2 * U-boot - x86 Startup Code
4 * (C) Copyright 2008-2011
5 * Graeme Russ, <graeme.russ@gmail.com>
8 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
10 * SPDX-License-Identifier: GPL-2.0+
15 #include <asm/global_data.h>
17 #include <asm/processor.h>
18 #include <asm/processor-flags.h>
19 #include <generated/generic-asm-offsets.h>
24 .type _start, @function
28 * This is the fail safe 32-bit bootstrap entry point. The
29 * following code is not executed from a cold-reset (actually, a
30 * lot of it is, but from real-mode after cold reset. It is
31 * repeated here to put the board into a state as close to cold
37 /* Turn off cache (this might require a 486-class CPU) */
39 orl $(X86_CR0_NW | X86_CR0_CD), %eax
43 /* Tell 32-bit code it is being entered from an in-RAM copy */
44 movw $GD_FLG_WARM_BOOT, %bx
48 * This is the 32-bit cold-reset entry point. Initialize %bx to 0
49 * in case we're preceeded by some sort of boot stub.
51 movw $GD_FLG_COLD_BOOT, %bx
56 /* Load the segement registes to match the gdt loaded in start16.S */
57 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
64 /* Clear the interrupt vectors */
67 /* Early platform init (setup gpio, etc ) */
69 .globl early_board_init_ret
73 /* Initialise Cache-As-RAM */
78 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
79 * or fully initialised SDRAM - we really don't care which)
80 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
81 * and early malloc area.
83 * Stack grows down from top of CAR. We have:
85 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
87 * x86 global descriptor table
90 * bottom-> CONFIG_SYS_CAR_ADDR
93 /* Stack grows down from top of CAR */
94 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp
96 /* Reserve space on stack for global data */
97 subl $GENERATED_GBL_DATA_SIZE, %esp
99 /* Align global data to 16-byte boundary */
100 andl $0xfffffff0, %esp
101 post_code(POST_START_STACK)
103 /* Zero the global data since it won't happen later */
105 movl $GENERATED_GBL_DATA_SIZE, %ecx
109 /* Setup first parameter to setup_gdt, pointer to global_data */
112 /* Reserve space for global descriptor table */
113 subl $X86_GDT_SIZE, %esp
115 /* Align temporary global descriptor table to 16-byte boundary */
116 andl $0xfffffff0, %esp
119 #if defined(CONFIG_SYS_MALLOC_F_LEN)
120 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
122 addl $GD_MALLOC_BASE, %edx
130 /* Set second parameter to setup_gdt */
133 /* Setup global descriptor table so gd->xyz works */
136 /* Set parameter to board_init_f() to boot flags */
137 post_code(POST_START_DONE)
143 /* indicate (lack of) progress */
147 .globl board_init_f_r_trampoline
148 .type board_init_f_r_trampoline, @function
149 board_init_f_r_trampoline:
151 * SDRAM has been initialised, U-Boot code has been copied into
152 * RAM, BSS has been cleared and relocation adjustments have been
153 * made. It is now time to jump into the in-RAM copy of U-Boot
155 * %eax = Address of top of new stack
158 /* Stack grows down from top of SDRAM */
161 /* Reserve space on stack for global data */
162 subl $GENERATED_GBL_DATA_SIZE, %esp
164 /* Align global data to 16-byte boundary */
165 andl $0xfffffff0, %esp
167 /* Setup first parameter to memcpy (and setup_gdt) */
170 /* Setup second parameter to memcpy */
173 /* Set third parameter to memcpy */
174 movl $GENERATED_GBL_DATA_SIZE, %ecx
176 /* Copy global data from CAR to SDRAM stack */
179 /* Reserve space for global descriptor table */
180 subl $X86_GDT_SIZE, %esp
182 /* Align global descriptor table to 16-byte boundary */
183 andl $0xfffffff0, %esp
185 /* Set second parameter to setup_gdt */
188 /* Setup global descriptor table so gd->xyz works */
191 /* Re-enter U-Boot by calling board_init_f_r */
203 .p2align 2 /* force 4-byte alignment */
211 .long -0x1BADB002 - (1 << 16)
213 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
215 .long CONFIG_SYS_TEXT_BASE
221 .long CONFIG_SYS_TEXT_BASE