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diff --git a/Documentation/hwmon/adt7473 b/Documentation/hwmon/adt7473 new file mode 100644 index 0000000..22d8b19 --- /dev/null +++ b/Documentation/hwmon/adt7473 @@ -0,0 +1,79 @@ +Kernel driver adt7473 +====================== + +Supported chips: + * Analog Devices ADT7473 + Prefix: 'adt7473' + Addresses scanned: I2C 0x2C, 0x2D, 0x2E + Datasheet: Publicly available at the Analog Devices website + +Author: Darrick J. Wong + +Description +----------- + +This driver implements support for the Analog Devices ADT7473 chip family. + +The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 +specification. Using an analog to digital converter it measures three (3) +temperatures and two (2) voltages. It has three (3) 16-bit counters for +measuring fan speed. There are three (3) PWM outputs that can be used +to control fan speed. + +A sophisticated control system for the PWM outputs is designed into the +LM85 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 ADT7473 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 ADT7473 will signal an ALARM if +any measured value exceeds either limit. + +The ADT7473 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 ADT7473 have a 10-bit ADC and can therefore measure temperatures +with 0.25 degC resolution. Temperature readings can be configured either +for twos complement format or "Offset 64" format, wherein 63 is subtracted +from the raw value to get the temperature value. + +The Analog Devices datasheet is very detailed and describes a procedure for +determining an optimal configuration for the automatic PWM control. + +Hardware Configurations +----------------------- + +The ADT7473 chips have an optional SMBALERT output that can be used to +signal the chipset in case a limit is exceeded or the temperature sensors +fail. Individual sensor interrupts can be masked so they won't trigger +SMBALERT. The SMBALERT output if configured replaces the PWM2 function. + +Configuration Notes +------------------- + +Besides standard interfaces driver adds the following: + +* PWM Control + +* pwm#_auto_point1_pwm and pwm#_auto_point1_temp and +* pwm#_auto_point2_pwm and pwm#_auto_point2_temp - + +point1: Set the pwm speed at a lower temperature bound. +point2: Set the pwm speed at a higher temperature bound. + +The ADT7473 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). + +Notes +----- + +The NVIDIA binary driver presents an ADT7473 chip via an on-card i2c bus. +Unfortunately, they fail to set the i2c adapter class, so this driver may +fail to find the chip until the nvidia driver is patched. |