5.1.2 Checking the Maximum Number of Devices That the Driver
Supports
The following code shows how to check for the maximum number of devices
that the
if_el
device driver supports:
if (unit >= el_MAXDEV) {
1
printf("el%d: el_probe: unit exceeds max supported devices\n",
unit);
return(0);
2
}
1
If the
unit
variable exceeds the maximum number of devices that
the
if_el
driver supports, calls the
printf( )
routine to display
an appropriate message on the console terminal. The
printf( )
routine also displays the controller number that is stored in the
unit
variable. The
el_probe( )
routine stores the controller number in
this variable by referencing the
ctlr_num
member of the
controller
data structure pointer.
The
el_MAXDEV
constant defines the maximum number of controllers
that the
if_el
driver can support.
2
Returns the value 0 (zero) to indicate that the probe operation failed.
5.1.3 Performing Bus-Specific Tasks
The following code shows how the
el_probe( )
routine performs tasks that
are specific to the PCMCIA and ISA buses. Only network device drivers
that operate on the PCMCIA and ISA buses perform these tasks. Your
probe
interface performs tasks that are related to the bus on which your
network driver operates. See the bus-specific manual for information on
data structures for that bus.
switch (ctlr->bus_hd->bus_type) {
1
case BUS_PCMCIA:
2
reg = iocard_infop->io_addr[0];
3
multi_func_flag = card_infop->card_option->multi_func_flag;
4
if (!multi_func_flag)
{
if (READ_BUS_D16(reg+W0_MID) != 0x6d50) {
5
WRITE_BUS_D16(reg+CMD_PORT, CMD_RESET);
DELAY(1000);
if (READ_BUS_D16(reg+W0_MID) != 0x6d50) {
6
printf("el%d: EtherLink III not found on bus\n", unit);
return(0);
7
}
}
}
break;
5–4 Implementing the Autoconfiguration Support Section (probe)
