GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/arch/arm/cpu/arm720t/start.S

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+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ *  armboot - Startup Code for ARM720 CPU-core
+ *
+ *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
+ *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
+ */
+
+#include <asm-offsets.h>
+#include <config.h>
+
+/*
+ *************************************************************************
+ *
+ * Startup Code (reset vector)
+ *
+ * do important init only if we don't start from RAM!
+ * relocate armboot to ram
+ * setup stack
+ * jump to second stage
+ *
+ *************************************************************************
+ */
+
+	.globl	reset
+
+reset:
+	/*
+	 * set the cpu to SVC32 mode
+	 */
+	mrs	r0,cpsr
+	bic	r0,r0,#0x1f
+	orr	r0,r0,#0xd3
+	msr	cpsr,r0
+
+	/*
+	 * we do sys-critical inits only at reboot,
+	 * not when booting from ram!
+	 */
+#if !defined(CONFIG_SKIP_LOWLEVEL_INIT) && \
+		!defined(CONFIG_SKIP_LOWLEVEL_INIT_ONLY)
+	bl	cpu_init_crit
+#endif
+
+	bl	_main
+
+/*------------------------------------------------------------------------------*/
+
+	.globl	c_runtime_cpu_setup
+c_runtime_cpu_setup:
+
+	mov	pc, lr
+
+/*
+ *************************************************************************
+ *
+ * CPU_init_critical registers
+ *
+ * setup important registers
+ * setup memory timing
+ *
+ *************************************************************************
+ */
+
+#if !defined(CONFIG_SKIP_LOWLEVEL_INIT) && \
+		!defined(CONFIG_SKIP_LOWLEVEL_INIT_ONLY)
+cpu_init_crit:
+
+	mov	ip, lr
+	/*
+	 * before relocating, we have to setup RAM timing
+	 * because memory timing is board-dependent, you will
+	 * find a lowlevel_init.S in your board directory.
+	 */
+	bl	lowlevel_init
+	mov	lr, ip
+
+	mov	pc, lr
+#endif /* CONFIG_SKIP_LOWLEVEL_INIT */