162306a36Sopenharmony_ciKernel driver pwm-fan 262306a36Sopenharmony_ci===================== 362306a36Sopenharmony_ci 462306a36Sopenharmony_ciThis driver enables the use of a PWM module to drive a fan. It uses the 562306a36Sopenharmony_cigeneric PWM interface thus it is hardware independent. It can be used on 662306a36Sopenharmony_cimany SoCs, as long as the SoC supplies a PWM line driver that exposes 762306a36Sopenharmony_cithe generic PWM API. 862306a36Sopenharmony_ci 962306a36Sopenharmony_ciAuthor: Kamil Debski <k.debski@samsung.com> 1062306a36Sopenharmony_ci 1162306a36Sopenharmony_ciDescription 1262306a36Sopenharmony_ci----------- 1362306a36Sopenharmony_ci 1462306a36Sopenharmony_ciThe driver implements a simple interface for driving a fan connected to 1562306a36Sopenharmony_cia PWM output. It uses the generic PWM interface, thus it can be used with 1662306a36Sopenharmony_cia range of SoCs. The driver exposes the fan to the user space through 1762306a36Sopenharmony_cithe hwmon's sysfs interface. 1862306a36Sopenharmony_ci 1962306a36Sopenharmony_ciThe fan rotation speed returned via the optional 'fan1_input' is extrapolated 2062306a36Sopenharmony_cifrom the sampled interrupts from the tachometer signal within 1 second. 2162306a36Sopenharmony_ci 2262306a36Sopenharmony_ciThe driver provides the following sensor accesses in sysfs: 2362306a36Sopenharmony_ci 2462306a36Sopenharmony_ci=============== ======= ======================================================= 2562306a36Sopenharmony_cifan1_input ro fan tachometer speed in RPM 2662306a36Sopenharmony_cipwm1_enable rw keep enable mode, defines behaviour when pwm1=0 2762306a36Sopenharmony_ci 0 -> disable pwm and regulator 2862306a36Sopenharmony_ci 1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled 2962306a36Sopenharmony_ci 2 -> enable pwm; if pwm==0, keep pwm and regulator enabled 3062306a36Sopenharmony_ci 3 -> enable pwm; if pwm==0, disable pwm and regulator 3162306a36Sopenharmony_cipwm1 rw relative speed (0-255), 255=max. speed. 3262306a36Sopenharmony_ci=============== ======= ======================================================= 33