Provided by: linux-doc-2.6.15_2.6.15-23.39_all
ata_mmio_devchk - PATA device presence detection
unsigned int ata_mmio_devchk (struct ata_port * ap,
unsigned int device);
ap ATA channel to examine
device Device to examine (starting at zero)
This technique was originally described in Hale Landis’s ATADRVR
(www.ata-atapi.com), and later found its way into the ATA/ATAPI spec.
Write a pattern to the ATA shadow registers, and if a device is
present, it will respond by correctly storing and echoing back the ATA
shadow register contents.