1Kernel driver pwm-fan 2===================== 3 4This driver enables the use of a PWM module to drive a fan. It uses the 5generic PWM interface thus it is hardware independent. It can be used on 6many SoCs, as long as the SoC supplies a PWM line driver that exposes 7the generic PWM API. 8 9Author: Kamil Debski <k.debski@samsung.com> 10 11Description 12----------- 13 14The driver implements a simple interface for driving a fan connected to 15a PWM output. It uses the generic PWM interface, thus it can be used with 16a range of SoCs. The driver exposes the fan to the user space through 17the hwmon's sysfs interface. 18 19The fan rotation speed returned via the optional 'fan1_input' is extrapolated 20from the sampled interrupts from the tachometer signal within 1 second. 21 22The driver provides the following sensor accesses in sysfs: 23 24=============== ======= ======================================================= 25fan1_input ro fan tachometer speed in RPM 26pwm1_enable rw keep enable mode, defines behaviour when pwm1=0 27 0 -> disable pwm and regulator 28 1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled 29 2 -> enable pwm; if pwm==0, keep pwm and regulator enabled 30 3 -> enable pwm; if pwm==0, disable pwm and regulator 31pwm1 rw relative speed (0-255), 255=max. speed. 32=============== ======= ======================================================= 33