xref: /linux/Documentation/hwmon/nct7904.rst (revision 2da68a77)
1Kernel driver nct7904
2=====================
3
4Supported chip:
5
6  * Nuvoton NCT7904D
7
8    Prefix: nct7904
9
10    Addresses: I2C 0x2d, 0x2e
11
12    Datasheet: Publicly available at Nuvoton website
13
14	http://www.nuvoton.com/
15
16Author: Vadim V. Vlasov <vvlasov@dev.rtsoft.ru>
17
18
19Description
20-----------
21
22The NCT7904D is a hardware monitor supporting up to 20 voltage sensors,
23internal temperature sensor, Intel PECI and AMD SB-TSI CPU temperature
24interface, up to 12 fan tachometer inputs, up to 4 fan control channels
25with SmartFan.
26
27
28Sysfs entries
29-------------
30
31Currently, the driver supports only the following features:
32
33======================= =======================================================
34in[1-20]_input		Input voltage measurements (mV)
35
36fan[1-12]_input		Fan tachometer measurements (rpm)
37
38temp1_input		Local temperature (1/1000 degree,
39			0.125 degree resolution)
40
41temp[2-9]_input		CPU temperatures (1/1000 degree,
42			0.125 degree resolution)
43
44pwm[1-4]_enable		R/W, 1/2 for manual or SmartFan mode
45			Setting SmartFan mode is supported only if it has been
46			previously configured by BIOS (or configuration EEPROM)
47
48pwm[1-4]		R/O in SmartFan mode, R/W in manual control mode
49======================= =======================================================
50
51The driver checks sensor control registers and does not export the sensors
52that are not enabled. Anyway, a sensor that is enabled may actually be not
53connected and thus provide zero readings.
54
55
56Limitations
57-----------
58
59The following features are not supported in current version:
60
61 - SmartFan control
62 - Watchdog
63 - GPIO
64 - external temperature sensors
65 - SMI
66 - min/max values
67 - many other...
68