arch/arm/cpu/arm920t/start.S - github/trini/u-boot - Gitiles

 /*
  *  armboot - Startup Code for ARM920 CPU-core
  *
  *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
  *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
  *  Copyright (c) 2002	Gary Jennejohn <garyj@denx.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
  */

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

 /*
  *************************************************************************
  *
  * Jump vector table as in table 3.1 in [1]
  *
  *************************************************************************
  */


 .globl _start
 _start:	b	start_code
 	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 (called from the ARM reset exception vector)
  *
  * do important init only if we don't start from memory!
  * relocate armboot to ram
  * setup stack
  * jump to second stage
  *
  *************************************************************************
  */

 .globl _TEXT_BASE
 _TEXT_BASE:
 #if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
 	.word	CONFIG_SPL_TEXT_BASE
 #else
 	.word	CONFIG_SYS_TEXT_BASE
 #endif

 /*
  * These are defined in the board-specific linker script.
  * Subtracting _start from them lets the linker put their
  * relative position in the executable instead of leaving
  * them null.
  */
 .globl _bss_start_ofs
 _bss_start_ofs:
 	.word __bss_start - _start

 .globl _image_copy_end_ofs
 _image_copy_end_ofs:
 	.word __image_copy_end - _start

 .globl _bss_end_ofs
 _bss_end_ofs:
 	.word __bss_end - _start

 .globl _end_ofs
 _end_ofs:
 	.word _end - _start

 #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

 /*
  * the actual start code
  */

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

 #if	defined(CONFIG_AT91RM9200DK) || defined(CONFIG_AT91RM9200EK)
 	/*
 	 * relocate exception table
 	 */
 	ldr	r0, =_start
 	ldr	r1, =0x0
 	mov	r2, #16
 copyex:
 	subs	r2, r2, #1
 	ldr	r3, [r0], #4
 	str	r3, [r1], #4
 	bne	copyex
 #endif

 #ifdef CONFIG_S3C24X0
 	/* turn off the watchdog */

 # if defined(CONFIG_S3C2400)
 #  define pWTCON	0x15300000
 #  define INTMSK	0x14400008	/* Interrupt-Controller base addresses */
 #  define CLKDIVN	0x14800014	/* clock divisor register */
 #else
 #  define pWTCON	0x53000000
 #  define INTMSK	0x4A000008	/* Interrupt-Controller base addresses */
 #  define INTSUBMSK	0x4A00001C
 #  define CLKDIVN	0x4C000014	/* clock divisor register */
 # endif

 	ldr	r0, =pWTCON
 	mov	r1, #0x0
 	str	r1, [r0]

 	/*
 	 * mask all IRQs by setting all bits in the INTMR - default
 	 */
 	mov	r1, #0xffffffff
 	ldr	r0, =INTMSK
 	str	r1, [r0]
 # if defined(CONFIG_S3C2410)
 	ldr	r1, =0x3ff
 	ldr	r0, =INTSUBMSK
 	str	r1, [r0]
 # endif

 	/* FCLK:HCLK:PCLK = 1:2:4 */
 	/* default FCLK is 120 MHz ! */
 	ldr	r0, =CLKDIVN
 	mov	r1, #3
 	str	r1, [r0]
 #endif	/* CONFIG_S3C24X0 */

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

 	bl	_main

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

 /*
  * void relocate_code(addr_moni)
  *
  * This function relocates the monitor code.
  */
 	.globl	relocate_code
 relocate_code:
 	mov	r6, r0	/* save addr of destination */

 	adr	r0, _start
 	subs	r9, r6, r0		/* r9 <- relocation offset */
 	beq	relocate_done		/* skip relocation */
 	mov	r1, r6			/* r1 <- scratch for copy_loop */
 	ldr	r3, _image_copy_end_ofs
 	add	r2, r0, r3		/* r2 <- source end address	    */

 copy_loop:
 	ldmia	r0!, {r10-r11}		/* copy from source address [r0]    */
 	stmia	r1!, {r10-r11}		/* copy to   target address [r1]    */
 	cmp	r0, r2			/* until source end address [r2]    */
 	blo	copy_loop

 #ifndef CONFIG_SPL_BUILD
 	/*
 	 * fix .rel.dyn relocations
 	 */
 	ldr	r0, _TEXT_BASE		/* r0 <- Text base */
 	ldr	r10, _dynsym_start_ofs	/* r10 <- sym table ofs */
 	add	r10, r10, r0		/* r10 <- sym table in FLASH */
 	ldr	r2, _rel_dyn_start_ofs	/* r2 <- rel dyn start ofs */
 	add	r2, r2, r0		/* r2 <- rel dyn start in FLASH */
 	ldr	r3, _rel_dyn_end_ofs	/* r3 <- rel dyn end ofs */
 	add	r3, r3, r0		/* r3 <- rel dyn end in FLASH */
 fixloop:
 	ldr	r0, [r2]		/* r0 <- location to fix up, IN FLASH! */
 	add	r0, r0, r9		/* r0 <- location to fix up in RAM */
 	ldr	r1, [r2, #4]
 	and	r7, r1, #0xff
 	cmp	r7, #23			/* relative fixup? */
 	beq	fixrel
 	cmp	r7, #2			/* absolute fixup? */
 	beq	fixabs
 	/* ignore unknown type of fixup */
 	b	fixnext
 fixabs:
 	/* absolute fix: set location to (offset) symbol value */
 	mov	r1, r1, LSR #4		/* r1 <- symbol index in .dynsym */
 	add	r1, r10, r1		/* r1 <- address of symbol in table */
 	ldr	r1, [r1, #4]		/* r1 <- symbol value */
 	add	r1, r1, r9		/* r1 <- relocated sym addr */
 	b	fixnext
 fixrel:
 	/* relative fix: increase location by offset */
 	ldr	r1, [r0]
 	add	r1, r1, r9
 fixnext:
 	str	r1, [r0]
 	add	r2, r2, #8		/* each rel.dyn entry is 8 bytes */
 	cmp	r2, r3
 	blo	fixloop
 #endif

 relocate_done:

 	mov	pc, lr

 _rel_dyn_start_ofs:
 	.word __rel_dyn_start - _start
 _rel_dyn_end_ofs:
 	.word __rel_dyn_end - _start
 _dynsym_start_ofs:
 	.word __dynsym_start - _start

 	.globl	c_runtime_cpu_setup
 c_runtime_cpu_setup:

 	mov	pc, lr

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


 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 cpu_init_crit:
 	/*
 	 * flush v4 I/D caches
 	 */
 	mov	r0, #0
 	mcr	p15, 0, r0, c7, c7, 0	/* flush v3/v4 cache */
 	mcr	p15, 0, r0, c8, c7, 0	/* flush v4 TLB */

 	/*
 	 * disable MMU stuff and caches
 	 */
 	mrc	p15, 0, r0, c1, c0, 0
 	bic	r0, r0, #0x00002300	@ clear bits 13, 9:8 (--V- --RS)
 	bic	r0, r0, #0x00000087	@ clear bits 7, 2:0 (B--- -CAM)
 	orr	r0, r0, #0x00000002	@ set bit 2 (A) Align
 	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-Cache
 	mcr	p15, 0, r0, c1, c0, 0

 	/*
 	 * before relocating, we have to setup RAM timing
 	 * because memory timing is board-dependend, you will
 	 * find a lowlevel_init.S in your board directory.
 	 */
 	mov	ip, lr

 	bl	lowlevel_init

 	mov	lr, ip
 	mov	pc, lr
 #endif /* CONFIG_SKIP_LOWLEVEL_INIT */

 /*
  *************************************************************************
  *
  * 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
 	sub	sp, sp, #S_FRAME_SIZE
 	stmia	sp, {r0 - r12}			@ Calling r0-r12
 	ldr	r2, IRQ_STACK_START_IN
 	ldmia	r2, {r2 - r3}			@ get pc, cpsr
 	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC

 	add	r5, sp, #S_SP
 	mov	r1, lr
 	stmia	r5, {r0 - r3}			@ save sp_SVC, lr_SVC, pc, cpsr
 	mov	r0, sp
 	.endm

 	.macro	irq_save_user_regs
 	sub	sp, sp, #S_FRAME_SIZE
 	stmia	sp, {r0 - r12}			@ Calling r0-r12
 	add	r7, sp, #S_PC
 	stmdb	r7, {sp, lr}^			@ Calling SP, LR
 	str	lr, [r7, #0]			@ Save calling PC
 	mrs	r6, spsr
 	str	r6, [r7, #4]			@ Save CPSR
 	str	r0, [r7, #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
 	/* return & move spsr_svc into cpsr */
 	subs	pc, lr, #4
 	.endm

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

 	str	lr, [r13]			@ save caller lr / spsr
 	mrs	lr, spsr
 	str	lr, [r13, #4]

 	mov	r13, #MODE_SVC			@ prepare SVC-Mode
 	@ msr	spsr_c, r13
 	msr	spsr, r13
 	mov	lr, pc
 	movs	pc, lr
 	.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
 undefined_instruction:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_undefined_instruction

 	.align	5
 software_interrupt:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_software_interrupt

 	.align	5
 prefetch_abort:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_prefetch_abort

 	.align	5
 data_abort:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_data_abort

 	.align	5
 not_used:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_not_used

 #ifdef CONFIG_USE_IRQ

 	.align	5
 irq:
 	get_irq_stack
 	irq_save_user_regs
 	bl	do_irq
 	irq_restore_user_regs

 	.align	5
 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
 irq:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_irq

 	.align	5
 fiq:
 	get_bad_stack
 	bad_save_user_regs
 	bl	do_fiq

 #endif
	/*
	* armboot - Startup Code for ARM920 CPU-core
	*
	* Copyright (c) 2001 Marius Gröger <mag@sysgo.de>
	* Copyright (c) 2002 Alex Züpke <azu@sysgo.de>
	* Copyright (c) 2002 Gary Jennejohn <garyj@denx.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
	*/

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

	/*
	*************************************************************************
	*
	* Jump vector table as in table 3.1 in [1]
	*
	*************************************************************************
	*/


	.globl _start
	_start: b start_code
	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 (called from the ARM reset exception vector)
	*
	* do important init only if we don't start from memory!
	* relocate armboot to ram
	* setup stack
	* jump to second stage
	*
	*************************************************************************
	*/

	.globl _TEXT_BASE
	_TEXT_BASE:
	#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
	.word CONFIG_SPL_TEXT_BASE
	#else
	.word CONFIG_SYS_TEXT_BASE
	#endif

	/*
	* These are defined in the board-specific linker script.
	* Subtracting _start from them lets the linker put their
	* relative position in the executable instead of leaving
	* them null.
	*/
	.globl _bss_start_ofs
	_bss_start_ofs:
	.word __bss_start - _start

	.globl _image_copy_end_ofs
	_image_copy_end_ofs:
	.word __image_copy_end - _start

	.globl _bss_end_ofs
	_bss_end_ofs:
	.word __bss_end - _start

	.globl _end_ofs
	_end_ofs:
	.word _end - _start

	#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

	/*
	* the actual start code
	*/

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

	#if defined(CONFIG_AT91RM9200DK) \|\| defined(CONFIG_AT91RM9200EK)
	/*
	* relocate exception table
	*/
	ldr r0, =_start
	ldr r1, =0x0
	mov r2, #16
	copyex:
	subs r2, r2, #1
	ldr r3, [r0], #4
	str r3, [r1], #4
	bne copyex
	#endif

	#ifdef CONFIG_S3C24X0
	/* turn off the watchdog */

	# if defined(CONFIG_S3C2400)
	# define pWTCON 0x15300000
	# define INTMSK 0x14400008 /* Interrupt-Controller base addresses */
	# define CLKDIVN 0x14800014 /* clock divisor register */
	#else
	# define pWTCON 0x53000000
	# define INTMSK 0x4A000008 /* Interrupt-Controller base addresses */
	# define INTSUBMSK 0x4A00001C
	# define CLKDIVN 0x4C000014 /* clock divisor register */
	# endif

	ldr r0, =pWTCON
	mov r1, #0x0
	str r1, [r0]

	/*
	* mask all IRQs by setting all bits in the INTMR - default
	*/
	mov r1, #0xffffffff
	ldr r0, =INTMSK
	str r1, [r0]
	# if defined(CONFIG_S3C2410)
	ldr r1, =0x3ff
	ldr r0, =INTSUBMSK
	str r1, [r0]
	# endif

	/* FCLK:HCLK:PCLK = 1:2:4 */
	/* default FCLK is 120 MHz ! */
	ldr r0, =CLKDIVN
	mov r1, #3
	str r1, [r0]
	#endif /* CONFIG_S3C24X0 */

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

	bl _main

	/------------------------------------------------------------------------------/

	/*
	* void relocate_code(addr_moni)
	*
	* This function relocates the monitor code.
	*/
	.globl relocate_code
	relocate_code:
	mov r6, r0 /* save addr of destination */

	adr r0, _start
	subs r9, r6, r0 /* r9 <- relocation offset */
	beq relocate_done /* skip relocation */
	mov r1, r6 /* r1 <- scratch for copy_loop */
	ldr r3, _image_copy_end_ofs
	add r2, r0, r3 /* r2 <- source end address */

	copy_loop:
	ldmia r0!, {r10-r11} /* copy from source address [r0] */
	stmia r1!, {r10-r11} /* copy to target address [r1] */
	cmp r0, r2 /* until source end address [r2] */
	blo copy_loop

	#ifndef CONFIG_SPL_BUILD
	/*
	* fix .rel.dyn relocations
	*/
	ldr r0, _TEXT_BASE /* r0 <- Text base */
	ldr r10, _dynsym_start_ofs /* r10 <- sym table ofs */
	add r10, r10, r0 /* r10 <- sym table in FLASH */
	ldr r2, _rel_dyn_start_ofs /* r2 <- rel dyn start ofs */
	add r2, r2, r0 /* r2 <- rel dyn start in FLASH */
	ldr r3, _rel_dyn_end_ofs /* r3 <- rel dyn end ofs */
	add r3, r3, r0 /* r3 <- rel dyn end in FLASH */
	fixloop:
	ldr r0, [r2] /* r0 <- location to fix up, IN FLASH! */
	add r0, r0, r9 /* r0 <- location to fix up in RAM */
	ldr r1, [r2, #4]
	and r7, r1, #0xff
	cmp r7, #23 /* relative fixup? */
	beq fixrel
	cmp r7, #2 /* absolute fixup? */
	beq fixabs
	/* ignore unknown type of fixup */
	b fixnext
	fixabs:
	/* absolute fix: set location to (offset) symbol value */
	mov r1, r1, LSR #4 /* r1 <- symbol index in .dynsym */
	add r1, r10, r1 /* r1 <- address of symbol in table */
	ldr r1, [r1, #4] /* r1 <- symbol value */
	add r1, r1, r9 /* r1 <- relocated sym addr */
	b fixnext
	fixrel:
	/* relative fix: increase location by offset */
	ldr r1, [r0]
	add r1, r1, r9
	fixnext:
	str r1, [r0]
	add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
	cmp r2, r3
	blo fixloop
	#endif

	relocate_done:

	mov pc, lr

	_rel_dyn_start_ofs:
	.word __rel_dyn_start - _start
	_rel_dyn_end_ofs:
	.word __rel_dyn_end - _start
	_dynsym_start_ofs:
	.word __dynsym_start - _start

	.globl c_runtime_cpu_setup
	c_runtime_cpu_setup:

	mov pc, lr

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


	#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	cpu_init_crit:
	/*
	* flush v4 I/D caches
	*/
	mov r0, #0
	mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */
	mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */

	/*
	* disable MMU stuff and caches
	*/
	mrc p15, 0, r0, c1, c0, 0
	bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
	bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
	orr r0, r0, #0x00000002 @ set bit 2 (A) Align
	orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
	mcr p15, 0, r0, c1, c0, 0

	/*
	* before relocating, we have to setup RAM timing
	* because memory timing is board-dependend, you will
	* find a lowlevel_init.S in your board directory.
	*/
	mov ip, lr

	bl lowlevel_init

	mov lr, ip
	mov pc, lr
	#endif /* CONFIG_SKIP_LOWLEVEL_INIT */

	/*
	*************************************************************************
	*
	* 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
	sub sp, sp, #S_FRAME_SIZE
	stmia sp, {r0 - r12} @ Calling r0-r12
	ldr r2, IRQ_STACK_START_IN
	ldmia r2, {r2 - r3} @ get pc, cpsr
	add r0, sp, #S_FRAME_SIZE @ restore sp_SVC

	add r5, sp, #S_SP
	mov r1, lr
	stmia r5, {r0 - r3} @ save sp_SVC, lr_SVC, pc, cpsr
	mov r0, sp
	.endm

	.macro irq_save_user_regs
	sub sp, sp, #S_FRAME_SIZE
	stmia sp, {r0 - r12} @ Calling r0-r12
	add r7, sp, #S_PC
	stmdb r7, {sp, lr}^ @ Calling SP, LR
	str lr, [r7, #0] @ Save calling PC
	mrs r6, spsr
	str r6, [r7, #4] @ Save CPSR
	str r0, [r7, #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
	/* return & move spsr_svc into cpsr */
	subs pc, lr, #4
	.endm

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

	str lr, [r13] @ save caller lr / spsr
	mrs lr, spsr
	str lr, [r13, #4]

	mov r13, #MODE_SVC @ prepare SVC-Mode
	@ msr spsr_c, r13
	msr spsr, r13
	mov lr, pc
	movs pc, lr
	.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
	undefined_instruction:
	get_bad_stack
	bad_save_user_regs
	bl do_undefined_instruction

	.align 5
	software_interrupt:
	get_bad_stack
	bad_save_user_regs
	bl do_software_interrupt

	.align 5
	prefetch_abort:
	get_bad_stack
	bad_save_user_regs
	bl do_prefetch_abort

	.align 5
	data_abort:
	get_bad_stack
	bad_save_user_regs
	bl do_data_abort

	.align 5
	not_used:
	get_bad_stack
	bad_save_user_regs
	bl do_not_used

	#ifdef CONFIG_USE_IRQ

	.align 5
	irq:
	get_irq_stack
	irq_save_user_regs
	bl do_irq
	irq_restore_user_regs

	.align 5
	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
	irq:
	get_bad_stack
	bad_save_user_regs
	bl do_irq

	.align 5
	fiq:
	get_bad_stack
	bad_save_user_regs
	bl do_fiq

	#endif