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This routine returns an opaque ihandler_id_t key, which is a unique number that identifies the interrupt handler to be acted on by subsequent calls to handler_del, handler_disable, and handler_enable. The hid member of the el_softc data structure stores this key.
If the return value from handler_add equals NULL, the if_el driver failed to register an interrupt handler for the if_el device. This is a fatal error, and the if_el driver will undo all previous operations and return an error to the caller.
5.1.12 Saving the controller and softc Data Structure Pointers
The following code shows how the el_probe( ) routine saves the controller and el_softc data structure pointers. All probe interfaces perform this task.
el_softc[unit] = sc; el_info[unit] = ctlr;
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Saves the el_softc data structure pointer for this instance of the 3Com 3C5x9 device in the array of el_softc data structures. The unit number is the offset to the data structure within the el_softc array.
Saves the controller data structure pointer for this instance of the 3Com 3C5x9 device in the array of controller data structures.
5.1.13 Trying to Allocate Another controller Data Structure
The following code shows how the el_probe( ) routine attempts to allocate another controller data structure. You make this call so that a driver can support multiple devices.
if
printf("el%d: WARNING: create_controller failed\n", unit);
}
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If this is the first time that the device has been probed, calls the lan_create_controller( ) routine to try to create a second controller data structure. If lan_create_controller( ) fails, calls the printf( ) routine to display a message. (Routines that begin with lan_ reside in the lan_common.c source file.)
