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 movw $GD_FLG_WARM_BOOT, %bx
48 * This is the 32-bit cold-reset entry point, coming from start16.
49 * Set %bx to 0 to indicate this.
51 movw $GD_FLG_COLD_BOOT, %bx
56 /* Load the segement registers 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 */
68 * Critical early platform init - generally not used, we prefer init
69 * to happen later when we have a console, in case something goes
73 .globl early_board_init_ret
77 /* Initialise Cache-As-RAM */
81 #ifndef CONFIG_HAVE_FSP
83 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
84 * or fully initialised SDRAM - we really don't care which)
85 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
86 * and early malloc() area. The MRC requires some space at the top.
88 * Stack grows down from top of CAR. We have:
90 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
93 * x86 global descriptor table
96 * bottom-> CONFIG_SYS_CAR_ADDR
98 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
99 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
100 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
104 * When we get here after car_init(), esp points to a temporary stack
105 * and esi holds the HOB list address returned by the FSP.
109 /* Reserve space on stack for global data */
110 subl $GENERATED_GBL_DATA_SIZE, %esp
112 /* Align global data to 16-byte boundary */
113 andl $0xfffffff0, %esp
114 post_code(POST_START_STACK)
116 /* Zero the global data since it won't happen later */
118 movl $GENERATED_GBL_DATA_SIZE, %ecx
122 #ifdef CONFIG_HAVE_FSP
128 addl $GD_HOB_LIST, %edx
133 /* Setup first parameter to setup_gdt, pointer to global_data */
136 /* Reserve space for global descriptor table */
137 subl $X86_GDT_SIZE, %esp
139 /* Align temporary global descriptor table to 16-byte boundary */
140 andl $0xfffffff0, %esp
143 #if defined(CONFIG_SYS_MALLOC_F_LEN)
144 /* Set up the pre-relocation malloc pool */
145 subl $CONFIG_SYS_MALLOC_F_LEN, %esp
147 addl $GD_MALLOC_BASE, %edx
150 /* Store BIST into global_data */
155 /* Set second parameter to setup_gdt() */
158 /* Setup global descriptor table so gd->xyz works */
161 /* Set parameter to board_init_f() to boot flags */
162 post_code(POST_START_DONE)
168 /* indicate (lack of) progress */
172 .globl board_init_f_r_trampoline
173 .type board_init_f_r_trampoline, @function
174 board_init_f_r_trampoline:
176 * SDRAM has been initialised, U-Boot code has been copied into
177 * RAM, BSS has been cleared and relocation adjustments have been
178 * made. It is now time to jump into the in-RAM copy of U-Boot
180 * %eax = Address of top of new stack
183 /* Stack grows down from top of SDRAM */
186 /* Reserve space on stack for global data */
187 subl $GENERATED_GBL_DATA_SIZE, %esp
189 /* Align global data to 16-byte boundary */
190 andl $0xfffffff0, %esp
192 /* Setup first parameter to memcpy() and setup_gdt() */
195 /* Setup second parameter to memcpy() */
198 /* Set third parameter to memcpy() */
199 movl $GENERATED_GBL_DATA_SIZE, %ecx
201 /* Copy global data from CAR to SDRAM stack */
204 /* Reserve space for global descriptor table */
205 subl $X86_GDT_SIZE, %esp
207 /* Align global descriptor table to 16-byte boundary */
208 andl $0xfffffff0, %esp
210 /* Set second parameter to setup_gdt() */
213 /* Setup global descriptor table so gd->xyz works */
216 /* Set if we need to disable CAR */
218 movl $car_uninit, %eax
224 /* Re-enter U-Boot by calling board_init_f_r() */
236 .p2align 2 /* force 4-byte alignment */
238 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */
245 .long -0x1BADB002 - (1 << 16)
247 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
249 .long CONFIG_SYS_TEXT_BASE
255 .long CONFIG_SYS_TEXT_BASE