Defining the Device Operations Structure

The dev_ops(9S) structure initializes interfaces that are used for operations such as attaching and detaching the driver. See the dev_ops(9S) man page to learn what each element is and what the value of each element should be. This dummy driver does not use all of the elements in the dev_ops(9S) structure. See the description that follows the code sample.

When you name this structure, use the same dummy_ prefix that you used for the names of the autoconfiguration routines and the names of the user context routines. Prepend the static type modifier to the declaration.

The following code is the dev_ops(9S) structure that you should enter into your dummy.c file:

static struct dev_ops dummy_dev_ops = {
    DEVO_REV,
    0,                         /* reference count */
    dummy_getinfo,             /* no getinfo(9E) */
    nulldev,                   /* no identify(9E) - nulldev returns 0 */
    nulldev,                   /* no probe(9E) */
    dummy_attach,
    dummy_detach,
    nodev,                     /* no reset - nodev returns ENXIO */
    &dummy_cb_ops,
    (struct bus_ops *)NULL,
    nodev,                     /* no power(9E) */
    ddi_quiesce_not_needed,    /* no quiesce(9E) */
};

The DEVO_REV element of the dev_ops(9S) structure is the driver build version. DEVO_REV is defined in the devops.h header file. The second element in this structure is the driver reference count. Initialize this value to zero. The driver reference count is the number of instances of this driver that are currently open. The driver cannot be unloaded if any instances of the driver are still open.

The next six elements of the dev_ops(9S) structure are the names of the getinfo(9E), identify(9E), probe(9E), attach(9E), detach(9E), and reset() functions for this particular driver. The identify(9E) function is obsolete. Initialize this structure element to nulldev(9F). The probe(9E) function determines whether the corresponding device exists and is valid. This dummy driver does not define a probe(9E) function. Initialize this structure element to nulldev. The nulldev(9F) function returns success. The reset() function is obsolete. Initialize the reset() function to nodev(9F).

The next element of the dev_ops(9S) structure is a pointer to the cb_ops(9S) structure for this driver. You initialized the cb_ops(9S) structure for this driver in Defining the Character and Block Operations Structure. Enter &dummy_cb_ops for the value of the pointer to the cb_ops(9S) structure.

The next element of the dev_ops(9S) structure is a pointer to the bus operations structure. Only nexus drivers have bus operations structures. This dummy driver is not a nexus driver. Set this value to NULL because this driver is a leaf driver.

The next element of the dev_ops(9S) structure is the name of the power(9E) routine for this driver. The power(9E) routine operates on a hardware device. This driver does not drive a hardware device. Set the value of this structure element to nodev.

The last element of the dev_ops(9S) structure is the name of the quiesce(9E) routine for this driver. The quiesce(9E) routine operates on a hardware device. This driver does not drive a hardware device. Set the value of this structure element to ddi_quiesce_not_needed()(9F).