summaryrefslogtreecommitdiff
path: root/Documentation/thinkpad-acpi.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/thinkpad-acpi.txt')
-rw-r--r--Documentation/thinkpad-acpi.txt40
1 files changed, 34 insertions, 6 deletions
diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index 1a42b77e2ece..0e4e053cface 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -1,7 +1,7 @@
ThinkPad ACPI Extras Driver
Version 0.14
- March 26th, 2007
+ April 21st, 2007
Borislav Deianov <borislav@users.sf.net>
Henrique de Moraes Holschuh <hmh@hmh.eng.br>
@@ -67,11 +67,39 @@ thinkpad-specific bay functionality.
Features
--------
-The driver creates the /proc/acpi/ibm directory. There is a file under
-that directory for each feature described below. Note that while the
-driver is still in the alpha stage, the exact proc file format and
-commands supported by the various features is guaranteed to change
-frequently.
+The driver exports two different interfaces to userspace, which can be
+used to access the features it provides. One is a legacy procfs-based
+interface, which will be removed at some time in the distant future.
+The other is a new sysfs-based interface which is not complete yet.
+
+The procfs interface creates the /proc/acpi/ibm directory. There is a
+file under that directory for each feature it supports. The procfs
+interface is mostly frozen, and will change very little if at all: it
+will not be extended to add any new functionality in the driver, instead
+all new functionality will be implemented on the sysfs interface.
+
+The sysfs interface tries to blend in the generic Linux sysfs subsystems
+and classes as much as possible. Since some of these subsystems are not
+yet ready or stabilized, it is expected that this interface will change,
+and any and all userspace programs must deal with it.
+
+
+Notes about the sysfs interface:
+
+Unlike what was done with the procfs interface, correctness when talking
+to the sysfs interfaces will be enforced, as will correctness in the
+thinkpad-acpi's implementation of sysfs interfaces.
+
+Also, any bugs in the thinkpad-acpi sysfs driver code or in the
+thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
+maximum correctness, even if that means changing an interface in
+non-compatible ways. As these interfaces mature both in the kernel and
+in thinkpad-acpi, such changes should become quite rare.
+
+Applications interfacing to the thinkpad-acpi sysfs interfaces must
+follow all sysfs guidelines and correctly process all errors (the sysfs
+interface makes extensive use of errors). File descriptors and open /
+close operations to the sysfs inodes must also be properly implemented.
Driver version -- /proc/acpi/ibm/driver
---------------------------------------