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/**
* @file
*
* @brief Boot and system start code.
*/
/*
* Copyright (c) 2008-2013 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Obere Lagerstr. 30
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#include <rtems/asm.h>
#include <rtems/system.h>
#include <rtems/score/cpu.h>
#include <bspopts.h>
#include <bsp/irq.h>
#include <bsp/linker-symbols.h>
/* External symbols */
.extern bsp_reset
.extern boot_card
.extern bsp_start_hook_0
.extern bsp_start_hook_1
.extern _ARMV4_Exception_undef_default
.extern _ARMV4_Exception_swi_default
.extern _ARMV4_Exception_data_abort_default
.extern _ARMV4_Exception_pref_abort_default
.extern _ARMV4_Exception_reserved_default
.extern _ARMV4_Exception_irq_default
.extern _ARMV4_Exception_fiq_default
/* Global symbols */
.globl _start
.globl bsp_start_vector_table_begin
.globl bsp_start_vector_table_end
.globl bsp_start_vector_table_size
.globl bsp_vector_table_size
.section ".bsp_start_text", "ax"
#if defined(ARM_MULTILIB_ARCH_V4)
.arm
/*
* This is the exception vector table and the pointers to the default
* exceptions handlers.
*/
bsp_start_vector_table_begin:
ldr pc, handler_addr_reset
ldr pc, handler_addr_undef
ldr pc, handler_addr_swi
ldr pc, handler_addr_prefetch
ldr pc, handler_addr_abort
/* Program signature checked by boot loader */
.word 0xb8a06f58
ldr pc, handler_addr_irq
ldr pc, handler_addr_fiq
handler_addr_reset:
#ifdef BSP_START_RESET_VECTOR
.word BSP_START_RESET_VECTOR
#else
.word _start
#endif
handler_addr_undef:
.word _ARMV4_Exception_undef_default
handler_addr_swi:
.word _ARMV4_Exception_swi_default
handler_addr_prefetch:
.word _ARMV4_Exception_data_abort_default
handler_addr_abort:
.word _ARMV4_Exception_pref_abort_default
handler_addr_reserved:
.word _ARMV4_Exception_reserved_default
handler_addr_irq:
.word _ARMV4_Exception_irq_default
handler_addr_fiq:
.word _ARMV4_Exception_fiq_default
bsp_start_vector_table_end:
/* Start entry */
_start:
/*
* We do not save the context since we do not return to the boot
* loader.
*/
/*
* Set SVC mode, disable interrupts and enable ARM instructions.
*/
mov r0, #(ARM_PSR_M_SVC | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
/* Initialize stack pointer registers for the various modes */
/* Enter IRQ mode and set up the IRQ stack pointer */
mov r0, #(ARM_PSR_M_IRQ | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
ldr sp, =bsp_stack_irq_end
/* Enter FIQ mode and set up the FIQ stack pointer */
mov r0, #(ARM_PSR_M_FIQ | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
ldr sp, =bsp_stack_fiq_end
/* Enter ABT mode and set up the ABT stack pointer */
mov r0, #(ARM_PSR_M_ABT | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
ldr sp, =bsp_stack_abt_end
/* Enter UND mode and set up the UND stack pointer */
mov r0, #(ARM_PSR_M_UND | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
ldr sp, =bsp_stack_und_end
/* Enter SVC mode and set up the SVC stack pointer */
mov r0, #(ARM_PSR_M_SVC | ARM_PSR_I | ARM_PSR_F)
msr cpsr, r0
ldr sp, =bsp_stack_svc_end
/* Stay in SVC mode */
/*
* Branch to start hook 0.
*
* The previous code and parts of the start hook 0 may run with an
* address offset. This implies that only branches relative to the
* program counter are allowed. After the start hook 0 it is assumed
* that the code can run at its intended position. Thus the link
* register will be loaded with the absolute address. In THUMB mode
* the start hook 0 must be within a 2kByte range due to the branch
* instruction limitation.
*/
ldr lr, =bsp_start_hook_0_done
#ifdef __thumb__
orr lr, #1
#endif
SWITCH_FROM_ARM_TO_THUMB r0
b bsp_start_hook_0
bsp_start_hook_0_done:
SWITCH_FROM_THUMB_TO_ARM
/*
* Initialize the exception vectors. This includes the exceptions
* vectors and the pointers to the default exception handlers.
*/
ldr r0, =bsp_vector_table_begin
adr r1, bsp_start_vector_table_begin
ldmia r1!, {r2-r9}
stmia r0!, {r2-r9}
ldmia r1!, {r2-r9}
stmia r0!, {r2-r9}
SWITCH_FROM_ARM_TO_THUMB r0
/* Branch to start hook 1 */
bl bsp_start_hook_1
/* Branch to boot card */
mov r0, #0
bl boot_card
twiddle:
/* Branch to reset function */
bl bsp_reset
b twiddle
#elif defined(ARM_MULTILIB_ARCH_V7M)
.syntax unified
.extern bsp_stack_main_end
.thumb
bsp_start_vector_table_begin:
.word bsp_stack_main_end
.word _start /* Reset */
.word bsp_reset /* NMI */
.word bsp_reset /* Hard Fault */
.word bsp_reset /* MPU Fault */
.word bsp_reset /* Bus Fault */
.word bsp_reset /* Usage Fault */
.word bsp_reset /* Reserved */
.word bsp_reset /* Reserved */
.word bsp_reset /* Reserved */
.word bsp_reset /* Reserved */
.word bsp_reset /* SVC */
.word bsp_reset /* Debug Monitor */
.word bsp_reset /* Reserved */
.word bsp_reset /* PendSV */
.word bsp_reset /* SysTick */
.rept BSP_INTERRUPT_VECTOR_MAX + 1
.word bsp_reset /* IRQ */
.endr
bsp_start_vector_table_end:
.thumb_func
_start:
ldr sp, =bsp_stack_main_end
ldr lr, =bsp_start_hook_0_done + 1
b bsp_start_hook_0
bsp_start_hook_0_done:
bl bsp_start_hook_1
movs r0, #0
bl boot_card
twiddle:
bl bsp_reset
b twiddle
#endif /* defined(ARM_MULTILIB_ARCH_V7M) */
.set bsp_start_vector_table_size, bsp_start_vector_table_end - bsp_start_vector_table_begin
.set bsp_vector_table_size, bsp_start_vector_table_size
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