From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-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! --- Documentation/power/interface.txt | 43 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 Documentation/power/interface.txt (limited to 'Documentation/power/interface.txt') diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt new file mode 100644 index 000000000000..f5ebda5f4276 --- /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. + -- cgit v1.2.3-59-g8ed1b