/*
* drivers/base/power/main.c - Where the driver meets power management.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Lab
*
* This file is released under the GPLv2
*
*
* The driver model core calls device_pm_add() when a device is registered.
* This will intialize the embedded device_pm_info object in the device
* and add it to the list of power-controlled devices. sysfs entries for
* controlling device power management will also be added.
*
* A different set of lists than the global subsystem list are used to
* keep track of power info because we use different lists to hold
* devices based on what stage of the power management process they
* are in. The power domain dependencies may also differ from the
* ancestral dependencies that the subsystem list maintains.
*/
#include <linux/device.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/resume-trace.h>
#include <linux/rwsem.h>
#include "../base.h"
#include "power.h"
/*
* The entries in the dpm_active list are in a depth first order, simply
* because children are guaranteed to be discovered after parents, and
* are inserted at the back of the list on discovery.
*
* All the other lists are kept in the same order, for consistency.
* However the lists aren't always traversed in the same order.
* Semaphores must be acquired from the top (i.e., front) down
* and released in the opposite order. Devices must be suspended
* from the bottom (i.e., end) up and resumed in the opposite order.
* That way no parent will be suspended while it still has an active
* child.
*
* Since device_pm_add() may be called with a device semaphore held,
* we must never try to acquire a device semaphore while holding
* dpm_list_mutex.
*/
LIST_HEAD(dpm_active);
static LIST_HEAD(dpm_locked);
static LIST_HEAD(dpm_off);
static LIST_HEAD(dpm_off_irq);
static LIST_HEAD(dpm_destroy);
static DEFINE_MUTEX(dpm_list_mtx);
static DECLARE_RWSEM(pm_sleep_rwsem);
int (*platform_enable_wakeup)(struct device *dev, int is_on);
/**
* device_pm_add - add a device to the list of active devices
* @dev: Device to be added to the list
*/
void device_pm_add(struct device *dev)
{
pr_debug("PM: Adding info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
mutex_lock(&dpm_list_mtx);
list_add_tail(&dev->power.entry, &dpm_active);
mutex_unlock(&dpm_list_mtx);
}
/**
* device_pm_remove - remove a device from the list of active devices
* @dev: Device to be removed from the list
*
* This function also removes the device's PM-related sysfs attributes.
*/
void device_pm_remove(struct device *dev)
{
/*
* If this function is called during a suspend, it will be blocked,
* because we're holding the device's semaphore at that time, which may
* lead to a deadlock. In that case we want to print a warning.
* However, it may also be called by unregister_dropped_devices() with
* the device's semaphore released, in which case the warning should
* not be printed.
*/
if (down_trylock(&dev->sem)) {
if (down_read_trylock(&pm_sleep_rwsem)) {
/* No suspend in progress, wait on dev->sem */
down(&dev->sem);
up_read(&pm_sleep_rwsem);
} else {
/* Suspend in progress, we may deadlock */
dev_warn(dev, "Suspicious %s during suspend\n",
__FUNCTION__);
dump_stack();
/* The user has been warned ... */
down(&dev->sem);
}
}
pr_debug("PM: Removing info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
mutex_lock(&dpm_list_mtx);
dpm_sysfs_remove(dev);
list_del_init(&dev->power.entry);
mutex_unlock(&dpm_list_mtx);
up(&dev->sem);
}
/**
* device_pm_schedule_removal - schedule the removal of a suspended device
* @dev: Device to destroy
*
* Moves the device to the dpm_destroy list for further processing by
* unregister_dropped_devices().
*/
void device_pm_schedule_removal(struct device *dev)
{
pr_debug("PM: Preparing for removal: %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
mutex_lock(&dpm_list_mtx);
list_move_tail(&dev->power.entry, &dpm_destroy);
mutex_unlock(&dpm_list_mtx);
}
/**
* pm_sleep_lock - mutual exclusion for registration and suspend
*
* Returns 0 if no suspend is underway and device registration
* may proceed, otherwise -EBUSY.
*/
int pm_sleep_lock(void)
{
if (down_read_trylock(&pm_sleep_rwsem))
return 0;
return -EBUSY;
}
/**
* pm_sleep_unlock - mutual exclusion for registration and suspend
*
* This routine undoes the effect of device_pm_add_lock
* when a device's registration is complete.
*/
void pm_sleep_unlock(void)
{
up_read(&pm_sleep_rwsem);
}
/*------------------------- Resume routines -------------------------*/
/**
* resume_device_early - Power on one device (early resume).
* @dev: Device.
*
* Must be called with interrupts disabled.
*/
static int resume_device_early(struct device *dev)
{
int error = 0;
TRACE_DEVICE(dev);
TRACE_RESUME(0);
if (dev->bus && dev->bus->resume_early) {
dev_dbg(dev, "EARLY resume\n");
error = dev->bus->resume_early(dev);
}
TRACE_RESUME(error);
return error;
}
/**
* dpm_power_up - Power on all regular (non-sysdev) devices.
*
* Walk the dpm_off_irq list and power each device up. This
* is used for devices that required they be powered down with
* interrupts disabled. As devices are powered on, they are moved
* to the dpm_off list.
*
* Must be called with interrupts disabled and only one CPU running.
*/
static void dpm_power_up(void)
{
while (!list_empty(&dpm_off_irq)) {
struct list_head *entry = dpm_off_irq.next;
struct device *dev = to_device(entry);
list_move_tail(entry, &dpm_off);
resume_device_early(dev);
}
}
/**
* device_power_up - Turn on all devices that need special attention.
*
* Power on system devices, then devices that required we shut them down
* with interrupts disabled.
*
* Must be called with interrupts disabled.
*/
void device_power_up(void)
{
sysdev_resume();
dpm_power_up();
}
EXPORT_SYMBOL_GPL(device_power_up);
/**
* resume_device - Restore state for one device.
* @dev: Device.
*
*/
static int resume_device(struct device *dev)
{
int error = 0;
TRACE_DEVICE(dev);
TRACE_RESUME(0);
if (dev->bus && dev->bus->resume) {
dev_dbg(dev,"resuming\n");
error = dev->bus->resume(dev);
}
if (!error && dev->type && dev->type->resume) {
dev_dbg(dev,"resuming\n");
error = dev->type->resume(dev);
}
if (!error && dev->class && dev->class->resume) {
dev_dbg(dev,"class resume\n");
error = dev->class->resume(dev);
}
TRACE_RESUME(error);
return error;
}
/**
* dpm_resume - Resume every device.
*
* Resume the devices that have either not gone through
* the late suspend, or that did go through it but also
* went through the early resume.
*
* Take devices from the dpm_off_list, resume them,
* and put them on the dpm_locked list.
*/
static void dpm_resume(void)
{
mutex_lock(&dpm_list_mtx);
while(!list_empty(&dpm_off)) {
struct list_head *entry = dpm_off.next;
struct device *dev = to_device(entry);
list_move_tail(entry, &dpm_locked);
mutex_unlock(&dpm_list_mtx);
resume_device(dev);
mutex_lock(&dpm_list_mtx);
}
mutex_unlock(&dpm_list_mtx);
}
/**
* unlock_all_devices - Release each device's semaphore
*
* Go through the dpm_off list. Put each device on the dpm_active
* list and unlock it.
*/
static void unlock_all_devices(void)
{
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_locked)) {
struct list_head *entry = dpm_locked.prev;
struct device *dev = to_device(entry);
list_move(entry, &dpm_active);
up(&dev->sem);
}
mutex_unlock(&dpm_list_mtx);
}
/**
* unregister_dropped_devices - Unregister devices scheduled for removal
*
* Unregister all devices on the dpm_destroy list.
*/
static void unregister_dropped_devices(void)
{
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_destroy)) {
struct list_head *entry = dpm_destroy.next;
struct device *dev = to_device(entry);
up(&dev->sem);
mutex_unlock(&dpm_list_mtx);
/* This also removes the device from the list */
device_unregister(dev);
mutex_lock(&dpm_list_mtx);
}
mutex_unlock(&dpm_list_mtx);
}
/**
* device_resume - Restore state of each device in system.
*
* Resume all the devices, unlock them all, and allow new
* devices to be registered once again.
*/
void device_resume(void)
{
might_sleep();
dpm_resume();
unlock_all_devices();
unregister_dropped_devices();
up_write(&pm_sleep_rwsem);
}
EXPORT_SYMBOL_GPL(device_resume);
/*------------------------- Suspend routines -------------------------*/
static inline char *suspend_verb(u32 event)
{
switch (event) {
case PM_EVENT_SUSPEND: return "suspend";
case PM_EVENT_FREEZE: return "freeze";
case PM_EVENT_PRETHAW: return "prethaw";
default: return "(unknown suspend event)";
}
}
static void
suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
{
dev_dbg(dev, "%s%s%s\n", info, suspend_verb(state.event),
((state.event == PM_EVENT_SUSPEND) && device_may_wakeup(dev)) ?
", may wakeup" : "");
}
/**
* suspend_device_late - Shut down one device (late suspend).
* @dev: Device.
* @state: Power state device is entering.
*
* This is called with interrupts off and only a single CPU running.
*/
static int suspend_device_late(struct device *dev, pm_message_t state)
{
int error = 0;
if (dev->bus && dev->bus->suspend_late) {
suspend_device_dbg(dev, state, "LATE ");
error = dev->bus->suspend_late(dev, state);
suspend_report_result(dev->bus->suspend_late, error);
}
return error;
}
/**
* device_power_down - Shut down special devices.
* @state: Power state to enter.
*
* Power down devices that require interrupts to be disabled
* and move them from the dpm_off list to the dpm_off_irq list.
* Then power down system devices.
*
* Must be called with interrupts disabled and only one CPU running.
*/
int device_power_down(pm_message_t state)
{
int error = 0;
while (!list_empty(&dpm_off)) {
struct list_head *entry = dpm_off.prev;
struct device *dev = to_device(entry);
list_del_init(&dev->power.entry);
error = suspend_device_late(dev, state);
if (error) {
printk(KERN_ERR "Could not power down device %s: "
"error %d\n",
kobject_name(&dev->kobj), error);
if (list_empty(&dev->power.entry))
list_add(&dev->power.entry, &dpm_off);
break;
}
if (list_empty(&dev->power.entry))
list_add(&dev->power.entry, &dpm_off_irq);
}
if (!error)
error = sysdev_suspend(state);
if (error)
dpm_power_up();
return error;
}
EXPORT_SYMBOL_GPL(device_power_down);
/**
* suspend_device - Save state of one device.
* @dev: Device.
* @state: Power state device is entering.
*/
int suspend_device(struct device *dev, pm_message_t state)
{
int error = 0;
if (dev->power.power_state.event) {
dev_dbg(dev, "PM: suspend %d-->%d\n",
dev->power.power_state.event, state.event);
}
if (dev->class && dev->class->suspend) {
suspend_device_dbg(dev, state, "class ");
error = dev->class->suspend(dev, state);
suspend_report_result(dev->class->suspend, error);
}
if (!error && dev->type && dev->type->suspend) {
suspend_device_dbg(dev, state, "type ");
error = dev->type->suspend(dev, state);
suspend_report_result(dev->type->suspend, error);
}
if (!error && dev->bus && dev->bus->suspend) {
suspend_device_dbg(dev, state, "");
error = dev->bus->suspend(dev, state);
suspend_report_result(dev->bus->suspend, error);
}
return error;
}
/**
* dpm_suspend - Suspend every device.
* @state: Power state to put each device in.
*
* Walk the dpm_locked list. Suspend each device and move it
* to the dpm_off list.
*
* (For historical reasons, if it returns -EAGAIN, that used to mean
* that the device would be called again with interrupts disabled.
* These days, we use the "suspend_late()" callback for that, so we
* print a warning and consider it an error).
*/
static int dpm_suspend(pm_message_t state)
{
int error = 0;
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_locked)) {
struct list_head *entry = dpm_locked.prev;
struct device *dev = to_device(entry);
list_del_init(&dev->power.entry);
mutex_unlock(&dpm_list_mtx);
error = suspend_device(dev, state);
if (error) {
printk(KERN_ERR "Could not suspend device %s: "
"error %d%s\n",
kobject_name(&dev->kobj),
error,
(error == -EAGAIN ?
" (please convert to suspend_late)" :
""));
mutex_lock(&dpm_list_mtx);
if (list_empty(&dev->power.entry))
list_add(&dev->power.entry, &dpm_locked);
mutex_unlock(&dpm_list_mtx);
break;
}
mutex_lock(&dpm_list_mtx);
if (list_empty(&dev->power.entry))
list_add(&dev->power.entry, &dpm_off);
}
mutex_unlock(&dpm_list_mtx);
return error;
}
/**
* lock_all_devices - Acquire every device's semaphore
*
* Go through the dpm_active list. Carefully lock each device's
* semaphore and put it in on the dpm_locked list.
*/
static void lock_all_devices(void)
{
mutex_lock(&dpm_list_mtx);
while (!list_empty(&dpm_active)) {
struct list_head *entry = dpm_active.next;
struct device *dev = to_device(entry);
/* Required locking order is dev->sem first,
* then dpm_list_mutex. Hence this awkward code.
*/
get_device(dev);
mutex_unlock(&dpm_list_mtx);
down(&dev->sem);
mutex_lock(&dpm_list_mtx);
if (list_empty(entry))
up(&dev->sem); /* Device was removed */
else
list_move_tail(entry, &dpm_locked);
put_device(dev);
}
mutex_unlock(&dpm_list_mtx);
}
/**
* device_suspend - Save state and stop all devices in system.
*
* Prevent new devices from being registered, then lock all devices
* and suspend them.
*/
int device_suspend(pm_message_t state)
{
int error;
might_sleep();
down_write(&pm_sleep_rwsem);
lock_all_devices();
error = dpm_suspend(state);
if (error)
device_resume();
return error;
}
EXPORT_SYMBOL_GPL(device_suspend);
void __suspend_report_result(const char *function, void *fn, int ret)
{
if (ret) {
printk(KERN_ERR "%s(): ", function);
print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
printk("%d\n", ret);
}
}
EXPORT_SYMBOL_GPL(__suspend_report_result);
