The attach(9E) routine should perform the common initialization tasks that all devices require. Typically, these tasks include:
Allocating per-instance state structures
Registering device interrupts
Mapping the device's registers
Initializing mutex and condition variables
Creating power-manageable components
Creating minor nodes
See The attach() Entry Point for code examples of these tasks.
Character device drivers create minor nodes of type S_IFCHR. This causes a character special file representing the node to eventually appear in the /devices hierarchy.
Example 10–1 shows a sample attach(9E) routine. It is common to declare any properties associated with the device in an attach() routine; in this example, it is the predefined Size property. Size is the equivalent of the Nblocks property used for getting the size of partition in a block device. If, for example, you are doing character I/O on a disk device, you might use Size to get the size of a partition. Since Size is a 64–bit property—the 32–bit version is size—you must use a 64–bit property interface, in this case ddi_prop_updtate_int64(9E) See Device Properties for more on properties.
static int xxattach(dev_info_t *dip, ddi_attach_cmd_t cmd) { int instance = ddi_get_instance(dip); switch (cmd) { case DDI_ATTACH: allocate a state structure and initialize it. map the device's registers. add the device driver's interrupt handler(s). initialize any mutexes and condition variables. create power manageable components. /* * Create the device's minor node. Note that the node_type * argument is set to DDI_NT_TAPE. */ if (ddi_create_minor_node(dip, "minor_name", S_IFCHR, instance, DDI_NT_TAPE, 0) == DDI_FAILURE) { free resources allocated so far. /* Remove any previously allocated minor nodes */ ddi_remove_minor_node(dip, NULL); return (DDI_FAILURE); } /* * Create driver properties like "Size." Use "Size" * instead of "size" to ensure the property works * for large bytecounts. */ xsp->Size = size of device in bytes; maj_number = ddi_driver_major(dip); if (ddi_prop_update_int64(makedevice(maj_number, instance), dip, "Size", xsp->Size) != DDI_PROP_SUCCESS) { cmn_err(CE_CONT, "%s: cannot create Size property\n", ddi_get_name(dip)); free resources allocated so far return (DDI_FAILURE); } ... return (DDI_SUCCESS); case DDI_RESUME: For information, see Chapter 9, Power Management default: return (DDI_FAILURE); } }