1 .. SPDX-License-Identifier: GPL-2.0-or-later 1 .. SPDX-License-Identifier: GPL-2.0-or-later
2 2
3 Kernel driver max31760 3 Kernel driver max31760
4 ====================== 4 ======================
5 5
6 Supported chips: 6 Supported chips:
7 * Analog Devices MAX31760 7 * Analog Devices MAX31760
8 8
9 Prefix: 'max31760' 9 Prefix: 'max31760'
10 10
11 Addresses scanned: none 11 Addresses scanned: none
12 12
13 Datasheet: https://datasheets.maximintegra 13 Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31760.pdf
14 14
15 15
16 Author: Ibrahim Tilki <Ibrahim.Tilki@analog.com 16 Author: Ibrahim Tilki <Ibrahim.Tilki@analog.com>
17 17
18 Description 18 Description
19 ----------- 19 -----------
20 20
21 The MAX31760 integrates temperature sensing al 21 The MAX31760 integrates temperature sensing along with precision PWM fan
22 control. It accurately measures its local die 22 control. It accurately measures its local die temperature and the remote
23 temperature of a discrete diode-connected tran 23 temperature of a discrete diode-connected transistor, such as a 2N3906,
24 or a thermal diode commonly found on CPUs, gra 24 or a thermal diode commonly found on CPUs, graphics processor units (GPUs),
25 and other ASICs. Multiple temperature threshol 25 and other ASICs. Multiple temperature thresholds, such as local
26 high/overtemperature (OT) and remote high/over 26 high/overtemperature (OT) and remote high/overtemperature, can be set by an
27 I2C-compatible interface. Fan speed is control 27 I2C-compatible interface. Fan speed is controlled based on the temperature
28 reading as an index to a 48-byte lookup table 28 reading as an index to a 48-byte lookup table (LUT) containing
29 user-programmed PWM values. The flexible LUT-b 29 user-programmed PWM values. The flexible LUT-based architecture enables
30 the user to program a smooth nonlinear fan spe 30 the user to program a smooth nonlinear fan speed vs. temperature transfer
31 function to minimize acoustic fan noise. Two t 31 function to minimize acoustic fan noise. Two tachometer inputs allow
32 measuring the speeds of two fans independently 32 measuring the speeds of two fans independently. When the local or remote
33 OT threshold is exceeded, the SHDN pin is asse 33 OT threshold is exceeded, the SHDN pin is asserted low and can be used to
34 shut down the system. A dedicated ALERT pin re 34 shut down the system. A dedicated ALERT pin reports that either a local or
35 remote high-temperature threshold has been exc 35 remote high-temperature threshold has been exceeded.
36 36
37 Temperature measurement range: from -55°C to 37 Temperature measurement range: from -55°C to 125°C
38 38
39 Temperature Resolution: 11 Bits, ±0.125°C 39 Temperature Resolution: 11 Bits, ±0.125°C
40 40
41 Please refer how to instantiate this driver: D 41 Please refer how to instantiate this driver: Documentation/i2c/instantiating-devices.rst
42 42
43 Lookup table for auto fan control 43 Lookup table for auto fan control
44 --------------------------------- 44 ---------------------------------
45 45
46 ========= ================================= 46 ========= =================================
47 LUT Index Name 47 LUT Index Name
48 ========= ================================= 48 ========= =================================
49 1 PWM value for T < +18°C 49 1 PWM value for T < +18°C
50 2 PWM value for +18°C ≤ T < +20°C 50 2 PWM value for +18°C ≤ T < +20°C
51 3 PWM value for +20°C ≤ T < +22°C 51 3 PWM value for +20°C ≤ T < +22°C
52 ... ... 52 ... ...
53 47 PWM value for +108°C ≤ T < +110° 53 47 PWM value for +108°C ≤ T < +110°C
54 48 PWM value for T ≥ +110°C 54 48 PWM value for T ≥ +110°C
55 ========= ================================= 55 ========= =================================
56 56
57 Sysfs entries 57 Sysfs entries
58 ------------- 58 -------------
59 59
60 =============================== ============== 60 =============================== =================================================================================
61 fan[1-2]_input Fan speed (in 61 fan[1-2]_input Fan speed (in RPM)
62 fan[1-2]_enable Enable fan rea 62 fan[1-2]_enable Enable fan readings and fan fault alarms
63 fan[1-2]_fault Fan fault stat 63 fan[1-2]_fault Fan fault status
64 temp[1-2]_label "Remote" and " 64 temp[1-2]_label "Remote" and "Local" temperature channel labels
65 temp[1-2]_input Temperature se 65 temp[1-2]_input Temperature sensor readings (in millidegrees Celsius)
66 temp1_fault Remote tempera 66 temp1_fault Remote temperature sensor fault status
67 temp[1-2]_max Temperature ma 67 temp[1-2]_max Temperature max value. Asserts "ALERT" pin when exceeded
68 temp[1-2]_max_alarm Temperature ma 68 temp[1-2]_max_alarm Temperature max alarm status
69 temp[1-2]_crit Temperature cr 69 temp[1-2]_crit Temperature critical value. Asserts "SHDN" pin when exceeded
70 temp[1-2]_crit_alarm Temperature cr 70 temp[1-2]_crit_alarm Temperature critical alarm status
71 pwm1 PWM value for 71 pwm1 PWM value for direct fan control
72 pwm1_enable 1: direct fan 72 pwm1_enable 1: direct fan control, 2: temperature based auto fan control
73 pwm1_freq PWM frequency 73 pwm1_freq PWM frequency in hertz
74 pwm1_auto_channels_temp Temperature so 74 pwm1_auto_channels_temp Temperature source for auto fan control. 1: temp1, 2: temp2, 3: max(temp1, temp2)
75 pwm1_auto_point[1-48]_pwm PWM value for 75 pwm1_auto_point[1-48]_pwm PWM value for LUT point
76 pwm1_auto_point_temp_hyst Temperature hy 76 pwm1_auto_point_temp_hyst Temperature hysteresis for auto fan control. Can be either 2000mC or 4000mC
77 =============================== ============== 77 =============================== =================================================================================
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.