = lpi_constraints_table[i].handle;
852 		struct acpi_device *adev;
853 
854 		if (!handle || acpi_bus_get_device(handle, &adev))
855 			continue;
856 
857 		acpi_handle_debug(handle,
858 			"LPI: required min power state:%s current power state:%s\n",
859 			acpi_power_state_string(lpi_constraints_table[i].min_dstate),
860 			acpi_power_state_string(adev->power.state));
861 
862 		if (!adev->flags.power_manageable) {
863 			acpi_handle_info(handle, "LPI: Device not power manageable\n");
864 			lpi_constraints_table[i].handle = NULL;
865 			continue;
866 		}
867 
868 		if (adev->power.state < lpi_constraints_table[i].min_dstate)
869 			acpi_handle_info(handle,
870 				"LPI: Constraint not met; min power state:%s current power state:%s\n",
871 				acpi_power_state_string(lpi_constraints_table[i].min_dstate),
872 				acpi_power_state_string(adev->power.state));
873 	}
874 }
875 
876 static void acpi_sleep_run_lps0_dsm(unsigned int func)
877 {
878 	union acpi_object *out_obj;
879 
880 	if (!(lps0_dsm_func_mask & (1 << func)))
881 		return;
882 
883 	out_obj = acpi_evaluate_dsm(lps0_device_handle, &lps0_dsm_guid, 1, func, NULL);
884 	ACPI_FREE(out_obj);
885 
886 	acpi_handle_debug(lps0_device_handle, "_DSM function %u evaluation %s\n",
887 			  func, out_obj ? "successful" : "failed");
888 }
889 
890 static int lps0_device_attach(struct acpi_device *adev,
891 			      const struct acpi_device_id *not_used)
892 {
893 	union acpi_object *out_obj;
894 
895 	if (lps0_device_handle)
896 		return 0;
897 
898 	if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
899 		return 0;
900 
901 	guid_parse(ACPI_LPS0_DSM_UUID, &lps0_dsm_guid);
902 	/* Check if the _DSM is present and as expected. */
903 	out_obj = acpi_evaluate_dsm(adev->handle, &lps0_dsm_guid, 1, 0, NULL);
904 	if (!out_obj || out_obj->type != ACPI_TYPE_BUFFER) {
905 		acpi_handle_debug(adev->handle,
906 				  "_DSM function 0 evaluation failed\n");
907 		return 0;
908 	}
909 
910 	lps0_dsm_func_mask = *(char *)out_obj->buffer.pointer;
911 
912 	ACPI_FREE(out_obj);
913 
914 	acpi_handle_debug(adev->handle, "_DSM function mask: 0x%x\n",
915 			  lps0_dsm_func_mask);
916 
917 	lps0_device_handle = adev->handle;
918 
919 	lpi_device_get_constraints();
920 
921 	/*
922 	 * Use suspend-to-idle by default if the default suspend mode was not
923 	 * set from the command line.
924 	 */
925 	if (mem_sleep_default > PM_SUSPEND_MEM && !acpi_sleep_default_s3)
926 		mem_sleep_current = PM_SUSPEND_TO_IDLE;
927 
928 	/*
929 	 * Some LPS0 systems, like ASUS Zenbook UX430UNR/i7-8550U, require the
930 	 * EC GPE to be enabled while suspended for certain wakeup devices to
931 	 * work, so mark it as wakeup-capable.
932 	 */
933 	acpi_ec_mark_gpe_for_wake();
934 
935 	return 0;
936 }
937 
938 static struct acpi_scan_handler lps0_handler = {
939 	.ids = lps0_device_ids,
940 	.attach = lps0_device_attach,
941 };
942 
943 static int acpi_s2idle_begin(void)
944 {
945 	acpi_scan_lock_acquire();
946 	return 0;
947 }
948 
949 static int acpi_s2idle_prepare(void)
950 {
951 	if (acpi_sci_irq_valid()) {
952 		enable_irq_wake(acpi_sci_irq);
953 		acpi_ec_set_gpe_wake_mask(ACPI_GPE_ENABLE);
954 	}
955 
956 	acpi_enable_wakeup_devices(ACPI_STATE_S0);
957 
958 	/* Change the configuration of GPEs to avoid spurious wakeup. */
959 	acpi_enable_all_wakeup_gpes();
960 	acpi_os_wait_events_complete();
961 
962 	s2idle_wakeup = true;
963 	return 0;
964 }
965 
966 static int acpi_s2idle_prepare_late(void)
967 {
968 	if (!lps0_device_handle || sleep_no_lps0)
969 		return 0;
970 
971 	if (pm_debug_messages_on)
972 		lpi_check_constraints();
973 
974 	acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF);
975 	acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY);
976 
977 	return 0;
978 }
979 
980 static void acpi_s2idle_sync(void)
981 {
982 	/*
983 	 * The EC driver uses the system workqueue and an additional special
984 	 * one, so those need to be flushed too.
985 	 */
986 	acpi_ec_flush_work();
987 	acpi_os_wait_events_complete(); /* synchronize Notify handling */
988 }
989 
990 static void acpi_s2idle_wake(void)
991 {
992 	/*
993 	 * If IRQD_WAKEUP_ARMED is set for the SCI at this point, the SCI has
994 	 * not triggered while suspended, so bail out.
995 	 */
996 	if (!acpi_sci_irq_valid() ||
997 	    irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq)))
998 		return;
999 
1000 	/*
1001 	 * If there are EC events to process, the wakeup may be a spurious one
1002 	 * coming from the EC.
1003 	 */
1004 	if (acpi_ec_dispatch_gpe()) {
1005 		/*
1006 		 * Cancel the wakeup and process all pending events in case
1007 		 * there are any wakeup ones in there.
1008 		 *
1009 		 * Note that if any non-EC GPEs are active at this point, the
1010 		 * SCI will retrigger after the rearming below, so no events
1011 		 * should be missed by canceling the wakeup here.
1012 		 */
1013 		pm_system_cancel_wakeup();
1014 
1015 		acpi_s2idle_sync();
1016 
1017 		rearm_wake_irq(acpi_sci_irq);
1018 	}
1019 }
1020 
1021 static void acpi_s2idle_restore_early(void)
1022 {
1023 	if (!lps0_device_handle || sleep_no_lps0)
1024 		return;
1025 
1026 	acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT);
1027 	acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON);
1028 }
1029 
1030 static void acpi_s2idle_restore(void)
1031 {
1032 	/*
1033 	 * Drain pending events before restoring the working-state configuration
1034 	 * of GPEs.
1035 	 */
1036 	acpi_os_wait_events_complete(); /* synchronize GPE processing */
1037 	acpi_s2idle_sync();
1038 
1039 	s2idle_wakeup = false;
1040 
1041 	acpi_enable_all_runtime_gpes();
1042 
1043 	acpi_disable_wakeup_devices(ACPI_STATE_S0);
1044 
1045 	if (acpi_sci_irq_valid()) {
1046 		acpi_ec_set_gpe_wake_mask(ACPI_GPE_DISABLE);
1047 		disable_irq_wake(acpi_sci_irq);
1048 	}
1049 }
1050 
1051 static void acpi_s2idle_end(void)
1052 {
1053 	acpi_scan_lock_release();
1054 }
1055 
1056 static const struct platform_s2idle_ops acpi_s2idle_ops = {
1057 	.begin = acpi_s2idle_begin,
1058 	.prepare = acpi_s2idle_prepare,
1059 	.prepare_late = acpi_s2idle_prepare_late,
1060 	.wake = acpi_s2idle_wake,
1061 	.restore_early = acpi_s2idle_restore_early,
1062 	.restore = acpi_s2idle_restore,
1063 	.end = acpi_s2idle_end,
1064 };
1065 
1066 static void acpi_sleep_suspend_setup(void)
1067 {
1068 	int i;
1069 
1070 	for (i = ACPI_STATE_S1; i < ACPI_STATE_S4; i++)
1071 		if (acpi_sleep_state_supported(i))
1072 			sleep_states[i] = 1;
1073 
1074 	suspend_set_ops(old_suspend_ordering ?
1075 		&acpi_suspend_ops_old : &acpi_suspend_ops);
1076 
1077 	acpi_scan_add_handler(&lps0_handler);
1078 	s2idle_set_ops(&acpi_s2idle_ops);
1079 }
1080 
1081 #else /* !CONFIG_SUSPEND */
1082 #define s2idle_wakeup		(false)
1083 #define lps0_device_handle	(NULL)
1084 static inline void acpi_sleep_suspend_setup(void) {}
1085 #endif /* !CONFIG_SUSPEND */
1086 
1087 bool acpi_s2idle_wakeup(void)
1088 {
1089 	return s2idle_wakeup;
1090 }
1091 
1092 #ifdef CONFIG_PM_SLEEP
1093 static u32 saved_bm_rld;
1094 
1095 static int  acpi_save_bm_rld(void)
1096 {
1097 	acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &saved_bm_rld);
1098 	return 0;
1099 }
1100 
1101 static void  acpi_restore_bm_rld(void)
1102 {
1103 	u32 resumed_bm_rld = 0;
1104 
1105 	acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &resumed_bm_rld);
1106 	if (resumed_bm_rld == saved_bm_rld)
1107 		return;
1108 
1109 	acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, saved_bm_rld);
1110 }
1111 
1112 static struct syscore_ops acpi_sleep_syscore_ops = {
1113 	.suspend = acpi_save_bm_rld,
1114 	.resume = acpi_restore_bm_rld,
1115 };
1116 
1117 static void acpi_sleep_syscore_init(void)
1118 {
1119 	register_syscore_ops(&acpi_sleep_syscore_ops);
1120 }
1121 #else
1122 static inline void acpi_sleep_syscore_init(void) {}
1123 #endif /* CONFIG_PM_SLEEP */
1124 
1125 #ifdef CONFIG_HIBERNATION
1126 static unsigned long s4_hardware_signature;
1127 static struct acpi_table_facs *facs;
1128 static bool nosigcheck;
1129 
1130 void __init acpi_no_s4_hw_signature(void)
1131 {
1132 	nosigcheck = true;
1133 }
1134 
1135 static int acpi_hibernation_begin(pm_message_t stage)
1136 {
1137 	if (!nvs_nosave) {
1138 		int error = suspend_nvs_alloc();
1139 		if (error)
1140 			return error;
1141 	}
1142 
1143 	if (stage.event == PM_EVENT_HIBERNATE)
1144 		pm_set_suspend_via_firmware();
1145 
1146 	acpi_pm_start(ACPI_STATE_S4);
1147 	return 0;
1148 }
1149 
1150 static int acpi_hibernation_enter(void)
1151 {
1152 	acpi_status status = AE_OK;
1153 
1154 	ACPI_FLUSH_CPU_CACHE();
1155 
1156 	/* This shouldn't return.  If it returns, we have a problem */
1157 	status = acpi_enter_sleep_state(ACPI_STATE_S4);
1158 	/* Reprogram control registers */
1159 	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
1160 
1161 	return ACPI_SUCCESS(status) ? 0 : -EFAULT;
1162 }
1163 
1164 static void acpi_hibernation_leave(void)
1165 {
1166 	pm_set_resume_via_firmware();
1167 	/*
1168 	 * If ACPI is not enabled by the BIOS and the boot kernel, we need to
1169 	 * enable it here.
1170 	 */
1171 	acpi_enable();
1172 	/* Reprogram control registers */
1173 	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
1174 	/* Check the hardware signature */
1175 	if (facs && s4_hardware_signature != facs->hardware_signature)
1176 		pr_crit("ACPI: Hardware changed while hibernated, success doubtful!\n");
1177 	/* Restore the NVS memory area */
1178 	suspend_nvs_restore();
1179 	/* Allow EC transactions to happen. */
1180 	acpi_ec_unblock_transactions();
1181 }
1182 
1183 static void acpi_pm_thaw(void)
1184 {
1185 	acpi_ec_unblock_transactions();
1186 	acpi_enable_all_runtime_gpes();
1187 }
1188 
1189 static const struct platform_hibernation_ops acpi_hibernation_ops = {
1190 	.begin = acpi_hibernation_begin,
1191 	.end = acpi_pm_end,
1192 	.pre_snapshot = acpi_pm_prepare,
1193 	.finish = acpi_pm_finish,
1194 	.prepare = acpi_pm_prepare,
1195 	.enter = acpi_hibernation_enter,
1196 	.leave = acpi_hibernation_leave,
1197 	.pre_restore = acpi_pm_freeze,
1198 	.restore_cleanup = acpi_pm_thaw,
1199 };
1200 
1201 /**
1202  *	acpi_hibernation_begin_old - Set the target system sleep state to
1203  *		ACPI_STATE_S4 and execute the _PTS control method.  This
1204  *		function is used if the pre-ACPI 2.0 suspend ordering has been
1205  *		requested.
1206  */
1207 static int acpi_hibernation_begin_old(pm_message_t stage)
1208 {
1209 	int error;
1210 	/*
1211 	 * The _TTS object should always be evaluated before the _PTS object.
1212 	 * When the old_suspended_ordering is true, the _PTS object is
1213 	 * evaluated in the acpi_sleep_prepare.
1214 	 */
1215 	acpi_sleep_tts_switch(ACPI_STATE_S4);
1216 
1217 	error = acpi_sleep_prepare(ACPI_STATE_S4);
1218 	if (error)
1219 		return error;
1220 
1221 	if (!nvs_nosave) {
1222 		error = suspend_nvs_alloc();
1223 		if (error)
1224 			return error;
1225 	}
1226 
1227 	if (stage.event == PM_EVENT_HIBERNATE)
1228 		pm_set_suspend_via_firmware();
1229 
1230 	acpi_target_sleep_state = ACPI_STATE_S4;
1231 	acpi_scan_lock_acquire();
1232 	return 0;
1233 }
1234 
1235 /*
1236  * The following callbacks are used if the pre-ACPI 2.0 suspend ordering has
1237  * been requested.
1238  */
1239 static const struct platform_hibernation_ops acpi_hibernation_ops_old = {
1240 	.begin = acpi_hibernation_begin_old,
1241 	.end = acpi_pm_end,
1242 	.pre_snapshot = acpi_pm_pre_suspend,
1243 	.prepare = acpi_pm_freeze,
1244 	.finish = acpi_pm_finish,
1245 	.enter = acpi_hibernation_enter,
1246 	.leave = acpi_hibernation_leave,
1247 	.pre_restore = acpi_pm_freeze,
1248 	.restore_cleanup = acpi_pm_thaw,
1249 	.recover = acpi_pm_finish,
1250 };
1251 
1252 static void acpi_sleep_hibernate_setup(void)
1253 {
1254 	if (!acpi_sleep_state_supported(ACPI_STATE_S4))
1255 		return;
1256 
1257 	hibernation_set_ops(old_suspend_ordering ?
1258 			&acpi_hibernation_ops_old : &acpi_hibernation_ops);
1259 	sleep_states[ACPI_STATE_S4] = 1;
1260 	if (nosigcheck)
1261 		return;
1262 
1263 	acpi_get_table(ACPI_SIG_FACS, 1, (struct acpi_table_header **)&facs);
1264 	if (facs)
1265 		s4_hardware_signature = facs->hardware_signature;
1266 }
1267 #else /* !CONFIG_HIBERNATION */
1268 static inline void acpi_sleep_hibernate_setup(void) {}
1269 #endif /* !CONFIG_HIBERNATION */
1270 
1271 static void acpi_power_off_prepare(void)
1272 {
1273 	/* Prepare to power off the system */
1274 	acpi_sleep_prepare(ACPI_STATE_S5);
1275 	acpi_disable_all_gpes();
1276 	acpi_os_wait_events_complete();
1277 }
1278 
1279 static void acpi_power_off(void)
1280 {
1281 	/* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
1282 	printk(KERN_DEBUG "%s called\n", __func__);
1283 	local_irq_disable();
1284 	acpi_enter_sleep_state(ACPI_STATE_S5);
1285 }
1286 
1287 int __init acpi_sleep_init(void)
1288 {
1289 	char supported[ACPI_S_STATE_COUNT * 3 + 1];
1290 	char *pos = supported;
1291 	int i;
1292 
1293 	acpi_sleep_dmi_check();
1294 
1295 	sleep_states[ACPI_STATE_S0] = 1;
1296 
1297 	acpi_sleep_syscore_init();
1298 	acpi_sleep_suspend_setup();
1299 	acpi_sleep_hibernate_setup();
1300 
1301 	if (acpi_sleep_state_supported(ACPI_STATE_S5)) {
1302 		sleep_states[ACPI_STATE_S5] = 1;
1303 		pm_power_off_prepare = acpi_power_off_prepare;
1304 		pm_power_off = acpi_power_off;
1305 	} else {
1306 		acpi_no_s5 = true;
1307 	}
1308 
1309 	supported[0] = 0;
1310 	for (i = 0; i < ACPI_S_STATE_COUNT; i++) {
1311 		if (sleep_states[i])
1312 			pos += sprintf(pos, " S%d", i);
1313 	}
1314 	pr_info(PREFIX "(supports%s)\n", supported);
1315 
1316 	/*
1317 	 * Register the tts_notifier to reboot notifier list so that the _TTS
1318 	 * object can also be evaluated when the system enters S5.
1319 	 */
1320 	register_reboot_notifier(&tts_notifier);
1321 	return 0;
1322 }
1323