xref: /linux/Documentation/hwmon/adm1025.rst (revision e7d759f31ca295d589f7420719c311870bb3166f)
1Kernel driver adm1025
2=====================
3
4Supported chips:
5
6  * Analog Devices ADM1025, ADM1025A
7
8    Prefix: 'adm1025'
9
10    Addresses scanned: I2C 0x2c - 0x2e
11
12    Datasheet: Publicly available at the Analog Devices website
13
14  * Philips NE1619
15
16    Prefix: 'ne1619'
17
18    Addresses scanned: I2C 0x2c - 0x2d
19
20    Datasheet: Publicly available at the Philips website
21
22The NE1619 presents some differences with the original ADM1025:
23
24  * Only two possible addresses (0x2c - 0x2d).
25  * No temperature offset register, but we don't use it anyway.
26  * No INT mode for pin 16. We don't play with it anyway.
27
28Authors:
29	- Chen-Yuan Wu <gwu@esoft.com>,
30	- Jean Delvare <jdelvare@suse.de>
31
32Description
33-----------
34
35(This is from Analog Devices.) The ADM1025 is a complete system hardware
36monitor for microprocessor-based systems, providing measurement and limit
37comparison of various system parameters. Five voltage measurement inputs
38are provided, for monitoring +2.5V, +3.3V, +5V and +12V power supplies and
39the processor core voltage. The ADM1025 can monitor a sixth power-supply
40voltage by measuring its own VCC. One input (two pins) is dedicated to a
41remote temperature-sensing diode and an on-chip temperature sensor allows
42ambient temperature to be monitored.
43
44One specificity of this chip is that the pin 11 can be hardwired in two
45different manners. It can act as the +12V power-supply voltage analog
46input, or as the a fifth digital entry for the VID reading (bit 4). It's
47kind of strange since both are useful, and the reason for designing the
48chip that way is obscure at least to me. The bit 5 of the configuration
49register can be used to define how the chip is hardwired. Please note that
50it is not a choice you have to make as the user. The choice was already
51made by your motherboard's maker. If the configuration bit isn't set
52properly, you'll have a wrong +12V reading or a wrong VID reading. The way
53the driver handles that is to preserve this bit through the initialization
54process, assuming that the BIOS set it up properly beforehand. If it turns
55out not to be true in some cases, we'll provide a module parameter to force
56modes.
57
58This driver also supports the ADM1025A, which differs from the ADM1025
59only in that it has "open-drain VID inputs while the ADM1025 has on-chip
60100k pull-ups on the VID inputs". It doesn't make any difference for us.
61