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. The MRC requires some space at the top.
83 * Stack grows down from top of CAR. We have:
85 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
88 * x86 global descriptor table
91 * bottom-> CONFIG_SYS_CAR_ADDR
93 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
94 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
95 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
98 /* Reserve space on stack for global data */
99 subl $GENERATED_GBL_DATA_SIZE, %esp
101 /* Align global data to 16-byte boundary */
102 andl $0xfffffff0, %esp
103 post_code(POST_START_STACK)
105 /* Zero the global data since it won't happen later */
107 movl $GENERATED_GBL_DATA_SIZE, %ecx
111 /* Setup first parameter to setup_gdt, pointer to global_data */
114 /* Reserve space for global descriptor table */
115 subl $X86_GDT_SIZE, %esp
117 /* Align temporary global descriptor table to 16-byte boundary */
118 andl $0xfffffff0, %esp
121 #if defined(CONFIG_SYS_MALLOC_F_LEN)
122 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
124 addl $GD_MALLOC_BASE, %edx
132 /* Set second parameter to setup_gdt */
135 /* Setup global descriptor table so gd->xyz works */
138 /* Set parameter to board_init_f() to boot flags */
139 post_code(POST_START_DONE)
145 /* indicate (lack of) progress */
149 .globl board_init_f_r_trampoline
150 .type board_init_f_r_trampoline, @function
151 board_init_f_r_trampoline:
153 * SDRAM has been initialised, U-Boot code has been copied into
154 * RAM, BSS has been cleared and relocation adjustments have been
155 * made. It is now time to jump into the in-RAM copy of U-Boot
157 * %eax = Address of top of new stack
160 /* Stack grows down from top of SDRAM */
163 /* Reserve space on stack for global data */
164 subl $GENERATED_GBL_DATA_SIZE, %esp
166 /* Align global data to 16-byte boundary */
167 andl $0xfffffff0, %esp
169 /* Setup first parameter to memcpy (and setup_gdt) */
172 /* Setup second parameter to memcpy */
175 /* Set third parameter to memcpy */
176 movl $GENERATED_GBL_DATA_SIZE, %ecx
178 /* Copy global data from CAR to SDRAM stack */
181 /* Reserve space for global descriptor table */
182 subl $X86_GDT_SIZE, %esp
184 /* Align global descriptor table to 16-byte boundary */
185 andl $0xfffffff0, %esp
187 /* Set second parameter to setup_gdt */
190 /* Setup global descriptor table so gd->xyz works */
193 /* Re-enter U-Boot by calling board_init_f_r */
205 .p2align 2 /* force 4-byte alignment */
213 .long -0x1BADB002 - (1 << 16)
215 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
217 .long CONFIG_SYS_TEXT_BASE
223 .long CONFIG_SYS_TEXT_BASE