sys: Remove $FreeBSD$: two-line .h pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

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

Fix build of stand/usb .

MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking

Provide userland notification of gpio pin changes ("userland gpio interrupts").

This is an import of the Google Summer of Code 2018 project completed by
Christian Kramer (and, sadly, ignored by us for two years now). The goals
stated for that project were:

FreeBSD already has support for interrupts implemented in the GPIO
controller drivers of several SoCs, but there are no interfaces to take
advantage of them out of user space yet. The goal of this work is to
implement such an interface by providing descriptors which integrate
with the common I/O system calls and multiplexing mechanisms.

The initial imported code supports the following functionality:

- A kernel driver that provides an interface to the user space; the
existing gpioc(4) driver was enhanced with this functionality.
- Implement support for the most common I/O system calls / multiplexing
mechanisms:
- read() Places the pin number on which the interrupt occurred in the
buffer. Blocking and non-blocking behaviour supported.
- poll()/select()
- kqueue()
- signal driven I/O. Posting SIGIO when the O_ASYNC was set.
- Many-to-many relationship between pins and file descriptors.
- A file descriptor can monitor several GPIO pins.
- A GPIO pin can be monitored by multiple file descriptors.
- Integration with gpioctl and libgpio.

I added some fixes (mostly to locking) and feature enhancements on top of
the original gsoc code. The feature ehancements allow the user to choose
between detailed and summary event reporting. Detailed reporting provides
a record describing each pin change event. Summary reporting provides the
time of the first and last change of each pin, and a count of how many times
it changed state since the last read(2) call. Another enhancement allows
the recording of multiple state change events on multiple pins between each
call to read(2) (the original code would track only a single event at a time).

The phabricator review for these changes timed out without approval, but I
cite it below anyway, because the review contains a series of diffs that
show how I evolved the code from its original state in Christian's github
repo for the gsoc project to what is being commited here. (In effect,
the phab review extends the VC history back to the original code.)

Submitted by: Christian Kramer
Obtained from: https://github.com/ckraemer/freebsd/tree/gsoc2018
Differential Revision: https://reviews.freebsd.org/D27398

SPDX: Fix some cases wrongly attributed to MIT.

In the cases of BSD-style license variants without clauses, use 0BSD for
the time being in lack of a better description.

sys/sys: further adoption of SPDX licensing ID tags.

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.

Add gpio methods to read/write/configure up to 32 pins simultaneously.

Sometimes it is necessary to combine several gpio pins into an ad-hoc bus
and manipulate the pins as a group. In such cases manipulating the pins
individualy is not an option, because the value on the "bus" assumes
potentially-invalid intermediate values as each pin is changed in turn. Note
that the "bus" may be something as simple as a bi-color LED where changing
colors requires changing both gpio pins at once, or something as complex as
a bitbanged multiplexed address/data bus connected to a microcontroller.

In addition to the absolute requirement of simultaneously changing the
output values of driven pins, a desirable feature of these new methods is to
provide a higher-performance mechanism for reading and writing multiple
pins, especially from userland where pin-at-a-time access incurs a noticible
syscall time penalty.

These new interfaces are NOT intended to abstract away all the ugly details
of how gpio is implemented on any given platform. In fact, to use these
properly you absolutely must know something about how the gpio hardware is
organized. Typically there are "banks" of gpio pins controlled by registers
which group several pins together. A bank may be as small as 2 pins or as
big as "all the pins on the device, hundreds of them." In the latter case, a
driver might support this interface by allowing access to any 32 adjacent
pins within the overall collection. Or, more likely, any 32 adjacent pins
starting at any multiple of 32. Whatever the hardware restrictions may be,
you would need to understand them to use this interface.

In additional to defining the interfaces, two example implementations are
included here, for imx5/6, and allwinner. These represent the two primary
types of gpio hardware drivers. imx6 has multiple gpio devices, each
implementing a single bank of 32 pins. Allwinner implements a single large
gpio number space from 1-n pins, and the driver internally translates that
linear number space to a bank+pin scheme based on how the pins are grouped
into control registers. The allwinner implementation imposes the restriction
that the first_pin argument to the new functions must always be pin 0 of a
bank.

Differential Revision: https://reviews.freebsd.org/D11810

GPIO: Add support for gpio pin interrupts.
Add new function gpio_alloc_intr_resource(), which allows an allocation
of interrupt resource associated to given gpio pin. It also allows to
specify interrupt configuration.

Note: This functionality is dependent on INTRNG, and must be
implemented in each GPIO controller.

Add a new ioctl to allow the setting of GPIO pin names.

When a gpiobus child is added, use its name to identify the mapped pin
names.

Make the respective changes to libgpio.

Add a new '-n' flag to gpioctl(8) to set the pin name.

Differential Revision: https://reviews.freebsd.org/D2002
Reviewed by: rpaulo
Requested by: many

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Initial GPIO bus support. Includes:
- GPIO bus controller interface
- GPIO bus interface
- Implementation of GPIO led(4) compatible device
- Implementation of iic(4) bus over GPIO (author: Luiz Otavio O Souza)

Tested by: Luiz Otavio O Souza, Alexandr Rybalko