ATA in Linux

SG_IO
The scsi-core (also known as the "mid level") contains the core of scsi support.
scsi generics driver (sg.o) represent the upper level drivers.

A significant addition in sg v3 is an ioctl() called SG_IO which is functionally equivalent to a write() followed by a blocking read(). In certain contexts the write()/read() combination have advantages over SG_IO (e.g. command queuing) and continue to be supported.

SG_IO call path, the IO request was put to block layer's queue, it is queue handlers responsibility to actually handle the request.

sd_ioctl
scsi_cmd_blk_ioctl
scsi_cmd_ioctl
sg_io
blk_execute_rq
blk_execute_rq_nowait
blk_mq_insert_request

sd_ioctl is registered as ioctl of block_device_operations, which will be registered to system via add_disk(), in function sd_probe_async().


And Here is the queue handling part:

scsi_queue_rq (queue_rq, registered as a blk_mq_ops)
scsi_dispatch_cmd
ata_scsi_queuecmd ( queuecommand )
__ata_scsi_queuecmd
ata_scsi_translate
ata_qc_issue


Zone ATA Command
sd_ioctl
_report_zones_ioctl
blk_zoned_report
blk_cmd_with_sense
blk_cmd_execute
blk_execute_rq



ATA Command Definition
include/linux/ata.h



LibATA
http://linuxmafia.com/faq/Hardware/sata.html

This is the newer ATA driver set for selected SATA chipsets only, maintained by Jeff Garzik, leveraging the kernel's well-tested SCSI layer. Garzik developed it in the 2.6 kernel series. 2.4 support was available only with a backported patch until libata's inclusion in 2.4.27 and later.

libata causes each SATA port appear as a new SCSI bus. There are individual low-level drivers for the individual SATA chipsets, e.g., ahci, pdc_adma, ata_piix, sata_nv, sata_mv, sata_promise, sata_qstor, sata_sil, sata_sil24, sata_sis, sata_sx4, sata_uli, sata_svw, sata_via, sata_vsc.


http://ftp.dei.uc.pt/pub/linux/kernel/people/jgarzik/libata/libata.pdf
struct ata_port_operations is defined for every low-level libata hardware driver, and it controls how the low-level driver interfaces with the ATA and SCSI layers.