1.. SPDX-License-Identifier: GPL-2.0-or-later 2 3Kernel driver max31760 4====================== 5 6Supported chips: 7 * Analog Devices MAX31760 8 9 Prefix: 'max31760' 10 11 Addresses scanned: none 12 13 Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31760.pdf 14 15 16Author: Ibrahim Tilki <Ibrahim.Tilki@analog.com> 17 18Description 19----------- 20 21The MAX31760 integrates temperature sensing along with precision PWM fan 22control. It accurately measures its local die temperature and the remote 23temperature of a discrete diode-connected transistor, such as a 2N3906, 24or a thermal diode commonly found on CPUs, graphics processor units (GPUs), 25and other ASICs. Multiple temperature thresholds, such as local 26high/overtemperature (OT) and remote high/overtemperature, can be set by an 27I2C-compatible interface. Fan speed is controlled based on the temperature 28reading as an index to a 48-byte lookup table (LUT) containing 29user-programmed PWM values. The flexible LUT-based architecture enables 30the user to program a smooth nonlinear fan speed vs. temperature transfer 31function to minimize acoustic fan noise. Two tachometer inputs allow 32measuring the speeds of two fans independently. When the local or remote 33OT threshold is exceeded, the SHDN pin is asserted low and can be used to 34shut down the system. A dedicated ALERT pin reports that either a local or 35remote high-temperature threshold has been exceeded. 36 37Temperature measurement range: from -55°C to 125°C 38 39Temperature Resolution: 11 Bits, ±0.125°C 40 41Please refer how to instantiate this driver: Documentation/i2c/instantiating-devices.rst 42 43Lookup table for auto fan control 44--------------------------------- 45 46========= ================================= 47LUT Index Name 48========= ================================= 491 PWM value for T < +18°C 502 PWM value for +18°C ≤ T < +20°C 513 PWM value for +20°C ≤ T < +22°C 52... ... 5347 PWM value for +108°C ≤ T < +110°C 5448 PWM value for T ≥ +110°C 55========= ================================= 56 57Sysfs entries 58------------- 59 60=============================== ================================================================================= 61fan[1-2]_input Fan speed (in RPM) 62fan[1-2]_enable Enable fan readings and fan fault alarms 63fan[1-2]_fault Fan fault status 64temp[1-2]_label "Remote" and "Local" temperature channel labels 65temp[1-2]_input Temperature sensor readings (in millidegrees Celsius) 66temp1_fault Remote temperature sensor fault status 67temp[1-2]_max Temperature max value. Asserts "ALERT" pin when exceeded 68temp[1-2]_max_alarm Temperature max alarm status 69temp[1-2]_crit Temperature critical value. Asserts "SHDN" pin when exceeded 70temp[1-2]_crit_alarm Temperature critical alarm status 71pwm1 PWM value for direct fan control 72pwm1_enable 1: direct fan control, 2: temperature based auto fan control 73pwm1_freq PWM frequency in hertz 74pwm1_auto_channels_temp Temperature source for auto fan control. 1: temp1, 2: temp2, 3: max(temp1, temp2) 75pwm1_auto_point[1-48]_pwm PWM value for LUT point 76pwm1_auto_point_temp_hyst Temperature hysteresis for auto fan control. Can be either 2000mC or 4000mC 77=============================== ================================================================================= 78