Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

9 files changed, 1279 insertions, 0 deletions

diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
new file mode 100644
index 00000000000..5d4ae9a39f1
--- /dev/null
+++ b/Documentation/power/devices.txt
@@ -0,0 +1,319 @@
+
+Device Power Management
+
+
+Device power management encompasses two areas - the ability to save
+state and transition a device to a low-power state when the system is
+entering a low-power state; and the ability to transition a device to
+a low-power state while the system is running (and independently of
+any other power management activity). 
+
+
+Methods
+
+The methods to suspend and resume devices reside in struct bus_type: 
+
+struct bus_type {
+       ...
+       int             (*suspend)(struct device * dev, pm_message_t state);
+       int             (*resume)(struct device * dev);
+};
+
+Each bus driver is responsible implementing these methods, translating
+the call into a bus-specific request and forwarding the call to the
+bus-specific drivers. For example, PCI drivers implement suspend() and
+resume() methods in struct pci_driver. The PCI core is simply
+responsible for translating the pointers to PCI-specific ones and
+calling the low-level driver.
+
+This is done to a) ease transition to the new power management methods
+and leverage the existing PM code in various bus drivers; b) allow
+buses to implement generic and default PM routines for devices, and c)
+make the flow of execution obvious to the reader. 
+
+
+System Power Management
+
+When the system enters a low-power state, the device tree is walked in
+a depth-first fashion to transition each device into a low-power
+state. The ordering of the device tree is guaranteed by the order in
+which devices get registered - children are never registered before
+their ancestors, and devices are placed at the back of the list when
+registered. By walking the list in reverse order, we are guaranteed to
+suspend devices in the proper order. 
+
+Devices are suspended once with interrupts enabled. Drivers are
+expected to stop I/O transactions, save device state, and place the
+device into a low-power state. Drivers may sleep, allocate memory,
+etc. at will. 
+
+Some devices are broken and will inevitably have problems powering
+down or disabling themselves with interrupts enabled. For these
+special cases, they may return -EAGAIN. This will put the device on a
+list to be taken care of later. When interrupts are disabled, before
+we enter the low-power state, their drivers are called again to put
+their device to sleep. 
+
+On resume, the devices that returned -EAGAIN will be called to power
+themselves back on with interrupts disabled. Once interrupts have been
+re-enabled, the rest of the drivers will be called to resume their
+devices. On resume, a driver is responsible for powering back on each
+device, restoring state, and re-enabling I/O transactions for that
+device. 
+
+System devices follow a slightly different API, which can be found in
+
+	include/linux/sysdev.h
+	drivers/base/sys.c
+
+System devices will only be suspended with interrupts disabled, and
+after all other devices have been suspended. On resume, they will be
+resumed before any other devices, and also with interrupts disabled.
+
+
+Runtime Power Management
+
+Many devices are able to dynamically power down while the system is
+still running. This feature is useful for devices that are not being
+used, and can offer significant power savings on a running system. 
+
+In each device's directory, there is a 'power' directory, which
+contains at least a 'state' file. Reading from this file displays what
+power state the device is currently in. Writing to this file initiates
+a transition to the specified power state, which must be a decimal in
+the range 1-3, inclusive; or 0 for 'On'.
+
+The PM core will call the ->suspend() method in the bus_type object
+that the device belongs to if the specified state is not 0, or
+->resume() if it is. 
+
+Nothing will happen if the specified state is the same state the
+device is currently in. 
+
+If the device is already in a low-power state, and the specified state
+is another, but different, low-power state, the ->resume() method will
+first be called to power the device back on, then ->suspend() will be
+called again with the new state. 
+
+The driver is responsible for saving the working state of the device
+and putting it into the low-power state specified. If this was
+successful, it returns 0, and the device's power_state field is
+updated. 
+
+The driver must take care to know whether or not it is able to
+properly resume the device, including all step of reinitialization
+necessary. (This is the hardest part, and the one most protected by
+NDA'd documents). 
+
+The driver must also take care not to suspend a device that is
+currently in use. It is their responsibility to provide their own
+exclusion mechanisms.
+
+The runtime power transition happens with interrupts enabled. If a
+device cannot support being powered down with interrupts, it may
+return -EAGAIN (as it would during a system power management
+transition),  but it will _not_ be called again, and the transaction
+will fail.
+
+There is currently no way to know what states a device or driver
+supports a priori. This will change in the future. 
+
+pm_message_t meaning
+
+pm_message_t has two fields. event ("major"), and flags.  If driver
+does not know event code, it aborts the request, returning error. Some
+drivers may need to deal with special cases based on the actual type
+of suspend operation being done at the system level. This is why
+there are flags.
+
+Event codes are:
+
+ON -- no need to do anything except special cases like broken
+HW.
+
+# NOTIFICATION -- pretty much same as ON?
+
+FREEZE -- stop DMA and interrupts, and be prepared to reinit HW from
+scratch. That probably means stop accepting upstream requests, the
+actual policy of what to do with them beeing specific to a given
+driver. It's acceptable for a network driver to just drop packets
+while a block driver is expected to block the queue so no request is
+lost. (Use IDE as an example on how to do that). FREEZE requires no
+power state change, and it's expected for drivers to be able to
+quickly transition back to operating state.
+
+SUSPEND -- like FREEZE, but also put hardware into low-power state. If
+there's need to distinguish several levels of sleep, additional flag
+is probably best way to do that.
+
+Transitions are only from a resumed state to a suspended state, never
+between 2 suspended states. (ON -> FREEZE or ON -> SUSPEND can happen,
+FREEZE -> SUSPEND or SUSPEND -> FREEZE can not).
+
+All events are:
+
+[NOTE NOTE NOTE: If you are driver author, you should not care; you
+should only look at event, and ignore flags.]
+
+#Prepare for suspend -- userland is still running but we are going to
+#enter suspend state. This gives drivers chance to load firmware from
+#disk and store it in memory, or do other activities taht require
+#operating userland, ability to kmalloc GFP_KERNEL, etc... All of these
+#are forbiden once the suspend dance is started.. event = ON, flags =
+#PREPARE_TO_SUSPEND
+
+Apm standby -- prepare for APM event. Quiesce devices to make life
+easier for APM BIOS. event = FREEZE, flags = APM_STANDBY
+
+Apm suspend -- same as APM_STANDBY, but it we should probably avoid
+spinning down disks. event = FREEZE, flags = APM_SUSPEND
+
+System halt, reboot -- quiesce devices to make life easier for BIOS. event
+= FREEZE, flags = SYSTEM_HALT or SYSTEM_REBOOT
+
+System shutdown -- at least disks need to be spun down, or data may be
+lost. Quiesce devices, just to make life easier for BIOS. event =
+FREEZE, flags = SYSTEM_SHUTDOWN
+
+Kexec    -- turn off DMAs and put hardware into some state where new
+kernel can take over. event = FREEZE, flags = KEXEC
+
+Powerdown at end of swsusp -- very similar to SYSTEM_SHUTDOWN, except wake
+may need to be enabled on some devices. This actually has at least 3
+subtypes, system can reboot, enter S4 and enter S5 at the end of
+swsusp. event = FREEZE, flags = SWSUSP and one of SYSTEM_REBOOT,
+SYSTEM_SHUTDOWN, SYSTEM_S4
+
+Suspend to ram  -- put devices into low power state. event = SUSPEND,
+flags = SUSPEND_TO_RAM
+
+Freeze for swsusp snapshot -- stop DMA and interrupts. No need to put
+devices into low power mode, but you must be able to reinitialize
+device from scratch in resume method. This has two flavors, its done
+once on suspending kernel, once on resuming kernel. event = FREEZE,
+flags = DURING_SUSPEND or DURING_RESUME
+
+Device detach requested from /sys -- deinitialize device; proably same as
+SYSTEM_SHUTDOWN, I do not understand this one too much. probably event
+= FREEZE, flags = DEV_DETACH.
+
+#These are not really events sent:
+#
+#System fully on -- device is working normally; this is probably never
+#passed to suspend() method... event = ON, flags = 0
+#
+#Ready after resume -- userland is now running, again. Time to free any
+#memory you ate during prepare to suspend... event = ON, flags =
+#READY_AFTER_RESUME
+#
+
+Driver Detach Power Management
+
+The kernel now supports the ability to place a device in a low-power
+state when it is detached from its driver, which happens when its
+module is removed. 
+
+Each device contains a 'detach_state' file in its sysfs directory
+which can be used to control this state. Reading from this file
+displays what the current detach state is set to. This is 0 (On) by
+default. A user may write a positive integer value to this file in the
+range of 1-4 inclusive. 
+
+A value of 1-3 will indicate the device should be placed in that
+low-power state, which will cause ->suspend() to be called for that
+device. A value of 4 indicates that the device should be shutdown, so
+->shutdown() will be called for that device. 
+
+The driver is responsible for reinitializing the device when the
+module is re-inserted during it's ->probe() (or equivalent) method. 
+The driver core will not call any extra functions when binding the
+device to the driver. 
+
+pm_message_t meaning
+
+pm_message_t has two fields. event ("major"), and flags.  If driver
+does not know event code, it aborts the request, returning error. Some
+drivers may need to deal with special cases based on the actual type
+of suspend operation being done at the system level. This is why
+there are flags.
+
+Event codes are:
+
+ON -- no need to do anything except special cases like broken
+HW.
+
+# NOTIFICATION -- pretty much same as ON?
+
+FREEZE -- stop DMA and interrupts, and be prepared to reinit HW from
+scratch. That probably means stop accepting upstream requests, the
+actual policy of what to do with them being specific to a given
+driver. It's acceptable for a network driver to just drop packets
+while a block driver is expected to block the queue so no request is
+lost. (Use IDE as an example on how to do that). FREEZE requires no
+power state change, and it's expected for drivers to be able to
+quickly transition back to operating state.
+
+SUSPEND -- like FREEZE, but also put hardware into low-power state. If
+there's need to distinguish several levels of sleep, additional flag
+is probably best way to do that.
+
+Transitions are only from a resumed state to a suspended state, never
+between 2 suspended states. (ON -> FREEZE or ON -> SUSPEND can happen,
+FREEZE -> SUSPEND or SUSPEND -> FREEZE can not).
+
+All events are:
+
+[NOTE NOTE NOTE: If you are driver author, you should not care; you
+should only look at event, and ignore flags.]
+
+#Prepare for suspend -- userland is still running but we are going to
+#enter suspend state. This gives drivers chance to load firmware from
+#disk and store it in memory, or do other activities taht require
+#operating userland, ability to kmalloc GFP_KERNEL, etc... All of these
+#are forbiden once the suspend dance is started.. event = ON, flags =
+#PREPARE_TO_SUSPEND
+
+Apm standby -- prepare for APM event. Quiesce devices to make life
+easier for APM BIOS. event = FREEZE, flags = APM_STANDBY
+
+Apm suspend -- same as APM_STANDBY, but it we should probably avoid
+spinning down disks. event = FREEZE, flags = APM_SUSPEND
+
+System halt, reboot -- quiesce devices to make life easier for BIOS. event
+= FREEZE, flags = SYSTEM_HALT or SYSTEM_REBOOT
+
+System shutdown -- at least disks need to be spun down, or data may be
+lost. Quiesce devices, just to make life easier for BIOS. event =
+FREEZE, flags = SYSTEM_SHUTDOWN
+
+Kexec    -- turn off DMAs and put hardware into some state where new
+kernel can take over. event = FREEZE, flags = KEXEC
+
+Powerdown at end of swsusp -- very similar to SYSTEM_SHUTDOWN, except wake
+may need to be enabled on some devices. This actually has at least 3
+subtypes, system can reboot, enter S4 and enter S5 at the end of
+swsusp. event = FREEZE, flags = SWSUSP and one of SYSTEM_REBOOT,
+SYSTEM_SHUTDOWN, SYSTEM_S4
+
+Suspend to ram  -- put devices into low power state. event = SUSPEND,
+flags = SUSPEND_TO_RAM
+
+Freeze for swsusp snapshot -- stop DMA and interrupts. No need to put
+devices into low power mode, but you must be able to reinitialize
+device from scratch in resume method. This has two flavors, its done
+once on suspending kernel, once on resuming kernel. event = FREEZE,
+flags = DURING_SUSPEND or DURING_RESUME
+
+Device detach requested from /sys -- deinitialize device; proably same as
+SYSTEM_SHUTDOWN, I do not understand this one too much. probably event
+= FREEZE, flags = DEV_DETACH.
+
+#These are not really events sent:
+#
+#System fully on -- device is working normally; this is probably never
+#passed to suspend() method... event = ON, flags = 0
+#
+#Ready after resume -- userland is now running, again. Time to free any
+#memory you ate during prepare to suspend... event = ON, flags =
+#READY_AFTER_RESUME
+#
diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt
new file mode 100644
index 00000000000..f5ebda5f427
--- /dev/null
+++ b/Documentation/power/interface.txt
@@ -0,0 +1,43 @@
+Power Management Interface
+
+
+The power management subsystem provides a unified sysfs interface to 
+userspace, regardless of what architecture or platform one is
+running. The interface exists in /sys/power/ directory (assuming sysfs
+is mounted at /sys). 
+
+/sys/power/state controls system power state. Reading from this file
+returns what states are supported, which is hard-coded to 'standby'
+(Power-On Suspend), 'mem' (Suspend-to-RAM), and 'disk'
+(Suspend-to-Disk). 
+
+Writing to this file one of those strings causes the system to
+transition into that state. Please see the file
+Documentation/power/states.txt for a description of each of those
+states.
+
+
+/sys/power/disk controls the operating mode of the suspend-to-disk
+mechanism. Suspend-to-disk can be handled in several ways. The
+greatest distinction is who writes memory to disk - the firmware or
+the kernel. If the firmware does it, we assume that it also handles
+suspending the system. 
+
+If the kernel does it, then we have three options for putting the system
+to sleep - using the platform driver (e.g. ACPI or other PM
+registers), powering off the system or rebooting the system (for
+testing). The system will support either 'firmware' or 'platform', and
+that is known a priori. But, the user may choose 'shutdown' or
+'reboot' as alternatives. 
+
+Reading from this file will display what the mode is currently set
+to. Writing to this file will accept one of
+
+       'firmware'
+       'platform'
+       'shutdown'
+       'reboot'
+
+It will only change to 'firmware' or 'platform' if the system supports
+it. 
+
diff --git a/Documentation/power/kernel_threads.txt b/Documentation/power/kernel_threads.txt
new file mode 100644
index 00000000000..60b548105ed
--- /dev/null
+++ b/Documentation/power/kernel_threads.txt
@@ -0,0 +1,41 @@
+KERNEL THREADS
+
+
+Freezer
+
+Upon entering a suspended state the system will freeze all
+tasks. This is done by delivering pseudosignals. This affects
+kernel threads, too. To successfully freeze a kernel thread
+the thread has to check for the pseudosignal and enter the
+refrigerator. Code to do this looks like this:
+
+	do {
+		hub_events();
+		wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
+		if (current->flags & PF_FREEZE)
+			refrigerator(PF_FREEZE);
+	} while (!signal_pending(current));
+
+from drivers/usb/core/hub.c::hub_thread()
+
+
+The Unfreezable
+
+Some kernel threads however, must not be frozen. The kernel must
+be able to finish pending IO operations and later on be able to
+write the memory image to disk. Kernel threads needed to do IO
+must stay awake. Such threads must mark themselves unfreezable
+like this:
+
+	/*
+	 * This thread doesn't need any user-level access,
+	 * so get rid of all our resources.
+	 */
+	daemonize("usb-storage");
+
+	current->flags |= PF_NOFREEZE;
+
+from drivers/usb/storage/usb.c::usb_stor_control_thread()
+
+Such drivers are themselves responsible for staying quiet during
+the actual snapshotting.
diff --git a/Documentation/power/pci.txt b/Documentation/power/pci.txt
new file mode 100644
index 00000000000..c85428e7ad9
--- /dev/null
+++ b/Documentation/power/pci.txt
@@ -0,0 +1,332 @@
+
+PCI Power Management
+~~~~~~~~~~~~~~~~~~~~
+
+An overview of the concepts and the related functions in the Linux kernel
+
+Patrick Mochel <mochel@transmeta.com>
+(and others)
+
+---------------------------------------------------------------------------
+
+1. Overview
+2. How the PCI Subsystem Does Power Management
+3. PCI Utility Functions
+4. PCI Device Drivers
+5. Resources
+
+1. Overview
+~~~~~~~~~~~
+
+The PCI Power Management Specification was introduced between the PCI 2.1 and
+PCI 2.2 Specifications. It a standard interface for controlling various 
+power management operations.
+
+Implementation of the PCI PM Spec is optional, as are several sub-components of
+it. If a device supports the PCI PM Spec, the device will have an 8 byte
+capability field in its PCI configuration space. This field is used to describe
+and control the standard PCI power management features.
+
+The PCI PM spec defines 4 operating states for devices (D0 - D3) and for buses
+(B0 - B3). The higher the number, the less power the device consumes. However,
+the higher the number, the longer the latency is for the device to return to 
+an operational state (D0).
+
+There are actually two D3 states.  When someone talks about D3, they usually
+mean D3hot, which corresponds to an ACPI D2 state (power is reduced, the
+device may lose some context).  But they may also mean D3cold, which is an
+ACPI D3 state (power is fully off, all state was discarded); or both.
+
+Bus power management is not covered in this version of this document.
+
+Note that all PCI devices support D0 and D3cold by default, regardless of
+whether or not they implement any of the PCI PM spec.
+
+The possible state transitions that a device can undergo are:
+
++---------------------------+
+| Current State | New State |
++---------------------------+
+| D0            | D1, D2, D3|
++---------------------------+
+| D1            | D2, D3    |
++---------------------------+
+| D2            | D3        |
++---------------------------+
+| D1, D2, D3    | D0        |
++---------------------------+
+
+Note that when the system is entering a global suspend state, all devices will
+be placed into D3 and when resuming, all devices will be placed into D0.
+However, when the system is running, other state transitions are possible.
+
+2. How The PCI Subsystem Handles Power Management
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The PCI suspend/resume functionality is accessed indirectly via the Power
+Management subsystem. At boot, the PCI driver registers a power management
+callback with that layer. Upon entering a suspend state, the PM layer iterates
+through all of its registered callbacks. This currently takes place only during
+APM state transitions.
+
+Upon going to sleep, the PCI subsystem walks its device tree twice. Both times,
+it does a depth first walk of the device tree. The first walk saves each of the
+device's state and checks for devices that will prevent the system from entering
+a global power state. The next walk then places the devices in a low power
+state.
+
+The first walk allows a graceful recovery in the event of a failure, since none
+of the devices have actually been powered down.
+
+In both walks, in particular the second, all children of a bridge are touched
+before the actual bridge itself. This allows the bridge to retain power while
+its children are being accessed.
+
+Upon resuming from sleep, just the opposite must be true: all bridges must be
+powered on and restored before their children are powered on. This is easily
+accomplished with a breadth-first walk of the PCI device tree.
+
+
+3. PCI Utility Functions
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+These are helper functions designed to be called by individual device drivers.
+Assuming that a device behaves as advertised, these should be applicable in most
+cases. However, results may vary.
+
+Note that these functions are never implicitly called for the driver. The driver
+is always responsible for deciding when and if to call these.
+
+
+pci_save_state
+--------------
+
+Usage:
+	pci_save_state(dev, buffer);
+
+Description:
+	Save first 64 bytes of PCI config space. Buffer must be allocated by
+	caller.
+
+
+pci_restore_state
+-----------------
+
+Usage:
+	pci_restore_state(dev, buffer);
+
+Description:
+	Restore previously saved config space. (First 64 bytes only);
+
+	If buffer is NULL, then restore what information we know about the
+	device from bootup: BARs and interrupt line.
+
+
+pci_set_power_state
+-------------------
+
+Usage:
+	pci_set_power_state(dev, state);
+
+Description:
+	Transition device to low power state using PCI PM Capabilities
+	registers.
+
+	Will fail under one of the following conditions:
+	- If state is less than current state, but not D0 (illegal transition)
+	- Device doesn't support PM Capabilities
+	- Device does not support requested state
+
+
+pci_enable_wake
+---------------
+
+Usage:
+	pci_enable_wake(dev, state, enable);
+
+Description:
+	Enable device to generate PME# during low power state using PCI PM 
+	Capabilities.
+
+	Checks whether if device supports generating PME# from requested state
+	and fail if it does not, unless enable == 0 (request is to disable wake
+	events, which is implicit if it doesn't even support it in the first
+	place).
+
+	Note that the PMC Register in the device's PM Capabilties has a bitmask
+	of the states it supports generating PME# from. D3hot is bit 3 and
+	D3cold is bit 4. So, while a value of 4 as the state may not seem
+	semantically correct, it is. 
+
+
+4. PCI Device Drivers
+~~~~~~~~~~~~~~~~~~~~~
+
+These functions are intended for use by individual drivers, and are defined in 
+struct pci_driver:
+
+        int  (*save_state) (struct pci_dev *dev, u32 state);
+        int  (*suspend) (struct pci_dev *dev, u32 state);
+        int  (*resume) (struct pci_dev *dev);
+        int  (*enable_wake) (struct pci_dev *dev, u32 state, int enable);
+
+
+save_state
+----------
+
+Usage:
+
+if (dev->driver && dev->driver->save_state)
+	dev->driver->save_state(dev,state);
+
+The driver should use this callback to save device state. It should take into
+account the current state of the device and the requested state in order to
+avoid any unnecessary operations.
+
+For example, a video card that supports all 4 states (D0-D3), all controller
+context is preserved when entering D1, but the screen is placed into a low power
+state (blanked). 
+
+The driver can also interpret this function as a notification that it may be
+entering a sleep state in the near future. If it knows that the device cannot
+enter the requested state, either because of lack of support for it, or because
+the device is middle of some critical operation, then it should fail.
+
+This function should not be used to set any state in the device or the driver
+because the device may not actually enter the sleep state (e.g. another driver
+later causes causes a global state transition to fail).
+
+Note that in intermediate low power states, a device's I/O and memory spaces may
+be disabled and may not be available in subsequent transitions to lower power
+states.
+
+
+suspend
+-------
+
+Usage:
+
+if (dev->driver && dev->driver->suspend)
+	dev->driver->suspend(dev,state);
+
+A driver uses this function to actually transition the device into a low power
+state. This should include disabling I/O, IRQs, and bus-mastering, as well as
+physically transitioning the device to a lower power state; it may also include
+calls to pci_enable_wake().
+
+Bus mastering may be disabled by doing:
+
+pci_disable_device(dev);
+
+For devices that support the PCI PM Spec, this may be used to set the device's
+power state to match the suspend() parameter:
+
+pci_set_power_state(dev,state);
+
+The driver is also responsible for disabling any other device-specific features
+(e.g blanking screen, turning off on-card memory, etc).
+
+The driver should be sure to track the current state of the device, as it may
+obviate the need for some operations.
+
+The driver should update the current_state field in its pci_dev structure in
+this function, except for PM-capable devices when pci_set_power_state is used.
+
+resume
+------
+
+Usage:
+
+if (dev->driver && dev->driver->suspend)
+	dev->driver->resume(dev)
+
+The resume callback may be called from any power state, and is always meant to
+transition the device to the D0 state. 
+
+The driver is responsible for reenabling any features of the device that had
+been disabled during previous suspend calls, such as IRQs and bus mastering,
+as well as calling pci_restore_state().
+
+If the device is currently in D3, it may need to be reinitialized in resume().
+
+  * Some types of devices, like bus controllers, will preserve context in D3hot
+    (using Vcc power).  Their drivers will often want to avoid re-initializing
+    them after re-entering D0 (perhaps to avoid resetting downstream devices).
+
+  * Other kinds of devices in D3hot will discard device context as part of a
+    soft reset when re-entering the D0 state.
+    
+  * Devices resuming from D3cold always go through a power-on reset.  Some
+    device context can also be preserved using Vaux power.
+
+  * Some systems hide D3cold resume paths from drivers.  For example, on PCs
+    the resume path for suspend-to-disk often runs BIOS powerup code, which
+    will sometimes re-initialize the device.
+
+To handle resets during D3 to D0 transitions, it may be convenient to share
+device initialization code between probe() and resume().  Device parameters
+can also be saved before the driver suspends into D3, avoiding re-probe.
+
+If the device supports the PCI PM Spec, it can use this to physically transition
+the device to D0:
+
+pci_set_power_state(dev,0);
+
+Note that if the entire system is transitioning out of a global sleep state, all
+devices will be placed in the D0 state, so this is not necessary. However, in
+the event that the device is placed in the D3 state during normal operation,
+this call is necessary. It is impossible to determine which of the two events is
+taking place in the driver, so it is always a good idea to make that call.
+
+The driver should take note of the state that it is resuming from in order to
+ensure correct (and speedy) operation.
+
+The driver should update the current_state field in its pci_dev structure in
+this function, except for PM-capable devices when pci_set_power_state is used.
+
+
+enable_wake
+-----------
+
+Usage:
+
+if (dev->driver && dev->driver->enable_wake)
+	dev->driver->enable_wake(dev,state,enable);
+
+This callback is generally only relevant for devices that support the PCI PM
+spec and have the ability to generate a PME# (Power Management Event Signal)
+to wake the system up. (However, it is possible that a device may support 
+some non-standard way of generating a wake event on sleep.)
+
+Bits 15:11 of the PMC (Power Mgmt Capabilities) Register in a device's
+PM Capabilties describe what power states the device supports generating a 
+wake event from:
+
++------------------+
+|  Bit  |  State   |
++------------------+
+|  11   |   D0     |
+|  12   |   D1     |
+|  13   |   D2     |
+|  14   |   D3hot  |
+|  15   |   D3cold |
++------------------+
+
+A device can use this to enable wake events:
+
+	 pci_enable_wake(dev,state,enable);
+
+Note that to enable PME# from D3cold, a value of 4 should be passed to 
+pci_enable_wake (since it uses an index into a bitmask). If a driver gets
+a request to enable wake events from D3, two calls should be made to 
+pci_enable_wake (one for both D3hot and D3cold).
+
+
+5. Resources
+~~~~~~~~~~~~
+
+PCI Local Bus Specification 
+PCI Bus Power Management Interface Specification
+
+  http://pcisig.org
+
diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt
new file mode 100644
index 00000000000..3e5e5d3ff41
--- /dev/null
+++ b/Documentation/power/states.txt
@@ -0,0 +1,79 @@
+
+System Power Management States
+
+
+The kernel supports three power management states generically, though
+each is dependent on platform support code to implement the low-level
+details for each state. This file describes each state, what they are
+commonly called, what ACPI state they map to, and what string to write
+to /sys/power/state to enter that state
+
+
+State:		Standby / Power-On Suspend
+ACPI State:	S1
+String:		"standby"
+
+This state offers minimal, though real, power savings, while providing
+a very low-latency transition back to a working system. No operating
+state is lost (the CPU retains power), so the system easily starts up
+again where it left off. 
+
+We try to put devices in a low-power state equivalent to D1, which
+also offers low power savings, but low resume latency. Not all devices
+support D1, and those that don't are left on. 
+
+A transition from Standby to the On state should take about 1-2
+seconds. 
+
+
+State:		Suspend-to-RAM
+ACPI State:	S3
+String:		"mem"
+
+This state offers significant power savings as everything in the
+system is put into a low-power state, except for memory, which is
+placed in self-refresh mode to retain its contents. 
+
+System and device state is saved and kept in memory. All devices are
+suspended and put into D3. In many cases, all peripheral buses lose
+power when entering STR, so devices must be able to handle the
+transition back to the On state. 
+
+For at least ACPI, STR requires some minimal boot-strapping code to
+resume the system from STR. This may be true on other platforms. 
+
+A transition from Suspend-to-RAM to the On state should take about
+3-5 seconds. 
+
+
+State:		Suspend-to-disk
+ACPI State:	S4
+String:		"disk"
+
+This state offers the greatest power savings, and can be used even in
+the absence of low-level platform support for power management. This
+state operates similarly to Suspend-to-RAM, but includes a final step
+of writing memory contents to disk. On resume, this is read and memory
+is restored to its pre-suspend state. 
+
+STD can be handled by the firmware or the kernel. If it is handled by
+the firmware, it usually requires a dedicated partition that must be
+setup via another operating system for it to use. Despite the
+inconvenience, this method requires minimal work by the kernel, since
+the firmware will also handle restoring memory contents on resume. 
+
+If the kernel is responsible for persistantly saving state, a mechanism 
+called 'swsusp' (Swap Suspend) is used to write memory contents to
+free swap space. swsusp has some restrictive requirements, but should
+work in most cases. Some, albeit outdated, documentation can be found
+in Documentation/power/swsusp.txt. 
+
+Once memory state is written to disk, the system may either enter a
+low-power state (like ACPI S4), or it may simply power down. Powering
+down offers greater savings, and allows this mechanism to work on any
+system. However, entering a real low-power state allows the user to
+trigger wake up events (e.g. pressing a key or opening a laptop lid). 
+
+A transition from Suspend-to-Disk to the On state should take about 30
+seconds, though it's typically a bit more with the current
+implementation. 
diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt
new file mode 100644
index 00000000000..c7c3459fde4
--- /dev/null
+++ b/Documentation/power/swsusp.txt
@@ -0,0 +1,235 @@
+From kernel/suspend.c:
+
+ * BIG FAT WARNING *********************************************************
+ *
+ * If you have unsupported (*) devices using DMA...
+ *				...say goodbye to your data.
+ *
+ * If you touch anything on disk between suspend and resume...
+ *				...kiss your data goodbye.
+ *
+ * If your disk driver does not support suspend... (IDE does)
+ *				...you'd better find out how to get along
+ *				   without your data.
+ *
+ * If you change kernel command line between suspend and resume...
+ *			        ...prepare for nasty fsck or worse.
+ *
+ * If you change your hardware while system is suspended...
+ *			        ...well, it was not good idea.
+ *
+ * (*) suspend/resume support is needed to make it safe.
+
+You need to append resume=/dev/your_swap_partition to kernel command
+line. Then you suspend by
+
+echo shutdown > /sys/power/disk; echo disk > /sys/power/state
+
+. If you feel ACPI works pretty well on your system, you might try
+
+echo platform > /sys/power/disk; echo disk > /sys/power/state
+
+
+
+Article about goals and implementation of Software Suspend for Linux
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Author: G‚ábor Kuti
+Last revised: 2003-10-20 by Pavel Machek
+
+Idea and goals to achieve
+
+Nowadays it is common in several laptops that they have a suspend button. It
+saves the state of the machine to a filesystem or to a partition and switches
+to standby mode. Later resuming the machine the saved state is loaded back to
+ram and the machine can continue its work. It has two real benefits. First we
+save ourselves the time machine goes down and later boots up, energy costs
+are real high when running from batteries. The other gain is that we don't have to
+interrupt our programs so processes that are calculating something for a long
+time shouldn't need to be written interruptible.
+
+swsusp saves the state of the machine into active swaps and then reboots or
+powerdowns.  You must explicitly specify the swap partition to resume from with
+``resume='' kernel option. If signature is found it loads and restores saved
+state. If the option ``noresume'' is specified as a boot parameter, it skips
+the resuming.
+
+In the meantime while the system is suspended you should not add/remove any
+of the hardware, write to the filesystems, etc.
+
+Sleep states summary
+====================