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Note: In these steps "zero" means either 00000000H or 00000001H, one
is zero in memory space and the other is zero in I/O space. Some
controllers use 00000000H instead of the more "correct" value
00000001H.
1) Scan system's PCI config space looking for ATA host controllers -
they probably have 0101H, 0180H or some other 01xxH value in the
class code - avoid SCSI controllers that also have 01xxH class code
values.
2) For each ATA controller found:
2a) Is it enabled? If no, blue screen.
2b) If any BARx (x=0 to 4) is ffffffffh, blue screen.
2c) Is it in legacy or native mode?
2d) If legacy mode and any BARx (x=0 to 3) not zero (see note),
blue screen.
2e) If native mode and any BARx (x=0 to 3) is zero (see note),
blue screen.
2f) If native mode and any BARx (x=0 to 3) not in I/O space,
blue screen.
2g) If BAR4 zero (see note), blue screen.
2h) If BAR4 not in I/O space, blue screen.
3a) if legacy mode
Pri Cmd block I/O address is 01f0H
Pri Ctrl Block I/O address is 03F6H
else
Pri Cmd block I/O address is (BAR0&0x0000fffeH)
Pri Ctrl block I/O address is ((BAR1&0x0000fffeH)+2)
Pri BMIDE regs I/O adress is (BAR4&0x0000fffeH)
3b) If legacy mode
Sec Cmd block I/O address is 0170H
Sec Ctrl block I/O address is 0376H
else
Sec Cmd block I/O address is (BAR2&0x0000fffeH)
Sec Cmd block I/O address is ((BAR3&0x0000fffeH)+2)
Sec BMIDE regs I/O address is ((BAR4&0x0000fffeH)+8)
4) If you must use interrupts, and you must if you want to use DMA
commands, then have fun figuring that out (PIC/APIC?, what is IRQ to
INT mapping? etc?).
Enjoy.
Hale
*** Hale Landis *** www.ata-atapi.com ***
