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freebsd/sys/boot/arm/uboot/start.S
2013-11-24 20:33:38 +00:00

101 lines
2.6 KiB
ArmAsm

/*-
* Copyright (c) 2008 Semihalf, Rafal Czubak
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <machine/asm.h>
#include <machine/armreg.h>
/*
* Entry point to the loader that U-Boot passes control to.
*/
.text
.globl _start
_start:
/* Hint where to look for the API signature */
ldr ip, =uboot_address
str sp, [ip]
/* Save U-Boot's r8 and r9 */
ldr ip, =saved_regs
str r8, [ip, #0]
str r9, [ip, #4]
#ifdef _ARM_ARCH_6
mrc p15, 0, r2, c1, c0, 0
orr r2, r2, #(CPU_CONTROL_UNAL_ENABLE)
orr r2, r2, #(CPU_CONTROL_AFLT_ENABLE)
mcr p15, 0, r2, c1, c0, 0
#endif
/* Start loader */
b main
/*
* syscall()
*/
ENTRY(syscall)
/* Save caller's lr, r8 and r9 */
ldr ip, =saved_regs
str r8, [ip, #8]
str r9, [ip, #12]
str lr, [ip, #16]
/* Restore U-Boot's r8 and r9 */
ldr r8, [ip, #0]
ldr r9, [ip, #4]
/* Call into U-Boot */
ldr lr, =return_from_syscall
ldr ip, =syscall_ptr
ldr pc, [ip]
return_from_syscall:
/* Restore loader's r8, r9 and lr */
ldr ip, =saved_regs
ldr lr, [ip, #16]
ldr r9, [ip, #12]
ldr r8, [ip, #8]
/* Return to caller */
mov pc, lr
/*
* Data section
*/
.data
.align 4
.globl syscall_ptr
syscall_ptr:
.long 0
.globl uboot_address
uboot_address:
.long 0
saved_regs:
.long 0 /* U-Boot's r8 */
.long 0 /* U-Boot's r9 */
.long 0 /* Loader's r8 */
.long 0 /* Loader's r9 */
.long 0 /* Loader's lr */