xref: /openbmc/linux/kernel/power/suspend.c (revision 31b90347)
1 /*
2  * kernel/power/suspend.c - Suspend to RAM and standby functionality.
3  *
4  * Copyright (c) 2003 Patrick Mochel
5  * Copyright (c) 2003 Open Source Development Lab
6  * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
7  *
8  * This file is released under the GPLv2.
9  */
10 
11 #include <linux/string.h>
12 #include <linux/delay.h>
13 #include <linux/errno.h>
14 #include <linux/init.h>
15 #include <linux/console.h>
16 #include <linux/cpu.h>
17 #include <linux/syscalls.h>
18 #include <linux/gfp.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/list.h>
22 #include <linux/mm.h>
23 #include <linux/slab.h>
24 #include <linux/export.h>
25 #include <linux/suspend.h>
26 #include <linux/syscore_ops.h>
27 #include <linux/ftrace.h>
28 #include <trace/events/power.h>
29 
30 #include "power.h"
31 
32 const char *const pm_states[PM_SUSPEND_MAX] = {
33 	[PM_SUSPEND_FREEZE]	= "freeze",
34 	[PM_SUSPEND_STANDBY]	= "standby",
35 	[PM_SUSPEND_MEM]	= "mem",
36 };
37 
38 static const struct platform_suspend_ops *suspend_ops;
39 
40 static bool need_suspend_ops(suspend_state_t state)
41 {
42 	return !!(state > PM_SUSPEND_FREEZE);
43 }
44 
45 static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
46 static bool suspend_freeze_wake;
47 
48 static void freeze_begin(void)
49 {
50 	suspend_freeze_wake = false;
51 }
52 
53 static void freeze_enter(void)
54 {
55 	wait_event(suspend_freeze_wait_head, suspend_freeze_wake);
56 }
57 
58 void freeze_wake(void)
59 {
60 	suspend_freeze_wake = true;
61 	wake_up(&suspend_freeze_wait_head);
62 }
63 EXPORT_SYMBOL_GPL(freeze_wake);
64 
65 /**
66  * suspend_set_ops - Set the global suspend method table.
67  * @ops: Suspend operations to use.
68  */
69 void suspend_set_ops(const struct platform_suspend_ops *ops)
70 {
71 	lock_system_sleep();
72 	suspend_ops = ops;
73 	unlock_system_sleep();
74 }
75 EXPORT_SYMBOL_GPL(suspend_set_ops);
76 
77 bool valid_state(suspend_state_t state)
78 {
79 	if (state == PM_SUSPEND_FREEZE) {
80 #ifdef CONFIG_PM_DEBUG
81 		if (pm_test_level != TEST_NONE &&
82 		    pm_test_level != TEST_FREEZER &&
83 		    pm_test_level != TEST_DEVICES &&
84 		    pm_test_level != TEST_PLATFORM) {
85 			printk(KERN_WARNING "Unsupported pm_test mode for "
86 					"freeze state, please choose "
87 					"none/freezer/devices/platform.\n");
88 			return false;
89 		}
90 #endif
91 			return true;
92 	}
93 	/*
94 	 * PM_SUSPEND_STANDBY and PM_SUSPEND_MEMORY states need lowlevel
95 	 * support and need to be valid to the lowlevel
96 	 * implementation, no valid callback implies that none are valid.
97 	 */
98 	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
99 }
100 
101 /**
102  * suspend_valid_only_mem - Generic memory-only valid callback.
103  *
104  * Platform drivers that implement mem suspend only and only need to check for
105  * that in their .valid() callback can use this instead of rolling their own
106  * .valid() callback.
107  */
108 int suspend_valid_only_mem(suspend_state_t state)
109 {
110 	return state == PM_SUSPEND_MEM;
111 }
112 EXPORT_SYMBOL_GPL(suspend_valid_only_mem);
113 
114 static int suspend_test(int level)
115 {
116 #ifdef CONFIG_PM_DEBUG
117 	if (pm_test_level == level) {
118 		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
119 		mdelay(5000);
120 		return 1;
121 	}
122 #endif /* !CONFIG_PM_DEBUG */
123 	return 0;
124 }
125 
126 /**
127  * suspend_prepare - Prepare for entering system sleep state.
128  *
129  * Common code run for every system sleep state that can be entered (except for
130  * hibernation).  Run suspend notifiers, allocate the "suspend" console and
131  * freeze processes.
132  */
133 static int suspend_prepare(suspend_state_t state)
134 {
135 	int error;
136 
137 	if (need_suspend_ops(state) && (!suspend_ops || !suspend_ops->enter))
138 		return -EPERM;
139 
140 	pm_prepare_console();
141 
142 	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
143 	if (error)
144 		goto Finish;
145 
146 	error = suspend_freeze_processes();
147 	if (!error)
148 		return 0;
149 
150 	suspend_stats.failed_freeze++;
151 	dpm_save_failed_step(SUSPEND_FREEZE);
152  Finish:
153 	pm_notifier_call_chain(PM_POST_SUSPEND);
154 	pm_restore_console();
155 	return error;
156 }
157 
158 /* default implementation */
159 void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
160 {
161 	local_irq_disable();
162 }
163 
164 /* default implementation */
165 void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
166 {
167 	local_irq_enable();
168 }
169 
170 /**
171  * suspend_enter - Make the system enter the given sleep state.
172  * @state: System sleep state to enter.
173  * @wakeup: Returns information that the sleep state should not be re-entered.
174  *
175  * This function should be called after devices have been suspended.
176  */
177 static int suspend_enter(suspend_state_t state, bool *wakeup)
178 {
179 	int error;
180 
181 	if (need_suspend_ops(state) && suspend_ops->prepare) {
182 		error = suspend_ops->prepare();
183 		if (error)
184 			goto Platform_finish;
185 	}
186 
187 	error = dpm_suspend_end(PMSG_SUSPEND);
188 	if (error) {
189 		printk(KERN_ERR "PM: Some devices failed to power down\n");
190 		goto Platform_finish;
191 	}
192 
193 	if (need_suspend_ops(state) && suspend_ops->prepare_late) {
194 		error = suspend_ops->prepare_late();
195 		if (error)
196 			goto Platform_wake;
197 	}
198 
199 	if (suspend_test(TEST_PLATFORM))
200 		goto Platform_wake;
201 
202 	/*
203 	 * PM_SUSPEND_FREEZE equals
204 	 * frozen processes + suspended devices + idle processors.
205 	 * Thus we should invoke freeze_enter() soon after
206 	 * all the devices are suspended.
207 	 */
208 	if (state == PM_SUSPEND_FREEZE) {
209 		freeze_enter();
210 		goto Platform_wake;
211 	}
212 
213 	ftrace_stop();
214 	error = disable_nonboot_cpus();
215 	if (error || suspend_test(TEST_CPUS))
216 		goto Enable_cpus;
217 
218 	arch_suspend_disable_irqs();
219 	BUG_ON(!irqs_disabled());
220 
221 	error = syscore_suspend();
222 	if (!error) {
223 		*wakeup = pm_wakeup_pending();
224 		if (!(suspend_test(TEST_CORE) || *wakeup)) {
225 			error = suspend_ops->enter(state);
226 			events_check_enabled = false;
227 		}
228 		syscore_resume();
229 	}
230 
231 	arch_suspend_enable_irqs();
232 	BUG_ON(irqs_disabled());
233 
234  Enable_cpus:
235 	enable_nonboot_cpus();
236 	ftrace_start();
237 
238  Platform_wake:
239 	if (need_suspend_ops(state) && suspend_ops->wake)
240 		suspend_ops->wake();
241 
242 	dpm_resume_start(PMSG_RESUME);
243 
244  Platform_finish:
245 	if (need_suspend_ops(state) && suspend_ops->finish)
246 		suspend_ops->finish();
247 
248 	return error;
249 }
250 
251 /**
252  * suspend_devices_and_enter - Suspend devices and enter system sleep state.
253  * @state: System sleep state to enter.
254  */
255 int suspend_devices_and_enter(suspend_state_t state)
256 {
257 	int error;
258 	bool wakeup = false;
259 
260 	if (need_suspend_ops(state) && !suspend_ops)
261 		return -ENOSYS;
262 
263 	trace_machine_suspend(state);
264 	if (need_suspend_ops(state) && suspend_ops->begin) {
265 		error = suspend_ops->begin(state);
266 		if (error)
267 			goto Close;
268 	}
269 	suspend_console();
270 	suspend_test_start();
271 	error = dpm_suspend_start(PMSG_SUSPEND);
272 	if (error) {
273 		pr_err("PM: Some devices failed to suspend, or early wake event detected\n");
274 		goto Recover_platform;
275 	}
276 	suspend_test_finish("suspend devices");
277 	if (suspend_test(TEST_DEVICES))
278 		goto Recover_platform;
279 
280 	do {
281 		error = suspend_enter(state, &wakeup);
282 	} while (!error && !wakeup && need_suspend_ops(state)
283 		&& suspend_ops->suspend_again && suspend_ops->suspend_again());
284 
285  Resume_devices:
286 	suspend_test_start();
287 	dpm_resume_end(PMSG_RESUME);
288 	suspend_test_finish("resume devices");
289 	resume_console();
290  Close:
291 	if (need_suspend_ops(state) && suspend_ops->end)
292 		suspend_ops->end();
293 	trace_machine_suspend(PWR_EVENT_EXIT);
294 	return error;
295 
296  Recover_platform:
297 	if (need_suspend_ops(state) && suspend_ops->recover)
298 		suspend_ops->recover();
299 	goto Resume_devices;
300 }
301 
302 /**
303  * suspend_finish - Clean up before finishing the suspend sequence.
304  *
305  * Call platform code to clean up, restart processes, and free the console that
306  * we've allocated. This routine is not called for hibernation.
307  */
308 static void suspend_finish(void)
309 {
310 	suspend_thaw_processes();
311 	pm_notifier_call_chain(PM_POST_SUSPEND);
312 	pm_restore_console();
313 }
314 
315 /**
316  * enter_state - Do common work needed to enter system sleep state.
317  * @state: System sleep state to enter.
318  *
319  * Make sure that no one else is trying to put the system into a sleep state.
320  * Fail if that's not the case.  Otherwise, prepare for system suspend, make the
321  * system enter the given sleep state and clean up after wakeup.
322  */
323 static int enter_state(suspend_state_t state)
324 {
325 	int error;
326 
327 	if (!valid_state(state))
328 		return -ENODEV;
329 
330 	if (!mutex_trylock(&pm_mutex))
331 		return -EBUSY;
332 
333 	if (state == PM_SUSPEND_FREEZE)
334 		freeze_begin();
335 
336 	printk(KERN_INFO "PM: Syncing filesystems ... ");
337 	sys_sync();
338 	printk("done.\n");
339 
340 	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
341 	error = suspend_prepare(state);
342 	if (error)
343 		goto Unlock;
344 
345 	if (suspend_test(TEST_FREEZER))
346 		goto Finish;
347 
348 	pr_debug("PM: Entering %s sleep\n", pm_states[state]);
349 	pm_restrict_gfp_mask();
350 	error = suspend_devices_and_enter(state);
351 	pm_restore_gfp_mask();
352 
353  Finish:
354 	pr_debug("PM: Finishing wakeup.\n");
355 	suspend_finish();
356  Unlock:
357 	mutex_unlock(&pm_mutex);
358 	return error;
359 }
360 
361 /**
362  * pm_suspend - Externally visible function for suspending the system.
363  * @state: System sleep state to enter.
364  *
365  * Check if the value of @state represents one of the supported states,
366  * execute enter_state() and update system suspend statistics.
367  */
368 int pm_suspend(suspend_state_t state)
369 {
370 	int error;
371 
372 	if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
373 		return -EINVAL;
374 
375 	error = enter_state(state);
376 	if (error) {
377 		suspend_stats.fail++;
378 		dpm_save_failed_errno(error);
379 	} else {
380 		suspend_stats.success++;
381 	}
382 	return error;
383 }
384 EXPORT_SYMBOL(pm_suspend);
385