start.S 3.3 KB

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  1. /*
  2. * U-boot - x86 Startup Code
  3. *
  4. * (C) Copyright 2008-2011
  5. * Graeme Russ, <graeme.russ@gmail.com>
  6. *
  7. * (C) Copyright 2002
  8. * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
  9. *
  10. * See file CREDITS for list of people who contributed to this
  11. * project.
  12. *
  13. * This program is free software; you can redistribute it and/or
  14. * modify it under the terms of the GNU General Public License as
  15. * published by the Free Software Foundation; either version 2 of
  16. * the License, or (at your option) any later version.
  17. *
  18. * This program is distributed in the hope that it will be useful,
  19. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  21. * GNU General Public License for more details.
  22. *
  23. * You should have received a copy of the GNU General Public License
  24. * along with this program; if not, write to the Free Software
  25. * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  26. * MA 02111-1307 USA
  27. */
  28. #include <config.h>
  29. #include <version.h>
  30. #include <asm/global_data.h>
  31. #include <asm/processor-flags.h>
  32. .section .text
  33. .code32
  34. .globl _start
  35. .type _start, @function
  36. .globl _x86boot_start
  37. _x86boot_start:
  38. /*
  39. * This is the fail safe 32-bit bootstrap entry point. The
  40. * following code is not executed from a cold-reset (actually, a
  41. * lot of it is, but from real-mode after cold reset. It is
  42. * repeated here to put the board into a state as close to cold
  43. * reset as necessary)
  44. */
  45. cli
  46. cld
  47. /* Turn of cache (this might require a 486-class CPU) */
  48. movl %cr0, %eax
  49. orl $(X86_CR0_NW | X86_CR0_CD), %eax
  50. movl %eax, %cr0
  51. wbinvd
  52. /* Tell 32-bit code it is being entered from an in-RAM copy */
  53. movw $GD_FLG_WARM_BOOT, %bx
  54. _start:
  55. /* This is the 32-bit cold-reset entry point */
  56. /* Load the segement registes to match the gdt loaded in start16.S */
  57. movl $0x18, %eax
  58. movw %ax, %fs
  59. movw %ax, %ds
  60. movw %ax, %gs
  61. movw %ax, %es
  62. movw %ax, %ss
  63. /* Clear the interrupt vectors */
  64. lidt blank_idt_ptr
  65. /* Early platform init (setup gpio, etc ) */
  66. jmp early_board_init
  67. .globl early_board_init_ret
  68. early_board_init_ret:
  69. /* Initialise Cache-As-RAM */
  70. jmp car_init
  71. .globl car_init_ret
  72. car_init_ret:
  73. /*
  74. * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
  75. * or fully initialised SDRAM - we really don't care which)
  76. * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
  77. */
  78. movl $CONFIG_SYS_INIT_SP_ADDR, %esp
  79. /* Set parameter to board_init_f() to boot flags */
  80. xorl %eax, %eax
  81. movw %bx, %ax
  82. /* Enter, U-boot! */
  83. call board_init_f
  84. /* indicate (lack of) progress */
  85. movw $0x85, %ax
  86. jmp die
  87. .globl relocate_code
  88. .type relocate_code, @function
  89. relocate_code:
  90. /*
  91. * SDRAM has been initialised, U-Boot code has been copied into
  92. * RAM, BSS has been cleared and relocation adjustments have been
  93. * made. It is now time to jump into the in-RAM copy of U-Boot
  94. *
  95. * %eax = Address of top of stack
  96. * %edx = Address of Global Data
  97. * %ecx = Base address of in-RAM copy of U-Boot
  98. */
  99. /* Setup stack in RAM */
  100. movl %eax, %esp
  101. /* Setup call address of in-RAM copy of board_init_r() */
  102. movl $board_init_r, %ebp
  103. addl (GD_RELOC_OFF * 4)(%edx), %ebp
  104. /* Setup parameters to board_init_r() */
  105. movl %edx, %eax
  106. movl %ecx, %edx
  107. /* Jump to in-RAM copy of board_init_r() */
  108. call *%ebp
  109. die: hlt
  110. jmp die
  111. hlt
  112. blank_idt_ptr:
  113. .word 0 /* limit */
  114. .long 0 /* base */