Merge branch 'master' of git://git.denx.de/u-boot-blackfin

[oweals/u-boot.git] / arch / x86 / cpu / start16.S

diff --git a/arch/x86/cpu/start16.S b/arch/x86/cpu/start16.S
index 9dabff2b9f3309f2253ead84d28130f7a28066f0..826e2b43615dbfd6775cd22ec08d58266a26913b 100644 (file)
--- a/arch/x86/cpu/start16.S
+++ b/arch/x86/cpu/start16.S
@@ -1,5 +1,5 @@
 /*
- *  U-boot - x86 Startup Code
+ *  U-Boot - x86 Startup Code
  *
  * (C) Copyright 2008-2011
  * Graeme Russ, <graeme.russ@gmail.com>
@@ -7,23 +7,7 @@
  * (C) Copyright 2002,2003
  * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
  *
- * See file CREDITS for list of people who contributed to this
- * project.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of
- * the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- * MA 02111-1307 USA
+ * SPDX-License-Identifier:    GPL-2.0+
  */
 
 #include <asm/global_data.h>
@@ -37,18 +21,16 @@
 .code16
 .globl start16
 start16:
+       /* Save BIST */
+       movl    %eax, %ecx
+
        /* Set the Cold Boot / Hard Reset flag */
        movl    $GD_FLG_COLD_BOOT, %ebx
 
-       /*
-        * First we let the BSP do some early initialization
-        * this code have to map the flash to its final position
-        */
-       jmp     board_init16
-.globl board_init16_ret
-board_init16_ret:
+       xorl    %eax, %eax
+       movl    %eax, %cr3      /* Invalidate TLB */
 
-       /* Turn of cache (this might require a 486-class CPU) */
+       /* Turn off cache (this might require a 486-class CPU) */
        movl    %cr0, %eax
        orl     $(X86_CR0_NW | X86_CR0_CD), %eax
        movl    %eax, %cr0
@@ -66,9 +48,11 @@ o32 cs       lgdt    gdt_ptr
        /* Flush the prefetch queue */
        jmp     ff
 ff:
-       /* Finally jump to the 32bit initialization code */
+
+       /* Finally restore BIST and jump to the 32-bit initialization code */
        movw    $code32start, %ax
        movw    %ax, %bp
+       movl    %ecx, %eax
 o32 cs ljmp    *(%bp)
 
        /* 48-bit far pointer */
@@ -80,16 +64,20 @@ idt_ptr:
        .word   0               /* limit */
        .long   0               /* base */
 
-/*
- * The following Global Descriptor Table is just enough to get us into
- * 'Flat Protected Mode' - It will be discarded as soon as the final
- * GDT is setup in a safe location in RAM
- */
+       /*
+        * The following Global Descriptor Table is just enough to get us into
+        * 'Flat Protected Mode' - It will be discarded as soon as the final
+        * GDT is setup in a safe location in RAM
+        */
 gdt_ptr:
-       .word   0x20            /* limit (32 bytes = 4 GDT entries) */
+       .word   0x1f            /* limit (31 bytes = 4 GDT entries - 1) */
        .long   BOOT_SEG + gdt  /* base */
 
-       /* The GDT table ...
+       /* Some CPUs are picky about GDT alignment... */
+       .align  16
+gdt:
+       /*
+        * The GDT table ...
         *
         *       Selector       Type
         *       0x00           NULL
@@ -97,17 +85,46 @@ gdt_ptr:
         *       0x10           32bit code
         *       0x18           32bit data/stack
         */
+       /* The NULL Desciptor - Mandatory */
+       .word   0x0000          /* limit_low */
+       .word   0x0000          /* base_low */
+       .byte   0x00            /* base_middle */
+       .byte   0x00            /* access */
+       .byte   0x00            /* flags + limit_high */
+       .byte   0x00            /* base_high */
 
-gdt:
-       .word   0, 0, 0, 0      /* NULL  */
-       .word   0, 0, 0, 0      /* unused */
-
-       .word   0xFFFF          /* 4Gb - (0x100000*0x1000 = 4Gb) */
-       .word   0               /* base address = 0 */
-       .word   0x9B00          /* code read/exec */
-       .word   0x00CF          /* granularity = 4096, 386 (+5th nibble of limit) */
-
-       .word   0xFFFF          /* 4Gb - (0x100000*0x1000 = 4Gb) */
-       .word   0x0             /* base address = 0 */
-       .word   0x9300          /* data read/write */
-       .word   0x00CF          /* granularity = 4096, 386 (+5th nibble of limit) */
+       /* Unused Desciptor - (matches Linux) */
+       .word   0x0000          /* limit_low */
+       .word   0x0000          /* base_low */
+       .byte   0x00            /* base_middle */
+       .byte   0x00            /* access */
+       .byte   0x00            /* flags + limit_high */
+       .byte   0x00            /* base_high */
+
+       /*
+        * The Code Segment Descriptor:
+        * - Base   = 0x00000000
+        * - Size   = 4GB
+        * - Access = Present, Ring 0, Exec (Code), Readable
+        * - Flags  = 4kB Granularity, 32-bit
+        */
+       .word   0xffff          /* limit_low */
+       .word   0x0000          /* base_low */
+       .byte   0x00            /* base_middle */
+       .byte   0x9b            /* access */
+       .byte   0xcf            /* flags + limit_high */
+       .byte   0x00            /* base_high */
+
+       /*
+        * The Data Segment Descriptor:
+        * - Base   = 0x00000000
+        * - Size   = 4GB
+        * - Access = Present, Ring 0, Non-Exec (Data), Writable
+        * - Flags  = 4kB Granularity, 32-bit
+        */
+       .word   0xffff          /* limit_low */
+       .word   0x0000          /* base_low */
+       .byte   0x00            /* base_middle */
+       .byte   0x93            /* access */
+       .byte   0xcf            /* flags + limit_high */
+       .byte   0x00            /* base_high */