1*4882a593SmuzhiyunKernel driver pwm-fan 2*4882a593Smuzhiyun===================== 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunThis driver enables the use of a PWM module to drive a fan. It uses the 5*4882a593Smuzhiyungeneric PWM interface thus it is hardware independent. It can be used on 6*4882a593Smuzhiyunmany SoCs, as long as the SoC supplies a PWM line driver that exposes 7*4882a593Smuzhiyunthe generic PWM API. 8*4882a593Smuzhiyun 9*4882a593SmuzhiyunAuthor: Kamil Debski <k.debski@samsung.com> 10*4882a593Smuzhiyun 11*4882a593SmuzhiyunDescription 12*4882a593Smuzhiyun----------- 13*4882a593Smuzhiyun 14*4882a593SmuzhiyunThe driver implements a simple interface for driving a fan connected to 15*4882a593Smuzhiyuna PWM output. It uses the generic PWM interface, thus it can be used with 16*4882a593Smuzhiyuna range of SoCs. The driver exposes the fan to the user space through 17*4882a593Smuzhiyunthe hwmon's sysfs interface. 18*4882a593Smuzhiyun 19*4882a593SmuzhiyunThe fan rotation speed returned via the optional 'fan1_input' is extrapolated 20*4882a593Smuzhiyunfrom the sampled interrupts from the tachometer signal within 1 second. 21