+++ /dev/null
-/*
- * 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>
-
-/*
- * 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;
-}
-
-/**
- * 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_send_all);
-
projects / users / hch / xfs.git / commitdiff