Integrating IIO triggered buffer support

It might be useful to be able to capture data based on some external signals or events (triggers) in data acquisition applications. These triggers might be the following:

• A data ready signal
• An IRQ line connected to some external system (GPIO or whatever)
• On processor periodic interrupt (a timer, for example)
• User space reading/writing a specific file in sysfs

IIO device drivers are completely decorrelated from the triggers, whose drivers are implemented in drivers/iio/trigger/. A trigger may initialize data capture on one or many devices. These triggers are used to fill buffers, exposed to user space through the character device created during the registration of the IIO device.

You can develop your own trigger driver, but it is out of the scope of this book. We will try to focus on existing ones only. These are as follows:

• iio-trig-interrupt: This allows using IRQs as IIO triggers. In old kernel versions...