meson/gxl: Initial port of Amlogic Meson S905x (GXL)

The Amlogic Meson S905x is a SoC with a quad core Arm Cortex-A53 running
at 1.5Ghz. It also contains a Cortex-M3 used as SCP.

This port is a minimal implementation of BL31 capable of booting
mainline U-Boot and Linux:

- Partial SCPI support.
- Basic PSCI support (CPU_ON, SYSTEM_RESET, SYSTEM_OFF).
- GICv2 driver set up.
- Basic SIP services (read efuse data, enable/disable JTAG).

This port has been tested on a lepotato.

Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
diff --git a/plat/meson/gxl/gxl_efuse.c b/plat/meson/gxl/gxl_efuse.c
new file mode 100644
index 0000000..b17d1b8
--- /dev/null
+++ b/plat/meson/gxl/gxl_efuse.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdint.h>
+
+#include "gxl_private.h"
+
+#define EFUSE_BASE	0x140
+#define EFUSE_SIZE	0xC0
+
+uint64_t gxbb_efuse_read(void *dst, uint32_t offset, uint32_t size)
+{
+	if ((uint64_t)(offset + size) > (uint64_t)EFUSE_SIZE)
+		return 0;
+
+	return scpi_efuse_read(dst, offset + EFUSE_BASE, size);
+}
+
+uint64_t gxbb_efuse_user_max(void)
+{
+	return EFUSE_SIZE;
+}