Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 Kernel driver adt7462 2 ====================== 3 4 Supported chips: 5 * Analog Devices ADT7462 6 Prefix: 'adt7462' 7 Addresses scanned: I2C 0x58, 0x5C 8 Datasheet: Publicly available at the Analog Devices website 9 10 Author: Darrick J. Wong 11 12 Description 13 ----------- 14 15 This driver implements support for the Analog Devices ADT7462 chip family. 16 17 This chip is a bit of a beast. It has 8 counters for measuring fan speed. It 18 can also measure 13 voltages or 4 temperatures, or various combinations of the 19 two. See the chip documentation for more details about the exact set of 20 configurations. This driver does not allow one to configure the chip; that is 21 left to the system designer. 22 23 A sophisticated control system for the PWM outputs is designed into the ADT7462 24 that allows fan speed to be adjusted automatically based on any of the three 25 temperature sensors. Each PWM output is individually adjustable and 26 programmable. Once configured, the ADT7462 will adjust the PWM outputs in 27 response to the measured temperatures without further host intervention. This 28 feature can also be disabled for manual control of the PWM's. 29 30 Each of the measured inputs (voltage, temperature, fan speed) has 31 corresponding high/low limit values. The ADT7462 will signal an ALARM if 32 any measured value exceeds either limit. 33 34 The ADT7462 samples all inputs continuously. The driver will not read 35 the registers more often than once every other second. Further, 36 configuration data is only read once per minute. 37 38 Special Features 39 ---------------- 40 41 The ADT7462 have a 10-bit ADC and can therefore measure temperatures 42 with 0.25 degC resolution. 43 44 The Analog Devices datasheet is very detailed and describes a procedure for 45 determining an optimal configuration for the automatic PWM control. 46 47 The driver will report sensor labels when it is able to determine that 48 information from the configuration registers. 49 50 Configuration Notes 51 ------------------- 52 53 Besides standard interfaces driver adds the following: 54 55 * PWM Control 56 57 * pwm#_auto_point1_pwm and temp#_auto_point1_temp and 58 * pwm#_auto_point2_pwm and temp#_auto_point2_temp - 59 60 point1: Set the pwm speed at a lower temperature bound. 61 point2: Set the pwm speed at a higher temperature bound. 62 63 The ADT7462 will scale the pwm between the lower and higher pwm speed when 64 the temperature is between the two temperature boundaries. PWM values range 65 from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the 66 temperature sensor associated with the PWM control exceeds temp#_max.