devtools: download scripts from linux if not found

diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
index 8f245ebdabc4..bfacd77f398a 100755
--- a/devtools/checkpatches.sh
+++ b/devtools/checkpatches.sh
@@ -43,6 +43,8 @@  print_usage () {
 	Run Linux kernel checkpatch.pl with DPDK options.
 	The environment variable DPDK_CHECKPATCH_PATH can be set, if not we will
 	try to find the script in the sources of the currently running kernel.
+	If the script cannot be found, you will be prompted for downloading it
+	from the upstream linux sources.
 
 	The patches to check can be from stdin, files specified on the command line,
 	latest git commits limited with -n option, or commits in the git range
@@ -376,10 +378,14 @@  while getopts hn:qr:v ARG ; do
 done
 shift $(($OPTIND - 1))
 
+url="https://raw.githubusercontent.com/torvalds/linux/master/scripts/checkpatch.pl"
+
 if [ ! -f "$DPDK_CHECKPATCH_PATH" ] || [ ! -x "$DPDK_CHECKPATCH_PATH" ] ; then
 	default_path="/lib/modules/$(uname -r)/source/scripts/checkpatch.pl"
 	if [ -f "$default_path" ] && [ -x "$default_path" ] ; then
 		DPDK_CHECKPATCH_PATH="$default_path"
+	elif download_script DPDK_CHECKPATCH_PATH "$url"; then
+		true
 	else
 		print_usage >&2
 		echo
diff --git a/devtools/get-maintainer.sh b/devtools/get-maintainer.sh
index bba4d3f68db8..010aef221226 100755
--- a/devtools/get-maintainer.sh
+++ b/devtools/get-maintainer.sh
@@ -18,10 +18,19 @@  print_usage () {
 	the get_maintainer.pl script located in Linux kernel sources. Example:
 	DPDK_GETMAINTAINER_PATH=~/linux/scripts/get_maintainer.pl
 
+	If the script cannot be found, you will be prompted for downloading it
+	from the upstream linux sources.
+
 	Also refer to devtools/load-devel-config to store your configuration.
 	END_OF_HELP
 }
 
+if [ ! -f "$DPDK_GETMAINTAINER_PATH" ] ||
+   [ ! -x "$DPDK_GETMAINTAINER_PATH" ] ; then
+	download_script DPDK_GETMAINTAINER_PATH \
+		"https://raw.githubusercontent.com/torvalds/linux/master/scripts/get_maintainer.pl"
+fi
+
 # Requires DPDK_GETMAINTAINER_PATH devel config option set
 if [ ! -f "$DPDK_GETMAINTAINER_PATH" ] ||
    [ ! -x "$DPDK_GETMAINTAINER_PATH" ] ; then
diff --git a/devtools/load-devel-config b/devtools/load-devel-config
index 69a0ac623a6e..46baf73fc0b3 100644
--- a/devtools/load-devel-config
+++ b/devtools/load-devel-config
@@ -1,4 +1,5 @@ 
 # SPDX-License-Identifier: BSD-3-Clause
+# vim: ft=sh
 
 # This file is intended to be sourced into shell
 
@@ -14,3 +15,47 @@  test ! -r $(dirname $(readlink -f $0))/../.develconfig ||
         . $(dirname $(readlink -f $0))/../.develconfig
 
 # The config files must export variables in the shell style
+
+# This function is called to download missing scripts by subcommands
+#
+# Example:
+#   download_script DPDK_CHECKPATCH_PATH \
+#       https://raw.githubusercontent.com/torvalds/linux/master/scripts/checkpatch.pl
+download_script() { # <var_name> <url>
+	var_name=$1
+	url=$2
+
+	script_name=$(basename "$url")
+	git_dir=$(git rev-parse --git-dir) || return 1
+	dl_path="$git_dir/$script_name"
+
+	if [ -f "$dl_path" ] && [ -x "$dl_path" ]; then
+		eval "$var_name='$dl_path'"
+		return 0
+	fi
+
+	if ! [ -t 0 ]; then
+		# not in an interactive terminal, abort
+		return 1
+	fi
+	prompt="Download $url and set $var_name=$dl_path? [y/n] "
+
+	while printf '%s' "$prompt" && read y && ! [ "$y" = y ]; do
+		if [ "$y" = n ]; then
+			return 1
+		fi
+	done
+
+	if which curl >/dev/null 2>&1; then
+		curl -Lo "$dl_path" "$url" || return 1
+	elif which wget >/dev/null 2>&1; then
+		wget -O "$dl_path" "$url" || return 1
+	else
+		echo "error: neither curl nor wget are available." >&2
+		return 1
+	fi
+	chmod 755 "$dl_path" || return 1
+
+	eval "$var_name='$dl_path'"
+	return 0
+}
diff --git a/doc/guides/contributing/patches.rst b/doc/guides/contributing/patches.rst
index e286d9e6d59e..d24327bebb6c 100644
--- a/doc/guides/contributing/patches.rst
+++ b/doc/guides/contributing/patches.rst
@@ -462,6 +462,7 @@  This uses the Linux kernel development tool ``checkpatch.pl`` which  can be obta
 updating the Linux kernel sources.
 
 The path to the original Linux script must be set in the environment variable ``DPDK_CHECKPATCH_PATH``.
+If this variable is not set, ``checkpatches.sh`` will prompt before downloading it locally.
 
 Spell checking of commonly misspelled words is enabled
 by default if installed in ``/usr/share/codespell/dictionary.txt``.