LICENSING: clarify licenses of imported / reused code

The Zephyr kernel tree has imported or reuses packages, scripts that
are not covered by the Apache LICENSE.

As in some places it is not clear (there is no LICENSE file or way to
put it there), here we list them to ensure there is proper license
acknowledgement.

This is an initial proposal--I welcome feedback on everything,
especially where to link the documentation (kind of kludgy now) and
more missed components from this initial list.

v5: Added David Kinder's feedback

v4: Fixed more typos in Makefile

v3: fixed some more typos, but still holding on to feedback on how it
can be done with SPDX files, as it is not yet all clear to me.

Jira: ZEP-1079
Change-Id: Ie1bf545e26b0d304cd3ea0d70cdfc13d520197fe
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>

LICENSING.rst

@@ -0,0 +1,66 @@
+.. _zephyr_licensing:
+
+Licensing of Zephyr Project components
+######################################
+
+The Zephyr kernel tree imports or reuses packages, scripts and other
+files that are not covered by the :download:`Apache License
+<../LICENSE>`. In some places there is no LICENSE file or way to put
+a LICENSE file there, so we describe the licensing in this document.
+
+
+- *kconfig* and *kbuild*
+
+  *Origin:* Linux Kernel
+  *Licensing:* *GPLv2*
+
+- *scripts/{checkpatch.pl,checkstack.pl,get_maintainers.pl,spelling.txt}*
+
+  *Origin:* Linux Kernel
+  *Licensing:* *GPLv2*
+
+- *ext/fs/fat/*
+
+  *Origin:* FatFs is a file system based on the FAT file system specification.  This is
+  provided by ELM Chan http://elm-chan.org/fsw/ff/00index_e.html
+
+  *Licensing*:
+
+    Copyright (C) 2016, ChaN, all right reserved.
+
+    FatFs module is an open source software. Redistribution and use of FatFs 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 condition and the following disclaimer.
+
+    This software is provided by the copyright holder and contributors "AS IS"
+    and any warranties related to this software are DISCLAIMED.
+    The copyright owner or contributors be NOT LIABLE for any damages caused
+    by use of this software.
+
+- *ext/hal/cmsis/*
+
+  *Origin:* https://github.com/ARM-software/CMSIS.git
+
+  *Licensing*: :download:`CMSIS_END_USER_LICENCE_AGREEMENT <../ext/hal/cmsis/CMSIS_END_USER_LICENCE_AGREEMENT.pdf>`
+
+- *ext/hal/ksdk/*
+
+  *Origin:* http://kex.nxp.com
+
+  *Licensing*: 3-clause BSD (see :download:`source
+  <../ext/hal/ksdk/drivers/fsl_rtc.h>`)
+
+- *ext/hal/nordic/*
+
+  *Origin:*
+
+  *Licensing*: 3-clause BSD (see :download:`source <../ext/hal/nordic/mdk/nrf51.h>`)
+
+- *ext/hal/qmsi/*
+
+  *Origin:* https://github.com/quark-mcu/qmsi/releases
+
+  *Licensing*: 3-clause BSD (see :download:`source <../ext/hal/qmsi/include/qm_common.h>`)

doc/LICENSING.rst

@@ -0,0 +1 @@
+.. include:: ../LICENSING.rst

doc/index.rst

@@ -39,6 +39,7 @@ Sections
    contribute/code.rst
    porting/porting.rst
    reference/kbuild/kbuild.rst
+   LICENSING.rst
 
 You can find further information on the `Zephyr Project Wiki`_.