http://mail-index.netbsd.org/tech-kern/2003/09/25/0006.html
This adds a device (atabus) between IDE controllers and wd or atapibus, to
have each ATA channel show up in the device tree. Later there will be atabus
devices in /dev, so that we can do IOCTL on them.
Each atabus has its own kernel thread, to handle operations that needs polling,
e.g. reset and others.
Device probing on each bus it defered to the atabus thread creation.
This allows to do the reset and basic device probes in parallel, which reduce
boot time on systems with several pciide controllers.
ready. This avoids gratuitously starting the motor on floppy and CD-ROM
drives, and eliminates the need for the audio playing test in cdopen().
Therefore, also remove PQUIRK_NOSTARTUNIT.
This eliminates problems where the underlying interrupt handler isn't the
specific layer calling scsipi_complete() for a given scsi transaction.
This avoids deadlocks where the kthread that called the autoconf routines
to configure a scsibus shouldn't be the one put to sleep waiting on a
scsipi_complete (only the scsibus's kthread should be doing that).
To avoid jitter this will force the scsibus's to probe in the order they
run through autoconf (so machines with multiple bus's don't move sd* devices
around on every reboot).
Set this to dv_xname for scsibus and atapibus.
Set the name of the kernel thread to chan_name instead of controller's
name:channel number (so that we can use this name for controller-specific
threads).
kill ata_atapi_attach. Change atapibus to use a struct scsipi_channel instead
of ata_atapi_attach as attach arch. Create a ata_device, compatible with
scsipi_channel, to attach wd.
This is a completely rewritten scsipi_xfer execution engine, and the
associated changes to HBA drivers. Overview of changes & features:
- All xfers are queued in the mid-layer, rather than doing so in an
ad-hoc fashion in individual adapter drivers.
- Adapter/channel resource management in the mid-layer, avoids even trying
to start running an xfer if the adapter/channel doesn't have the resources.
- Better communication between the mid-layer and the adapters.
- Asynchronous event notification mechanism from adapter to mid-layer and
peripherals.
- Better peripheral queue management: freeze/thaw, sorted requeueing during
recovery, etc.
- Clean separation of peripherals, adapters, and adapter channels (no more
scsipi_link).
- Kernel thread for each scsipi_channel makes error recovery much easier
(no more dealing with interrupt context when recovering from an error).
- Mid-layer support for tagged queueing: commands can have the tag type
set explicitly, tag IDs are allocated in the mid-layer (thus eliminating
the need to use buggy tag ID allocation schemes in many adapter drivers).
- support for QUEUE FULL and CHECK CONDITION status in mid-layer; the command
will be requeued, or a REQUEST SENSE will be sent as appropriate.
Just before the merge syssrc has been tagged with thorpej_scsipi_beforemerge
if an IRQ was not detected, unless the force flag was given. Use this to
detect if the IRQ was for us (closer to shared IRQ for controllers which
don't have their own IRQ handler in pciide.c) and to poll for DMA xfer.
Also makes the timeout recovery code simpler.
- ATAPI cleanup: don't call controller-specific functions from atapiconf.c
(wdc_*), so that it's possible to attach an atapibus to something else
than a wdc/pciide (Hi Lennart :).
Overload struct scsi_adapter with struct atapi_adapter, defined
as struct scsi_adapter + atapi-specific callbacks. scsipi_link still points
to an scsi_adapter, atapi code casts it to atapi_adapter if needed.
Move atapi_softc to atapiconf.h so that it can be used by the underlying
controller code (e.g. atapi_wdc.c).
Add an atapi-specific callback *atapi_probedev(), which probe a drive
in a controller-specific way, allocate the sc_link and fills in the
ataparams if needed. It then calls atapi_probedev() (from atapiconf.c)
to do the generic initialisations and attach the device.
- While I'm there merge and centralise the state definitions in atavar.h.
It should now be possible to use a common ata/atapi routine to set the
drive's modes (will do later).
- `flags' is now gone, replaced with `xs_control' and `xs_status'.
- Massive cleanup of the control flags. Now we explicitly say that
a job is to complete asynchronously, rather than relying on side-effects,
and use a new flag to now that device discovery is being performed.
- Do SCSI device discovery interrupt-driven.
mycroft