1 Kernel driver adt7475
2 =====================
3
4 Supported chips:
5
6 * Analog Devices ADT7473
7
8 Prefix: 'adt7473'
9
10 Addresses scanned: I2C 0x2C, 0x2D, 0x2E
11
12 Datasheet: Publicly available at the On Se
13
14 * Analog Devices ADT7475
15
16 Prefix: 'adt7475'
17
18 Addresses scanned: I2C 0x2E
19
20 Datasheet: Publicly available at the On Se
21
22 * Analog Devices ADT7476
23
24 Prefix: 'adt7476'
25
26 Addresses scanned: I2C 0x2C, 0x2D, 0x2E
27
28 Datasheet: Publicly available at the On Se
29
30 * Analog Devices ADT7490
31
32 Prefix: 'adt7490'
33
34 Addresses scanned: I2C 0x2C, 0x2D, 0x2E
35
36 Datasheet: Publicly available at the On Se
37
38 Authors:
39 - Jordan Crouse
40 - Hans de Goede
41 - Darrick J. Wong (documentation)
42 - Jean Delvare
43
44
45 Description
46 -----------
47
48 This driver implements support for the Analog
49 ADT7476 and ADT7490 chip family. The ADT7473 a
50 minor details. The ADT7476 has additional feat
51 measurement inputs and VID support. The ADT749
52 features, including extra voltage measurement
53 the supported chips will be collectively desig
54 the rest of this document.
55
56 The ADT747x uses the 2-wire interface compatib
57 specification. Using an analog to digital conv
58 temperatures and two (2) or more voltages. It
59 for measuring fan speed. There are three (3) P
60 to control fan speed.
61
62 A sophisticated control system for the PWM out
63 ADT747x that allows fan speed to be adjusted a
64 three temperature sensors. Each PWM output is
65 programmable. Once configured, the ADT747x wil
66 response to the measured temperatures without
67 This feature can also be disabled for manual c
68
69 Each of the measured inputs (voltage, temperat
70 corresponding high/low limit values. The ADT74
71 any measured value exceeds either limit.
72
73 The ADT747x samples all inputs continuously. T
74 the registers more often than once every other
75 configuration data is only read once per minut
76
77 Chip Differences Summary
78 ------------------------
79
80 ADT7473:
81 * 2 voltage inputs
82 * system acoustics optimizations (not implem
83
84 ADT7475:
85 * 2 voltage inputs
86
87 ADT7476:
88 * 5 voltage inputs
89 * VID support
90
91 ADT7490:
92 * 6 voltage inputs
93 * 1 Imon input
94 * PECI support (not implemented)
95 * 2 GPIO pins (not implemented)
96 * system acoustics optimizations (not implem
97
98 Sysfs Mapping
99 -------------
100
101 ==== =========== =========== ========= =======
102 in ADT7490 ADT7476 ADT7475 ADT7473
103 ==== =========== =========== ========= =======
104 in0 2.5VIN (22) 2.5VIN (22) - -
105 in1 VCCP (23) VCCP (23) VCCP (14) VCCP (1
106 in2 VCC (4) VCC (4) VCC (4) VCC (3
107 in3 5VIN (20) 5VIN (20)
108 in4 12VIN (21) 12VIN (21)
109 in5 VTT (8)
110 in6 Imon (19)
111 ==== =========== =========== ========= =======
112
113 Special Features
114 ----------------
115
116 The ADT747x has a 10-bit ADC and can therefore
117 with a resolution of 0.25 degree Celsius. Temp
118 configured either for two's complement format
119 wherein 64 is subtracted from the raw value to
120
121 The datasheet is very detailed and describes a
122 an optimal configuration for the automatic PWM
123
124 Fan Speed Control
125 -----------------
126
127 The driver exposes two trip points per PWM cha
128
129 - point1: Set the PWM speed at the lower tempe
130 - point2: Set the PWM speed at the higher temp
131
132 The ADT747x will scale the PWM linearly betwee
133 speed when the temperature is between the two
134 Temperature boundaries are associated to tempe
135 PWM outputs, and a given PWM output can be con
136 channels. As a result, the ADT747x may compute
137 for a channel at a given time, in which case t
138 fan speed) is applied. PWM values range from 0
139
140 Fan speed may be set to maximum when the tempe
141 the PWM control exceeds temp#_max.
142
143 At Tmin - hysteresis the PWM output can either
144 minimum (i.e. auto_point1_pwm). This behaviour
145 `pwm[1-*]_stall_disable sysfs attribute`. A va
146 off. A value of 1 means the fans will run at a
147
148 The responsiveness of the ADT747x to temperatu
149 This allows smoothing of the fan speed transit
150 set the value in ms in the `temp[1-*]_smoothin
151
152 Notes
153 -----
154
155 The nVidia binary driver presents an ADT7473 c
156 Unfortunately, they fail to set the i2c adapte
157 fail to find the chip until the nvidia driver
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