/* *  pm.c - Power management interface * *  Copyright (C) 2000 Andrew Henroid * *  This program is free software; you can redistribute it and/or modify *  it under the terms of the GNU General Public License as published by *  the Free Software Foundation; either version 2 of the License, or *  (at your option) any later version. * *  This program is distributed in the hope that it will be useful, *  but WITHOUT ANY WARRANTY; without even the implied warranty of *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the *  GNU General Public License for more details. * *  You should have received a copy of the GNU General Public License *  along with this program; if not, write to the Free Software *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */#include <linux/init.h>#include <linux/module.h>#include <linux/spinlock.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/pm.h>#include <linux/pm_legacy.h>#include <linux/interrupt.h>#include <linux/mutex.h> int pm_active; /* *	Locking notes: *		pm_devs_lock can be a semaphore providing pm ops are not called *	from an interrupt handler (already a bad idea so no change here). Each *	change must be protected so that an unlink of an entry doesn't clash *	with a pm send - which is permitted to sleep in the current architecture * *	Module unloads clashing with pm events now work out safely, the module  *	unload path will block until the event has been sent. It may well block *	until a resume but that will be fine. */ static DEFINE_MUTEX(pm_devs_lock);static LIST_HEAD(pm_devs); /** *	pm_register - register a device with power management *	@type: device type  *	@id: device ID *	@callback: callback function * *	Add a device to the list of devices that wish to be notified about *	power management events. A &pm_dev structure is returned on success, *	on failure the return is %NULL. * *      The callback function will be called in process context and *      it may sleep. */ struct pm_dev *pm_register(pm_dev_t type,			   unsigned long id,			   pm_callback callback){	struct pm_dev *dev = kzalloc(sizeof(struct pm_dev), GFP_KERNEL);	if (dev) {		dev->type = type;		dev->id = id;		dev->callback = callback; 		mutex_lock(&pm_devs_lock);		list_add(&dev->entry, &pm_devs);		mutex_unlock(&pm_devs_lock);	}	return dev;} static void __pm_unregister(struct pm_dev *dev){	if (dev) {		list_del(&dev->entry);		kfree(dev);	}} /** *	pm_unregister_all - unregister all devices with matching callback *	@callback: callback function pointer * *	Unregister every device that would call the callback passed. This *	is primarily meant as a helper function for loadable modules. It *	enables a module to give up all its managed devices without keeping *	its own private list. */ void pm_unregister_all(pm_callback callback){	struct list_head *entry; 	if (!callback)		return; 	mutex_lock(&pm_devs_lock);	entry = pm_devs.next;	while (entry != &pm_devs) {		struct pm_dev *dev = list_entry(entry, struct pm_dev, entry);		entry = entry->next;		if (dev->callback == callback)			__pm_unregister(dev);	}	mutex_unlock(&pm_devs_lock);} /** *	pm_send - send request to a single device *	@dev: device to send to *	@rqst: power management request *	@data: data for the callback * *	Issue a power management request to a given device. The  *	%PM_SUSPEND and %PM_RESUME events are handled specially. The *	data field must hold the intended next state. No call is made *	if the state matches. * *	BUGS: what stops two power management requests occurring in parallel *	and conflicting. * *	WARNING: Calling pm_send directly is not generally recommended, in *	particular there is no locking against the pm_dev going away. The *	caller must maintain all needed locking or have 'inside knowledge' *	on the safety. Also remember that this function is not locked against *	pm_unregister. This means that you must handle SMP races on callback *	execution and unload yourself. */ static int pm_send(struct pm_dev *dev, pm_request_t rqst, void *data){	int status = 0;	unsigned long prev_state, next_state; 	if (in_interrupt())		BUG(); 	switch (rqst) {	case PM_SUSPEND:	case PM_RESUME:		prev_state = dev->state;		next_state = (unsigned long) data;		if (prev_state != next_state) {			if (dev->callback)				status = (*dev->callback)(dev, rqst, data);			if (!status) {				dev->state = next_state;				dev->prev_state = prev_state;			}		}		else {			dev->prev_state = prev_state;		}		break;	default:		if (dev->callback)			status = (*dev->callback)(dev, rqst, data);		break;	}	return status;} /* * Undo incomplete request */static void pm_undo_all(struct pm_dev *last){	struct list_head *entry = last->entry.prev;	while (entry != &pm_devs) {		struct pm_dev *dev = list_entry(entry, struct pm_dev, entry);		if (dev->state != dev->prev_state) {			/* previous state was zero (running) resume or			 * previous state was non-zero (suspended) suspend			 */			pm_request_t undo = (dev->prev_state					     ? PM_SUSPEND:PM_RESUME);			pm_send(dev, undo, (void*) dev->prev_state);		}		entry = entry->prev;	}} /** *	pm_send_all - send request to all managed devices *	@rqst: power management request *	@data: data for the callback * *	Issue a power management request to a all devices. The  *	%PM_SUSPEND events are handled specially. Any device is  *	permitted to fail a suspend by returning a non zero (error) *	value from its callback function. If any device vetoes a  *	suspend request then all other devices that have suspended  *	during the processing of this request are restored to their *	previous state. * *	WARNING:  This function takes the pm_devs_lock. The lock is not dropped until *	the callbacks have completed. This prevents races against pm locking *	functions, races against module unload pm_unregister code. It does *	mean however that you must not issue pm_ functions within the callback *	or you will deadlock and users will hate you. * *	Zero is returned on success. If a suspend fails then the status *	from the device that vetoes the suspend is returned. * *	BUGS: what stops two power management requests occurring in parallel *	and conflicting. */ int pm_send_all(pm_request_t rqst, void *data){	struct list_head *entry;		mutex_lock(&pm_devs_lock);	entry = pm_devs.next;	while (entry != &pm_devs) {		struct pm_dev *dev = list_entry(entry, struct pm_dev, entry);		if (dev->callback) {			int status = pm_send(dev, rqst, data);			if (status) {				/* return devices to previous state on				 * failed suspend request				 */				if (rqst == PM_SUSPEND)					pm_undo_all(dev);				mutex_unlock(&pm_devs_lock);				return status;			}		}		entry = entry->next;	}	mutex_unlock(&pm_devs_lock);	return 0;} EXPORT_SYMBOL(pm_register);EXPORT_SYMBOL(pm_unregister_all);EXPORT_SYMBOL(pm_send_all);EXPORT_SYMBOL(pm_active);