Merge DTC-d75b33af.

This is a split merge because of non-uniform licensing of the DTC package
contents and the way these components will be used in the FreeBSD environment.

The original DTC package is composed of the following two major pieces:

1. sys/contrib/libfdt (BSD [dual] license)
2. contrib/dtc (GPLv2)

The libfdt component is going to be shared in all aspects of the environment:
- /boot/loader
- kernel
- dtc (the device tree compiler proper, userspace tool)

1 files changed, 56 insertions, 0 deletions

diff --git a/contrib/dtc/README.license b/contrib/dtc/README.license
new file mode 100644
index 000000000000..d56c88f528a3
--- /dev/null
+++ b/contrib/dtc/README.license
@@ -0,0 +1,56 @@
+Licensing and contribution policy of dtc and libfdt
+===================================================
+
+This dtc package contains two pieces of software: dtc itself, and
+libfdt which comprises the files in the libfdt/ subdirectory.  These
+two pieces of software, although closely related, are quite distinct.
+dtc does not incoporate or rely on libfdt for its operation, nor vice
+versa.  It is important that these two pieces of software have
+different license conditions.
+
+As the copyright banners in each source file attest, dtc is licensed
+under the GNU GPL.  The full text of the GPL can be found in the file
+entitled 'GPL' which should be included in this package.  dtc code,
+therefore, may not be incorporated into works which do not have a GPL
+compatible license.
+
+libfdt, however, is GPL/BSD dual-licensed.  That is, it may be used
+either under the terms of the GPL, or under the terms of the 2-clause
+BSD license (aka the ISC license).  The full terms of that license are
+given in the copyright banners of each of the libfdt source files.
+This is, in practice, equivalent to being BSD licensed, since the
+terms of the BSD license are strictly more permissive than the GPL.
+
+I made the decision to license libfdt in this way because I want to
+encourage widespread and correct usage of flattened device trees,
+including by proprietary or otherwise GPL-incompatible firmware or
+tools.  Allowing libfdt to be used under the terms of the BSD license
+makes that it easier for vendors or authors of such software to do so.
+
+This does mean that libfdt code could be "stolen" - say, included in a
+proprietary fimware and extended without contributing those extensions
+back to the libfdt mainline.  While I hope that doesn't happen, I
+believe the goal of allowing libfdt to be widely used is more
+important than avoiding that.  libfdt is quite small, and hardly
+rocket science; so the incentive for such impolite behaviour is small,
+and the inconvenience caused therby is not dire.
+
+Licenses such as the LGPL which would allow code to be used in non-GPL
+software, but also require contributions to be returned were
+considered.  However, libfdt is designed to be used in firmwares and
+other environments with unusual technical constraints.  It's difficult
+to anticipate all possible changes which might be needed to meld
+libfdt into such environments and so difficult to suitably word a
+license that puts the boundary between what is and isn't permitted in
+the intended place.  Again, I judged encouraging widespread use of
+libfdt by keeping the license terms simple and familiar to be the more
+important goal.
+
+**IMPORTANT** It's intended that all of libfdt as released remain
+permissively licensed this way.  Therefore only contributions which
+are released under these terms can be merged into the libfdt mainline.
+
+
+David Gibson <david@gibson.dropbear.id.au>
+(principal original author of dtc and libfdt)
+2 November 2007