diff options
Diffstat (limited to 'roms/u-boot/arch/x86/cpu/start.S')
| -rw-r--r-- | roms/u-boot/arch/x86/cpu/start.S | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/roms/u-boot/arch/x86/cpu/start.S b/roms/u-boot/arch/x86/cpu/start.S new file mode 100644 index 00000000..329bb3ab --- /dev/null +++ b/roms/u-boot/arch/x86/cpu/start.S @@ -0,0 +1,188 @@ +/* + * U-boot - x86 Startup Code + * + * (C) Copyright 2008-2011 + * Graeme Russ, <graeme.russ@gmail.com> + * + * (C) Copyright 2002 + * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <config.h> +#include <version.h> +#include <asm/global_data.h> +#include <asm/processor.h> +#include <asm/processor-flags.h> +#include <generated/generic-asm-offsets.h> + +.section .text +.code32 +.globl _start +.type _start, @function +.globl _x86boot_start +_x86boot_start: + /* + * This is the fail safe 32-bit bootstrap entry point. The + * following code is not executed from a cold-reset (actually, a + * lot of it is, but from real-mode after cold reset. It is + * repeated here to put the board into a state as close to cold + * reset as necessary) + */ + cli + cld + + /* Turn off cache (this might require a 486-class CPU) */ + movl %cr0, %eax + orl $(X86_CR0_NW | X86_CR0_CD), %eax + movl %eax, %cr0 + wbinvd + + /* Tell 32-bit code it is being entered from an in-RAM copy */ + movw $GD_FLG_WARM_BOOT, %bx + jmp 1f +_start: + /* + * This is the 32-bit cold-reset entry point. Initialize %bx to 0 + * in case we're preceeded by some sort of boot stub. + */ + movw $GD_FLG_COLD_BOOT, %bx +1: + + /* Load the segement registes to match the gdt loaded in start16.S */ + movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax + movw %ax, %fs + movw %ax, %ds + movw %ax, %gs + movw %ax, %es + movw %ax, %ss + + /* Clear the interrupt vectors */ + lidt blank_idt_ptr + + /* Early platform init (setup gpio, etc ) */ + jmp early_board_init +.globl early_board_init_ret +early_board_init_ret: + + /* Initialise Cache-As-RAM */ + jmp car_init +.globl car_init_ret +car_init_ret: + /* + * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, + * or fully initialised SDRAM - we really don't care which) + * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack + */ + + /* Stack grows down from top of CAR */ + movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp + + /* Reserve space on stack for global data */ + subl $GENERATED_GBL_DATA_SIZE, %esp + + /* Align global data to 16-byte boundary */ + andl $0xfffffff0, %esp + + /* Setup first parameter to setup_gdt */ + movl %esp, %eax + + /* Reserve space for global descriptor table */ + subl $X86_GDT_SIZE, %esp + + /* Align temporary global descriptor table to 16-byte boundary */ + andl $0xfffffff0, %esp + + /* Set second parameter to setup_gdt */ + movl %esp, %edx + + /* Setup global descriptor table so gd->xyz works */ + call setup_gdt + + /* Set parameter to board_init_f() to boot flags */ + xorl %eax, %eax + movw %bx, %ax + + /* Enter, U-boot! */ + call board_init_f + + /* indicate (lack of) progress */ + movw $0x85, %ax + jmp die + +.globl board_init_f_r_trampoline +.type board_init_f_r_trampoline, @function +board_init_f_r_trampoline: + /* + * SDRAM has been initialised, U-Boot code has been copied into + * RAM, BSS has been cleared and relocation adjustments have been + * made. It is now time to jump into the in-RAM copy of U-Boot + * + * %eax = Address of top of new stack + */ + + /* Stack grows down from top of SDRAM */ + movl %eax, %esp + + /* Reserve space on stack for global data */ + subl $GENERATED_GBL_DATA_SIZE, %esp + + /* Align global data to 16-byte boundary */ + andl $0xfffffff0, %esp + + /* Setup first parameter to memcpy (and setup_gdt) */ + movl %esp, %eax + + /* Setup second parameter to memcpy */ + fs movl 0, %edx + + /* Set third parameter to memcpy */ + movl $GENERATED_GBL_DATA_SIZE, %ecx + + /* Copy global data from CAR to SDRAM stack */ + call memcpy + + /* Reserve space for global descriptor table */ + subl $X86_GDT_SIZE, %esp + + /* Align global descriptor table to 16-byte boundary */ + andl $0xfffffff0, %esp + + /* Set second parameter to setup_gdt */ + movl %esp, %edx + + /* Setup global descriptor table so gd->xyz works */ + call setup_gdt + + /* Re-enter U-Boot by calling board_init_f_r */ + call board_init_f_r + +die: + hlt + jmp die + hlt + +blank_idt_ptr: + .word 0 /* limit */ + .long 0 /* base */ + + .p2align 2 /* force 4-byte alignment */ + +multiboot_header: + /* magic */ + .long 0x1BADB002 + /* flags */ + .long (1 << 16) + /* checksum */ + .long -0x1BADB002 - (1 << 16) + /* header addr */ + .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE + /* load addr */ + .long CONFIG_SYS_TEXT_BASE + /* load end addr */ + .long 0 + /* bss end addr */ + .long 0 + /* entry addr */ + .long CONFIG_SYS_TEXT_BASE |