| 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. |
| |