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- 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.
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