User space <==> kernel space for device wakeups.

[buyitian]

> 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 

Once kernel gets interrupt, it can use netlink to notify user space, if you are using Android, it is using UEVENT.