#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",
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));
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);
+}
+EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
+
+/**
+ * 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");
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) {
}
}
-
static void
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);
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)
{
git.openpandora.org / pandora-kernel.git / blobdiff