Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix a bunch of "xref refers to *this* page" igor(1) warnings.

MFC after: 1 month

- Replace references to sio(4) with uart(4) instead.
- We no longer use the same data structure in as NetBSD in pucdata.c.
- ppc(4) has had a puc(4) attachment for a while now.

Approved by: re (blackend)
MFC after: 3 days

There is no PUC_FASTINTR option anymore.

MFC after: 2 weeks

mdoc(7): Fix common mistakes made in the SEE ALSO section.

Add printer support to puc(4) driver.
- Move isa/ppc* to sys/dev/ppc (repo-copy)
- Add an attachment method to ppc for puc
- In puc we need to walk the chain of parents.
Still to do, is to make ppc(4) & puc(4) work on other platforms. Testers
wanted.

PR: 38372 (in spirit done differently)
Verified by: Make universe (if I messed up a platform please fix)

mdoc(7) police: tidy up.

Add the puc (PCI "Universal" Communications) driver. The idea and some of
the structure definitions come from NetBSD to make it easier to share card
definitions. The driver only acts as a shim between the pci bus and the
sio driver. Later pci parallel ports could also be supported through this
driver. Support for most single and multiport pci serial cards should be
as simple as adding its definition to pucdata.c

Tested with the following pci cards:
Moxa Industio CP-114, 4 port RS-232,RS-422/485
Syba Tech Ltd. PCI-4S2P-550-ECP, 4 port RS-232 + 2 parallel ports
Netmos NM9835 PCI-2S-550, 2 port RS-232