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+
14 #include <asm/global_data.h>
16 #include <asm/processor.h>
17 #include <asm/processor-flags.h>
18 #include <generated/generic-asm-offsets.h>
19 #include <generated/asm-offsets.h>
24 .type _start, @function
28 * This is the fail-safe 32-bit bootstrap entry point.
30 * This code is used when booting from another boot loader like
31 * coreboot or EFI. So we repeat some of the same init found in
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 movl $GD_FLG_WARM_BOOT, %ebx
47 /* Add a way for tools to discover the _start entry point */
52 * This is the 32-bit cold-reset entry point, coming from start16.
53 * Set %ebx to GD_FLG_COLD_BOOT to indicate this.
55 movl $GD_FLG_COLD_BOOT, %ebx
60 /* Load the segement registers to match the GDT loaded in start16.S */
61 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
68 /* Clear the interrupt vectors */
72 * Critical early platform init - generally not used, we prefer init
73 * to happen later when we have a console, in case something goes
77 .globl early_board_init_ret
81 /* Initialise Cache-As-RAM */
85 #ifndef CONFIG_HAVE_FSP
87 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
88 * or fully initialised SDRAM - we really don't care which)
89 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
90 * and early malloc() area. The MRC requires some space at the top.
92 * Stack grows down from top of CAR. We have:
94 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
97 * x86 global descriptor table
100 * bottom-> CONFIG_SYS_CAR_ADDR
102 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
103 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
104 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
108 * When we get here after car_init(), esp points to a temporary stack
109 * and esi holds the HOB list address returned by the FSP.
113 /* Reserve space on stack for global data */
114 subl $GENERATED_GBL_DATA_SIZE, %esp
116 /* Align global data to 16-byte boundary */
117 andl $0xfffffff0, %esp
118 post_code(POST_START_STACK)
120 /* Zero the global data since it won't happen later */
122 movl $GENERATED_GBL_DATA_SIZE, %ecx
126 #ifdef CONFIG_HAVE_FSP
132 addl $GD_HOB_LIST, %edx
137 /* Setup first parameter to setup_gdt, pointer to global_data */
140 /* Reserve space for global descriptor table */
141 subl $X86_GDT_SIZE, %esp
143 /* Align temporary global descriptor table to 16-byte boundary */
144 andl $0xfffffff0, %esp
147 #if defined(CONFIG_SYS_MALLOC_F_LEN)
148 /* Set up the pre-relocation malloc pool */
149 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
151 addl $GD_MALLOC_BASE, %edx
154 /* Store BIST into global_data */
159 /* Set second parameter to setup_gdt() */
162 /* Setup global descriptor table so gd->xyz works */
165 /* Set parameter to board_init_f() to boot flags */
166 post_code(POST_START_DONE)
172 /* indicate (lack of) progress */
176 .globl board_init_f_r_trampoline
177 .type board_init_f_r_trampoline, @function
178 board_init_f_r_trampoline:
180 * SDRAM has been initialised, U-Boot code has been copied into
181 * RAM, BSS has been cleared and relocation adjustments have been
182 * made. It is now time to jump into the in-RAM copy of U-Boot
184 * %eax = Address of top of new stack
187 /* Stack grows down from top of SDRAM */
190 /* Reserve space on stack for global data */
191 subl $GENERATED_GBL_DATA_SIZE, %esp
193 /* Align global data to 16-byte boundary */
194 andl $0xfffffff0, %esp
196 /* Setup first parameter to memcpy() and setup_gdt() */
199 /* Setup second parameter to memcpy() */
202 /* Set third parameter to memcpy() */
203 movl $GENERATED_GBL_DATA_SIZE, %ecx
205 /* Copy global data from CAR to SDRAM stack */
208 /* Reserve space for global descriptor table */
209 subl $X86_GDT_SIZE, %esp
211 /* Align global descriptor table to 16-byte boundary */
212 andl $0xfffffff0, %esp
214 /* Set second parameter to setup_gdt() */
217 /* Setup global descriptor table so gd->xyz works */
220 /* Set if we need to disable CAR */
222 movl $car_uninit, %eax
228 /* Re-enter U-Boot by calling board_init_f_r() */
240 .p2align 2 /* force 4-byte alignment */
242 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */
249 .long -0x1BADB002 - (1 << 16)
251 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
253 .long CONFIG_SYS_TEXT_BASE
259 .long CONFIG_SYS_TEXT_BASE