Opening the Device, Closing the Device, and Getting Module Information

The open(9E) and close(9E) entry points are identical in this sample driver. In each case, the entry point first calls the getminor(9F) function to retrieve the minor number of the device. Then each entry point uses this instance number to call the ddi_get_soft_state(9F) function to retrieve the state structure for this device instance. If no state structure is retrieved, an error code is returned. If a state structure is retrieved, the open(9E) and close(9E) entry points both verify the type of this device. If this device is not a character device, the EINVAL (invalid) error code is returned.

If the user wants device information for this device instance, the getinfo(9E) entry point returns the device information from the state structure. If the user wants the instance number of this device instance, the getinfo(9E) entry point uses the getminor(9F) function to return the minor number.