feat(ast2700): add Aspeed AST2700 platform support

Aspeed AST2700 is a quad-core SoC with ARM Cortex-A35 integrated.
This patch adds the initial platform support for AST2700 and also
updates the documents.

Change-Id: I1796f7aae5ed2d1799e91fabb8949607959cd9b3
Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
diff --git a/plat/aspeed/ast2700/plat_helpers.S b/plat/aspeed/ast2700/plat_helpers.S
new file mode 100644
index 0000000..1457692
--- /dev/null
+++ b/plat/aspeed/ast2700/plat_helpers.S
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2023, Aspeed Technology Inc.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm_macros.S>
+#include <assert_macros.S>
+#include <arch.h>
+#include <cortex_a35.h>
+#include <platform_def.h>
+
+	.globl	plat_is_my_cpu_primary
+	.globl	plat_my_core_pos
+	.globl	plat_secondary_cold_boot_setup
+	.globl	plat_get_syscnt_freq2
+	.globl	plat_crash_console_init
+	.globl	plat_crash_console_putc
+	.globl	plat_crash_console_flush
+
+/* unsigned int plat_is_my_cpu_primary(void); */
+func plat_is_my_cpu_primary
+	mrs	x0, mpidr_el1
+	and	x0, x0, #(MPIDR_CLUSTER_MASK | MPIDR_CPU_MASK)
+	cmp	x0, #PLATFORM_CORE_PRIMARY
+	cset	w0, eq
+	ret
+endfunc plat_is_my_cpu_primary
+
+/* unsigned int plat_my_core_pos(void); */
+func plat_my_core_pos
+	mrs	x0, mpidr_el1
+	mov	x2, #PLATFORM_CORE_COUNT_PER_CLUSTER
+	and	x1, x0, #MPIDR_CPU_MASK
+	and	x0, x0, #MPIDR_CLUSTER_MASK
+	madd	x0, x0, x2, x1
+	ret
+endfunc plat_my_core_pos
+
+/* unsigned int plat_get_syscnt_freq2(void); */
+func plat_get_syscnt_freq2
+	mov_imm	w0, PLAT_SYSCNT_CLKIN_HZ
+	ret
+endfunc plat_get_syscnt_freq2
+
+/* int plat_crash_console_init(void); */
+func plat_crash_console_init
+	mov_imm	x0, CONSOLE_UART_BASE
+	mov_imm	x1, CONSOLE_UART_CLKIN_HZ
+	mov_imm	x2, CONSOLE_UART_BAUDRATE
+	b	console_16550_core_init
+endfunc plat_crash_console_init
+
+/* int plat_crash_console_putc(int); */
+func plat_crash_console_putc
+	mov_imm	x1, CONSOLE_UART_BASE
+	b	console_16550_core_putc
+endfunc plat_crash_console_putc
+
+/* void plat_crash_console_flush(void); */
+func plat_crash_console_flush
+	mov_imm	x0, CONSOLE_UART_BASE
+	b	console_16550_core_flush
+endfunc plat_crash_console_flush