1====================================
2Toshiba HDD Active Protection Sensor
3====================================
4
5Kernel driver: toshiba_haps
6
7Author: Azael Avalos <coproscefalo@gmail.com>
8
9
10.. 0. Contents
11
12   1. Description
13   2. Interface
14   3. Accelerometer axes
15   4. Supported devices
16   5. Usage
17
18
191. Description
20--------------
21
22This driver provides support for the accelerometer found in various Toshiba
23laptops, being called "Toshiba HDD Protection - Shock Sensor" officially,
24and detects laptops automatically with this device.
25On Windows, Toshiba provided software monitors this device and provides
26automatic HDD protection (head unload) on sudden moves or harsh vibrations,
27however, this driver only provides a notification via a sysfs file to let
28userspace tools or daemons act accordingly, as well as providing a sysfs
29file to set the desired protection level or sensor sensibility.
30
31
322. Interface
33------------
34
35This device comes with 3 methods:
36
37====	=====================================================================
38_STA    Checks existence of the device, returning Zero if the device does not
39	exists or is not supported.
40PTLV    Sets the desired protection level.
41RSSS    Shuts down the HDD protection interface for a few seconds,
42	then restores normal operation.
43====	=====================================================================
44
45Note:
46  The presence of Solid State Drives (SSD) can make this driver to fail loading,
47  given the fact that such drives have no movable parts, and thus, not requiring
48  any "protection" as well as failing during the evaluation of the _STA method
49  found under this device.
50
51
523. Accelerometer axes
53---------------------
54
55This device does not report any axes, however, to query the sensor position
56a couple HCI (Hardware Configuration Interface) calls (0x6D and 0xA6) are
57provided to query such information, handled by the kernel module toshiba_acpi
58since kernel version 3.15.
59
60
614. Supported devices
62--------------------
63
64This driver binds itself to the ACPI device TOS620A, and any Toshiba laptop
65with this device is supported, given the fact that they have the presence of
66conventional HDD and not only SSD, or a combination of both HDD and SSD.
67
68
695. Usage
70--------
71
72The sysfs files under /sys/devices/LNXSYSTM:00/LNXSYBUS:00/TOS620A:00/ are:
73
74================   ============================================================
75protection_level   The protection_level is readable and writeable, and
76		   provides a way to let userspace query the current protection
77		   level, as well as set the desired protection level, the
78		   available protection levels are::
79
80		     ============   =======   ==========   ========
81		     0 - Disabled   1 - Low   2 - Medium   3 - High
82		     ============   =======   ==========   ========
83
84reset_protection   The reset_protection entry is writeable only, being "1"
85		   the only parameter it accepts, it is used to trigger
86		   a reset of the protection interface.
87================   ============================================================
88