Compaq TRU64 AA-RNG2A-TE - Manual (Page 63)

case BUS_ISA: 8
if (get_config(ctlr, RES_PORT, NULL, &port_sel, 0) >= 0) { 9
reg = port_sel.base_address; 10
} else { 11
printf("el%d: Can’t get assigned IOBASE\n",unit);
return(0);
}
if (get_config(ctlr, RES_IRQ, NULL, &irq_sel, 0) < 0) { 12
printf("el%d: Can’t get assigned IRQ\n", unit);
return(0);
}
if (el_isa_reset++ == 0) 13
el_isa_reset_all(reg, &isatag, ctlr);
if (el_isa_activate(reg, &isatag, ctlr)) { 14
printf("el%d: 3C509 not present or not responding at 0x%x\n",
unit, reg);
return(0);
}
break;
default: 15
printf("el%d: Unrecognized bus type\n", unit);
return(0);
break;
}
1 Determines which bus the if_el driver operates on by examining the
constant that the bus configuration code has stored in the bus_type
member. The el_probe( ) routine references this value through the
controller
data structure pointer’s bus_hd member. This pointer is
the data structure that is associated with this 3Com 3C5x9 device.
2 Performs tasks related to the PCMCIA bus if bus_type evaluates to
the constant BUS_PCMCIA.
3 Adds the I/O handle to the base address of the card and stores it in the
reg
variable. The reg variable becomes an argument in subsequent
calls to the read and write macros.
4 Determines whether the card is a multifunction card or a single-function
card.
5 Calls the READ_BUS_D16 macro to read a word (16 bits) from a device
register that is located in the bus I/O address space. This read operation
verifies that the EtherLink III card is attached.
If the data that READ_BUS_D16 returns is not equal to 0x6d50, calls
the WRITE_BUS_D16 and DELAY macros. The WRITE_BUS_D16 macro
writes a word (16 bits) to a device register that is located in the bus
I/O address space. This specific write operation resets the card. The
DELAY
macro spins, waiting the specified number of microseconds before
continuing execution.
Implementing the Autoconfiguration Support Section (probe) 5–5