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>
16 #include <asm/processor.h>
17 #include <asm/processor-flags.h>
18 #include <generated/generic-asm-offsets.h>
23 .type _start, @function
27 * This is the fail safe 32-bit bootstrap entry point. The
28 * following code is not executed from a cold-reset (actually, a
29 * lot of it is, but from real-mode after cold reset. It is
30 * repeated here to put the board into a state as close to cold
36 /* Turn off cache (this might require a 486-class CPU) */
38 orl $(X86_CR0_NW | X86_CR0_CD), %eax
42 /* Tell 32-bit code it is being entered from an in-RAM copy */
43 movw $GD_FLG_WARM_BOOT, %bx
47 * This is the 32-bit cold-reset entry point. Initialize %bx to 0
48 * in case we're preceeded by some sort of boot stub.
50 movw $GD_FLG_COLD_BOOT, %bx
53 /* Load the segement registes to match the gdt loaded in start16.S */
54 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
61 /* Clear the interrupt vectors */
64 /* Early platform init (setup gpio, etc ) */
66 .globl early_board_init_ret
69 /* Initialise Cache-As-RAM */
74 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
75 * or fully initialised SDRAM - we really don't care which)
76 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
77 * and early malloc area.
79 * Stack grows down from top of CAR. We have:
81 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
83 * x86 global descriptor table
86 * bottom-> CONFIG_SYS_CAR_ADDR
89 /* Stack grows down from top of CAR */
90 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp
92 /* Reserve space on stack for global data */
93 subl $GENERATED_GBL_DATA_SIZE, %esp
95 /* Align global data to 16-byte boundary */
96 andl $0xfffffff0, %esp
98 /* Zero the global data since it won't happen later */
100 movl $GENERATED_GBL_DATA_SIZE, %ecx
104 /* Setup first parameter to setup_gdt, pointer to global_data */
107 /* Reserve space for global descriptor table */
108 subl $X86_GDT_SIZE, %esp
110 /* Align temporary global descriptor table to 16-byte boundary */
111 andl $0xfffffff0, %esp
114 #if defined(CONFIG_SYS_MALLOC_F_LEN)
115 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
117 addl $GD_MALLOC_BASE, %edx
121 /* Align temporary global descriptor table to 16-byte boundary */
122 andl $0xfffffff0, %esp
124 /* Set second parameter to setup_gdt */
127 /* Setup global descriptor table so gd->xyz works */
130 /* Set parameter to board_init_f() to boot flags */
136 /* indicate (lack of) progress */
140 .globl board_init_f_r_trampoline
141 .type board_init_f_r_trampoline, @function
142 board_init_f_r_trampoline:
144 * SDRAM has been initialised, U-Boot code has been copied into
145 * RAM, BSS has been cleared and relocation adjustments have been
146 * made. It is now time to jump into the in-RAM copy of U-Boot
148 * %eax = Address of top of new stack
151 /* Stack grows down from top of SDRAM */
154 /* Reserve space on stack for global data */
155 subl $GENERATED_GBL_DATA_SIZE, %esp
157 /* Align global data to 16-byte boundary */
158 andl $0xfffffff0, %esp
160 /* Setup first parameter to memcpy (and setup_gdt) */
163 /* Setup second parameter to memcpy */
166 /* Set third parameter to memcpy */
167 movl $GENERATED_GBL_DATA_SIZE, %ecx
169 /* Copy global data from CAR to SDRAM stack */
172 /* Reserve space for global descriptor table */
173 subl $X86_GDT_SIZE, %esp
175 /* Align global descriptor table to 16-byte boundary */
176 andl $0xfffffff0, %esp
178 /* Set second parameter to setup_gdt */
181 /* Setup global descriptor table so gd->xyz works */
184 /* Re-enter U-Boot by calling board_init_f_r */
196 .p2align 2 /* force 4-byte alignment */
204 .long -0x1BADB002 - (1 << 16)
206 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
208 .long CONFIG_SYS_TEXT_BASE
214 .long CONFIG_SYS_TEXT_BASE