Putting it all together

So far, we have described the structures used when writing drivers for input devices, and how they can be managed from the user space:

1. Allocate a new input device, according to its type (polled, or not), using input_allocate_polled_device() or input_allocate_device().
2. Fill in the mandatory fields (if necessary):

• • Specify the type of event the device supports by using the set_bit() helper macro on the input_dev.evbit field.
  • Depending on the event type, EV_REL, EV_ABS, EV_KEY, or other, indicate the code this device can report, using either input_dev.relbit, input_dev.absbit, input_dev.keybit, or other.
  • Specify input_dev.dev, in order to set up a proper device tree.
  • Fill abs_info if necessary.
  • For polled devices, indicate at which interval the poll() function should be called.

3. Write the open() function, if necessary, in which you should prepare and set up the resources used by the device. This function is called only once. In this function, set up GPIO, request an interrupt...