On Tuesday, May 28, 2013 6:56 PM, Greg Kroah-Hartman wrote: > On Tue, May 28, 2013 at 08:46:58PM -0500, H Hartley Sweeten wrote: >> Greg, >> >> I'm trying to create a simple directory in the sysfs hierarchy following >> Documentation/kobject.txt and samples/kobject-example.c. > > Hint, don't :) That's kind of what I figured... >> I have been able to create the subdirectory and attributes but now >> I'm stuck. > > You really don't want to do this, trust me :) > >> In the sample, the attribute files all use static data (foo, baz, bar). >> Is there any way to pass a pointer to the data needed by the >> attributes when using kobject_create_and_add()? > > What do you mean by this? You should be getting a callback with your > kobject in it, so that you can then dig out the needed information to > fill in the show/store data. > > But let's take a step back, what are you trying to do by creating a new > sysfs directory? You should never create a subdir in the device tree in > sysfs, that is not a 'struct device'. That is because udev / userspace > will not see the directory, so any attribute under it will not be > accessable by the tools that users use to access them. I'm cleaning up the ep93xx pwm driver for conversion to the PWM framework. My use of that driver requires user space control so I'm trying to add a sysfs interface to the PWM framework as suggested by Thierry Reding. Lars Poeschel did some initial work on this: [0]: http://marc.info/?l=linux-kernel&m=136499756101273&w=2 Unfortunately he will not be able to do any further work for a couple months. Lars initially followed the sysfs implementation in gpiolib which looks like this: /sys/class/pwm /export ... asks the kernel to export a PWM to userspace /unexport ... returns a PWM to the kernel /pwmN ... for each exported PWM #N /duty_ns ... r/w, duty cycle in ns /period_ns ... r/w, PWM period in ns /polarity ... r/w, normal(0) or inverse(1) polarity /run ... r/w, start(1) and stop(0) the PWM /pwmchipN ... for each pwmchip; #N is its first PWM /base ... (r/o), same as N /npwm ... (r/o), number of PWM Thierry Reding did a pretty thorough review and said he would rather have the exported PWMs appear under the associated pwmchip. The PWM subsystem was designed to do per-chip indexing and the global namespace was introduced only for backwards compatibility. The goal is to remove the global namespace. It appears Thierry wants the sysfs hierarchy to look like this: /sys/class/pwm /pwmchipN ... for each pwmchip; #N is its first PWM /npwm ... (r/o), number of PWM /export ... asks the kernel to export a PWM to userspace /unexport ... returns a PWM to the kernel /pwmN ... for each exported PWM #N (of this pwmchip) /duty_ns ... r/w, duty cycle in ns /period_ns ... r/w, PWM period in ns /polarity ... r/w, normal(0) or inverse(1) polarity /enable ... r/w, start(1) and stop(0) the PWM The pwmN subdirectory and the attributes under it are the ones I'm trying to add. I've been searching the kernel source trying to find something similar but the only this I have found is the kobject_create_and_add() stuff. Do you have any other suggestions? Thanks, Hartley _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
