1 .. SPDX-License-Identifier: GPL-2.0-or-later 2 3 Kernel driver max31760 4 ====================== 5 6 Supported 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 16 Author: Ibrahim Tilki <Ibrahim.Tilki@analog.com> 17 18 Description 19 ----------- 20 21 The MAX31760 integrates temperature sensing along with precision PWM fan 22 control. It accurately measures its local die temperature and the remote 23 temperature of a discrete diode-connected transistor, such as a 2N3906, 24 or a thermal diode commonly found on CPUs, graphics processor units (GPUs), 25 and other ASICs. Multiple temperature thresholds, such as local 26 high/overtemperature (OT) and remote high/overtemperature, can be set by an 27 I2C-compatible interface. Fan speed is controlled based on the temperature 28 reading as an index to a 48-byte lookup table (LUT) containing 29 user-programmed PWM values. The flexible LUT-based architecture enables 30 the user to program a smooth nonlinear fan speed vs. temperature transfer 31 function to minimize acoustic fan noise. Two tachometer inputs allow 32 measuring the speeds of two fans independently. When the local or remote 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 reports that either a local or 35 remote high-temperature threshold has been exceeded. 36 37 Temperature measurement range: from -55°C to 125°C 38 39 Temperature Resolution: 11 Bits, ±0.125°C 40 41 Please refer how to instantiate this driver: Documentation/i2c/instantiating-devices.rst 42 43 Lookup table for auto fan control 44 --------------------------------- 45 46 ========= ================================= 47 LUT Index Name 48 ========= ================================= 49 1 PWM value for T < +18°C 50 2 PWM value for +18°C ≤ T < +20°C 51 3 PWM value for +20°C ≤ T < +22°C 52 ... ... 53 47 PWM value for +108°C ≤ T < +110°C 54 48 PWM value for T ≥ +110°C 55 ========= ================================= 56 57 Sysfs entries 58 ------------- 59 60 =============================== ================================================================================= 61 fan[1-2]_input Fan speed (in RPM) 62 fan[1-2]_enable Enable fan readings and fan fault alarms 63 fan[1-2]_fault Fan fault status 64 temp[1-2]_label "Remote" and "Local" temperature channel labels 65 temp[1-2]_input Temperature sensor readings (in millidegrees Celsius) 66 temp1_fault Remote temperature sensor fault status 67 temp[1-2]_max Temperature max value. Asserts "ALERT" pin when exceeded 68 temp[1-2]_max_alarm Temperature max alarm status 69 temp[1-2]_crit Temperature critical value. Asserts "SHDN" pin when exceeded 70 temp[1-2]_crit_alarm Temperature critical alarm status 71 pwm1 PWM value for direct fan control 72 pwm1_enable 1: direct fan control, 2: temperature based auto fan control 73 pwm1_freq PWM frequency in hertz 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 LUT point 76 pwm1_auto_point_temp_hyst Temperature hysteresis for auto fan control. Can be either 2000mC or 4000mC 77 =============================== =================================================================================
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