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>
20 #include <generated/asm-offsets.h>
25 .type _start, @function
29 * This is the fail safe 32-bit bootstrap entry point. The
30 * following code is not executed from a cold-reset (actually, a
31 * lot of it is, but from real-mode after cold reset. It is
32 * repeated here to put the board into a state as close to cold
38 /* Turn off cache (this might require a 486-class CPU) */
40 orl $(X86_CR0_NW | X86_CR0_CD), %eax
44 /* Tell 32-bit code it is being entered from an in-RAM copy */
45 movw $GD_FLG_WARM_BOOT, %bx
49 * This is the 32-bit cold-reset entry point. Initialize %bx to 0
50 * in case we're preceeded by some sort of boot stub.
52 movw $GD_FLG_COLD_BOOT, %bx
57 /* Load the segement registes to match the gdt loaded in start16.S */
58 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
65 /* Clear the interrupt vectors */
68 /* Early platform init (setup gpio, etc ) */
70 .globl early_board_init_ret
74 /* Initialise Cache-As-RAM */
79 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
80 * or fully initialised SDRAM - we really don't care which)
81 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
82 * and early malloc area. The MRC requires some space at the top.
84 * Stack grows down from top of CAR. We have:
86 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
89 * x86 global descriptor table
92 * bottom-> CONFIG_SYS_CAR_ADDR
94 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
95 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
96 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
99 /* Reserve space on stack for global data */
100 subl $GENERATED_GBL_DATA_SIZE, %esp
102 /* Align global data to 16-byte boundary */
103 andl $0xfffffff0, %esp
104 post_code(POST_START_STACK)
106 /* Zero the global data since it won't happen later */
108 movl $GENERATED_GBL_DATA_SIZE, %ecx
112 /* Setup first parameter to setup_gdt, pointer to global_data */
115 /* Reserve space for global descriptor table */
116 subl $X86_GDT_SIZE, %esp
118 /* Align temporary global descriptor table to 16-byte boundary */
119 andl $0xfffffff0, %esp
122 #if defined(CONFIG_SYS_MALLOC_F_LEN)
123 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
125 addl $GD_MALLOC_BASE, %edx
133 /* Set second parameter to setup_gdt */
136 /* Setup global descriptor table so gd->xyz works */
139 /* Set parameter to board_init_f() to boot flags */
140 post_code(POST_START_DONE)
146 /* indicate (lack of) progress */
150 .globl board_init_f_r_trampoline
151 .type board_init_f_r_trampoline, @function
152 board_init_f_r_trampoline:
154 * SDRAM has been initialised, U-Boot code has been copied into
155 * RAM, BSS has been cleared and relocation adjustments have been
156 * made. It is now time to jump into the in-RAM copy of U-Boot
158 * %eax = Address of top of new stack
161 /* Stack grows down from top of SDRAM */
164 /* Reserve space on stack for global data */
165 subl $GENERATED_GBL_DATA_SIZE, %esp
167 /* Align global data to 16-byte boundary */
168 andl $0xfffffff0, %esp
170 /* Setup first parameter to memcpy (and setup_gdt) */
173 /* Setup second parameter to memcpy */
176 /* Set third parameter to memcpy */
177 movl $GENERATED_GBL_DATA_SIZE, %ecx
179 /* Copy global data from CAR to SDRAM stack */
182 /* Reserve space for global descriptor table */
183 subl $X86_GDT_SIZE, %esp
185 /* Align global descriptor table to 16-byte boundary */
186 andl $0xfffffff0, %esp
188 /* Set second parameter to setup_gdt */
191 /* Setup global descriptor table so gd->xyz works */
194 /* Re-enter U-Boot by calling board_init_f_r */
206 .p2align 2 /* force 4-byte alignment */
214 .long -0x1BADB002 - (1 << 16)
216 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
218 .long CONFIG_SYS_TEXT_BASE
224 .long CONFIG_SYS_TEXT_BASE