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 */
78 #ifndef CONFIG_HAVE_FSP
80 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
81 * or fully initialised SDRAM - we really don't care which)
82 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
83 * and early malloc area. The MRC requires some space at the top.
85 * Stack grows down from top of CAR. We have:
87 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
90 * x86 global descriptor table
93 * bottom-> CONFIG_SYS_CAR_ADDR
95 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
96 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
97 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
101 * When we get here after car_init, esp points to a temporary stack
102 * and esi holds the HOB list address returned by the FSP.
106 /* Reserve space on stack for global data */
107 subl $GENERATED_GBL_DATA_SIZE, %esp
109 /* Align global data to 16-byte boundary */
110 andl $0xfffffff0, %esp
111 post_code(POST_START_STACK)
113 /* Zero the global data since it won't happen later */
115 movl $GENERATED_GBL_DATA_SIZE, %ecx
119 #ifdef CONFIG_HAVE_FSP
122 addl $GD_HOB_LIST, %edx
126 /* Setup first parameter to setup_gdt, pointer to global_data */
129 /* Reserve space for global descriptor table */
130 subl $X86_GDT_SIZE, %esp
132 /* Align temporary global descriptor table to 16-byte boundary */
133 andl $0xfffffff0, %esp
136 #if defined(CONFIG_SYS_MALLOC_F_LEN)
137 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
139 addl $GD_MALLOC_BASE, %edx
147 /* Set second parameter to setup_gdt */
150 /* Setup global descriptor table so gd->xyz works */
153 /* Set parameter to board_init_f() to boot flags */
154 post_code(POST_START_DONE)
160 /* indicate (lack of) progress */
164 .globl board_init_f_r_trampoline
165 .type board_init_f_r_trampoline, @function
166 board_init_f_r_trampoline:
168 * SDRAM has been initialised, U-Boot code has been copied into
169 * RAM, BSS has been cleared and relocation adjustments have been
170 * made. It is now time to jump into the in-RAM copy of U-Boot
172 * %eax = Address of top of new stack
175 /* Stack grows down from top of SDRAM */
178 /* Reserve space on stack for global data */
179 subl $GENERATED_GBL_DATA_SIZE, %esp
181 /* Align global data to 16-byte boundary */
182 andl $0xfffffff0, %esp
184 /* Setup first parameter to memcpy (and setup_gdt) */
187 /* Setup second parameter to memcpy */
190 /* Set third parameter to memcpy */
191 movl $GENERATED_GBL_DATA_SIZE, %ecx
193 /* Copy global data from CAR to SDRAM stack */
196 /* Reserve space for global descriptor table */
197 subl $X86_GDT_SIZE, %esp
199 /* Align global descriptor table to 16-byte boundary */
200 andl $0xfffffff0, %esp
202 /* Set second parameter to setup_gdt */
205 /* Setup global descriptor table so gd->xyz works */
208 /* Re-enter U-Boot by calling board_init_f_r */
220 .p2align 2 /* force 4-byte alignment */
228 .long -0x1BADB002 - (1 << 16)
230 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
232 .long CONFIG_SYS_TEXT_BASE
238 .long CONFIG_SYS_TEXT_BASE