http://lxr.free-electrons.com/source/drivers/pwm/sysfs.c https://www.kernel.org/doc/Documentation/pwm.txt https://lwn.net/Articles/553755/
On Mon, Aug 1, 2016 at 1:50 PM, Mark A. Yoder <[email protected]> wrote: > I have a question about building a kernel driver for my PRU software pwm > that mimics the hardware pwm sysfs interface. > *Background:* > I have a simple kernel driver[1] now working with my PRU based pwd code. > Once you have the code running on the PRU you can: > bone$ *insmod pwm.ko channel=1* > bone$ *cd /sys/kernel/pwm/pwm1* > bone$ *ls* > *duty_cycle enable period* > bone$ *echo 2000 > period* > bone$ *echo 1000 > duty_cycle* > > Now you have a pwm signal on channel 1 with a period of 2000ns and an on > time of 1000 ns. > > The hardware pwms appear in /sys/class/pwm. You can use them via: > bone$ *cd /sys/class/pwm/pwmchip0* > bone$ *echo 0 > export* > bone$ *cd pwm0* > bone$ *echo 2000 > period* > bone$ *echo 1000 > duty_cycle* > > *The question:* > How do I build a kernel module so my software pwms will appear along with > the hardware pwms? That is, I want my software pwms to appear as > *pwmchipX* and then you could: > bone$ *cd /sys/class/pwm/pwmchipX* > bone$ *echo 0 > export* > bone$ *cd pwm0* > bone$ *echo 2000 > period* > bone$ *echo 1000 > duty_cycle* > To run the PRU pwms. > > Does anyone have pointers to kernel tutorials to do this? > > Thanks... > > --Mark > [1] > https://github.com/MarkAYoder/BeagleBoard-exercises/tree/master/pru/examples/pwm/kernel > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/b8ef1af3-914f-48cd-b555-22b47dee072f%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/b8ef1af3-914f-48cd-b555-22b47dee072f%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALHSORqY78cBhVCFwzKurwjhQ2AeJEaArRZ%3D9Ep3z1_XYBfobA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
