Quelle  suspend.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/power/suspend.c - Suspend to RAM and standby functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 */

#define pr_fmt(fmt) "PM: " fmt

#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/gfp.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/suspend.h>
#include <linux/syscore_ops.h>
#include <linux/swait.h>
#include <linux/ftrace.h>
#include <trace/events/power.h>
#include <linux/compiler.h>
#include <linux/moduleparam.h>
#include <linux/fs.h>

#include "power.h"

const char * const pm_labels[] = {
 [PM_SUSPEND_TO_IDLE] = "freeze",
 [PM_SUSPEND_STANDBY] = "standby",
 [PM_SUSPEND_MEM] = "mem",
};
const char *pm_states[PM_SUSPEND_MAX];
static const char * const mem_sleep_labels[] = {
 [PM_SUSPEND_TO_IDLE] = "s2idle",
 [PM_SUSPEND_STANDBY] = "shallow",
 [PM_SUSPEND_MEM] = "deep",
};
const char *mem_sleep_states[PM_SUSPEND_MAX];

suspend_state_t mem_sleep_current = PM_SUSPEND_TO_IDLE;
suspend_state_t mem_sleep_default = PM_SUSPEND_MAX;
suspend_state_t pm_suspend_target_state;
EXPORT_SYMBOL_GPL(pm_suspend_target_state);

unsigned int pm_suspend_global_flags;
EXPORT_SYMBOL_GPL(pm_suspend_global_flags);

static const struct platform_suspend_ops *suspend_ops;
static const struct platform_s2idle_ops *s2idle_ops;
static DECLARE_SWAIT_QUEUE_HEAD(s2idle_wait_head);

enum s2idle_states __read_mostly s2idle_state;
static DEFINE_RAW_SPINLOCK(s2idle_lock);

/**
 * pm_suspend_default_s2idle - Check if suspend-to-idle is the default suspend.
 *
 * Return 'true' if suspend-to-idle has been selected as the default system
 * suspend method.
 */
bool pm_suspend_default_s2idle(void)
{
 return mem_sleep_current == PM_SUSPEND_TO_IDLE;
}
EXPORT_SYMBOL_GPL(pm_suspend_default_s2idle);

void s2idle_set_ops(const struct platform_s2idle_ops *ops)
{
 unsigned int sleep_flags;

 sleep_flags = lock_system_sleep();
 s2idle_ops = ops;
 unlock_system_sleep(sleep_flags);
}

static void s2idle_begin(void)
{
 s2idle_state = S2IDLE_STATE_NONE;
}

static void s2idle_enter(void)
{
 trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true);

 /*
  * The correctness of the code below depends on the number of online
  * CPUs being stable, but CPUs cannot be taken offline or put online
  * while it is running.
  *
  * The s2idle_lock must be acquired before the pending wakeup check to
  * prevent pm_system_wakeup() from running as a whole between that check
  * and the subsequent s2idle_state update in which case a wakeup event
  * would get lost.
 */
 raw_spin_lock_irq(&s2idle_lock);
 if (pm_wakeup_pending())
  goto out;

 s2idle_state = S2IDLE_STATE_ENTER;
 raw_spin_unlock_irq(&s2idle_lock);

 /* Push all the CPUs into the idle loop. */
 wake_up_all_idle_cpus();
 /* Make the current CPU wait so it can enter the idle loop too. */
 swait_event_exclusive(s2idle_wait_head,
      s2idle_state == S2IDLE_STATE_WAKE);

 /*
  * Kick all CPUs to ensure that they resume their timers and restore
  * consistent system state.
 */
 wake_up_all_idle_cpus();

 raw_spin_lock_irq(&s2idle_lock);

 out:
 s2idle_state = S2IDLE_STATE_NONE;
 raw_spin_unlock_irq(&s2idle_lock);

 trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, false);
}

static void s2idle_loop(void)
{
 pm_pr_dbg("suspend-to-idle\n");

 /*
  * Suspend-to-idle equals:
  * frozen processes + suspended devices + idle processors.
  * Thus s2idle_enter() should be called right after all devices have
  * been suspended.
  *
  * Wakeups during the noirq suspend of devices may be spurious, so try
  * to avoid them upfront.
 */
 for (;;) {
  if (s2idle_ops && s2idle_ops->wake) {
   if (s2idle_ops->wake())
    break;
  } else if (pm_wakeup_pending()) {
   break;
  }

  if (s2idle_ops && s2idle_ops->check)
   s2idle_ops->check();

  s2idle_enter();
 }

 pm_pr_dbg("resume from suspend-to-idle\n");
}

void s2idle_wake(void)
{
 unsigned long flags;

 raw_spin_lock_irqsave(&s2idle_lock, flags);
 if (s2idle_state > S2IDLE_STATE_NONE) {
  s2idle_state = S2IDLE_STATE_WAKE;
  swake_up_one(&s2idle_wait_head);
 }
 raw_spin_unlock_irqrestore(&s2idle_lock, flags);
}
EXPORT_SYMBOL_GPL(s2idle_wake);

static bool valid_state(suspend_state_t state)
{
 /*
  * The PM_SUSPEND_STANDBY and PM_SUSPEND_MEM states require low-level
  * support and need to be valid to the low-level implementation.
  *
  * No ->valid() or ->enter() callback implies that none are valid.
 */
 return suspend_ops && suspend_ops->valid && suspend_ops->valid(state) &&
  suspend_ops->enter;
}

void __init pm_states_init(void)
{
 /* "mem" and "freeze" are always present in /sys/power/state. */
 pm_states[PM_SUSPEND_MEM] = pm_labels[PM_SUSPEND_MEM];
 pm_states[PM_SUSPEND_TO_IDLE] = pm_labels[PM_SUSPEND_TO_IDLE];
 /*
  * Suspend-to-idle should be supported even without any suspend_ops,
  * initialize mem_sleep_states[] accordingly here.
 */
 mem_sleep_states[PM_SUSPEND_TO_IDLE] = mem_sleep_labels[PM_SUSPEND_TO_IDLE];
}

static int __init mem_sleep_default_setup(char *str)
{
 suspend_state_t state;

 for (state = PM_SUSPEND_TO_IDLE; state <= PM_SUSPEND_MEM; state++)
  if (mem_sleep_labels[state] &&
      !strcmp(str, mem_sleep_labels[state])) {
   mem_sleep_default = state;
   mem_sleep_current = state;
   break;
  }

 return 1;
}
__setup("mem_sleep_default=", mem_sleep_default_setup);

/**
 * suspend_set_ops - Set the global suspend method table.
 * @ops: Suspend operations to use.
 */
void suspend_set_ops(const struct platform_suspend_ops *ops)
{
 unsigned int sleep_flags;

 sleep_flags = lock_system_sleep();

 suspend_ops = ops;

 if (valid_state(PM_SUSPEND_STANDBY)) {
  mem_sleep_states[PM_SUSPEND_STANDBY] = mem_sleep_labels[PM_SUSPEND_STANDBY];
  pm_states[PM_SUSPEND_STANDBY] = pm_labels[PM_SUSPEND_STANDBY];
  if (mem_sleep_default == PM_SUSPEND_STANDBY)
   mem_sleep_current = PM_SUSPEND_STANDBY;
 }
 if (valid_state(PM_SUSPEND_MEM)) {
  mem_sleep_states[PM_SUSPEND_MEM] = mem_sleep_labels[PM_SUSPEND_MEM];
  if (mem_sleep_default >= PM_SUSPEND_MEM)
   mem_sleep_current = PM_SUSPEND_MEM;
 }

 unlock_system_sleep(sleep_flags);
}
EXPORT_SYMBOL_GPL(suspend_set_ops);

/**
 * suspend_valid_only_mem - Generic memory-only valid callback.
 * @state: Target system sleep state.
 *
 * Platform drivers that implement mem suspend only and only need to check for
 * that in their .valid() callback can use this instead of rolling their own
 * .valid() callback.
 */
int suspend_valid_only_mem(suspend_state_t state)
{
 return state == PM_SUSPEND_MEM;
}
EXPORT_SYMBOL_GPL(suspend_valid_only_mem);

static bool sleep_state_supported(suspend_state_t state)
{
 return state == PM_SUSPEND_TO_IDLE ||
        (valid_state(state) && !cxl_mem_active());
}

static int platform_suspend_prepare(suspend_state_t state)
{
 return state != PM_SUSPEND_TO_IDLE && suspend_ops->prepare ?
  suspend_ops->prepare() : 0;
}

static int platform_suspend_prepare_late(suspend_state_t state)
{
 return state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->prepare ?
  s2idle_ops->prepare() : 0;
}

static int platform_suspend_prepare_noirq(suspend_state_t state)
{
 if (state == PM_SUSPEND_TO_IDLE)
  return s2idle_ops && s2idle_ops->prepare_late ?
   s2idle_ops->prepare_late() : 0;

 return suspend_ops->prepare_late ? suspend_ops->prepare_late() : 0;
}

static void platform_resume_noirq(suspend_state_t state)
{
 if (state == PM_SUSPEND_TO_IDLE) {
  if (s2idle_ops && s2idle_ops->restore_early)
   s2idle_ops->restore_early();
 } else if (suspend_ops->wake) {
  suspend_ops->wake();
 }
}

static void platform_resume_early(suspend_state_t state)
{
 if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->restore)
  s2idle_ops->restore();
}

static void platform_resume_finish(suspend_state_t state)
{
 if (state != PM_SUSPEND_TO_IDLE && suspend_ops->finish)
  suspend_ops->finish();
}

static int platform_suspend_begin(suspend_state_t state)
{
 if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->begin)
  return s2idle_ops->begin();
 else if (suspend_ops && suspend_ops->begin)
  return suspend_ops->begin(state);
 else
  return 0;
}

static void platform_resume_end(suspend_state_t state)
{
 if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->end)
  s2idle_ops->end();
 else if (suspend_ops && suspend_ops->end)
  suspend_ops->end();
}

static void platform_recover(suspend_state_t state)
{
 if (state != PM_SUSPEND_TO_IDLE && suspend_ops->recover)
  suspend_ops->recover();
}

static bool platform_suspend_again(suspend_state_t state)
{
 return state != PM_SUSPEND_TO_IDLE && suspend_ops->suspend_again ?
  suspend_ops->suspend_again() : false;
}

#ifdef CONFIG_PM_DEBUG
static unsigned int pm_test_delay = 5;
module_param(pm_test_delay, uint, 0644);
MODULE_PARM_DESC(pm_test_delay,
   "Number of seconds to wait before resuming from suspend test");
#endif

static int suspend_test(int level)
{
#ifdef CONFIG_PM_DEBUG
 if (pm_test_level == level) {
  pr_info("suspend debug: Waiting for %d second(s).\n",
    pm_test_delay);
  mdelay(pm_test_delay * 1000);
  return 1;
 }
#endif /* !CONFIG_PM_DEBUG */
 return 0;
}

/**
 * suspend_prepare - Prepare for entering system sleep state.
 * @state: Target system sleep state.
 *
 * Common code run for every system sleep state that can be entered (except for
 * hibernation).  Run suspend notifiers, allocate the "suspend" console and
 * freeze processes.
 */
static int suspend_prepare(suspend_state_t state)
{
 int error;

 if (!sleep_state_supported(state))
  return -EPERM;

 pm_prepare_console();

 error = pm_notifier_call_chain_robust(PM_SUSPEND_PREPARE, PM_POST_SUSPEND);
 if (error)
  goto Restore;

 if (filesystem_freeze_enabled)
  filesystems_freeze();
 trace_suspend_resume(TPS("freeze_processes"), 0, true);
 error = suspend_freeze_processes();
 trace_suspend_resume(TPS("freeze_processes"), 0, false);
 if (!error)
  return 0;

 dpm_save_failed_step(SUSPEND_FREEZE);
 filesystems_thaw();
 pm_notifier_call_chain(PM_POST_SUSPEND);
 Restore:
 pm_restore_console();
 return error;
}

/* default implementation */
void __weak arch_suspend_disable_irqs(void)
{
 local_irq_disable();
}

/* default implementation */
void __weak arch_suspend_enable_irqs(void)
{
 local_irq_enable();
}

/**
 * suspend_enter - Make the system enter the given sleep state.
 * @state: System sleep state to enter.
 * @wakeup: Returns information that the sleep state should not be re-entered.
 *
 * This function should be called after devices have been suspended.
 */
static int suspend_enter(suspend_state_t state, bool *wakeup)
{
 int error;

 error = platform_suspend_prepare(state);
 if (error)
  goto Platform_finish;

 error = dpm_suspend_late(PMSG_SUSPEND);
 if (error) {
  pr_err("late suspend of devices failed\n");
  goto Platform_finish;
 }
 error = platform_suspend_prepare_late(state);
 if (error)
  goto Devices_early_resume;

 error = dpm_suspend_noirq(PMSG_SUSPEND);
 if (error) {
  pr_err("noirq suspend of devices failed\n");
  goto Platform_early_resume;
 }
 error = platform_suspend_prepare_noirq(state);
 if (error)
  goto Platform_wake;

 if (suspend_test(TEST_PLATFORM))
  goto Platform_wake;

 if (state == PM_SUSPEND_TO_IDLE) {
  s2idle_loop();
  goto Platform_wake;
 }

 error = pm_sleep_disable_secondary_cpus();
 if (error || suspend_test(TEST_CPUS))
  goto Enable_cpus;

 arch_suspend_disable_irqs();
 BUG_ON(!irqs_disabled());

 system_state = SYSTEM_SUSPEND;

 error = syscore_suspend();
 if (!error) {
  *wakeup = pm_wakeup_pending();
  if (!(suspend_test(TEST_CORE) || *wakeup)) {
   trace_suspend_resume(TPS("machine_suspend"),
    state, true);
   error = suspend_ops->enter(state);
   trace_suspend_resume(TPS("machine_suspend"),
    state, false);
  } else if (*wakeup) {
   error = -EBUSY;
  }
  syscore_resume();
 }

 system_state = SYSTEM_RUNNING;

 arch_suspend_enable_irqs();
 BUG_ON(irqs_disabled());

 Enable_cpus:
 pm_sleep_enable_secondary_cpus();

 Platform_wake:
 platform_resume_noirq(state);
 dpm_resume_noirq(PMSG_RESUME);

 Platform_early_resume:
 platform_resume_early(state);

 Devices_early_resume:
 dpm_resume_early(PMSG_RESUME);

 Platform_finish:
 platform_resume_finish(state);
 return error;
}

/**
 * suspend_devices_and_enter - Suspend devices and enter system sleep state.
 * @state: System sleep state to enter.
 */
int suspend_devices_and_enter(suspend_state_t state)
{
 int error;
 bool wakeup = false;

 if (!sleep_state_supported(state))
  return -ENOSYS;

 pm_suspend_target_state = state;

 if (state == PM_SUSPEND_TO_IDLE)
  pm_set_suspend_no_platform();

 error = platform_suspend_begin(state);
 if (error)
  goto Close;

 console_suspend_all();
 suspend_test_start();
 error = dpm_suspend_start(PMSG_SUSPEND);
 if (error) {
  pr_err("Some devices failed to suspend, or early wake event detected\n");
  goto Recover_platform;
 }
 suspend_test_finish("suspend devices");
 if (suspend_test(TEST_DEVICES))
  goto Recover_platform;

 do {
  error = suspend_enter(state, &wakeup);
 } while (!error && !wakeup && platform_suspend_again(state));

 Resume_devices:
 suspend_test_start();
 dpm_resume_end(PMSG_RESUME);
 suspend_test_finish("resume devices");
 trace_suspend_resume(TPS("console_resume_all"), state, true);
 console_resume_all();
 trace_suspend_resume(TPS("console_resume_all"), state, false);

 Close:
 platform_resume_end(state);
 pm_suspend_target_state = PM_SUSPEND_ON;
 return error;

 Recover_platform:
 platform_recover(state);
 goto Resume_devices;
}

/**
 * suspend_finish - Clean up before finishing the suspend sequence.
 *
 * Call platform code to clean up, restart processes, and free the console that
 * we've allocated. This routine is not called for hibernation.
 */
static void suspend_finish(void)
{
 suspend_thaw_processes();
 filesystems_thaw();
 pm_notifier_call_chain(PM_POST_SUSPEND);
 pm_restore_console();
}

/**
 * enter_state - Do common work needed to enter system sleep state.
 * @state: System sleep state to enter.
 *
 * Make sure that no one else is trying to put the system into a sleep state.
 * Fail if that's not the case.  Otherwise, prepare for system suspend, make the
 * system enter the given sleep state and clean up after wakeup.
 */
static int enter_state(suspend_state_t state)
{
 int error;

 trace_suspend_resume(TPS("suspend_enter"), state, true);
 if (state == PM_SUSPEND_TO_IDLE) {
#ifdef CONFIG_PM_DEBUG
  if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
   pr_warn("Unsupported test mode for suspend to idle, please choose none/freezer/devices/platform.\n");
   return -EAGAIN;
  }
#endif
 } else if (!valid_state(state)) {
  return -EINVAL;
 }
 if (!mutex_trylock(&system_transition_mutex))
  return -EBUSY;

 if (state == PM_SUSPEND_TO_IDLE)
  s2idle_begin();

 if (sync_on_suspend_enabled) {
  trace_suspend_resume(TPS("sync_filesystems"), 0, true);
  ksys_sync_helper();
  trace_suspend_resume(TPS("sync_filesystems"), 0, false);
 }

 pm_pr_dbg("Preparing system for sleep (%s)\n", mem_sleep_labels[state]);
 pm_suspend_clear_flags();
 error = suspend_prepare(state);
 if (error)
  goto Unlock;

 if (suspend_test(TEST_FREEZER))
  goto Finish;

 trace_suspend_resume(TPS("suspend_enter"), state, false);
 pm_pr_dbg("Suspending system (%s)\n", mem_sleep_labels[state]);
 error = suspend_devices_and_enter(state);

 Finish:
 events_check_enabled = false;
 pm_pr_dbg("Finishing wakeup.\n");
 suspend_finish();
 Unlock:
 mutex_unlock(&system_transition_mutex);
 return error;
}

/**
 * pm_suspend - Externally visible function for suspending the system.
 * @state: System sleep state to enter.
 *
 * Check if the value of @state represents one of the supported states,
 * execute enter_state() and update system suspend statistics.
 */
int pm_suspend(suspend_state_t state)
{
 int error;

 if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
  return -EINVAL;

 pr_info("suspend entry (%s)\n", mem_sleep_labels[state]);
 error = enter_state(state);
 dpm_save_errno(error);
 pr_info("suspend exit\n");
 return error;
}
EXPORT_SYMBOL(pm_suspend);