From mboxrd@z Thu Jan  1 00:00:00 1970
From: greg@kroah.com (Greg Kroah-Hartman)
Date: Wed, 8 Oct 2014 10:32:37 -0700
Subject: User space <==> kernel space for device wakeups.
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On Wed, Oct 08, 2014 at 10:23:32PM +0530, Jeshwanth Kumar N K wrote:
> My case was: I have a hall sensor connected to Beaglebone black, And Userspace
> needed a wakeup once the interrupt occur (example: every rising edge of GPIO).
> Before that, the program will register (ioctl) the User space task pointer with
> my kernel module, then my kernel module start sending signal for every
> interrupt occur. We can consider roughly around 100 to 200 interrupts per
> second maximum. ( I have not done this, but may be we can consider kernel will
> get notified when userspace program stops. so that it will not send any
> signal). So for this case, any other alternative implementation ?

select() on the GPIO sysfs file instead of a custom ioctl?

And what do you do in userspace with that information?

greg k-h