xref: /linux/Documentation/hwmon/max31785.rst (revision c39f2d9db0fd81ea20bb5cce9b3f082ca63753e2)
1Kernel driver max31785
2======================
3
4Supported chips:
5
6  * Maxim MAX31785, MAX31785A
7
8    Prefix: 'max31785' or 'max31785a'
9
10    Addresses scanned: -
11
12    Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31785.pdf
13
14Author: Andrew Jeffery <andrew@aj.id.au>
15
16Description
17-----------
18
19The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan
20management with temperature and remote voltage sensing. Various fan control
21features are provided, including PWM frequency control, temperature hysteresis,
22dual tachometer measurements, and fan health monitoring.
23
24For dual-rotor configurations the MAX31785A exposes the second rotor tachometer
25readings in attributes fan[5-8]_input. By contrast the MAX31785 only exposes
26the slowest rotor measurement, and does so in the fan[1-4]_input attributes.
27
28Usage Notes
29-----------
30
31This driver does not probe for PMBus devices. You will have to instantiate
32devices explicitly.
33
34Sysfs attributes
35----------------
36
37======================= =======================================================
38fan[1-4]_alarm		Fan alarm.
39fan[1-4]_fault		Fan fault.
40fan[1-8]_input		Fan RPM. On the MAX31785A, inputs 5-8 correspond to the
41			second rotor of fans 1-4
42fan[1-4]_target		Fan input target
43
44in[1-6]_crit		Critical maximum output voltage
45in[1-6]_crit_alarm	Output voltage critical high alarm
46in[1-6]_input		Measured output voltage
47in[1-6]_label		"vout[18-23]"
48in[1-6]_lcrit		Critical minimum output voltage
49in[1-6]_lcrit_alarm	Output voltage critical low alarm
50in[1-6]_max		Maximum output voltage
51in[1-6]_max_alarm	Output voltage high alarm
52in[1-6]_min		Minimum output voltage
53in[1-6]_min_alarm	Output voltage low alarm
54
55pwm[1-4]		Fan target duty cycle (0..255)
56pwm[1-4]_enable		0: Full-speed
57			1: Manual PWM control
58			2: Automatic PWM (tach-feedback RPM fan-control)
59			3: Automatic closed-loop (temp-feedback fan-control)
60
61temp[1-11]_crit		Critical high temperature
62temp[1-11]_crit_alarm	Chip temperature critical high alarm
63temp[1-11]_input	Measured temperature
64temp[1-11]_max		Maximum temperature
65temp[1-11]_max_alarm	Chip temperature high alarm
66======================= =======================================================
67