1*4882a593SmuzhiyunKernel driver adt7462 2*4882a593Smuzhiyun===================== 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunSupported chips: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun * Analog Devices ADT7462 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun Prefix: 'adt7462' 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun Addresses scanned: I2C 0x58, 0x5C 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun Datasheet: Publicly available at the Analog Devices website 13*4882a593Smuzhiyun 14*4882a593SmuzhiyunAuthor: Darrick J. Wong 15*4882a593Smuzhiyun 16*4882a593SmuzhiyunDescription 17*4882a593Smuzhiyun----------- 18*4882a593Smuzhiyun 19*4882a593SmuzhiyunThis driver implements support for the Analog Devices ADT7462 chip family. 20*4882a593Smuzhiyun 21*4882a593SmuzhiyunThis chip is a bit of a beast. It has 8 counters for measuring fan speed. It 22*4882a593Smuzhiyuncan also measure 13 voltages or 4 temperatures, or various combinations of the 23*4882a593Smuzhiyuntwo. See the chip documentation for more details about the exact set of 24*4882a593Smuzhiyunconfigurations. This driver does not allow one to configure the chip; that is 25*4882a593Smuzhiyunleft to the system designer. 26*4882a593Smuzhiyun 27*4882a593SmuzhiyunA sophisticated control system for the PWM outputs is designed into the ADT7462 28*4882a593Smuzhiyunthat allows fan speed to be adjusted automatically based on any of the three 29*4882a593Smuzhiyuntemperature sensors. Each PWM output is individually adjustable and 30*4882a593Smuzhiyunprogrammable. Once configured, the ADT7462 will adjust the PWM outputs in 31*4882a593Smuzhiyunresponse to the measured temperatures without further host intervention. This 32*4882a593Smuzhiyunfeature can also be disabled for manual control of the PWM's. 33*4882a593Smuzhiyun 34*4882a593SmuzhiyunEach of the measured inputs (voltage, temperature, fan speed) has 35*4882a593Smuzhiyuncorresponding high/low limit values. The ADT7462 will signal an ALARM if 36*4882a593Smuzhiyunany measured value exceeds either limit. 37*4882a593Smuzhiyun 38*4882a593SmuzhiyunThe ADT7462 samples all inputs continuously. The driver will not read 39*4882a593Smuzhiyunthe registers more often than once every other second. Further, 40*4882a593Smuzhiyunconfiguration data is only read once per minute. 41*4882a593Smuzhiyun 42*4882a593SmuzhiyunSpecial Features 43*4882a593Smuzhiyun---------------- 44*4882a593Smuzhiyun 45*4882a593SmuzhiyunThe ADT7462 have a 10-bit ADC and can therefore measure temperatures 46*4882a593Smuzhiyunwith 0.25 degC resolution. 47*4882a593Smuzhiyun 48*4882a593SmuzhiyunThe Analog Devices datasheet is very detailed and describes a procedure for 49*4882a593Smuzhiyundetermining an optimal configuration for the automatic PWM control. 50*4882a593Smuzhiyun 51*4882a593SmuzhiyunThe driver will report sensor labels when it is able to determine that 52*4882a593Smuzhiyuninformation from the configuration registers. 53*4882a593Smuzhiyun 54*4882a593SmuzhiyunConfiguration Notes 55*4882a593Smuzhiyun------------------- 56*4882a593Smuzhiyun 57*4882a593SmuzhiyunBesides standard interfaces driver adds the following: 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun* PWM Control 60*4882a593Smuzhiyun 61*4882a593Smuzhiyun* pwm#_auto_point1_pwm and temp#_auto_point1_temp and 62*4882a593Smuzhiyun* pwm#_auto_point2_pwm and temp#_auto_point2_temp - 63*4882a593Smuzhiyun 64*4882a593Smuzhiyun - point1: Set the pwm speed at a lower temperature bound. 65*4882a593Smuzhiyun - point2: Set the pwm speed at a higher temperature bound. 66*4882a593Smuzhiyun 67*4882a593SmuzhiyunThe ADT7462 will scale the pwm between the lower and higher pwm speed when 68*4882a593Smuzhiyunthe temperature is between the two temperature boundaries. PWM values range 69*4882a593Smuzhiyunfrom 0 (off) to 255 (full speed). Fan speed will be set to maximum when the 70*4882a593Smuzhiyuntemperature sensor associated with the PWM control exceeds temp#_max. 71