feat(msm8916): initial platform port

Introduce the bare mimimum base of the msm8916 BL31 port. This is
pretty much just a standard platform "skeleton" with CPU/memory
initialization and an UART driver. This allows booting into
e.g. U-Boot with working UART output.

Note that the plat/qti/msm8916 port is completely separate and does not
make use of anything in plat/qti/common at the moment. The main reason
for that is that plat/qti/common is heavily focused around having a
binary "qtiseclib" component, while the MSM8916 port is fully
open-source (and therefore somewhat limited to publicly documented
functionality).

In the future it might be possible to re-use some of the open-source
parts in plat/qti/common (e.g. spmi_arb.c or pm_ps_hold.c) but it's
not strictly required for the basic functionality supported so far.

Change-Id: I7b4375df0f947b3bd1e55b0b52b21edb6e6d175b
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
diff --git a/plat/qti/msm8916/include/plat_macros.S b/plat/qti/msm8916/include/plat_macros.S
new file mode 100644
index 0000000..552add2
--- /dev/null
+++ b/plat/qti/msm8916/include/plat_macros.S
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef PLAT_MACROS_S
+#define PLAT_MACROS_S
+
+#include <arm_macros.S>
+
+#include <msm8916_mmap.h>
+
+	/* ---------------------------------------------
+	 * The below required platform porting macro
+	 * prints out relevant GIC registers whenever
+	 * an unhandled exception is taken in BL31.
+	 * Clobbers: x0 - x10, x16, x17, sp
+	 * ---------------------------------------------
+	 */
+	.macro plat_crash_print_regs
+	mov_imm	x16, APCS_QGIC2_GICD
+	mov_imm	x17, APCS_QGIC2_GICC
+	arm_print_gic_regs
+	.endm
+
+#endif /* PLAT_MACROS_S */