0001 Kernel driver adt7462
0002 =====================
0003
0004 Supported chips:
0005
0006 * Analog Devices ADT7462
0007
0008 Prefix: 'adt7462'
0009
0010 Addresses scanned: I2C 0x58, 0x5C
0011
0012 Datasheet: Publicly available at the Analog Devices website
0013
0014 Author: Darrick J. Wong
0015
0016 Description
0017 -----------
0018
0019 This driver implements support for the Analog Devices ADT7462 chip family.
0020
0021 This chip is a bit of a beast. It has 8 counters for measuring fan speed. It
0022 can also measure 13 voltages or 4 temperatures, or various combinations of the
0023 two. See the chip documentation for more details about the exact set of
0024 configurations. This driver does not allow one to configure the chip; that is
0025 left to the system designer.
0026
0027 A sophisticated control system for the PWM outputs is designed into the ADT7462
0028 that allows fan speed to be adjusted automatically based on any of the three
0029 temperature sensors. Each PWM output is individually adjustable and
0030 programmable. Once configured, the ADT7462 will adjust the PWM outputs in
0031 response to the measured temperatures without further host intervention. This
0032 feature can also be disabled for manual control of the PWM's.
0033
0034 Each of the measured inputs (voltage, temperature, fan speed) has
0035 corresponding high/low limit values. The ADT7462 will signal an ALARM if
0036 any measured value exceeds either limit.
0037
0038 The ADT7462 samples all inputs continuously. The driver will not read
0039 the registers more often than once every other second. Further,
0040 configuration data is only read once per minute.
0041
0042 Special Features
0043 ----------------
0044
0045 The ADT7462 have a 10-bit ADC and can therefore measure temperatures
0046 with 0.25 degC resolution.
0047
0048 The Analog Devices datasheet is very detailed and describes a procedure for
0049 determining an optimal configuration for the automatic PWM control.
0050
0051 The driver will report sensor labels when it is able to determine that
0052 information from the configuration registers.
0053
0054 Configuration Notes
0055 -------------------
0056
0057 Besides standard interfaces driver adds the following:
0058
0059 * PWM Control
0060
0061 * pwm#_auto_point1_pwm and temp#_auto_point1_temp and
0062 * pwm#_auto_point2_pwm and temp#_auto_point2_temp -
0063
0064 - point1: Set the pwm speed at a lower temperature bound.
0065 - point2: Set the pwm speed at a higher temperature bound.
0066
0067 The ADT7462 will scale the pwm between the lower and higher pwm speed when
0068 the temperature is between the two temperature boundaries. PWM values range
0069 from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the
0070 temperature sensor associated with the PWM control exceeds temp#_max.
