diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index 80c0bf2..339ce21 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -642,8 +642,11 @@
 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
------------------------------------------------------------------
+EXPERIMENTAL: fan speed, fan enable/disable
+-------------------------------------------
+
+procfs: /proc/acpi/ibm/fan
+sysfs device attributes: (hwmon) fan_input, pwm1, pwm1_enable
 
 This feature is marked EXPERIMENTAL because the implementation
 directly accesses hardware registers and may not work as expected. USE
@@ -656,27 +659,26 @@
 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.
+Fan levels:
 
-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.
+Most ThinkPad fans work in "levels" at the firmware interface.  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.
 
-The fan may be enabled or disabled with the following commands:
+Level "auto" means the EC changes the fan level according to some
+internal algorithm, usually based on readings from the thermal sensors.
 
-	echo enable  >/proc/acpi/ibm/fan
-	echo disable >/proc/acpi/ibm/fan
+There is also a "full-speed" level, also known as "disengaged" level.
+In this level, 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.
 
-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.
+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 full-speed level may take up to two minutes to ramp up to
+maximum speed, and in some ThinkPads, the tachometer readings go stale
+while the EC is transitioning to the full-speed level.
 
 WARNING WARNING WARNING: do not leave the fan disabled unless you are
 monitoring all of the temperature sensor readings and you are ready to
@@ -694,48 +696,101 @@
 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
-
-Where <level> is an integer from 0 to 7, or one of the words "auto"
-or "disengaged" (without the quotes).  Not all ThinkPads support the
-"auto" and "disengaged" levels.
-
-On the X31 and X40 (and ONLY on those models), the fan speed can be
-controlled to a certain degree. Once the fan is running, it can be
-forced to run faster or slower with the following command:
-
-	echo 'speed <speed>' > /proc/acpi/ibm/thermal
-
-The sustainable range of fan speeds on the X40 appears to be from
-about 3700 to about 7350. Values outside this range either do not have
-any effect or the fan speed eventually settles somewhere in that
-range. The fan cannot be stopped or started with this command.
-
 The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
 certain conditions are met.  It will override any fan programming done
 through thinkpad-acpi.
 
 The thinkpad-acpi kernel driver can be programmed to revert the fan
-level to a safe setting if userspace does not issue one of the fan
-commands: "enable", "disable", "level" or "watchdog" within a
-configurable ammount of time.  To do this, use the "watchdog" command.
+level to a safe setting if userspace does not issue one of the procfs
+fan commands: "enable", "disable", "level" or "watchdog", or if there
+are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
+set to 1, manual mode) within a configurable amount of time of up to
+120 seconds.  This functionality is called fan safety watchdog.
 
-	echo 'watchdog <interval>' > /proc/acpi/ibm/fan
+Note that the watchdog timer stops after it enables the fan.  It will be
+rearmed again automatically (using the same interval) when one of the
+above mentioned fan commands is received.  The fan watchdog is,
+therefore, not suitable to protect against fan mode changes made through
+means other than the "enable", "disable", and "level" procfs fan
+commands, or the hwmon fan control sysfs interface.
 
-Interval is the ammount of time in seconds to wait for one of the
-above mentioned fan commands before reseting the fan level to a safe
-one.  If set to zero, the watchdog is disabled (default).  When the
-watchdog timer runs out, it does the exact equivalent of the "enable"
-fan command.
+Procfs notes:
 
-Note that the watchdog timer stops after it enables the fan.  It will
-be rearmed again automatically (using the same interval) when one of
-the above mentioned fan commands is received.  The fan watchdog is,
-therefore, not suitable to protect against fan mode changes made
-through means other than the "enable", "disable", and "level" 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.
+
+The fan level can be controlled with the command:
+
+	echo 'level <level>' > /proc/acpi/ibm/fan
+
+Where <level> is an integer from 0 to 7, or one of the words "auto" or
+"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
+and "full-speed" levels.  The driver accepts "disengaged" as an alias for
+"full-speed", and reports it as "disengaged" for backwards
+compatibility.
+
+On the X31 and X40 (and ONLY on those models), the fan speed can be
+controlled to a certain degree.  Once the fan is running, it can be
+forced to run faster or slower with the following command:
+
+	echo 'speed <speed>' > /proc/acpi/ibm/fan
+
+The sustainable range of fan speeds on the X40 appears to be from about
+3700 to about 7350. Values outside this range either do not have any
+effect or the fan speed eventually settles somewhere in that range.  The
+fan cannot be stopped or started with this command.  This functionality
+is incomplete, and not available through the sysfs interface.
+
+To program the safety watchdog, use the "watchdog" command.
+
+	echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
+
+If you want to disable the watchdog, use 0 as the interval.
+
+Sysfs notes:
+
+The sysfs interface follows the hwmon subsystem guidelines for the most
+part, and the exception is the fan safety watchdog.
+
+hwmon device attribute pwm1_enable:
+	0: PWM offline (fan is set to full-speed mode)
+	1: Manual PWM control (use pwm1 to set fan level)
+	2: Hardware PWM control (EC "auto" mode)
+	3: reserved (Software PWM control, not implemented yet)
+
+	Modes 0 and 2 are not supported by all ThinkPads, and the driver
+	is not always able to detect this.  If it does know a mode is
+	unsupported, it will return -EINVAL.
+
+hwmon device attribute pwm1:
+	Fan level, scaled from the firmware values of 0-7 to the hwmon
+	scale of 0-255.  0 means fan stopped, 255 means highest normal
+	speed (level 7).
+
+	This attribute only commands the fan if pmw1_enable is set to 1
+	(manual PWM control).
+
+hwmon device attribute fan1_input:
+	Fan tachometer reading, in RPM.  May go stale on certain
+	ThinkPads while the EC transitions the PWM to offline mode,
+	which can take up to two minutes.  May return rubbish on older
+	ThinkPads.
+
+driver attribute fan_watchdog:
+	Fan safety watchdog timer interval, in seconds.  Minimum is
+	1 second, maximum is 120 seconds.  0 disables the watchdog.
+
+To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
+
+To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
+with ENOTSUP, set it to 1 and set pwm1 to at least 128 (255 would be the
+safest choice, though).
+
 
 EXPERIMENTAL: WAN -- /proc/acpi/ibm/wan
 ---------------------------------------