start.S

/*
 * armboot - Startup Code for OMAP3530/ARM Cortex CPU-core
 *
 * Copyright (c) 2004	Texas Instruments <r-woodruff2@ti.com>
 *
 * 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>
 * Copyright (c) 2006-2008 Syed Mohammed Khasim <x0khasim@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 <config.h>
#include <version.h>

.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
_pad:			.word 0x12345678 /* now 16*4=64 */
.global _end_vect
_end_vect:

	.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	TEXT_BASE

#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
.globl _armboot_start
_armboot_start:
	.word _start
#endif

/*
 * 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

#if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
/* 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

#if (CONFIG_OMAP34XX)
	/* Copy vectors to mask ROM indirect addr */
	adr	r0, _start		@ r0 <- current position of code
	add	r0, r0, #4		@ skip reset vector
	mov	r2, #64			@ r2 <- size to copy
	add	r2, r0, r2		@ r2 <- source end address
	mov	r1, #SRAM_OFFSET0	@ build vect addr
	mov	r3, #SRAM_OFFSET1
	add	r1, r1, r3
	mov	r3, #SRAM_OFFSET2
	add	r1, r1, r3
next:
	ldmia	r0!, {r3 - r10}		@ copy from source address [r0]
	stmia	r1!, {r3 - r10}		@ copy to   target address [r1]
	cmp	r0, r2			@ until source end address [r2]
	bne	next			@ loop until equal */
#if !defined(CONFIG_SYS_NAND_BOOT) && !defined(CONFIG_SYS_ONENAND_BOOT)
	/* No need to copy/exec the clock code - DPLL adjust already done
	 * in NAND/oneNAND Boot.
	 */
	bl	cpy_clk_code		@ put dpll adjust code behind vectors
#endif /* NAND Boot */
#endif
	/* the mask ROM code should have PLL and others stable */
#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

#ifndef CONFIG_SKIP_RELOCATE_UBOOT
	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
#ifndef CONFIG_PRELOADER
	beq	jump_2_ram
#endif

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 addreee [r2]    */
	ble	copy_loop

#ifndef CONFIG_PRELOADER
	/* fix got entries */
	ldr	r1, _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
	bne	fixloop

clear_bss:
	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
#endif	/* #ifndef CONFIG_PRELOADER */
#endif	/* #ifndef CONFIG_SKIP_RELOCATE_UBOOT */

/*
 * We are done. Do not return, instead branch to second part of board
 * initialization, now running from RAM.
 */
jump_2_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
#else /* #if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */
/*
 * 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

#if (CONFIG_OMAP34XX)
	/* Copy vectors to mask ROM indirect addr */
	adr	r0, _start		@ r0 <- current position of code
	add	r0, r0, #4		@ skip reset vector
	mov	r2, #64			@ r2 <- size to copy
	add	r2, r0, r2		@ r2 <- source end address
	mov	r1, #SRAM_OFFSET0	@ build vect addr
	mov	r3, #SRAM_OFFSET1
	add	r1, r1, r3
	mov	r3, #SRAM_OFFSET2
	add	r1, r1, r3
next:
	ldmia	r0!, {r3 - r10}		@ copy from source address [r0]
	stmia	r1!, {r3 - r10}		@ copy to   target address [r1]
	cmp	r0, r2			@ until source end address [r2]
	bne	next			@ loop until equal */
#if !defined(CONFIG_SYS_NAND_BOOT) && !defined(CONFIG_SYS_ONENAND_BOOT)
	/* No need to copy/exec the clock code - DPLL adjust already done
	 * in NAND/oneNAND Boot.
	 */
	bl	cpy_clk_code		@ put dpll adjust code behind vectors
#endif /* NAND Boot */
#endif
	/* the mask ROM code should have PLL and others stable */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	bl	cpu_init_crit
#endif

#ifndef CONFIG_SKIP_RELOCATE_UBOOT
relocate:				@ relocate U-Boot to RAM
	adr	r0, _start		@ r0 <- current position of code
	ldr	r1, _TEXT_BASE		@ test if we run from flash or RAM
	cmp	r0, r1			@ don't reloc during debug
	beq	stack_setup

	ldr	r2, _armboot_start
	ldr	r3, _bss_start
	sub	r2, r3, r2		@ r2 <- size of armboot
	add	r2, r0, r2		@ r2 <- source end address

copy_loop:				@ copy 32 bytes at a time
	ldmia	r0!, {r3 - r10}		@ copy from source address [r0]
	stmia	r1!, {r3 - r10}		@ copy to   target address [r1]
	cmp	r0, r2			@ until source end addreee [r2]
	ble	copy_loop
#endif	/* CONFIG_SKIP_RELOCATE_UBOOT */

	/* Set up the stack */
stack_setup:
	ldr	r0, _TEXT_BASE		@ upper 128 KiB: relocated uboot
	sub	r0, r0, #CONFIG_SYS_MALLOC_LEN @ malloc area
	sub	r0, r0, #CONFIG_SYS_GBL_DATA_SIZE @ bdinfo
#ifdef CONFIG_USE_IRQ
	sub	r0, r0, #(CONFIG_STACKSIZE_IRQ + CONFIG_STACKSIZE_FIQ)
#endif
	sub	sp, r0, #12		@ leave 3 words for abort-stack
	bic	sp, sp, #7		@ 8-byte alignment for ABI compliance

	/* Clear BSS (if any). Is below tx (watch load addr - need space) */
clear_bss:
	ldr	r0, _bss_start		@ find start of bss segment
	ldr	r1, _bss_end		@ stop here
	mov	r2, #0x00000000		@ clear value
clbss_l:
	str	r2, [r0]		@ clear BSS location
	cmp	r0, r1			@ are we at the end yet
	add	r0, r0, #4		@ increment clear index pointer
	bne	clbss_l			@ keep clearing till at end

	ldr	pc, _start_armboot	@ jump to C code

_start_armboot: .word start_armboot
#endif /* #if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */

/*************************************************************************
 *
 * CPU_init_critical registers
 *
 * setup important registers
 * setup memory timing
 *
 *************************************************************************/
cpu_init_crit:
	/*
	 * Invalidate L1 I/D
	 */
	mov	r0, #0			@ set up for MCR
	mcr	p15, 0, r0, c8, c7, 0	@ invalidate TLBs
	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache

	/*
	 * disable MMU stuff and caches
	 */
	mrc	p15, 0, r0, c1, c0, 0
	bic	r0, r0, #0x00002000	@ clear bits 13 (--V-)
	bic	r0, r0, #0x00000007	@ clear bits 2:0 (-CAM)
	orr	r0, r0, #0x00000002	@ set bit 1 (--A-) Align
	orr	r0, r0, #0x00000800	@ set bit 12 (Z---) BTB
	mcr	p15, 0, r0, c1, c0, 0

	/*
	 * Jump to board specific initialization...
	 * The Mask ROM will have already initialized
	 * basic memory. Go here to bump up clock rate and handle
	 * wake up conditions.
	 */
	mov	ip, lr			@ persevere link reg across call
	bl	lowlevel_init		@ go setup pll,mux,memory
	mov	lr, ip			@ restore link
	mov	pc, lr			@ back to my caller
/*
 *************************************************************************
 *
 * 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		@ carve out a frame on current
						@ user stack
	stmia	sp, {r0 - r12}			@ Save user registers (now in
						@ svc mode) r0-r12
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
	ldr	r2, _armboot_start
	sub	r2, r2, #(CONFIG_SYS_MALLOC_LEN)
	sub	r2, r2, #(CONFIG_SYS_GBL_DATA_SIZE + 8)	@ set base 2 words into abort
#else
	ldr	r2, IRQ_STACK_START_IN		@ set base 2 words into abort
						@ stack
#endif
	ldmia	r2, {r2 - r3}			@ get values for "aborted" pc
						@ and cpsr (into parm regs)
	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
	add	r8, sp, #S_PC			@ !! R8 NEEDS to be saved !!
						@ a reserved stack spot would
						@ be good.
	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
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
	ldr	r13, _armboot_start		@ setup our mode stack (enter
	sub	r13, r13, #(CONFIG_SYS_MALLOC_LEN)	@ move past malloc pool
	sub	r13, r13, #(CONFIG_SYS_GBL_DATA_SIZE + 8) @ move to reserved a couple
#else
	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack (enter
						@ in banked mode)
#endif

	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_bad_stack_swi
	sub	r13, r13, #4			@ space on current stack for
						@ scratch reg.
	str	r0, [r13]			@ save R0's value.
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
	ldr	r0, _armboot_start		@ get data regions start
	sub	r0, r0, #(CONFIG_SYS_MALLOC_LEN)	@ move past malloc pool
	sub	r0, r0, #(CONFIG_SYS_GBL_DATA_SIZE + 8)	@ move past gbl and a couple
#else
	ldr	r0, IRQ_STACK_START_IN		@ get data regions start
						@ spots for abort stack
#endif
	str	lr, [r0]			@ save caller lr in position 0
						@ of saved stack
	mrs	r0, spsr			@ get the spsr
	str	lr, [r0, #4]			@ save spsr in position 1 of
						@ saved stack
	ldr	r0, [r13]			@ restore r0
	add	r13, r13, #4			@ pop stack entry
	.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_swi
	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 effective 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