projects / mirror_ubuntu-kernels.git / blame
| Commit | Line | Data |
|---|---|---|
| d82d5776 KD |
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. | |
| 285d7483 SW |
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. | |
| b99152d4 AS |
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 | =============== ======= ======================================================= |