Documentation/hwmon/pwm-fan.rst
This driver enables the use of a PWM module to drive a fan. It uses the generic PWM interface thus it is hardware independent. It can be used on many SoCs, as long as the SoC supplies a PWM line driver that exposes the generic PWM API.
Author: Kamil Debski [email protected]
The driver implements a simple interface for driving a fan connected to a PWM output. It uses the generic PWM interface, thus it can be used with a range of SoCs. The driver exposes the fan to the user space through the hwmon's sysfs interface.
The fan rotation speed returned via the optional 'fan1_input' is extrapolated from the sampled interrupts from the tachometer signal within 1 second.
The driver provides the following sensor accesses in sysfs:
=============== ======= ======================================================= fan1_input ro fan tachometer speed in RPM pwm1_enable rw keep enable mode, defines behaviour when pwm1=0 0 -> disable pwm and regulator 1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled 2 -> enable pwm; if pwm==0, keep pwm and regulator enabled 3 -> enable pwm; if pwm==0, disable pwm and regulator pwm1 rw relative speed (0-255), 255=max. speed. =============== ======= =======================================================