# Crust Firmware Licensing

The Crust firmware itself is dual-licensed as BSD-3-clause or GPL-2.0-only. You
may use and redistribute it under either set of license terms.

It uses some third-party BSD-1-Clause and MIT-licensed headers; those licenses
are compatible with either main license.

The Kconfig configuration system is licensed as GPL-2.0-only. However, it is a
build time dependency only, and all GPL-2.0-only files are restricted to the
`3rdparty/kconfig` directory.

## BSD 1-clause License

    Copyright © 2014 OpenRISC Project Maintainers. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following condition is met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

---

## BSD 3-clause License

    Copyright © 2013-2017, ARM Limited and Contributors. All rights reserved.
    Copyright © 2017-2021 The Crust Firmware Authors.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

---

## GNU General Public License

Version 2, June 1991

    Copyright (C) 1989, 1991 Free Software Foundation, Inc.
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies of this license
document, but changing it is not allowed.

### Preamble

The licenses for most software are designed to take away your freedom to share
and change it. By contrast, the GNU General Public License is intended to
guarantee your freedom to share and change free software--to make sure the
software is free for all its users. This General Public License applies to most
of the Free Software Foundation's software and to any other program whose
authors commit to using it. (Some other Free Software Foundation software is
covered by the GNU Lesser General Public License instead.) You can apply it to
your programs, too.

When we speak of free software, we are referring to freedom, not price. Our
General Public Licenses are designed to make sure that you have the freedom to
distribute copies of free software (and charge for this service if you wish),
that you receive source code or can get it if you want it, that you can change
the software or use pieces of it in new free programs; and that you know you
can do these things.

To protect your rights, we need to make restrictions that forbid anyone to deny
you these rights or to ask you to surrender the rights. These restrictions
translate to certain responsibilities for you if you distribute copies of the
software, or if you modify it.

For example, if you distribute copies of such a program, whether gratis or for
a fee, you must give the recipients all the rights that you have. You must make
sure that they, too, receive or can get the source code. And you must show them
these terms so they know their rights.

We protect your rights with two steps: (1) copyright the software, and (2)
offer you this license which gives you legal permission to copy, distribute
and/or modify the software.

Also, for each author's protection and ours, we want to make certain that
everyone understands that there is no warranty for this free software. If the
software is modified by someone else and passed on, we want its recipients to
know that what they have is not the original, so that any problems introduced
by others will not reflect on the original authors' reputations.

Finally, any free program is threatened constantly by software patents. We wish
to avoid the danger that redistributors of a free program will individually
obtain patent licenses, in effect making the program proprietary. To prevent
this, we have made it clear that any patent must be licensed for everyone's
free use or not licensed at all.

The precise terms and conditions for copying, distribution and modification
follow.

### Terms and Conditions for Copying, Distribution and Modification

0.  This License applies to any program or other work which contains a notice
    placed by the copyright holder saying it may be distributed under the terms
    of this General Public License. The "Program", below, refers to any such
    program or work, and a "work based on the Program" means either the Program
    or any derivative work under copyright law: that is to say, a work
    containing the Program or a portion of it, either verbatim or with
    modifications and/or translated into another language. (Hereinafter,
    translation is included without limitation in the term "modification".)
    Each licensee is addressed as "you".

    Activities other than copying, distribution and modification are not
    covered by this License; they are outside its scope. The act of running the
    Program is not restricted, and the output from the Program is covered only
    if its contents constitute a work based on the Program (independent of
    having been made by running the Program). Whether that is true depends on
    what the Program does.

1.  You may copy and distribute verbatim copies of the Program's source code as
    you receive it, in any medium, provided that you conspicuously and
    appropriately publish on each copy an appropriate copyright notice and
    disclaimer of warranty; keep intact all the notices that refer to this
    License and to the absence of any warranty; and give any other recipients
    of the Program a copy of this License along with the Program.

    You may charge a fee for the physical act of transferring a copy, and you
    may at your option offer warranty protection in exchange for a fee.

2.  You may modify your copy or copies of the Program or any portion of it,
    thus forming a work based on the Program, and copy and distribute such
    modifications or work under the terms of Section 1 above, provided that you
    also meet all of these conditions:


    a) You must cause the modified files to carry prominent notices stating
    that you changed the files and the date of any change.


    b) You must cause any work that you distribute or publish, that in whole or
    in part contains or is derived from the Program or any part thereof, to be
    licensed as a whole at no charge to all third parties under the terms of
    this License.


    c) If the modified program normally reads commands interactively when run,
    you must cause it, when started running for such interactive use in the
    most ordinary way, to print or display an announcement including an
    appropriate copyright notice and a notice that there is no warranty (or
    else, saying that you provide a warranty) and that users may redistribute
    the program under these conditions, and telling the user how to view a copy
    of this License. (Exception: if the Program itself is interactive but does
    not normally print such an announcement, your work based on the Program is
    not required to print an announcement.)

    These requirements apply to the modified work as a whole. If identifiable
    sections of that work are not derived from the Program, and can be
    reasonably considered independent and separate works in themselves, then
    this License, and its terms, do not apply to those sections when you
    distribute them as separate works. But when you distribute the same
    sections as part of a whole which is a work based on the Program, the
    distribution of the whole must be on the terms of this License, whose
    permissions for other licensees extend to the entire whole, and thus to
    each and every part regardless of who wrote it.

    Thus, it is not the intent of this section to claim rights or contest your
    rights to work written entirely by you; rather, the intent is to exercise
    the right to control the distribution of derivative or collective works
    based on the Program.

    In addition, mere aggregation of another work not based on the Program with
    the Program (or with a work based on the Program) on a volume of a storage
    or distribution medium does not bring the other work under the scope of
    this License.

3.  You may copy and distribute the Program (or a work based on it, under
    Section 2) in object code or executable form under the terms of Sections 1
    and 2 above provided that you also do one of the following:


    a) Accompany it with the complete corresponding machine-readable source
    code, which must be distributed under the terms of Sections 1 and 2 above
    on a medium customarily used for software interchange; or,


    b) Accompany it with a written offer, valid for at least three years, to
    give any third party, for a charge no more than your cost of physically
    performing source distribution, a complete machine-readable copy of the
    corresponding source code, to be distributed under the terms of Sections 1
    and 2 above on a medium customarily used for software interchange; or,


    c) Accompany it with the information you received as to the offer to
    distribute corresponding source code. (This alternative is allowed only for
    noncommercial distribution and only if you received the program in object
    code or executable form with such an offer, in accord with Subsection b
    above.)

    The source code for a work means the preferred form of the work for making
    modifications to it. For an executable work, complete source code means all
    the source code for all modules it contains, plus any associated interface
    definition files, plus the scripts used to control compilation and
    installation of the executable. However, as a special exception, the source
    code distributed need not include anything that is normally distributed (in
    either source or binary form) with the major components (compiler, kernel,
    and so on) of the operating system on which the executable runs, unless
    that component itself accompanies the executable.

    If distribution of executable or object code is made by offering access to
    copy from a designated place, then offering equivalent access to copy the
    source code from the same place counts as distribution of the source code,
    even though third parties are not compelled to copy the source along with
    the object code.

4.  You may not copy, modify, sublicense, or distribute the Program except as
    expressly provided under this License. Any attempt otherwise to copy,
    modify, sublicense or distribute the Program is void, and will
    automatically terminate your rights under this License. However, parties
    who have received copies, or rights, from you under this License will not
    have their licenses terminated so long as such parties remain in full
    compliance.

5.  You are not required to accept this License, since you have not signed it.
    However, nothing else grants you permission to modify or distribute the
    Program or its derivative works. These actions are prohibited by law if you
    do not accept this License. Therefore, by modifying or distributing the
    Program (or any work based on the Program), you indicate your acceptance of
    this License to do so, and all its terms and conditions for copying,
    distributing or modifying the Program or works based on it.

6.  Each time you redistribute the Program (or any work based on the Program),
    the recipient automatically receives a license from the original licensor
    to copy, distribute or modify the Program subject to these terms and
    conditions. You may not impose any further restrictions on the recipients'
    exercise of the rights granted herein. You are not responsible for
    enforcing compliance by third parties to this License.

7.  If, as a consequence of a court judgment or allegation of patent
    infringement or for any other reason (not limited to patent issues),
    conditions are imposed on you (whether by court order, agreement or
    otherwise) that contradict the conditions of this License, they do not
    excuse you from the conditions of this License. If you cannot distribute so
    as to satisfy simultaneously your obligations under this License and any
    other pertinent obligations, then as a consequence you may not distribute
    the Program at all. For example, if a patent license would not permit
    royalty-free redistribution of the Program by all those who receive copies
    directly or indirectly through you, then the only way you could satisfy
    both it and this License would be to refrain entirely from distribution of
    the Program.

    If any portion of this section is held invalid or unenforceable under any
    particular circumstance, the balance of the section is intended to apply
    and the section as a whole is intended to apply in other circumstances.

    It is not the purpose of this section to induce you to infringe any patents
    or other property right claims or to contest validity of any such claims;
    this section has the sole purpose of protecting the integrity of the free
    software distribution system, which is implemented by public license
    practices. Many people have made generous contributions to the wide range
    of software distributed through that system in reliance on consistent
    application of that system; it is up to the author/donor to decide if he or
    she is willing to distribute software through any other system and a
    licensee cannot impose that choice.

    This section is intended to make thoroughly clear what is believed to be a
    consequence of the rest of this License.

8.  If the distribution and/or use of the Program is restricted in certain
    countries either by patents or by copyrighted interfaces, the original
    copyright holder who places the Program under this License may add an
    explicit geographical distribution limitation excluding those countries, so
    that distribution is permitted only in or among countries not thus
    excluded. In such case, this License incorporates the limitation as if
    written in the body of this License.

9.  The Free Software Foundation may publish revised and/or new versions of the
    General Public License from time to time. Such new versions will be similar
    in spirit to the present version, but may differ in detail to address new
    problems or concerns.

    Each version is given a distinguishing version number. If the Program
    specifies a version number of this License which applies to it and "any
    later version", you have the option of following the terms and conditions
    either of that version or of any later version published by the Free
    Software Foundation. If the Program does not specify a version number of
    this License, you may choose any version ever published by the Free
    Software Foundation.

10. If you wish to incorporate parts of the Program into other free programs
    whose distribution conditions are different, write to the author to ask for
    permission. For software which is copyrighted by the Free Software
    Foundation, write to the Free Software Foundation; we sometimes make
    exceptions for this. Our decision will be guided by the two goals of
    preserving the free status of all derivatives of our free software and of
    promoting the sharing and reuse of software generally.

### NO WARRANTY

11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR
    THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
    PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
    OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
    MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO
    THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM
    PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
    CORRECTION.

12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL
    ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE
    THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
    GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
    USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
    DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
    PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
    EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
    SUCH DAMAGES.

### End of Terms and Conditions

### How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible
use to the public, the best way to achieve this is to make it free software
which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach
them to the start of each source file to most effectively convey the exclusion
of warranty; and each file should have at least the "copyright" line and a
pointer to where the full notice is found.

    <one line to give the program's name and an idea of what it does.>
    Copyright (C) <year> <name of author>

    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2 of the License, or (at your option)
    any later version.

    This program is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this when it
starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type 'show w'.
    This is free software, and you are welcome to redistribute it under certain
    conditions; type 'show c' for details.

The hypothetical commands 'show w' and 'show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may be
called something other than 'show w' and 'show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your school,
if any, to sign a "copyright disclaimer" for the program, if necessary. Here is
a sample; alter the names:

    Yoyodyne, Inc., hereby disclaims all copyright interest in the program
    'Gnomovision' (which makes passes at compilers) written by James Hacker.

    signature of Ty Coon, 1 April 1989
    Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may consider
it more useful to permit linking proprietary applications with the library. If
this is what you want to do, use the [GNU Lesser General Public
License](https://www.gnu.org/licenses/lgpl.html) instead of this License.

---

## MIT License

    Copyright © 2005-2014 Rich Felker, et al.

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
