Add FreeRTOS as a submodule

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>

.gitmodules

diff --git a/.gitmodules b/.gitmodules
index cb9fe20..f8890cf 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "CMSIS_5"]
 	path = CMSIS_5
 	url = https://github.com/ARM-software/CMSIS_5
+[submodule "freertos"]
+	path = freertos
+	url = https://github.com/FreeRTOS/FreeRTOS-Kernel

freertos

diff --git a/freertos b/freertos
new file mode 160000
index 0000000..2dfdfc4
--- /dev/null
+++ b/freertos
@@ -0,0 +1 @@
+Subproject commit 2dfdfc4ba4d8bb487c8ea6b5428d7d742ce162b8