Use a submodule for the SDK

Relying on whatever SDK people have at hand is no good to reproduce
issues. Instead, move over to a local copy of the SDK using a git
submodule.

Disk space is free, right?

Signed-off-by: Marc Zyngier <maz@kernel.org>

4 files changed, 9 insertions, 14 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..7733770
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "pico-sdk"]
+	path = pico-sdk
+	url = https://github.com/raspberrypi/pico-sdk.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0029ab0..19b367b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 cmake_minimum_required(VERSION 3.12)
 
 # Include build functions from Pico SDK
-include($ENV{PICO_SDK_PATH}/external/pico_sdk_import.cmake)
+include(pico-sdk/external/pico_sdk_import.cmake)
 
 # Set name of project (as PROJECT_NAME) and C/C++ standards
 project(m1_ubmc C CXX ASM)
diff --git a/README b/README
index 0abea34..ae03f3a 100644
--- a/README
+++ b/README
@@ -32,21 +32,9 @@ On a Debian system, this is what you need:
 I'm sure there is an equivalent for other OSs, but life is too short
 to use anything else.
 
-** Install the pico-sdk:
-
-I've used versions 1.4 and 1.5 of the SDK. YMMV.
-
-  git clone -b master https://github.com/raspberrypi/pico-sdk.git
-
-  export PICO_SDK_PATH=/the/long/and/winding/road/to/pico-sdk
-
-  cd pico-sdk
-
-  git submodule update --init
-
 ** Build the Pico firmware:
 
-It builds just like any other pico-sdk project:
+I'm now relying on git submodules for the Pico SDK, currently 1.5.1.
 
   git clone git://git.kernel.org/pub/scm/linux/kernel/git/maz/cs-sw
 
@@ -54,6 +42,10 @@ It builds just like any other pico-sdk project:
 
   [optionally checkout the dev branch you want]
 
+  git submodule update --init --recursive
+
+  [this will download a fsckload of useless things... oh well]
+
   mkdir build
 
   cd build
diff --git a/pico-sdk b/pico-sdk
new file mode 160000
+Subproject 6a7db34ff63345a7badec79ebea3aaef1712f37