projects / people / ms / u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| 2262cfee | 1 | /* |
| fea25720 | 2 | * U-boot - x86 Startup Code |
| 2262cfee | 3 | * |
| dbf7115a GR |
4 | * (C) Copyright 2008-2011 |
| 5 | * Graeme Russ, <graeme.russ@gmail.com> | |
| 6 | * | |
| 7 | * (C) Copyright 2002,2003 | |
| fa82f871 | 8 | * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> |
| 2262cfee | 9 | * |
| 1a459660 | 10 | * SPDX-License-Identifier: GPL-2.0+ |
| 2262cfee WD |
11 | */ |
| 12 | ||
| c81b26be | 13 | #include <asm/global_data.h> |
| 0c24c9cc | 14 | #include <asm/processor-flags.h> |
| 2262cfee WD |
15 | |
| 16 | #define BOOT_SEG 0xffff0000 /* linear segment of boot code */ | |
| 17 | #define a32 .byte 0x67; | |
| 18 | #define o32 .byte 0x66; | |
| 19 | ||
| 20 | .section .start16, "ax" | |
| 21 | .code16 | |
| 22 | .globl start16 | |
| 8bde7f77 | 23 | start16: |
| 91d82a29 GB |
24 | /* Set the Cold Boot / Hard Reset flag */ |
| 25 | movl $GD_FLG_COLD_BOOT, %ebx | |
| 26 | ||
| 8ffb2e8f GR |
27 | /* |
| 28 | * First we let the BSP do some early initialization | |
| 2262cfee WD |
29 | * this code have to map the flash to its final position |
| 30 | */ | |
| 2262cfee | 31 | jmp board_init16 |
| 88fa0a6e | 32 | .globl board_init16_ret |
| 8bde7f77 WD |
33 | board_init16_ret: |
| 34 | ||
| 2262cfee | 35 | /* Turn of cache (this might require a 486-class CPU) */ |
| 53677ef1 | 36 | movl %cr0, %eax |
| 7b3d5380 | 37 | orl $(X86_CR0_NW | X86_CR0_CD), %eax |
| 53677ef1 | 38 | movl %eax, %cr0 |
| 8bde7f77 WD |
39 | wbinvd |
| 40 | ||
| c14a3669 | 41 | /* load the temporary Global Descriptor Table */ |
| 797960fd | 42 | o32 cs lidt idt_ptr |
| 53677ef1 | 43 | o32 cs lgdt gdt_ptr |
| 2262cfee | 44 | |
| 2262cfee | 45 | /* Now, we enter protected mode */ |
| 53677ef1 | 46 | movl %cr0, %eax |
| 0c24c9cc | 47 | orl $X86_CR0_PE, %eax |
| 53677ef1 | 48 | movl %eax, %cr0 |
| 8bde7f77 | 49 | |
| 2262cfee | 50 | /* Flush the prefetch queue */ |
| 53677ef1 | 51 | jmp ff |
| 2262cfee | 52 | ff: |
| 2262cfee | 53 | /* Finally jump to the 32bit initialization code */ |
| 8bde7f77 | 54 | movw $code32start, %ax |
| 8ffb2e8f | 55 | movw %ax, %bp |
| 2262cfee WD |
56 | o32 cs ljmp *(%bp) |
| 57 | ||
| 58 | /* 48-bit far pointer */ | |
| 59 | code32start: | |
| 53677ef1 WD |
60 | .long _start /* offset */ |
| 61 | .word 0x10 /* segment */ | |
| 2262cfee | 62 | |
| 797960fd GR |
63 | idt_ptr: |
| 64 | .word 0 /* limit */ | |
| 65 | .long 0 /* base */ | |
| 66 | ||
| c14a3669 GR |
67 | /* |
| 68 | * The following Global Descriptor Table is just enough to get us into | |
| 69 | * 'Flat Protected Mode' - It will be discarded as soon as the final | |
| 70 | * GDT is setup in a safe location in RAM | |
| 71 | */ | |
| 2262cfee | 72 | gdt_ptr: |
| c14a3669 | 73 | .word 0x20 /* limit (32 bytes = 4 GDT entries) */ |
| 53677ef1 | 74 | .long BOOT_SEG + gdt /* base */ |
| 2262cfee | 75 | |
| 58c7a675 GR |
76 | /* Some CPUs are picky about GDT alignment... */ |
| 77 | .align 16 | |
| 78 | gdt: | |
| 79 | /* | |
| 80 | * The GDT table ... | |
| 2262cfee | 81 | * |
| 53677ef1 WD |
82 | * Selector Type |
| 83 | * 0x00 NULL | |
| 84 | * 0x08 Unused | |
| 8bde7f77 | 85 | * 0x10 32bit code |
| 2262cfee | 86 | * 0x18 32bit data/stack |
| 2262cfee | 87 | */ |
| 58c7a675 GR |
88 | /* The NULL Desciptor - Mandatory */ |
| 89 | .word 0x0000 /* limit_low */ | |
| 90 | .word 0x0000 /* base_low */ | |
| 91 | .byte 0x00 /* base_middle */ | |
| 92 | .byte 0x00 /* access */ | |
| 93 | .byte 0x00 /* flags + limit_high */ | |
| 94 | .byte 0x00 /* base_high */ | |
| 2262cfee | 95 | |
| 58c7a675 GR |
96 | /* Unused Desciptor - (matches Linux) */ |
| 97 | .word 0x0000 /* limit_low */ | |
| 98 | .word 0x0000 /* base_low */ | |
| 99 | .byte 0x00 /* base_middle */ | |
| 100 | .byte 0x00 /* access */ | |
| 101 | .byte 0x00 /* flags + limit_high */ | |
| 102 | .byte 0x00 /* base_high */ | |
| 53677ef1 | 103 | |
| 58c7a675 GR |
104 | /* |
| 105 | * The Code Segment Descriptor: | |
| 106 | * - Base = 0x00000000 | |
| 107 | * - Size = 4GB | |
| 108 | * - Access = Present, Ring 0, Exec (Code), Readable | |
| 109 | * - Flags = 4kB Granularity, 32-bit | |
| 110 | */ | |
| 111 | .word 0xffff /* limit_low */ | |
| 112 | .word 0x0000 /* base_low */ | |
| 113 | .byte 0x00 /* base_middle */ | |
| 114 | .byte 0x9b /* access */ | |
| 115 | .byte 0xcf /* flags + limit_high */ | |
| 116 | .byte 0x00 /* base_high */ | |
| 53677ef1 | 117 | |
| 58c7a675 GR |
118 | /* |
| 119 | * The Data Segment Descriptor: | |
| 120 | * - Base = 0x00000000 | |
| 121 | * - Size = 4GB | |
| 122 | * - Access = Present, Ring 0, Non-Exec (Data), Writable | |
| 123 | * - Flags = 4kB Granularity, 32-bit | |
| 124 | */ | |
| 125 | .word 0xffff /* limit_low */ | |
| 126 | .word 0x0000 /* base_low */ | |
| 127 | .byte 0x00 /* base_middle */ | |
| 128 | .byte 0x93 /* access */ | |
| 129 | .byte 0xcf /* flags + limit_high */ | |
| 130 | .byte 0x00 /* base_high */ |