u-boot/arch/i386/cpu/cpu.c
Graeme Russ 59c6d0ef9a x86: Move loading of GTD to C code
Linux has C macros and code to load the GTD after switching to Protected
Mode. Using these greatly simplifies the assembler code
2010-10-07 20:03:21 +11:00

149 lines
4.1 KiB
C

/*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, daniel@omicron.se.
*
* (C) Copyright 2002
* Sysgo Real-Time Solutions, GmbH <www.elinos.com>
* Marius Groeger <mgroeger@sysgo.de>
*
* (C) Copyright 2002
* Sysgo Real-Time Solutions, GmbH <www.elinos.com>
* Alex Zuepke <azu@sysgo.de>
*
* 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
*/
/*
* CPU specific code
*/
#include <common.h>
#include <command.h>
#include <asm/interrupt.h>
/* Constructor for a conventional segment GDT (or LDT) entry */
/* This is a macro so it can be used in initializers */
#define GDT_ENTRY(flags, base, limit) \
((((base) & 0xff000000ULL) << (56-24)) | \
(((flags) & 0x0000f0ffULL) << 40) | \
(((limit) & 0x000f0000ULL) << (48-16)) | \
(((base) & 0x00ffffffULL) << 16) | \
(((limit) & 0x0000ffffULL)))
/* Simple and small GDT entries for booting only */
#define GDT_ENTRY_32BIT_CS 2
#define GDT_ENTRY_32BIT_DS (GDT_ENTRY_32BIT_CS + 1)
#define GDT_ENTRY_16BIT_CS (GDT_ENTRY_32BIT_DS + 1)
#define GDT_ENTRY_16BIT_DS (GDT_ENTRY_16BIT_CS + 1)
/*
* Set up the GDT
*/
struct gdt_ptr {
u16 len;
u32 ptr;
} __attribute__((packed));
static void reload_gdt(void)
{
/* There are machines which are known to not boot with the GDT
being 8-byte unaligned. Intel recommends 16 byte alignment. */
static const u64 boot_gdt[] __attribute__((aligned(16))) = {
/* CS: code, read/execute, 4 GB, base 0 */
[GDT_ENTRY_32BIT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
/* DS: data, read/write, 4 GB, base 0 */
[GDT_ENTRY_32BIT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
/* 16-bit CS: code, read/execute, 64 kB, base 0 */
[GDT_ENTRY_16BIT_CS] = GDT_ENTRY(0x109b, 0, 0x0ffff),
/* 16-bit DS: data, read/write, 64 kB, base 0 */
[GDT_ENTRY_16BIT_DS] = GDT_ENTRY(0x1093, 0, 0x0ffff),
};
static struct gdt_ptr gdt;
gdt.len = sizeof(boot_gdt)-1;
gdt.ptr = (u32)&boot_gdt;
asm volatile("lgdtl %0\n" \
"movl $((2+1)*8), %%ecx\n" \
"movl %%ecx, %%ds\n" \
"movl %%ecx, %%es\n" \
"movl %%ecx, %%fs\n" \
"movl %%ecx, %%gs\n" \
"movl %%ecx, %%ss" \
: : "m" (gdt) : "ecx");
}
int cpu_init_f(void)
{
/* initialize FPU, reset EM, set MP and NE */
asm ("fninit\n" \
"movl %cr0, %eax\n" \
"andl $~0x4, %eax\n" \
"orl $0x22, %eax\n" \
"movl %eax, %cr0\n" );
return 0;
}
int cpu_init_r(void)
{
reload_gdt();
/* Initialize core interrupt and exception functionality of CPU */
cpu_init_interrupts ();
return 0;
}
int do_reset(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
printf ("resetting ...\n");
udelay(50000); /* wait 50 ms */
disable_interrupts();
reset_cpu(0);
/*NOTREACHED*/
return 0;
}
void flush_cache (unsigned long dummy1, unsigned long dummy2)
{
asm("wbinvd\n");
return;
}
void __attribute__ ((regparm(0))) generate_gpf(void);
/* segment 0x70 is an arbitrary segment which does not exist */
asm(".globl generate_gpf\n"
".hidden generate_gpf\n"
".type generate_gpf, @function\n"
"generate_gpf:\n"
"ljmp $0x70, $0x47114711\n");
void __reset_cpu(ulong addr)
{
printf("Resetting using i386 Triple Fault\n");
set_vector(13, generate_gpf); /* general protection fault handler */
set_vector(8, generate_gpf); /* double fault handler */
generate_gpf(); /* start the show */
}
void reset_cpu(ulong addr) __attribute__((weak, alias("__reset_cpu")));