1 files changed, 112 insertions, 0 deletions
diff --git a/arch/i386/cpu/start16.S b/arch/i386/cpu/start16.S
new file mode 100644
index 0000000..1ebb6bc
--- /dev/null
+++ b/arch/i386/cpu/start16.S
@@ -0,0 +1,112 @@
+/*
+ *  U-boot - i386 Startup Code
+ *
+ *  Copyright (c) 2002, 2003 Omicron Ceti AB, Daniel Engström <denaiel@omicron.se>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+
+#define BOOT_SEG	0xffff0000	/* linear segment of boot code */
+#define a32		.byte 0x67;
+#define o32		.byte 0x66;
+
+.section .start16, "ax"
+.code16
+.globl start16
+start16:
+	/* First we let the BSP do some early initialization
+	 * this code have to map the flash to its final position
+	 */
+	mov	$board_init16_ret, %bp
+	jmp	board_init16
+board_init16_ret:
+
+	/* Turn of cache (this might require a 486-class CPU) */
+	movl	%cr0, %eax
+	orl	$0x60000000,%eax
+	movl	%eax, %cr0
+	wbinvd
+
+	/* load the descriptor tables */
+o32 cs	lidt	idt_ptr
+o32 cs	lgdt	gdt_ptr
+
+
+	/* Now, we enter protected mode */
+	movl	%cr0, %eax
+	orl	$1,%eax
+	movl	%eax, %cr0
+
+	/* Flush the prefetch queue */
+	jmp	ff
+ff:
+
+	/* Finally jump to the 32bit initialization code */
+	movw	$code32start, %ax
+	movw	%ax,%bp
+o32 cs	ljmp	*(%bp)
+
+	/* 48-bit far pointer */
+code32start:
+	.long	_start		/* offset */
+	.word	0x10		/* segment */
+
+idt_ptr:
+	.word	0		/* limit */
+	.long	0		/* base */
+
+gdt_ptr:
+	.word	0x30		/* limit (48 bytes = 6 GDT entries) */
+	.long	BOOT_SEG + gdt	/* base */
+
+	/* The GDT table ...
+	 *
+	 *	 Selector	Type
+	 *	 0x00		NULL
+	 *	 0x08		Unused
+	 *	 0x10		32bit code
+	 *	 0x18		32bit data/stack
+	 *	 0x20		16bit code
+	 *	 0x28		16bit data/stack
+	 */
+
+gdt:
+	.word	0, 0, 0, 0	/* NULL  */
+	.word	0, 0, 0, 0	/* unused */
+
+	.word	0xFFFF		/* 4Gb - (0x100000*0x1000 = 4Gb) */
+	.word	0		/* base address = 0 */
+	.word	0x9B00		/* code read/exec */
+	.word	0x00CF		/* granularity = 4096, 386 (+5th nibble of limit) */
+
+	.word	0xFFFF		/* 4Gb - (0x100000*0x1000 = 4Gb) */
+	.word	0x0		/* base address = 0 */
+	.word	0x9300		/* data read/write */
+	.word	0x00CF		/* granularity = 4096, 386 (+5th nibble of limit) */
+
+	.word	0xFFFF		/* 64kb */
+	.word	0		/* base address = 0 */
+	.word	0x9b00		/* data read/write */
+	.word	0x0010		/* granularity = 1  (+5th nibble of limit) */
+
+	.word	0xFFFF		/* 64kb */
+	.word	0		/* base address = 0 */
+	.word	0x9300		/* data read/write */
+	.word	0x0010		/* granularity = 1 (+5th nibble of limit) */