1 Kernel driver adt7462 1 Kernel driver adt7462
2 ===================== 2 =====================
3 3
4 Supported chips: 4 Supported chips:
5 5
6 * Analog Devices ADT7462 6 * Analog Devices ADT7462
7 7
8 Prefix: 'adt7462' 8 Prefix: 'adt7462'
9 9
10 Addresses scanned: I2C 0x58, 0x5C 10 Addresses scanned: I2C 0x58, 0x5C
11 11
12 Datasheet: Publicly available at the Analo 12 Datasheet: Publicly available at the Analog Devices website
13 13
14 Author: Darrick J. Wong 14 Author: Darrick J. Wong
15 15
16 Description 16 Description
17 ----------- 17 -----------
18 18
19 This driver implements support for the Analog 19 This driver implements support for the Analog Devices ADT7462 chip family.
20 20
21 This chip is a bit of a beast. It has 8 count 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 22 can also measure 13 voltages or 4 temperatures, or various combinations of the
23 two. See the chip documentation for more deta 23 two. See the chip documentation for more details about the exact set of
24 configurations. This driver does not allow on 24 configurations. This driver does not allow one to configure the chip; that is
25 left to the system designer. 25 left to the system designer.
26 26
27 A sophisticated control system for the PWM out 27 A sophisticated control system for the PWM outputs is designed into the ADT7462
28 that allows fan speed to be adjusted automatic 28 that allows fan speed to be adjusted automatically based on any of the three
29 temperature sensors. Each PWM output is indivi 29 temperature sensors. Each PWM output is individually adjustable and
30 programmable. Once configured, the ADT7462 wil 30 programmable. Once configured, the ADT7462 will adjust the PWM outputs in
31 response to the measured temperatures without 31 response to the measured temperatures without further host intervention. This
32 feature can also be disabled for manual contro 32 feature can also be disabled for manual control of the PWM's.
33 33
34 Each of the measured inputs (voltage, temperat 34 Each of the measured inputs (voltage, temperature, fan speed) has
35 corresponding high/low limit values. The ADT74 35 corresponding high/low limit values. The ADT7462 will signal an ALARM if
36 any measured value exceeds either limit. 36 any measured value exceeds either limit.
37 37
38 The ADT7462 samples all inputs continuously. T 38 The ADT7462 samples all inputs continuously. The driver will not read
39 the registers more often than once every other 39 the registers more often than once every other second. Further,
40 configuration data is only read once per minut 40 configuration data is only read once per minute.
41 41
42 Special Features 42 Special Features
43 ---------------- 43 ----------------
44 44
45 The ADT7462 have a 10-bit ADC and can therefor 45 The ADT7462 have a 10-bit ADC and can therefore measure temperatures
46 with 0.25 degC resolution. 46 with 0.25 degC resolution.
47 47
48 The Analog Devices datasheet is very detailed 48 The Analog Devices datasheet is very detailed and describes a procedure for
49 determining an optimal configuration for the a 49 determining an optimal configuration for the automatic PWM control.
50 50
51 The driver will report sensor labels when it i 51 The driver will report sensor labels when it is able to determine that
52 information from the configuration registers. 52 information from the configuration registers.
53 53
54 Configuration Notes 54 Configuration Notes
55 ------------------- 55 -------------------
56 56
57 Besides standard interfaces driver adds the fo 57 Besides standard interfaces driver adds the following:
58 58
59 * PWM Control 59 * PWM Control
60 60
61 * pwm#_auto_point1_pwm and temp#_auto_point1_t 61 * pwm#_auto_point1_pwm and temp#_auto_point1_temp and
62 * pwm#_auto_point2_pwm and temp#_auto_point2_t 62 * pwm#_auto_point2_pwm and temp#_auto_point2_temp -
63 63
64 - point1: Set the pwm speed at a lower tempe 64 - point1: Set the pwm speed at a lower temperature bound.
65 - point2: Set the pwm speed at a higher temp 65 - point2: Set the pwm speed at a higher temperature bound.
66 66
67 The ADT7462 will scale the pwm between the low 67 The ADT7462 will scale the pwm between the lower and higher pwm speed when
68 the temperature is between the two temperature 68 the temperature is between the two temperature boundaries. PWM values range
69 from 0 (off) to 255 (full speed). Fan speed w 69 from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the
70 temperature sensor associated with the PWM con 70 temperature sensor associated with the PWM control exceeds temp#_max.
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