5.1.14 Registering the shutdown Routine
The following code shows how the el_probe( ) routine registers its shutdown( ) routine. The kernel calls this routine when the system shuts down. The driver can specify an argument for the kernel to pass to the routine at that time.
if
drvr_register_shutdown(el_shutdown, (void*)sc, DRVR_REGISTER); return( ~ 0);
}
1
1
Registers the shutdown( ) routine and directs the kernel to pass a pointer to the driver’s softc data structure to the routine. The shutdown( ) routine is important for those devices that perform
5.2 Implementing the el_shutdown Routine
The driver’s shutdown( ) routine shuts down the controller. The kernel calls all registered shutdown( ) routines when the system shuts down.
The el_probe( ) routine registers a shutdown( ) routine called
el_shutdown( ). The if_el device driver implements the routine as follows:
static void el_shutdown(struct el_softc *sc)
{
1
WRITE_CMD(sc, CMD_RESET); DELAY(1000); 3
}
2
1
2
3
Specifies the argument that the kernel passes to the routine, which is a pointer to the driver’s el_softc data structure. The driver specifies this argument when it registers the shutdown( ) routine in its probe interface.
Calls the WRITE_CMD macro to write data to the command port register. In this call, the el_softc data structure for this 3Com 3C5x9 device contains the I/O handle to reference the device’s command register. The data to be written is the CMD_RESET bit, which resets the device.
Calls the DELAY macro to delay the execution of el_shutdown( ) for 1 millisecond before continuing execution. This gives the reset command time to complete.
5.3 Implementing the el_autosense_thread Routine
The if_el device driver implements a
el_autosense_thread( ) to determine the mode of the network interface. The el_probe( ) routine calls el_autosense_thread( ) during device autoconfiguration.
