+ 15 - three high-pitched beeps repeating constantly, stop with 0
+ 16 - one medium-pitched beep repeating constantly, stop with 17
+ 17 - stop 16
+
+Temperature sensors -- /proc/acpi/ibm/thermal
+---------------------------------------------
+
+Most ThinkPads include six or more separate temperature sensors but
+only expose the CPU temperature through the standard ACPI methods.
+This feature shows readings from up to eight different sensors on older
+ThinkPads, and it has experimental support for up to sixteen different
+sensors on newer ThinkPads. Readings from sensors that are not available
+return -128.
+
+No commands can be written to this file.
+
+EXPERIMENTAL: The 16-sensors feature is marked EXPERIMENTAL because the
+implementation directly accesses hardware registers and may not work as
+expected. USE WITH CAUTION! To use this feature, you need to supply the
+experimental=1 parameter when loading the module. When EXPERIMENTAL
+mode is enabled, reading the first 8 sensors on newer ThinkPads will
+also use an new experimental thermal sensor access mode.
+
+For example, on the X40, a typical output may be:
+temperatures: 42 42 45 41 36 -128 33 -128
+
+EXPERIMENTAL: On the T43/p, a typical output may be:
+temperatures: 48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
+
+The mapping of thermal sensors to physical locations varies depending on
+system-board model (and thus, on ThinkPad model).
+
+http://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
+tries to track down these locations for various models.
+
+Most (newer?) models seem to follow this pattern:
+
+1: CPU
+2: (depends on model)
+3: (depends on model)
+4: GPU
+5: Main battery: main sensor
+6: Bay battery: main sensor
+7: Main battery: secondary sensor
+8: Bay battery: secondary sensor
+9-15: (depends on model)
+
+For the R51 (source: Thomas Gruber):
+2: Mini-PCI
+3: Internal HDD
+
+For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
+http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
+2: System board, left side (near PCMCIA slot), reported as HDAPS temp
+3: PCMCIA slot
+9: MCH (northbridge) to DRAM Bus
+10: ICH (southbridge), under Mini-PCI card, under touchpad
+11: Power regulator, underside of system board, below F2 key
+
+The A31 has a very atypical layout for the thermal sensors
+(source: Milos Popovic, http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
+1: CPU
+2: Main Battery: main sensor
+3: Power Converter
+4: Bay Battery: main sensor
+5: MCH (northbridge)
+6: PCMCIA/ambient
+7: Main Battery: secondary sensor
+8: Bay Battery: secondary sensor
+
+
+EXPERIMENTAL: Embedded controller register dump -- /proc/acpi/ibm/ecdump
+------------------------------------------------------------------------
+
+This feature is marked EXPERIMENTAL because the implementation
+directly accesses hardware registers and may not work as expected. USE
+WITH CAUTION! To use this feature, you need to supply the
+experimental=1 parameter when loading the module.
+
+This feature dumps the values of 256 embedded controller
+registers. Values which have changed since the last time the registers
+were dumped are marked with a star:
+
+[root@x40 ibm-acpi]# cat /proc/acpi/ibm/ecdump
+EC +00 +01 +02 +03 +04 +05 +06 +07 +08 +09 +0a +0b +0c +0d +0e +0f
+EC 0x00: a7 47 87 01 fe 96 00 08 01 00 cb 00 00 00 40 00
+EC 0x10: 00 00 ff ff f4 3c 87 09 01 ff 42 01 ff ff 0d 00
+EC 0x20: 00 00 00 00 00 00 00 00 00 00 00 03 43 00 00 80
+EC 0x30: 01 07 1a 00 30 04 00 00 *85 00 00 10 00 50 00 00
+EC 0x40: 00 00 00 00 00 00 14 01 00 04 00 00 00 00 00 00
+EC 0x50: 00 c0 02 0d 00 01 01 02 02 03 03 03 03 *bc *02 *bc
+EC 0x60: *02 *bc *02 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0x70: 00 00 00 00 00 12 30 40 *24 *26 *2c *27 *20 80 *1f 80
+EC 0x80: 00 00 00 06 *37 *0e 03 00 00 00 0e 07 00 00 00 00
+EC 0x90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xa0: *ff 09 ff 09 ff ff *64 00 *00 *00 *a2 41 *ff *ff *e0 00
+EC 0xb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xd0: 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xe0: 00 00 00 00 00 00 00 00 11 20 49 04 24 06 55 03
+EC 0xf0: 31 55 48 54 35 38 57 57 08 2f 45 73 07 65 6c 1a
+
+This feature can be used to determine the register holding the fan
+speed on some models. To do that, do the following:
+
+ - make sure the battery is fully charged
+ - make sure the fan is running
+ - run 'cat /proc/acpi/ibm/ecdump' several times, once per second or so
+
+The first step makes sure various charging-related values don't
+vary. The second ensures that the fan-related values do vary, since
+the fan speed fluctuates a bit. The third will (hopefully) mark the
+fan register with a star:
+
+[root@x40 ibm-acpi]# cat /proc/acpi/ibm/ecdump
+EC +00 +01 +02 +03 +04 +05 +06 +07 +08 +09 +0a +0b +0c +0d +0e +0f
+EC 0x00: a7 47 87 01 fe 96 00 08 01 00 cb 00 00 00 40 00
+EC 0x10: 00 00 ff ff f4 3c 87 09 01 ff 42 01 ff ff 0d 00
+EC 0x20: 00 00 00 00 00 00 00 00 00 00 00 03 43 00 00 80
+EC 0x30: 01 07 1a 00 30 04 00 00 85 00 00 10 00 50 00 00
+EC 0x40: 00 00 00 00 00 00 14 01 00 04 00 00 00 00 00 00
+EC 0x50: 00 c0 02 0d 00 01 01 02 02 03 03 03 03 bc 02 bc
+EC 0x60: 02 bc 02 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0x70: 00 00 00 00 00 12 30 40 24 27 2c 27 21 80 1f 80
+EC 0x80: 00 00 00 06 *be 0d 03 00 00 00 0e 07 00 00 00 00
+EC 0x90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xa0: ff 09 ff 09 ff ff 64 00 00 00 a2 41 ff ff e0 00
+EC 0xb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xd0: 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+EC 0xe0: 00 00 00 00 00 00 00 00 11 20 49 04 24 06 55 03
+EC 0xf0: 31 55 48 54 35 38 57 57 08 2f 45 73 07 65 6c 1a
+
+Another set of values that varies often is the temperature
+readings. Since temperatures don't change vary fast, you can take
+several quick dumps to eliminate them.
+
+You can use a similar method to figure out the meaning of other
+embedded controller registers - e.g. make sure nothing else changes
+except the charging or discharging battery to determine which
+registers contain the current battery capacity, etc. If you experiment
+with this, do send me your results (including some complete dumps with
+a description of the conditions when they were taken.)
+
+LCD brightness control -- /proc/acpi/ibm/brightness
+---------------------------------------------------
+
+This feature allows software control of the LCD brightness on ThinkPad
+models which don't have a hardware brightness slider. The available
+commands are:
+
+ echo up >/proc/acpi/ibm/brightness
+ echo down >/proc/acpi/ibm/brightness
+ echo 'level <level>' >/proc/acpi/ibm/brightness
+
+The <level> number range is 0 to 7, although not all of them may be
+distinct. The current brightness level is shown in the file.
+
+Volume control -- /proc/acpi/ibm/volume
+---------------------------------------
+
+This feature allows volume control on ThinkPad models which don't have
+a hardware volume knob. The available commands are:
+
+ echo up >/proc/acpi/ibm/volume
+ echo down >/proc/acpi/ibm/volume
+ echo mute >/proc/acpi/ibm/volume
+ echo 'level <level>' >/proc/acpi/ibm/volume
+
+The <level> number range is 0 to 15 although not all of them may be
+distinct. The unmute the volume after the mute command, use either the
+up or down command (the level command will not unmute the volume).
+The current volume level and mute state is shown in the file.
+
+EXPERIMENTAL: fan speed, fan enable/disable -- /proc/acpi/ibm/fan
+-----------------------------------------------------------------
+
+This feature is marked EXPERIMENTAL because the implementation
+directly accesses hardware registers and may not work as expected. USE
+WITH CAUTION! To use this feature, you need to supply the
+experimental=1 parameter when loading the module.
+
+This feature attempts to show the current fan speed, control mode and
+other fan data that might be available. The speed is read directly
+from the hardware registers of the embedded controller. This is known
+to work on later R, T and X series ThinkPads but may show a bogus
+value on other models.
+
+Most ThinkPad fans work in "levels". Level 0 stops the fan. The higher
+the level, the higher the fan speed, although adjacent levels often map
+to the same fan speed. 7 is the highest level, where the fan reaches
+the maximum recommended speed. Level "auto" means the EC changes the
+fan level according to some internal algorithm, usually based on
+readings from the thermal sensors. Level "disengaged" means the EC
+disables the speed-locked closed-loop fan control, and drives the fan as
+fast as it can go, which might exceed hardware limits, so use this level
+with caution.
+
+The fan usually ramps up or down slowly from one speed to another,
+and it is normal for the EC to take several seconds to react to fan
+commands.
+
+The fan may be enabled or disabled with the following commands:
+
+ echo enable >/proc/acpi/ibm/fan
+ echo disable >/proc/acpi/ibm/fan
+
+Placing a fan on level 0 is the same as disabling it. Enabling a fan
+will try to place it in a safe level if it is too slow or disabled.
+
+WARNING WARNING WARNING: do not leave the fan disabled unless you are
+monitoring all of the temperature sensor readings and you are ready to
+enable it if necessary to avoid overheating.
+
+An enabled fan in level "auto" may stop spinning if the EC decides the
+ThinkPad is cool enough and doesn't need the extra airflow. This is
+normal, and the EC will spin the fan up if the varios thermal readings
+rise too much.
+
+On the X40, this seems to depend on the CPU and HDD temperatures.
+Specifically, the fan is turned on when either the CPU temperature
+climbs to 56 degrees or the HDD temperature climbs to 46 degrees. The
+fan is turned off when the CPU temperature drops to 49 degrees and the
+HDD temperature drops to 41 degrees. These thresholds cannot
+currently be controlled.
+
+The fan level can be controlled with the command:
+
+ echo 'level <level>' > /proc/acpi/ibm/thermal