33 lines
1.3 KiB
ReStructuredText
33 lines
1.3 KiB
ReStructuredText
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Kernel driver pwm-fan
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=====================
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This driver enables the use of a PWM module to drive a fan. It uses the
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generic PWM interface thus it is hardware independent. It can be used on
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many SoCs, as long as the SoC supplies a PWM line driver that exposes
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the generic PWM API.
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Author: Kamil Debski <k.debski@samsung.com>
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Description
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-----------
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The driver implements a simple interface for driving a fan connected to
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a PWM output. It uses the generic PWM interface, thus it can be used with
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a range of SoCs. The driver exposes the fan to the user space through
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the hwmon's sysfs interface.
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The fan rotation speed returned via the optional 'fan1_input' is extrapolated
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from the sampled interrupts from the tachometer signal within 1 second.
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The driver provides the following sensor accesses in sysfs:
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=============== ======= =======================================================
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fan1_input ro fan tachometer speed in RPM
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pwm1_enable rw keep enable mode, defines behaviour when pwm1=0
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0 -> disable pwm and regulator
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1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled
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2 -> enable pwm; if pwm==0, keep pwm and regulator enabled
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3 -> enable pwm; if pwm==0, disable pwm and regulator
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pwm1 rw relative speed (0-255), 255=max. speed.
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=============== ======= =======================================================
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