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Diffstat (limited to 'arch/arm/cpu/arm920t/start.S')
| -rw-r--r-- | arch/arm/cpu/arm920t/start.S | 436 |
1 files changed, 436 insertions, 0 deletions
diff --git a/arch/arm/cpu/arm920t/start.S b/arch/arm/cpu/arm920t/start.S new file mode 100644 index 0000000..779f192 --- /dev/null +++ b/arch/arm/cpu/arm920t/start.S @@ -0,0 +1,436 @@ +/* + * 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 <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 + * + ************************************************************************* + */ + +_TEXT_BASE: + .word TEXT_BASE + +.globl _armboot_start +_armboot_start: + .word _start + +/* + * 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 + + +/* + * 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 + + bl coloured_LED_init + bl red_LED_on + +#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 /* Interupt-Controller base addresses */ +# define CLKDIVN 0x14800014 /* clock divisor register */ +#else +# define pWTCON 0x53000000 +# define INTMSK 0x4A000008 /* Interupt-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 + +#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: + 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 */ + +clear_bss: + ldr r0, _bss_start /* find start of bss segment */ + ldr r1, _bss_end /* stop here */ + mov r2, #0x00000000 /* clear */ + +clbss_l:str r2, [r0] /* clear loop... */ + add r0, r0, #4 + cmp r0, r1 + ble clbss_l + + ldr pc, _start_armboot + +_start_armboot: .word start_armboot + + +/* + ************************************************************************* + * + * 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, _armboot_start + sub r2, r2, #(CONFIG_STACKSIZE) + sub r2, r2, #(CONFIG_SYS_MALLOC_LEN) + /* set base 2 words into abort stack */ + sub r2, r2, #(CONFIG_SYS_GBL_DATA_SIZE+8) + 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, _armboot_start @ setup our mode stack + sub r13, r13, #(CONFIG_STACKSIZE) + sub r13, r13, #(CONFIG_SYS_MALLOC_LEN) + /* reserve a couple spots in abort stack */ + sub r13, r13, #(CONFIG_SYS_GBL_DATA_SIZE+8) + + 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 |