Some IVAR indices are special in that they have global meaning across
multiple buses where as other IVARs are always private to the local bus.
Try to document this a bit and add constants for the various ranges to
avoid future conflicts.

This is a no-op, but IVAR indices are now generally defined as enums
as that makes it easier to define them in terms of ranges.

Reviewed by:	imp, royger, andrew
Differential Revision:	https://reviews.freebsd.org/D54159

Replace priorities specified by a base priority and some hardcoded
offset value by symbolic constants.  Hardcoded offsets prevent changing
the difference between priorities without changing their relative
ordering, and is generally a dangerous practice since the resulting
priority may inadvertently belong to a different selection policy's
range.

Since RQ_PPQ is 4, differences of less than 4 are insignificant, so just
remove them.  These small differences have not been changed for years,
so it is likely they have no real meaning (besides having no practical
effect).  One can still consult the changes history to recover them if
ever needed.

No functional change (intended).

MFC after:      1 month
Event:          Kitchener-Waterloo Hackathon 202506
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D45390

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

Since we take a lock when we enter the ioctl, we need to set driver_mtx
in the pps structure so it can be dropped while sleeping during a call
to timepps_fetch() with a non-zero timeout (PPS_CANWAIT feature).

MFC After:		5 days
Sponsored by:		Netflix
Reviewed by:		ian
Differential Revision:	https://reviews.freebsd.org/D31763

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

sys/dev/ppbus/ppb_1284.c:296:46: error: implicit conversion from 'int'
to 'char' changes value from 144 to -112 [-Werror,-Wconstant-conversion]
        if ((error = do_peripheral_wait(bus, SELECT | nBUSY, 0))) {
                     ~~~~~~~~~~~~~~~~~~      ~~~~~~~^~~~~~~
sys/dev/ppbus/ppb_1284.c:785:48: error: implicit conversion from 'int'
to 'char' changes value from 240 to -16 [-Werror,-Wconstant-conversion]
                if (do_1284_wait(bus, nACK | SELECT | PERROR | nBUSY,
                    ~~~~~~~~~~~~      ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
sys/dev/ppbus/ppb_1284.c:786:29: error: implicit conversion from 'int'
to 'char' changes value from 240 to -16 [-Werror,-Wconstant-conversion]
                                        nACK | SELECT | PERROR | nBUSY)) {
                                        ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~

This is because nBUSY is 0x80, so the plain char argument is wrapped to
a negative value.  Fix this in a minimal fashion, by using uint8_t in a
few places.

Reviewed by:	emaste
MFC after:	3 days
Differential Revision: https://reviews.freebsd.org/D7771

constants used for the ppi(4) ioctls for bits in the control and status
registers.

Reviewed by:	db

- To avoid having a bunch of locks that end up always getting acquired as
  a group, give each ppc(4) device a mutex which it shares with all the
  child devices including ppbus(4), lpt(4), plip(4), etc.  This mutex
  is then used for all the locking.
- Rework the interrupt handling stuff yet again.  Now ppbus drivers setup
  their interrupt handler during attach and tear it down during detach
  like most other drivers.  ppbus(4) only invokes the interrupt handler
  of the device that currently owns the bus (if any) when an interrupt
  occurs, however.  Also, interrupt handlers in general now accept their
  softc pointers as their argument rather than the device_t.  Another
  feature of the ppbus interrupt handlers is that they are called with
  the parent ppc device's lock already held.  This minimizes the number
  of lock operations during an interrupt.
- Mark plip(4), lpt(4), pcfclock(4), ppi(4), vpo(4) MPSAFE.
- lpbb(4) uses the ppc lock instead of Giant.
- Other plip(4) changes:
  - Add a mutex to protect the global tables in plip(4) and free them on
    module unload.
  - Add a detach routine.
  - Split out the init/stop code from the ioctl routine into separate
    functions.
- Other lpt(4) changes:
  - Use device_printf().
  - Use a dedicated callout for the lptout timer.
  - Allocate the I/O buffers at attach and detach rather than during
    open and close as this simplifies the locking at the cost of
    1024+32 bytes when the driver is attached.
- Other ppi(4) changes:
  - Use an sx lock to serialize open and close.
  - Remove unused HADBUS flag.
  - Add a detach routine.
  - Use a malloc'd buffer for each read and write to avoid races with
    concurrent read/write.
- Other pps(4) changes:
  - Use a callout rather than a callout handle with timeout().
  - Conform to the new ppbus requirements (regular mutex, non-filter
    interrupt handler).  pps(4) is probably going to have to become a
    standalone driver that doesn't use ppbus(4) to satisfy it's
    requirements for low latency as a result.
  - Use an sx lock to serialize open and close.
- Other vpo(4) changes:
  - Use the parent ppc device's lock to create the CAM sim instead of
    Giant.
- Other ppc(4) changes:
  - Fix ppc_isa's detach method to detach instead of calling attach.

Tested by:	  no one :-(