diff options
Diffstat (limited to 'drivers/base/power')
| -rw-r--r-- | drivers/base/power/main.c | 502 | ||||
| -rw-r--r-- | drivers/base/power/power.h | 12 |
2 files changed, 342 insertions, 172 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index 691ffb64cc37..200ed5fafd50 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -24,20 +24,45 @@ #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_mtx); static DEFINE_MUTEX(dpm_list_mtx); -int (*platform_enable_wakeup)(struct device *dev, int is_on); +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", @@ -48,8 +73,36 @@ void device_pm_add(struct device *dev) 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)); @@ -57,25 +110,124 @@ void device_pm_remove(struct device *dev) 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 - Restore state for one device. + * resume_device_early - Power on one device (early resume). * @dev: Device. * + * Must be called with interrupts disabled. */ - -static int resume_device(struct device * dev) +static int resume_device_early(struct device *dev) { int error = 0; TRACE_DEVICE(dev); TRACE_RESUME(0); - down(&dev->sem); + 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"); @@ -92,126 +244,94 @@ static int resume_device(struct device * dev) error = dev->class->resume(dev); } - up(&dev->sem); - TRACE_RESUME(error); return error; } - -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; -} - -/* - * 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 +/** + * 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); - - get_device(dev); - list_move_tail(entry, &dpm_active); + 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); - put_device(dev); } mutex_unlock(&dpm_list_mtx); } - /** - * device_resume - Restore state of each device in system. + * unlock_all_devices - Release each device's semaphore * - * Walk the dpm_off list, remove each entry, resume the device, - * then add it to the dpm_active list. + * Go through the dpm_off list. Put each device on the dpm_active + * list and unlock it. */ - -void device_resume(void) +static void unlock_all_devices(void) { - might_sleep(); - mutex_lock(&dpm_mtx); - dpm_resume(); - mutex_unlock(&dpm_mtx); -} - -EXPORT_SYMBOL_GPL(device_resume); + 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); +} /** - * dpm_power_up - Power on some 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_active list. + * unregister_dropped_devices - Unregister devices scheduled for removal * - * Interrupts must be disabled when calling this. + * Unregister all devices on the dpm_destroy list. */ - -static void dpm_power_up(void) +static void unregister_dropped_devices(void) { - while(!list_empty(&dpm_off_irq)) { - struct list_head * entry = dpm_off_irq.next; - struct device * dev = to_device(entry); + mutex_lock(&dpm_list_mtx); + while (!list_empty(&dpm_destroy)) { + struct list_head *entry = dpm_destroy.next; + struct device *dev = to_device(entry); - list_move_tail(entry, &dpm_off); - resume_device_early(dev); + 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_power_up - Turn on all devices that need special attention. + * device_resume - Restore state of each device in system. * - * Power on system devices then devices that required we shut them down - * with interrupts disabled. - * Called with interrupts disabled. + * Resume all the devices, unlock them all, and allow new + * devices to be registered once again. */ - -void device_power_up(void) +void device_resume(void) { - sysdev_resume(); - dpm_power_up(); + might_sleep(); + dpm_resume(); + unlock_all_devices(); + unregister_dropped_devices(); + up_write(&pm_sleep_rwsem); } - -EXPORT_SYMBOL_GPL(device_power_up); +EXPORT_SYMBOL_GPL(device_resume); /*------------------------- Suspend routines -------------------------*/ -/* - * 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 list on the suspend path are done in reverse order, so we operate - * on the leaves of the device tree (or forests, depending on how you want - * to look at it ;) first. As nodes are removed from the back of the list, - * they are inserted into the front of their destintation lists. - * - * Things are the reverse on the resume path - iterations are done in - * forward order, and nodes are inserted at the back of their destination - * lists. This way, the ancestors will be accessed before their descendents. - */ - static inline char *suspend_verb(u32 event) { switch (event) { @@ -222,7 +342,6 @@ static inline char *suspend_verb(u32 event) } } - static void suspend_device_dbg(struct device *dev, pm_message_t state, char *info) { @@ -232,16 +351,73 @@ suspend_device_dbg(struct device *dev, pm_message_t state, char *info) } /** - * suspend_device - Save state of one device. + * 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; -static int suspend_device(struct device * dev, pm_message_t state) + 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; - down(&dev->sem); if (dev->power.power_state.event) { dev_dbg(dev, "PM: suspend %d-->%d\n", dev->power.power_state.event, state.event); @@ -264,123 +440,105 @@ static int suspend_device(struct device * dev, pm_message_t state) error = dev->bus->suspend(dev, state); suspend_report_result(dev->bus->suspend, error); } - up(&dev->sem); - return error; -} - - -/* - * This is called with interrupts off, only a single CPU - * running. We can't acquire a mutex or semaphore (and we don't - * need the protection) - */ -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_suspend - Save state and stop all devices in system. - * @state: Power state to put each device in. + * dpm_suspend - Suspend every device. + * @state: Power state to put each device in. * - * Walk the dpm_active list, call ->suspend() for each device, and move - * it to the dpm_off list. + * 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). - * - * If we get a different error, try and back out. - * - * If we hit a failure with any of the devices, call device_resume() - * above to bring the suspended devices back to life. - * */ - -int device_suspend(pm_message_t state) +static int dpm_suspend(pm_message_t state) { int error = 0; - might_sleep(); - mutex_lock(&dpm_mtx); mutex_lock(&dpm_list_mtx); - while (!list_empty(&dpm_active) && error == 0) { - struct list_head * entry = dpm_active.prev; - struct device * dev = to_device(entry); + while (!list_empty(&dpm_locked)) { + struct list_head *entry = dpm_locked.prev; + struct device *dev = to_device(entry); - get_device(dev); + list_del_init(&dev->power.entry); mutex_unlock(&dpm_list_mtx); - error = suspend_device(dev, state); - - mutex_lock(&dpm_list_mtx); - - /* Check if the device got removed */ - if (!list_empty(&dev->power.entry)) { - /* Move it to the dpm_off list */ - if (!error) - list_move(&dev->power.entry, &dpm_off); - } - if (error) + 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)" : ""); - put_device(dev); + "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); - if (error) - dpm_resume(); - mutex_unlock(&dpm_mtx); return error; } -EXPORT_SYMBOL_GPL(device_suspend); - /** - * device_power_down - Shut down special devices. - * @state: Power state to enter. + * lock_all_devices - Acquire every device's semaphore * - * Walk the dpm_off_irq list, calling ->power_down() for each device that - * couldn't power down the device with interrupts enabled. When we're - * done, power down system devices. + * Go through the dpm_active list. Carefully lock each device's + * semaphore and put it in on the dpm_locked list. */ - -int device_power_down(pm_message_t state) +static void lock_all_devices(void) { - int error = 0; - struct device * dev; + mutex_lock(&dpm_list_mtx); + while (!list_empty(&dpm_active)) { + struct list_head *entry = dpm_active.next; + struct device *dev = to_device(entry); - while (!list_empty(&dpm_off)) { - struct list_head * entry = dpm_off.prev; + /* 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); - dev = to_device(entry); - error = suspend_device_late(dev, state); - if (error) - goto Error; - list_move(&dev->power.entry, &dpm_off_irq); + 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; - error = sysdev_suspend(state); - Done: + might_sleep(); + down_write(&pm_sleep_rwsem); + lock_all_devices(); + error = dpm_suspend(state); + if (error) + device_resume(); return error; - Error: - printk(KERN_ERR "Could not power down device %s: " - "error %d\n", kobject_name(&dev->kobj), error); - dpm_power_up(); - goto Done; } - -EXPORT_SYMBOL_GPL(device_power_down); +EXPORT_SYMBOL_GPL(device_suspend); void __suspend_report_result(const char *function, void *fn, int ret) { diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h index 379da4e958e0..10c20840395e 100644 --- a/drivers/base/power/power.h +++ b/drivers/base/power/power.h @@ -20,6 +20,9 @@ static inline struct device *to_device(struct list_head *entry) extern void device_pm_add(struct device *); extern void device_pm_remove(struct device *); +extern void device_pm_schedule_removal(struct device *); +extern int pm_sleep_lock(void); +extern void pm_sleep_unlock(void); #else /* CONFIG_PM_SLEEP */ @@ -32,6 +35,15 @@ static inline void device_pm_remove(struct device *dev) { } +static inline int pm_sleep_lock(void) +{ + return 0; +} + +static inline void pm_sleep_unlock(void) +{ +} + #endif #ifdef CONFIG_PM |