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f890c6a3 JD |
1 | Kernel driver adt7475 |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
f890c6a3 | 6 | * Analog Devices ADT7473 |
b04f2f7d | 7 | |
f890c6a3 | 8 | Prefix: 'adt7473' |
b04f2f7d | 9 | |
f890c6a3 | 10 | Addresses scanned: I2C 0x2C, 0x2D, 0x2E |
b04f2f7d | 11 | |
f890c6a3 | 12 | Datasheet: Publicly available at the On Semiconductors website |
b04f2f7d | 13 | |
f890c6a3 | 14 | * Analog Devices ADT7475 |
b04f2f7d | 15 | |
f890c6a3 | 16 | Prefix: 'adt7475' |
b04f2f7d | 17 | |
f890c6a3 | 18 | Addresses scanned: I2C 0x2E |
b04f2f7d | 19 | |
f890c6a3 | 20 | Datasheet: Publicly available at the On Semiconductors website |
b04f2f7d | 21 | |
d8d2ee07 | 22 | * Analog Devices ADT7476 |
b04f2f7d | 23 | |
d8d2ee07 | 24 | Prefix: 'adt7476' |
b04f2f7d | 25 | |
d8d2ee07 | 26 | Addresses scanned: I2C 0x2C, 0x2D, 0x2E |
b04f2f7d | 27 | |
d8d2ee07 | 28 | Datasheet: Publicly available at the On Semiconductors website |
b04f2f7d | 29 | |
3d849981 | 30 | * Analog Devices ADT7490 |
b04f2f7d | 31 | |
3d849981 | 32 | Prefix: 'adt7490' |
b04f2f7d | 33 | |
3d849981 | 34 | Addresses scanned: I2C 0x2C, 0x2D, 0x2E |
b04f2f7d | 35 | |
3d849981 | 36 | Datasheet: Publicly available at the On Semiconductors website |
f890c6a3 JD |
37 | |
38 | Authors: | |
b04f2f7d MCC |
39 | - Jordan Crouse |
40 | - Hans de Goede | |
41 | - Darrick J. Wong (documentation) | |
42 | - Jean Delvare | |
f890c6a3 JD |
43 | |
44 | ||
45 | Description | |
46 | ----------- | |
47 | ||
d8d2ee07 JD |
48 | This driver implements support for the Analog Devices ADT7473, ADT7475, |
49 | ADT7476 and ADT7490 chip family. The ADT7473 and ADT7475 differ only in | |
50 | minor details. The ADT7476 has additional features, including extra voltage | |
51 | measurement inputs and VID support. The ADT7490 also has additional | |
52 | features, including extra voltage measurement inputs and PECI support. All | |
53 | the supported chips will be collectively designed by the name "ADT747x" in | |
54 | the rest of this document. | |
f890c6a3 JD |
55 | |
56 | The ADT747x uses the 2-wire interface compatible with the SMBus 2.0 | |
57 | specification. Using an analog to digital converter it measures three (3) | |
3d849981 JD |
58 | temperatures and two (2) or more voltages. It has four (4) 16-bit counters |
59 | for measuring fan speed. There are three (3) PWM outputs that can be used | |
f890c6a3 JD |
60 | to control fan speed. |
61 | ||
62 | A sophisticated control system for the PWM outputs is designed into the | |
63 | ADT747x that allows fan speed to be adjusted automatically based on any of the | |
64 | three temperature sensors. Each PWM output is individually adjustable and | |
65 | programmable. Once configured, the ADT747x will adjust the PWM outputs in | |
66 | response to the measured temperatures without further host intervention. | |
67 | This feature can also be disabled for manual control of the PWM's. | |
68 | ||
69 | Each of the measured inputs (voltage, temperature, fan speed) has | |
70 | corresponding high/low limit values. The ADT747x will signal an ALARM if | |
71 | any measured value exceeds either limit. | |
72 | ||
73 | The ADT747x samples all inputs continuously. The driver will not read | |
74 | the registers more often than once every other second. Further, | |
75 | configuration data is only read once per minute. | |
76 | ||
3d849981 JD |
77 | Chip Differences Summary |
78 | ------------------------ | |
79 | ||
80 | ADT7473: | |
81 | * 2 voltage inputs | |
82 | * system acoustics optimizations (not implemented) | |
83 | ||
84 | ADT7475: | |
85 | * 2 voltage inputs | |
86 | ||
d8d2ee07 JD |
87 | ADT7476: |
88 | * 5 voltage inputs | |
54fe4671 | 89 | * VID support |
d8d2ee07 | 90 | |
3d849981 JD |
91 | ADT7490: |
92 | * 6 voltage inputs | |
93 | * 1 Imon input (not implemented) | |
94 | * PECI support (not implemented) | |
95 | * 2 GPIO pins (not implemented) | |
96 | * system acoustics optimizations (not implemented) | |
97 | ||
f1af9321 CP |
98 | Sysfs Mapping |
99 | ------------- | |
100 | ||
b04f2f7d MCC |
101 | ==== =========== =========== ========= ========== |
102 | in ADT7490 ADT7476 ADT7475 ADT7473 | |
103 | ==== =========== =========== ========= ========== | |
f1af9321 CP |
104 | in0 2.5VIN (22) 2.5VIN (22) - - |
105 | in1 VCCP (23) VCCP (23) VCCP (14) VCCP (14) | |
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) | |
b04f2f7d | 110 | ==== =========== =========== ========= ========== |
f1af9321 | 111 | |
f890c6a3 JD |
112 | Special Features |
113 | ---------------- | |
114 | ||
115 | The ADT747x has a 10-bit ADC and can therefore measure temperatures | |
116 | with a resolution of 0.25 degree Celsius. Temperature readings can be | |
117 | configured either for two's complement format or "Offset 64" format, | |
118 | wherein 64 is subtracted from the raw value to get the temperature value. | |
119 | ||
120 | The datasheet is very detailed and describes a procedure for determining | |
121 | an optimal configuration for the automatic PWM control. | |
122 | ||
123 | Fan Speed Control | |
124 | ----------------- | |
125 | ||
126 | The driver exposes two trip points per PWM channel. | |
127 | ||
b04f2f7d MCC |
128 | - point1: Set the PWM speed at the lower temperature bound |
129 | - point2: Set the PWM speed at the higher temperature bound | |
f890c6a3 JD |
130 | |
131 | The ADT747x will scale the PWM linearly between the lower and higher PWM | |
132 | speed when the temperature is between the two temperature boundaries. | |
133 | Temperature boundaries are associated to temperature channels rather than | |
134 | PWM outputs, and a given PWM output can be controlled by several temperature | |
135 | channels. As a result, the ADT747x may compute more than one PWM value | |
136 | for a channel at a given time, in which case the maximum value (fastest | |
137 | fan speed) is applied. PWM values range from 0 (off) to 255 (full speed). | |
138 | ||
139 | Fan speed may be set to maximum when the temperature sensor associated with | |
140 | the PWM control exceeds temp#_max. | |
141 | ||
1d58f5ef CP |
142 | At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or at the |
143 | minimum (i.e. auto_point1_pwm). This behaviour can be configured using the | |
b04f2f7d | 144 | `pwm[1-*]_stall_disable sysfs attribute`. A value of 0 means the fans will shut |
1d58f5ef CP |
145 | off. A value of 1 means the fans will run at auto_point1_pwm. |
146 | ||
8f05bcc3 CP |
147 | The responsiveness of the ADT747x to temperature changes can be configured. |
148 | This allows smoothing of the fan speed transition. To set the transition time | |
b04f2f7d | 149 | set the value in ms in the `temp[1-*]_smoothing` sysfs attribute. |
8f05bcc3 | 150 | |
f890c6a3 JD |
151 | Notes |
152 | ----- | |
153 | ||
154 | The nVidia binary driver presents an ADT7473 chip via an on-card i2c bus. | |
155 | Unfortunately, they fail to set the i2c adapter class, so this driver may | |
156 | fail to find the chip until the nvidia driver is patched. |