[PATCH 2/6] aspeed: ast2500: Add lowlevel_init assembly

[Chia-Wei, Wang <chiawei_wang@aspeedtech.com>]

The original lowlevel_init function of AST2500 is written
in C. However, the C runtime environment is not ready until
_main execution.

This patch adds the assembly version of the lowlevel_init
function. Additional initialization to DRAM configuration
and LPC reset source are also added.

Signed-off-by: Chia-Wei, Wang <chiawei_wang@aspeedtech.com>
---
 arch/arm/mach-aspeed/ast2500-board.c         | 25 ------------
 arch/arm/mach-aspeed/ast2500/Makefile        |  1 +
 arch/arm/mach-aspeed/ast2500/lowlevel_init.S | 41 ++++++++++++++++++++
 3 files changed, 42 insertions(+), 25 deletions(-)
 create mode 100644 arch/arm/mach-aspeed/ast2500/lowlevel_init.S

diff --git a/arch/arm/mach-aspeed/ast2500-board.c b/arch/arm/mach-aspeed/ast2500-board.c
index f74dcbbb62..3482ee91ef 100644
--- a/arch/arm/mach-aspeed/ast2500-board.c
+++ b/arch/arm/mach-aspeed/ast2500-board.c
@@ -28,31 +28,6 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-void lowlevel_init(void)
-{
-	/*
-	 * These two watchdogs need to be stopped as soon as possible,
-	 * otherwise the board might hang. By default they are set to
-	 * a very short timeout and even simple debug write to serial
-	 * console early in the init process might cause them to fire.
-	 */
-	struct ast_wdt *flash_addr_wdt =
-	    (struct ast_wdt *)(WDT_BASE +
-			       sizeof(struct ast_wdt) *
-			       AST_FLASH_ADDR_DETECT_WDT);
-
-	clrbits_le32(&flash_addr_wdt->ctrl, WDT_CTRL_EN);
-
-#ifndef CONFIG_FIRMWARE_2ND_BOOT
-	struct ast_wdt *sec_boot_wdt =
-	    (struct ast_wdt *)(WDT_BASE +
-			       sizeof(struct ast_wdt) *
-			       AST_2ND_BOOT_WDT);
-
-	clrbits_le32(&sec_boot_wdt->ctrl, WDT_CTRL_EN);
-#endif
-}
-
 int board_init(void)
 {
 	gd->bd->bi_boot_params = CONFIG_SYS_SDRAM_BASE + 0x100;
diff --git a/arch/arm/mach-aspeed/ast2500/Makefile b/arch/arm/mach-aspeed/ast2500/Makefile
index a35b239ef3..2e9e15d831 100644
--- a/arch/arm/mach-aspeed/ast2500/Makefile
+++ b/arch/arm/mach-aspeed/ast2500/Makefile
@@ -1 +1,2 @@
+obj-y += lowlevel_init.o
 obj-y += clk_ast2500.o sdram_ast2500.o
diff --git a/arch/arm/mach-aspeed/ast2500/lowlevel_init.S b/arch/arm/mach-aspeed/ast2500/lowlevel_init.S
new file mode 100644
index 0000000000..9ec3dd46b7
--- /dev/null
+++ b/arch/arm/mach-aspeed/ast2500/lowlevel_init.S
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ */
+#include <asm/arch/scu_ast2500.h>
+
+/* registers for low level init */
+#define SCU_PROT_KEY		0x1e6e2000
+#define SCU_VGA_HANDSHAKE	0x1e6e2040
+#define SCU_HW_STRAP		0x1e6e2070
+#define SCU_HW_STRAP_CLR	0x1e6e207c
+#define WDT3_CTRL		0x1e78504c
+
+.global lowlevel_init
+lowlevel_init:
+
+	/* unlock SCU */
+	ldr	r0, =SCU_PROT_KEY
+	ldr	r1, =SCU_UNLOCK_VALUE
+	str	r1, [r0]
+
+	/* set BMC FW as DRAM initializer */
+	ldr	r0, =SCU_VGA_HANDSHAKE
+	ldr	r1, [r0]
+	orr	r1, #0x80
+	str	r1, [r0]
+
+	/* set PERST# as LPC reset source if eSPI mode is enabled*/
+	ldr	r0, =SCU_HW_STRAP
+	ldr	r1, [r0]
+	tst	r1, #(0x1 << 25)
+	ldrne	r0, =SCU_HW_STRAP_CLR
+	movne	r1, #(0x1 << 14)
+	strne	r1, [r0]
+
+	/* disable WDT3 for SPI 3/4 bytes auto-detection */
+	ldr	r0, =WDT3_CTRL
+	mov	r1, #0x0
+	str	r1, [r0]
+
+	mov	pc, lr
-- 
2.17.1