1 Kernel driver pwm-fan 2 ===================== 3 4 This driver enables the use of a PWM module to drive a fan. It uses the 5 generic PWM interface thus it is hardware independent. It can be used on 6 many SoCs, as long as the SoC supplies a PWM line driver that exposes 7 the generic PWM API. 8 9 Author: Kamil Debski <k.debski@samsung.com> 10 11 Description 12 ----------- 13 14 The driver implements a simple interface for driving a fan connected to 15 a PWM output. It uses the generic PWM interface, thus it can be used with 16 a range of SoCs. The driver exposes the fan to the user space through 17 the hwmon's sysfs interface. 18 19 The fan rotation speed returned via the optional 'fan1_input' is extrapolated 20 from the sampled interrupts from the tachometer signal within 1 second. 21 22 The driver provides the following sensor accesses in sysfs: 23 24 =============== ======= ======================================================= 25 fan1_input ro fan tachometer speed in RPM 26 pwm1_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 31 pwm1 rw relative speed (0-255), 255=max. speed. 32 =============== ======= =======================================================
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