| Kernel driver pwm-fan |
| ===================== |
| |
| 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 <k.debski@samsung.com> |
| |
| Description |
| ----------- |
| |
| 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. |
| =============== ======= ======================================================= |
