1 Kernel driver adt7462 2 ===================== 3 4 Supported chips: 5 6 * Analog Devices ADT7462 7 8 Prefix: 'adt7462' 9 10 Addresses scanned: I2C 0x58, 0x5C 11 12 Datasheet: Publicly available at the Analog Devices website 13 14 Author: Darrick J. Wong 15 16 Description 17 ----------- 18 19 This driver implements support for the Analog Devices ADT7462 chip family. 20 21 This chip is a bit of a beast. It has 8 counters for measuring fan speed. It 22 can also measure 13 voltages or 4 temperatures, or various combinations of the 23 two. See the chip documentation for more details about the exact set of 24 configurations. This driver does not allow one to configure the chip; that is 25 left to the system designer. 26 27 A sophisticated control system for the PWM outputs is designed into the ADT7462 28 that allows fan speed to be adjusted automatically based on any of the three 29 temperature sensors. Each PWM output is individually adjustable and 30 programmable. Once configured, the ADT7462 will adjust the PWM outputs in 31 response to the measured temperatures without further host intervention. This 32 feature can also be disabled for manual control of the PWM's. 33 34 Each of the measured inputs (voltage, temperature, fan speed) has 35 corresponding high/low limit values. The ADT7462 will signal an ALARM if 36 any measured value exceeds either limit. 37 38 The ADT7462 samples all inputs continuously. The driver will not read 39 the registers more often than once every other second. Further, 40 configuration data is only read once per minute. 41 42 Special Features 43 ---------------- 44 45 The ADT7462 have a 10-bit ADC and can therefore measure temperatures 46 with 0.25 degC resolution. 47 48 The Analog Devices datasheet is very detailed and describes a procedure for 49 determining an optimal configuration for the automatic PWM control. 50 51 The driver will report sensor labels when it is able to determine that 52 information from the configuration registers. 53 54 Configuration Notes 55 ------------------- 56 57 Besides standard interfaces driver adds the following: 58 59 * PWM Control 60 61 * pwm#_auto_point1_pwm and temp#_auto_point1_temp and 62 * pwm#_auto_point2_pwm and temp#_auto_point2_temp - 63 64 - point1: Set the pwm speed at a lower temperature bound. 65 - point2: Set the pwm speed at a higher temperature bound. 66 67 The ADT7462 will scale the pwm between the lower and higher pwm speed when 68 the temperature is between the two temperature boundaries. PWM values range 69 from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the 70 temperature sensor associated with the PWM control exceeds temp#_max.
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