diff options
author | Darrick J. Wong <djwong@us.ibm.com> | 2008-11-12 21:27:03 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-11-13 01:17:17 (GMT) |
commit | c0b4e3ab0c769913438aeb078535ff117eeba5fb (patch) | |
tree | aef089b13f7850971025851dedd958f10bdf928a /Documentation | |
parent | 455fbdd376c3ed3a5be8c039348896fdd87e9930 (diff) | |
download | linux-c0b4e3ab0c769913438aeb078535ff117eeba5fb.tar.xz |
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 <djwong@us.ibm.com>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/hwmon/adt7462 | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/hwmon/adt7462 b/Documentation/hwmon/adt7462 new file mode 100644 index 0000000..ec660b3 --- /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 + +Description +----------- + +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. + |