diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/power/interface.txt |
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!
Diffstat (limited to 'Documentation/power/interface.txt')
-rw-r--r-- | Documentation/power/interface.txt | 43 |
1 files changed, 43 insertions, 0 deletions
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 | |||
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1 | Power Management Interface | ||
2 | |||
3 | |||
4 | The power management subsystem provides a unified sysfs interface to | ||
5 | userspace, regardless of what architecture or platform one is | ||
6 | running. The interface exists in /sys/power/ directory (assuming sysfs | ||
7 | is mounted at /sys). | ||
8 | |||
9 | /sys/power/state controls system power state. Reading from this file | ||
10 | returns what states are supported, which is hard-coded to 'standby' | ||
11 | (Power-On Suspend), 'mem' (Suspend-to-RAM), and 'disk' | ||
12 | (Suspend-to-Disk). | ||
13 | |||
14 | Writing to this file one of those strings causes the system to | ||
15 | transition into that state. Please see the file | ||
16 | Documentation/power/states.txt for a description of each of those | ||
17 | states. | ||
18 | |||
19 | |||
20 | /sys/power/disk controls the operating mode of the suspend-to-disk | ||
21 | mechanism. Suspend-to-disk can be handled in several ways. The | ||
22 | greatest distinction is who writes memory to disk - the firmware or | ||
23 | the kernel. If the firmware does it, we assume that it also handles | ||
24 | suspending the system. | ||
25 | |||
26 | If the kernel does it, then we have three options for putting the system | ||
27 | to sleep - using the platform driver (e.g. ACPI or other PM | ||
28 | registers), powering off the system or rebooting the system (for | ||
29 | testing). The system will support either 'firmware' or 'platform', and | ||
30 | that is known a priori. But, the user may choose 'shutdown' or | ||
31 | 'reboot' as alternatives. | ||
32 | |||
33 | Reading from this file will display what the mode is currently set | ||
34 | to. Writing to this file will accept one of | ||
35 | |||
36 | 'firmware' | ||
37 | 'platform' | ||
38 | 'shutdown' | ||
39 | 'reboot' | ||
40 | |||
41 | It will only change to 'firmware' or 'platform' if the system supports | ||
42 | it. | ||
43 | |||