Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r261083, r261092, r261126, r261127, r261128, r261129, r261130, r261131

Add Atmel serial drivers.

uart clock-frequency is a FreeBSD-specific extention. Make it optional and
allow the client uart drivers to decide if a frequency is required.

Remove redundant declaration for uart devclass.
Commit some unrelated, but harmless, FDT ifdefs.

Add at91 NAND support, Fix comment.

Remove obsolete options and fix comments

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

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

This file is no longer AT91RM9200 specific, but now is generic to all
Atmel AT91 SoC's we support. Rename to reflect that.

Remember where we found the DBGU and use that for our console.

Eliminate the AT91XXXX_BASE for each SoC. AT91_BASE is the right way
to spell this since we only have one AT91_BASE for all Atmel arm9 SoCs.

Strip trailing whitespace before other changes.

Remove support for SKYEYE simulator

if_ate.c:

* Support for sam9 "EMAC" controller.
* Support for rmii interface to phy.

at91.c & at91sam9.c:

* Eliminate separate at91sam9.c file.
* Add new devices to at91sam9_devs table.

at91_machdep.c & at at91sam9_machdep.c:

* Automatic chip type determination.
* Remove compile time chip dependencies.
* Eliminate separate at91sam9_machdep.c file.

at91_pmc.c:

* Corrected support for all of the sam926? and sam9g20 chips.
* Remove compile time chip dependencies.

My apologies to Greg for taking so long to take care of it.

Migrate towards using at91_master_clock. Initialize the clocks for
the serial port class when we set the devclass since it is now
no-longer a compile time constant. Eliminate the pci include, as it
isn't relevant or necessary.

Tweak the disclaimer section of the license to match COPYRIGHT, for
better or worse. Ok'd by folks that have additional copyrights to the
files in cases where there's joint authorship.

Correct a comment, this was not true anymore.

Revert to the previous version where the return value of uart_getenv()
is being ignored. It's optional and the lack of environment variable
is not an error condition.

Don't expose the uart_ops structure directly, but instead have
it obtained through the uart_class structure. This allows us
to declare the uart_class structure as weak and as such allows
us to reference it even when it's not compiled-in.
It also allows is to get the uart_ops structure by name, which
makes it possible to implement the dt tag handling in uart_getenv().
The side-effect of all this is that we're using the uart_class
structure more consistently which means that we now also have
access to the size of the bus space block needed by the hardware
when we map the bus space, eliminating any hardcoding.

Resurrect Skyeye support :
Add a new option, SKYEYE_WORKAROUNDS, which as the name suggests adds
workarounds for things skyeye doesn't simulate. Specifically :
- Use USART0 instead of DBGU as the console, make it not use DMA, and manually provoke an interrupt when we're done in the transmit function.
- Skyeye maintains an internal counter for clock, but apparently there's
no way to access it, so hack the timecounter code to return a value which
is increased at every clock interrupts. This is gross, but I didn't find a
better way to implement timecounters without hacking Skyeye to get the
counter value.
- Force the write-back of PTEs once we're done writing them, even if they
are supposed to be write-through. I don't know why I have to do that.

Import support for the Atmel AT91RM9200 CPU/Microcontroller. This SoC
is a ARM920T based CPU with a bunch of built-in peripherals. The
inital import supports the SPI bus, the TWI bus (although iicbus
integration is not complete), the uarts, the system timer and the
onboard ethernet. Support for the Kwikbyte KB9202
(http://www.kwikbyte.com) board is also included, although there's no
reason why the 9200 and the 9201 wouldn't also work. Primitive
support for running under the skyeye emulator is also provided
(although skyeye's support for the AT91RM9200 is a little weak).

The code has been structured so that other members of Atmel's arm family can
be supported in the future. The AT91SAM9260 is not presently supported
due to lack of hardware. The arm7tdmi families are also not supported
becasue they lack an MMU.

Many thanks to cognet@ for his help and assistance in bringing up this
board. He did much of the vm work and wrote parts of the uart and
system timer code as well as the bus space implementation.

The system boots to single user w/o problem, although the serial
console is a little slow and the ethernet driver is still in flux.

This work was sponsored by Timing Solutions, Corporation. I am
grateful to their support of the FreeBSD project in this manner.