rpi3: add RPI3_RUNTIME_UART build option
Some OSes (e.g. Ubuntu 18.04 LTS on Raspberry Pi 3) may disable the
runtime UART in a manner that prevents the system from rebooting if
ATF tries to send runtime messages there.
Also, we don't want the firmware to share the UART with normal
world, as this can be a DoS attack vector into the secure world.
This patch fixes these 2 issues by introducing new build option
RPI3_RUNTIME_UART, that disables the runtime UART by default.
Fixes ARM-software/tf-issues#647
Signed-off-by: Pete Batard <pete@akeo.ie>
diff --git a/plat/rpi3/platform.mk b/plat/rpi3/platform.mk
index 36c1ee2..07d2bf1 100644
--- a/plat/rpi3/platform.mk
+++ b/plat/rpi3/platform.mk
@@ -109,6 +109,10 @@
# Assume that BL33 isn't the Linux kernel by default
RPI3_DIRECT_LINUX_BOOT := 0
+# UART to use at runtime. -1 means the runtime UART is disabled.
+# Any other value means the default UART will be used.
+RPI3_RUNTIME_UART := -1
+
# BL32 location
RPI3_BL32_RAM_LOCATION := tdram
ifeq (${RPI3_BL32_RAM_LOCATION}, tsram)
@@ -126,6 +130,7 @@
$(eval $(call add_define,RPI3_BL33_IN_AARCH32))
$(eval $(call add_define,RPI3_DIRECT_LINUX_BOOT))
$(eval $(call add_define,RPI3_PRELOADED_DTB_BASE))
+$(eval $(call add_define,RPI3_RUNTIME_UART))
# Verify build config
# -------------------