start.S

/*
 *  armboot - Startup Code for ARM720 CPU-core
 *
 *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
 *  Copyright (c) 2002	Alex Züpke <azu@sysgo.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 <config.h>
#include <version.h>
#include <asm/hardware.h>

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


.globl _start
_start: b	reset
	ldr	pc, _undefined_instruction
	ldr	pc, _software_interrupt
	ldr	pc, _prefetch_abort
	ldr	pc, _data_abort
#ifdef CONFIG_LPC2292
	.word	0xB4405F76 /* 2's complement of the checksum of the vectors */
#else
	ldr	pc, _not_used
#endif
	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 RAM!
 * relocate armboot to ram
 * setup stack
 * jump to second stage
 *
 *************************************************************************
 */

.globl _TEXT_BASE
_TEXT_BASE:
	.word	CONFIG_SYS_TEXT_BASE

/*
 * 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 _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 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

#ifdef CONFIG_LPC2292
	bl	lowlevel_init
#endif

/* Set stackpointer in internal RAM to call board_init_f */
call_board_init_f:
	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
	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 */

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

	adr	r0, _start
	cmp	r0, r6
	beq	clear_bss		/* skip relocation */
	mov	r1, r6			/* r1 <- scratch for copy_loop */
	ldr	r3, _bss_start_ofs
	add	r2, r0, r3		/* r2 <- source end address	    */

copy_loop:
	ldmia	r0!, {r9-r10}		/* copy from source address [r0]    */
	stmia	r1!, {r9-r10}		/* 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 */
	sub	r9, r6, r0		/* r9 <- relocation offset */
	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

clear_bss:
#ifndef CONFIG_SPL_BUILD
	ldr	r0, _bss_start_ofs
	ldr	r1, _bss_end_ofs
	mov	r4, r6			/* reloc addr */
	add	r0, r0, r4
	add	r1, r1, r4
	mov	r2, #0x00000000		/* clear			    */

clbss_l:cmp	r0, r1			/* clear loop... */
	bhs	clbss_e			/* if reached end of bss, exit */
	str	r2, [r0]
	add	r0, r0, #4
	b	clbss_l
clbss_e:

	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, _board_init_r_ofs
	adr	r1, _start
	add	lr, r0, r1
	add	lr, lr, r9
	/* setup parameters for board_init_r */
	mov	r0, r5		/* gd_t */
	mov	r1, r6		/* dest_addr */
	/* jump to it ... */
	mov	pc, lr

_board_init_r_ofs:
	.word board_init_r - _start

_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

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

#if defined(CONFIG_LPC2292)
PLLCFG_ADR:	.word	PLLCFG
PLLFEED_ADR:	.word	PLLFEED
PLLCON_ADR:	.word	PLLCON
PLLSTAT_ADR:	.word	PLLSTAT
VPBDIV_ADR:	.word	VPBDIV
MEMMAP_ADR:	.word	MEMMAP

#endif

cpu_init_crit:
#if defined(CONFIG_NETARM)
	/*
	 * prior to software reset : need to set pin PORTC4 to be *HRESET
	 */
	ldr	r0, =NETARM_GEN_MODULE_BASE
	ldr	r1, =(NETARM_GEN_PORT_MODE(0x10) | \
			NETARM_GEN_PORT_DIR(0x10))
	str	r1, [r0, #+NETARM_GEN_PORTC]
	/*
	 * software reset : see HW Ref. Guide 8.2.4 : Software Service register
	 *		    for an explanation of this process
	 */
	ldr	r0, =NETARM_GEN_MODULE_BASE
	ldr	r1, =NETARM_GEN_SW_SVC_RESETA
	str	r1, [r0, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETB
	str	r1, [r0, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETA
	str	r1, [r0, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETB
	str	r1, [r0, #+NETARM_GEN_SOFTWARE_SERVICE]
	/*
	 * setup PLL and System Config
	 */
	ldr	r0, =NETARM_GEN_MODULE_BASE

	ldr	r1, =(	NETARM_GEN_SYS_CFG_LENDIAN | \
			NETARM_GEN_SYS_CFG_BUSFULL | \
			NETARM_GEN_SYS_CFG_USER_EN | \
			NETARM_GEN_SYS_CFG_ALIGN_ABORT | \
			NETARM_GEN_SYS_CFG_BUSARB_INT | \
			NETARM_GEN_SYS_CFG_BUSMON_EN )

	str	r1, [r0, #+NETARM_GEN_SYSTEM_CONTROL]

#ifndef CONFIG_NETARM_PLL_BYPASS
	ldr	r1, =(	NETARM_GEN_PLL_CTL_PLLCNT(NETARM_PLL_COUNT_VAL) | \
			NETARM_GEN_PLL_CTL_POLTST_DEF | \
			NETARM_GEN_PLL_CTL_INDIV(1) | \
			NETARM_GEN_PLL_CTL_ICP_DEF | \
			NETARM_GEN_PLL_CTL_OUTDIV(2) )
	str	r1, [r0, #+NETARM_GEN_PLL_CONTROL]
#endif

	/*
	 * mask all IRQs by clearing all bits in the INTMRs
	 */
	mov	r1, #0
	ldr	r0, =NETARM_GEN_MODULE_BASE
	str	r1, [r0, #+NETARM_GEN_INTR_ENABLE]

#elif defined(CONFIG_S3C4510B)

	/*
	 * Mask off all IRQ sources
	 */
	ldr	r1, =REG_INTMASK
	ldr	r0, =0x3FFFFF
	str	r0, [r1]

	/*
	 * Disable Cache
	 */
	ldr r0, =REG_SYSCFG
	ldr r1, =0x83ffffa0	/* cache-disabled  */
	str r1, [r0]

#elif defined(CONFIG_INTEGRATOR) && defined(CONFIG_ARCH_INTEGRATOR)
	/* No specific initialisation for IntegratorAP/CM720T as yet */
#elif defined(CONFIG_LPC2292)
	/* Set-up PLL */
	mov	r3, #0xAA
	mov	r4, #0x55
	/* First disconnect and disable the PLL */
	ldr	r0, PLLCON_ADR
	mov	r1, #0x00
	str	r1, [r0]
	ldr	r0, PLLFEED_ADR /* start feed sequence */
	str	r3, [r0]
	str	r4, [r0]	/* feed sequence done */
	/* Set new M and P values */
	ldr	r0, PLLCFG_ADR
	mov	r1, #0x23	/* M=4 and P=2 */
	str	r1, [r0]
	ldr	r0, PLLFEED_ADR /* start feed sequence */
	str	r3, [r0]
	str	r4, [r0]	/* feed sequence done */
	/* Then enable the PLL */
	ldr	r0, PLLCON_ADR
	mov	r1, #0x01	/* PLL enable bit */
	str	r1, [r0]
	ldr	r0, PLLFEED_ADR /* start feed sequence */
	str	r3, [r0]
	str	r4, [r0]	/* feed sequence done */
	/* Wait for the lock */
	ldr	r0, PLLSTAT_ADR
	mov	r1, #0x400	/* lock bit */
lock_loop:
	ldr	r2, [r0]
	and	r2, r1, r2
	cmp	r2, #0
	beq	lock_loop
	/* And finally connect the PLL */
	ldr	r0, PLLCON_ADR
	mov	r1, #0x03	/* PLL enable bit and connect bit */
	str	r1, [r0]
	ldr	r0, PLLFEED_ADR /* start feed sequence */
	str	r3, [r0]
	str	r4, [r0]	/* feed sequence done */
	/* Set-up VPBDIV register */
	ldr	r0, VPBDIV_ADR
	mov	r1, #0x01	/* VPB clock is same as process clock */
	str	r1, [r0]
#else
#error No cpu_init_crit() defined for current CPU type
#endif

#ifdef CONFIG_ARM7_REVD
	/* set clock speed */
	/* !!! we run @ 36 MHz due to a hardware flaw in Rev. D processors */
	/* !!! not doing DRAM refresh properly! */
	ldr	r0, SYSCON3
	ldr	r1, [r0]
	bic	r1, r1, #CLKCTL
	orr	r1, r1, #CLKCTL_36
	str	r1, [r0]
#endif

#ifndef CONFIG_LPC2292
	mov	ip, lr
	/*
	 * before relocating, we have to setup RAM timing
	 * because memory timing is board-dependent, you will
	 * find a lowlevel_init.S in your board directory.
	 */
	bl	lowlevel_init
	mov	lr, ip
#endif

	mov	pc, lr


/*
 *************************************************************************
 *
 * 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
	add	r8, sp, #S_PC

	ldr	r2, IRQ_STACK_START_IN
	ldmia	r2, {r2 - r4}			@ get pc, cpsr, old_r0
	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC

	add	r5, sp, #S_SP
	mov	r1, lr
	stmia	r5, {r0 - r4}			@ save sp_SVC, lr_SVC, pc, cpsr, old_r
	mov	r0, sp
	.endm

	.macro	irq_save_user_regs
	sub	sp, sp, #S_FRAME_SIZE
	stmia	sp, {r0 - r12}			@ Calling r0-r12
	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 / spsr
	mrs	lr, spsr
	str	lr, [r13, #4]

	mov	r13, #MODE_SVC			@ prepare SVC-Mode
	msr	spsr_c, 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

#if defined(CONFIG_NETARM)
	.align	5
.globl reset_cpu
reset_cpu:
	ldr	r1, =NETARM_MEM_MODULE_BASE
	ldr	r0, [r1, #+NETARM_MEM_CS0_BASE_ADDR]
	ldr	r1, =0xFFFFF000
	and	r0, r1, r0
	ldr	r1, =(relocate-CONFIG_SYS_TEXT_BASE)
	add	r0, r1, r0
	ldr	r4, =NETARM_GEN_MODULE_BASE
	ldr	r1, =NETARM_GEN_SW_SVC_RESETA
	str	r1, [r4, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETB
	str	r1, [r4, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETA
	str	r1, [r4, #+NETARM_GEN_SOFTWARE_SERVICE]
	ldr	r1, =NETARM_GEN_SW_SVC_RESETB
	str	r1, [r4, #+NETARM_GEN_SOFTWARE_SERVICE]
	mov	pc, r0
#elif defined(CONFIG_S3C4510B)
/* Nothing done here as reseting the CPU is board specific, depending
 * on external peripherals such as watchdog timers, etc. */
#elif defined(CONFIG_INTEGRATOR) && defined(CONFIG_ARCH_INTEGRATOR)
	/* No specific reset actions for IntegratorAP/CM720T as yet */
#elif defined(CONFIG_LPC2292)
	.align	5
.globl reset_cpu
reset_cpu:
	mov	pc, r0
#else
#error No reset_cpu() defined for current CPU type
#endif