u-boot/arch/arm/cpu/arm_intcm/start.S

/*
 *  armboot - Startup Code for ARM926EJS CPU-core
 *
 *  Copyright (c) 2003  Texas Instruments
 *
 *  ----- Adapted for OMAP1610 OMAP730 from ARM925t code ------
 *
 *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
 *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
 *  Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
 *  Copyright (c) 2003	Richard Woodruff <r-woodruff2@ti.com>
 *  Copyright (c) 2003	Kshitij <kshitij@ti.com>
 *
 * 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
 */

#include <asm-offsets.h>
#include <config.h>
#include <version.h>

/*
 *************************************************************************
 *
 * Jump vector table
 *
 *************************************************************************
 */

.globl _start
_start:
	b	reset
	ldr	pc, _undefined_instruction
	ldr	pc, _software_interrupt
	ldr	pc, _prefetch_abort
	ldr	pc, _data_abort
	ldr	pc, _not_used
	ldr	pc, _irq
	ldr	pc, _fiq

_undefined_instruction:
	.word undefined_instruction
_software_interrupt:
	.word software_interrupt
_prefetch_abort:
	.word prefetch_abort
_data_abort:
	.word data_abort
_not_used:
	.word not_used
_irq:
	.word irq
_fiq:
	.word fiq

	.balignl 16,0xdeadbeef

/*
 *************************************************************************
 *
 * Startup Code (reset vector)
 *
 * do important init only if we don't start from memory!
 * setup memory and board specific bits prior to relocation.
 * relocate armboot to ram
 * setup stack
 *
 *************************************************************************
 */

.globl _TEXT_BASE
_TEXT_BASE:
	.word	CONFIG_SYS_TEXT_BASE /* address of _start in the linked image */

/*
 * These are defined in the board-specific linker script.
 */
.globl _bss_start
_bss_start:
	.word __bss_start

.globl _bss_end
_bss_end:
	.word _end

#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
	.word	0x0badc0de

/* IRQ stack memory (calculated at run-time) */
.globl FIQ_STACK_START
FIQ_STACK_START:
	.word 0x0badc0de
#endif

/* IRQ stack memory (calculated at run-time) + 8 bytes */
.globl IRQ_STACK_START_IN
IRQ_STACK_START_IN:
	.word	0x0badc0de

.globl _datarel_start
_datarel_start:
	.word __datarel_start

.globl _datarelrolocal_start
_datarelrolocal_start:
	.word __datarelrolocal_start

.globl _datarellocal_start
_datarellocal_start:
	.word __datarellocal_start

.globl _datarelro_start
_datarelro_start:
	.word __datarelro_start

.globl _got_start
_got_start:
	.word __got_start

.globl _got_end
_got_end:
	.word __got_end

/*
 * the actual reset code
 */

reset:
	/*
	 * set the cpu to SVC32 mode
	 */
	mrs	r0,cpsr
	bic	r0,r0,#0x1f
	orr	r0,r0,#0xd3
	msr	cpsr,r0

	/*
	 * we do sys-critical inits only at reboot,
	 * not when booting from ram!
	 */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	bl	cpu_init_crit
#endif

/* Set stackpointer in internal RAM to call board_init_f */
call_board_init_f:
	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
	ldr	r0,=0x00000000
	bl	board_init_f

/*------------------------------------------------------------------------------*/

/*
 * void relocate_code (addr_sp, gd, addr_moni)
 *
 * This "function" does not return, instead it continues in RAM
 * after relocating the monitor code.
 *
 */
	.globl	relocate_code
relocate_code:
	mov	r4, r0	/* save addr_sp */
	mov	r5, r1	/* save addr of gd */
	mov	r6, r2	/* save addr of destination */
	mov	r7, r2	/* save addr of destination */

	/* Set up the stack						    */
stack_setup:
	mov	sp, r4

	adr	r0, _start
	ldr	r2, _TEXT_BASE
	ldr	r3, _bss_start
	sub	r2, r3, r2		/* r2 <- size of armboot	    */
	add	r2, r0, r2		/* r2 <- source end address	    */
	cmp	r0, r6
	beq	clear_bss

copy_loop:
	ldmia	r0!, {r9-r10}		/* copy from source address [r0]    */
	stmia	r6!, {r9-r10}		/* copy to   target address [r1]    */
	cmp	r0, r2			/* until source end address [r2]    */
	blo	copy_loop

#ifndef CONFIG_PRELOADER
	/* fix got entries */
	ldr	r1, _TEXT_BASE		/* Text base */
	mov	r0, r7			/* reloc addr */
	ldr	r2, _got_start		/* addr in Flash */
	ldr	r3, _got_end		/* addr in Flash */
	sub	r3, r3, r1
	add	r3, r3, r0
	sub	r2, r2, r1
	add	r2, r2, r0

fixloop:
	ldr	r4, [r2]
	sub	r4, r4, r1
	add	r4, r4, r0
	str	r4, [r2]
	add	r2, r2, #4
	cmp	r2, r3
	blo	fixloop
#endif

clear_bss:
#ifndef CONFIG_PRELOADER
	ldr	r0, _bss_start
	ldr	r1, _bss_end
	ldr	r3, _TEXT_BASE		/* Text base */
	mov	r4, r7			/* reloc addr */
	sub	r0, r0, r3
	add	r0, r0, r4
	sub	r1, r1, r3
	add	r1, r1, r4
	mov	r2, #0x00000000		/* clear			    */

clbss_l:str	r2, [r0]		/* clear loop...		    */
	add	r0, r0, #4
	cmp	r0, r1
	bne	clbss_l

	bl coloured_LED_init
	bl red_LED_on
#endif

/*
 * We are done. Do not return, instead branch to second part of board
 * initialization, now running from RAM.
 */
	ldr	r0, _TEXT_BASE
	ldr	r2, _board_init_r
	sub	r2, r2, r0
	add	r2, r2, r7	/* position from board_init_r in RAM */
	/* setup parameters for board_init_r */
	mov	r0, r5		/* gd_t */
	mov	r1, r7		/* dest_addr */
	/* jump to it ... */
	mov	lr, r2
	mov	pc, lr

_board_init_r: .word board_init_r

/*
 *************************************************************************
 *
 * CPU_init_critical registers
 *
 * setup important registers
 * setup memory timing
 *
 *************************************************************************
 */

#ifndef CONFIG_SKIP_LOWLEVEL_INIT
cpu_init_crit:
	/*  arm_int_generic assumes the ARM boot monitor, or user software,
	 * has initialized the platform
	 */
	mov	pc, lr		/* back to my caller */
#endif
/*
 *************************************************************************
 *
 * Interrupt handling
 *
 *************************************************************************
 */

@
@ IRQ stack frame.
@
#define S_FRAME_SIZE	72

#define S_OLD_R0	68
#define S_PSR		64
#define S_PC		60
#define S_LR		56
#define S_SP		52

#define S_IP		48
#define S_FP		44
#define S_R10		40
#define S_R9		36
#define S_R8		32
#define S_R7		28
#define S_R6		24
#define S_R5		20
#define S_R4		16
#define S_R3		12
#define S_R2		8
#define S_R1		4
#define S_R0		0

#define MODE_SVC 0x13
#define I_BIT	 0x80

/*
 * use bad_save_user_regs for abort/prefetch/undef/swi ...
 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
 */

	.macro	bad_save_user_regs
	@ carve out a frame on current user stack
	sub	sp, sp, #S_FRAME_SIZE
	stmia	sp, {r0 - r12}	@ Save user registers (now in svc mode) r0-r12

	ldr	r2, IRQ_STACK_START_IN
	@ get values for "aborted" pc and cpsr (into parm regs)
	ldmia	r2, {r2 - r3}
	add	r0, sp, #S_FRAME_SIZE		@ grab pointer to old stack
	add	r5, sp, #S_SP
	mov	r1, lr
	stmia	r5, {r0 - r3}	@ save sp_SVC, lr_SVC, pc, cpsr
	mov	r0, sp		@ save current stack into r0 (param register)
	.endm

	.macro	irq_save_user_regs
	sub	sp, sp, #S_FRAME_SIZE
	stmia	sp, {r0 - r12}			@ Calling r0-r12
	@ !!!! R8 NEEDS to be saved !!!! a reserved stack spot would be good.
	add	r8, sp, #S_PC
	stmdb	r8, {sp, lr}^		@ Calling SP, LR
	str	lr, [r8, #0]		@ Save calling PC
	mrs	r6, spsr
	str	r6, [r8, #4]		@ Save CPSR
	str	r0, [r8, #8]		@ Save OLD_R0
	mov	r0, sp
	.endm

	.macro	irq_restore_user_regs
	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
	mov	r0, r0
	ldr	lr, [sp, #S_PC]			@ Get PC
	add	sp, sp, #S_FRAME_SIZE
	subs	pc, lr, #4		@ return & move spsr_svc into cpsr
	.endm

	.macro get_bad_stack
	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack

	str	lr, [r13]	@ save caller lr in position 0 of saved stack
	mrs	lr, spsr	@ get the spsr
	str	lr, [r13, #4]	@ save spsr in position 1 of saved stack
	mov	r13, #MODE_SVC	@ prepare SVC-Mode
	@ msr	spsr_c, r13
	msr	spsr, r13	@ switch modes, make sure moves will execute
	mov	lr, pc		@ capture return pc
	movs	pc, lr		@ jump to next instruction & switch modes.
	.endm

	.macro get_irq_stack			@ setup IRQ stack
	ldr	sp, IRQ_STACK_START
	.endm

	.macro get_fiq_stack			@ setup FIQ stack
	ldr	sp, FIQ_STACK_START
	.endm

/*
 * exception handlers
 */
	.align  5
.globl undefined_instruction
undefined_instruction:
	get_bad_stack
	bad_save_user_regs
	bl	do_undefined_instruction

	.align	5
.globl software_interrupt
software_interrupt:
	get_bad_stack
	bad_save_user_regs
	bl	do_software_interrupt

	.align	5
.globl prefetch_abort
prefetch_abort:
	get_bad_stack
	bad_save_user_regs
	bl	do_prefetch_abort

	.align	5
.globl data_abort
data_abort:
	get_bad_stack
	bad_save_user_regs
	bl	do_data_abort

	.align	5
.globl not_used
not_used:
	get_bad_stack
	bad_save_user_regs
	bl	do_not_used

#ifdef CONFIG_USE_IRQ
	.align	5
.globl irq
irq:
	get_irq_stack
	irq_save_user_regs
	bl	do_irq
	irq_restore_user_regs

	.align	5
.globl fiq
fiq:
	get_fiq_stack
	/* someone ought to write a more effiction fiq_save_user_regs */
	irq_save_user_regs
	bl	do_fiq
	irq_restore_user_regs

#else

	.align	5
.globl irq
irq:
	get_bad_stack
	bad_save_user_regs
	bl	do_irq

	.align	5
.globl fiq
fiq:
	get_bad_stack
	bad_save_user_regs
	bl	do_fiq

#endif