- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

- Use NULL instead of 0 for pointers.
- Remove unnecessary __RMAN_RESOURCE_VISIBLE.

- There's no need to overwrite the default device method with the default
one. Interestingly, these are actually the default for quite some time
(bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
since r52045) but even recently added device drivers do this unnecessarily.
Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
Discussed with: jhb
- Also while at it, use __FBSDID.

With rev 1.24 of sys/powerpc/powermac/macio.c, we now get a
total of 6 interrupt resources for scc(4) on macio(4). This
is 3 per channel, of which the 1st of each channel is the
interrupt associated with the SCC. The other 2 are for DMA
operation.
Change scc_bfe_attach() to accept an argument that's the
number of interrupts per channel (ipc) and change each bus
front-end (bfe) to pass that argument through a wrapper
for the device_attach method.

For now, we only allocate the 1st interrupt of each channel
to perserve behaviour.

Pass the RID from the bus frontends to the core probe function.
Currently all RIDs are 0, but for PCI devices this typically
isn't the case. This change is made with future PCI support in
mind.

Add a MacIO bus attachment. The Z8530 as present in the Mac needs
a different register shift and is fed by a different clock than
we use for UltraSPARC hardware. To deal with this, the regshft and
rclk fields in the class structure are removed and bus frontends
now pass the right regshft and rclk to the probe function where
they're put in the BAS and passed in to subordinate drivers.

Fix cut-n-paste braino in previous commit: s/puc/scc/g

Pointy hat: marcel@

Add a DRIVER_MODULE declaration for fhc(4) as this attachement is
also used for the FHC bus.

Pointed out by: marius@

Add scc(4), a driver for serial communications controllers. These
controllers typically have multiple channels and support a number
of serial communications protocols. The scc(4) driver is itself
an umbrella driver that delegates the control over each channel
and mode to a subordinate driver (like uart(4)).
The scc(4) driver supports the Siemens SAB 82532 and the Zilog
Z8530 and replaces puc(4) for these devices.