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- .. SPDX-License-Identifier: GPL-2.0-or-later
- Kernel driver max31760
- ======================
- Supported chips:
- * Analog Devices MAX31760
- Prefix: 'max31760'
- Addresses scanned: none
- Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31760.pdf
- Author: Ibrahim Tilki <[email protected]>
- Description
- -----------
- The MAX31760 integrates temperature sensing along with precision PWM fan
- control. It accurately measures its local die temperature and the remote
- temperature of a discrete diode-connected transistor, such as a 2N3906,
- or a thermal diode commonly found on CPUs, graphics processor units (GPUs),
- and other ASICs. Multiple temperature thresholds, such as local
- high/overtemperature (OT) and remote high/overtemperature, can be set by an
- I2C-compatible interface. Fan speed is controlled based on the temperature
- reading as an index to a 48-byte lookup table (LUT) containing
- user-programmed PWM values. The flexible LUT-based architecture enables
- the user to program a smooth nonlinear fan speed vs. temperature transfer
- function to minimize acoustic fan noise. Two tachometer inputs allow
- measuring the speeds of two fans independently. When the local or remote
- OT threshold is exceeded, the SHDN pin is asserted low and can be used to
- shut down the system. A dedicated ALERT pin reports that either a local or
- remote high-temperature threshold has been exceeded.
- Temperature measurement range: from -55°C to 125°C
- Temperature Resolution: 11 Bits, ±0.125°C
- Please refer how to instantiate this driver: Documentation/i2c/instantiating-devices.rst
- Lookup table for auto fan control
- ---------------------------------
- ========= =================================
- LUT Index Name
- ========= =================================
- 1 PWM value for T < +18°C
- 2 PWM value for +18°C ≤ T < +20°C
- 3 PWM value for +20°C ≤ T < +22°C
- ... ...
- 47 PWM value for +108°C ≤ T < +110°C
- 48 PWM value for T ≥ +110°C
- ========= =================================
- Sysfs entries
- -------------
- =============================== =================================================================================
- fan[1-2]_input Fan speed (in RPM)
- fan[1-2]_enable Enable fan readings and fan fault alarms
- fan[1-2]_fault Fan fault status
- temp[1-2]_label "Remote" and "Local" temperature channel labels
- temp[1-2]_input Temperature sensor readings (in millidegrees Celsius)
- temp1_fault Remote temperature sensor fault status
- temp[1-2]_max Temperature max value. Asserts "ALERT" pin when exceeded
- temp[1-2]_max_alarm Temperature max alarm status
- temp[1-2]_crit Temperature critical value. Asserts "SHDN" pin when exceeded
- temp[1-2]_crit_alarm Temperature critical alarm status
- pwm1 PWM value for direct fan control
- pwm1_enable 1: direct fan control, 2: temperature based auto fan control
- pwm1_freq PWM frequency in hertz
- pwm1_auto_channels_temp Temperature source for auto fan control. 1: temp1, 2: temp2, 3: max(temp1, temp2)
- pwm1_auto_point[1-48]_pwm PWM value for LUT point
- pwm1_auto_point_temp_hyst Temperature hysteresis for auto fan control. Can be either 2000mC or 4000mC
- =============================== =================================================================================
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