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70 lines
2.5 KiB
70 lines
2.5 KiB
Kernel driver adt7462 |
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===================== |
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Supported chips: |
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* Analog Devices ADT7462 |
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Prefix: 'adt7462' |
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Addresses scanned: I2C 0x58, 0x5C |
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Datasheet: Publicly available at the Analog Devices website |
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Author: Darrick J. Wong |
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Description |
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----------- |
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This driver implements support for the Analog Devices ADT7462 chip family. |
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This chip is a bit of a beast. It has 8 counters for measuring fan speed. It |
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can also measure 13 voltages or 4 temperatures, or various combinations of the |
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two. See the chip documentation for more details about the exact set of |
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configurations. This driver does not allow one to configure the chip; that is |
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left to the system designer. |
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A sophisticated control system for the PWM outputs is designed into the ADT7462 |
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that allows fan speed to be adjusted automatically based on any of the three |
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temperature sensors. Each PWM output is individually adjustable and |
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programmable. Once configured, the ADT7462 will adjust the PWM outputs in |
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response to the measured temperatures without further host intervention. This |
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feature can also be disabled for manual control of the PWM's. |
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Each of the measured inputs (voltage, temperature, fan speed) has |
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corresponding high/low limit values. The ADT7462 will signal an ALARM if |
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any measured value exceeds either limit. |
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The ADT7462 samples all inputs continuously. The driver will not read |
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the registers more often than once every other second. Further, |
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configuration data is only read once per minute. |
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Special Features |
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---------------- |
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The ADT7462 have a 10-bit ADC and can therefore measure temperatures |
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with 0.25 degC resolution. |
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The Analog Devices datasheet is very detailed and describes a procedure for |
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determining an optimal configuration for the automatic PWM control. |
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The driver will report sensor labels when it is able to determine that |
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information from the configuration registers. |
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Configuration Notes |
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------------------- |
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Besides standard interfaces driver adds the following: |
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* PWM Control |
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* pwm#_auto_point1_pwm and temp#_auto_point1_temp and |
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* pwm#_auto_point2_pwm and temp#_auto_point2_temp - |
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- point1: Set the pwm speed at a lower temperature bound. |
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- point2: Set the pwm speed at a higher temperature bound. |
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The ADT7462 will scale the pwm between the lower and higher pwm speed when |
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the temperature is between the two temperature boundaries. PWM values range |
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from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the |
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temperature sensor associated with the PWM control exceeds temp#_max.
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