path: root/Documentation/hwmon/adt7462
diff options
authorDarrick J. Wong <>2008-11-12 13:27:03 -0800
committerLinus Torvalds <>2008-11-12 17:17:17 -0800
commitc0b4e3ab0c769913438aeb078535ff117eeba5fb (patch)
treeaef089b13f7850971025851dedd958f10bdf928a /Documentation/hwmon/adt7462
parent455fbdd376c3ed3a5be8c039348896fdd87e9930 (diff)
adt7462: new hwmon driver
New driver to play with. As Jean mentioned a couple of years ago, this chip is a beast with odd combinations of 8 fans, 4 temperatures, and 13 voltage sensors. This driver has been tested on an IntelliStation Z30. Signed-off-by: Darrick J. Wong <> Cc: Jean Delvare <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'Documentation/hwmon/adt7462')
1 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/hwmon/adt7462 b/Documentation/hwmon/adt7462
new file mode 100644
index 000000000000..ec660b328275
--- /dev/null
+++ b/Documentation/hwmon/adt7462
@@ -0,0 +1,67 @@
+Kernel driver adt7462
+Supported chips:
+ * Analog Devices ADT7462
+ Prefix: 'adt7462'
+ Addresses scanned: I2C 0x58, 0x5C
+ Datasheet: Publicly available at the Analog Devices website
+Author: Darrick J. Wong
+This driver implements support for the Analog Devices ADT7462 chip family.
+This chip is a bit of a beast. It has 8 counters for measuring fan speed. It
+can also measure 13 voltages or 4 temperatures, or various combinations of the
+two. See the chip documentation for more details about the exact set of
+configurations. This driver does not allow one to configure the chip; that is
+left to the system designer.
+A sophisticated control system for the PWM outputs is designed into the ADT7462
+that allows fan speed to be adjusted automatically based on any of the three
+temperature sensors. Each PWM output is individually adjustable and
+programmable. Once configured, the ADT7462 will adjust the PWM outputs in
+response to the measured temperatures without further host intervention. This
+feature can also be disabled for manual control of the PWM's.
+Each of the measured inputs (voltage, temperature, fan speed) has
+corresponding high/low limit values. The ADT7462 will signal an ALARM if
+any measured value exceeds either limit.
+The ADT7462 samples all inputs continuously. The driver will not read
+the registers more often than once every other second. Further,
+configuration data is only read once per minute.
+Special Features
+The ADT7462 have a 10-bit ADC and can therefore measure temperatures
+with 0.25 degC resolution.
+The Analog Devices datasheet is very detailed and describes a procedure for
+determining an optimal configuration for the automatic PWM control.
+The driver will report sensor labels when it is able to determine that
+information from the configuration registers.
+Configuration Notes
+Besides standard interfaces driver adds the following:
+* PWM Control
+* pwm#_auto_point1_pwm and temp#_auto_point1_temp and
+* pwm#_auto_point2_pwm and temp#_auto_point2_temp -
+point1: Set the pwm speed at a lower temperature bound.
+point2: Set the pwm speed at a higher temperature bound.
+The ADT7462 will scale the pwm between the lower and higher pwm speed when
+the temperature is between the two temperature boundaries. PWM values range
+from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the
+temperature sensor associated with the PWM control exceeds temp#_max.