1 Kernel driver pwm-fan 1 Kernel driver pwm-fan
2 ===================== 2 =====================
3 3
4 This driver enables the use of a PWM module to 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 inde 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 l 6 many SoCs, as long as the SoC supplies a PWM line driver that exposes
7 the generic PWM API. 7 the generic PWM API.
8 8
9 Author: Kamil Debski <k.debski@samsung.com> 9 Author: Kamil Debski <k.debski@samsung.com>
10 10
11 Description 11 Description
12 ----------- 12 -----------
13 13
14 The driver implements a simple interface for d 14 The driver implements a simple interface for driving a fan connected to
15 a PWM output. It uses the generic PWM interfac 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 16 a range of SoCs. The driver exposes the fan to the user space through
17 the hwmon's sysfs interface. 17 the hwmon's sysfs interface.
18 18
19 The fan rotation speed returned via the option 19 The fan rotation speed returned via the optional 'fan1_input' is extrapolated
20 from the sampled interrupts from the tachomete 20 from the sampled interrupts from the tachometer signal within 1 second.
21 21
22 The driver provides the following sensor acces 22 The driver provides the following sensor accesses in sysfs:
23 23
24 =============== ======= ====================== 24 =============== ======= =======================================================
25 fan1_input ro fan tachometer speed i 25 fan1_input ro fan tachometer speed in RPM
26 pwm1_enable rw keep enable mode, defi 26 pwm1_enable rw keep enable mode, defines behaviour when pwm1=0
27 0 -> disable pwm and r 27 0 -> disable pwm and regulator
28 1 -> enable pwm; if pw 28 1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled
29 2 -> enable pwm; if pw 29 2 -> enable pwm; if pwm==0, keep pwm and regulator enabled
30 3 -> enable pwm; if pw 30 3 -> enable pwm; if pwm==0, disable pwm and regulator
31 pwm1 rw relative speed (0-255) 31 pwm1 rw relative speed (0-255), 255=max. speed.
32 =============== ======= ====================== 32 =============== ======= =======================================================
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