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Diffstat (limited to 'cpu/ixp/start.S')
| -rw-r--r-- | cpu/ixp/start.S | 527 |
1 files changed, 527 insertions, 0 deletions
diff --git a/cpu/ixp/start.S b/cpu/ixp/start.S new file mode 100644 index 0000000..de33e8b --- /dev/null +++ b/cpu/ixp/start.S @@ -0,0 +1,527 @@ +/* vi: set ts=8 sw=8 noet: */ +/* + * u-boot - Startup Code for XScale IXP + * + * Copyright (C) 2003 Kyle Harris <kharris@nexus-tech.net> + * + * Based on startup code example contained in the + * Intel IXP4xx Programmer's Guide and past u-boot Start.S + * samples. + * + * 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> +#include <asm/arch/ixp425.h> + +#define MMU_Control_M 0x001 // Enable MMU +#define MMU_Control_A 0x002 // Enable address alignment faults +#define MMU_Control_C 0x004 // Enable cache +#define MMU_Control_W 0x008 // Enable write-buffer +#define MMU_Control_P 0x010 // Compatability: 32 bit code +#define MMU_Control_D 0x020 // Compatability: 32 bit data +#define MMU_Control_L 0x040 // Compatability: +#define MMU_Control_B 0x080 // Enable Big-Endian +#define MMU_Control_S 0x100 // Enable system protection +#define MMU_Control_R 0x200 // Enable ROM protection +#define MMU_Control_I 0x1000 // Enable Instruction cache +#define MMU_Control_X 0x2000 // Set interrupt vectors at 0xFFFF0000 +#define MMU_Control_Init (MMU_Control_P|MMU_Control_D|MMU_Control_L) + + +/* + * Macro definitions + */ + // Delay a bit + .macro DELAY_FOR cycles, reg0 + ldr \reg0, =\cycles + subs \reg0, \reg0, #1 + subne pc, pc, #0xc + .endm + + // wait for coprocessor write complete + .macro CPWAIT reg + mrc p15,0,\reg,c2,c0,0 + mov \reg,\reg + sub pc,pc,#4 + .endm + +.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! + * - relocate armboot to ram + * - setup stack + * - jump to second stage + */ + +_TEXT_BASE: + .word TEXT_BASE + +.globl _armboot_start +_armboot_start: + .word _start + +/* + * Note: _armboot_end_data and _armboot_end are defined + * by the (board-dependent) linker script. + * _armboot_end_data is the first usable FLASH address after armboot + */ +.globl _armboot_end_data +_armboot_end_data: + .word armboot_end_data +.globl _armboot_end +_armboot_end: + .word armboot_end + +/* + * This is defined in the board specific linker script + */ +.globl _bss_start +_bss_start: + .word bss_start + +.globl _bss_end +_bss_end: + .word bss_end + +/* + * _armboot_real_end is the first usable RAM address behind armboot + * and the various stacks + */ +.globl _armboot_real_end +_armboot_real_end: + .word 0x0badc0de + +/* + * We relocate uboot to this address (end of RAM - 128 KiB) + */ +.globl _uboot_reloc +_uboot_reloc: + .word TEXT_BASE + +#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 reset code */ +/* */ +/****************************************************************************/ + +reset: + /* disable mmu, set big-endian */ + mov r0, #0xf8 + mcr p15, 0, r0, c1, c0, 0 + CPWAIT r0 + + /* invalidate I & D caches & BTB */ + mcr p15, 0, r0, c7, c7, 0 + CPWAIT r0 + + /* invalidate I & Data TLB */ + mcr p15, 0, r0, c8, c7, 0 + CPWAIT r0 + + /* drain write and fill buffers */ + mcr p15, 0, r0, c7, c10, 4 + CPWAIT r0 + + /* disable write buffer coalescing */ + mrc p15, 0, r0, c1, c0, 1 + orr r0, r0, #1 + mcr p15, 0, r0, c1, c0, 1 + CPWAIT r0 + + /* set EXP CS0 to the optimum timing */ + ldr r1, =CFG_EXP_CS0 + ldr r2, =IXP425_EXP_CS0 + str r1, [r2] + + /* make sure flash is visible at 0 */ + ldr r2, =IXP425_EXP_CFG0 + ldr r1, [r2] + orr r1, r1, #0x80000000 + str r1, [r2] + + mov r1, #CFG_SDR_CONFIG + ldr r2, =IXP425_SDR_CONFIG + str r1, [r2] + + /* disable refresh cycles */ + mov r1, #0 + ldr r3, =IXP425_SDR_REFRESH + str r1, [r3] + + /* send nop command */ + mov r1, #3 + ldr r4, =IXP425_SDR_IR + str r1, [r4] + DELAY_FOR 0x4000, r0 + + /* set SDRAM internal refresh val */ + ldr r1, =CFG_SDRAM_REFRESH_CNT + str r1, [r3] + DELAY_FOR 0x4000, r0 + + /* send precharge-all command to close all open banks */ + mov r1, #2 + str r1, [r4] + DELAY_FOR 0x4000, r0 + + /* provide 8 auto-refresh cycles */ + mov r1, #4 + mov r5, #8 +111: str r1, [r4] + DELAY_FOR 0x100, r0 + subs r5, r5, #1 + bne 111b + + /* set mode register in sdram */ + mov r1, #1 + str r1, [r4] + DELAY_FOR 0x4000, r0 + + /* send normal operation command */ + mov r1, #6 + str r1, [r4] + DELAY_FOR 0x4000, r0 + + /* copy */ + mov r0, #0 + mov r4, r0 + add r2, r0, #0x40000 + mov r1, #0x10000000 + mov r5, r1 + + 30: + ldr r3, [r0], #4 + str r3, [r1], #4 + cmp r0, r2 + bne 30b + + /* invalidate I & D caches & BTB */ + mcr p15, 0, r0, c7, c7, 0 + CPWAIT r0 + + /* invalidate I & Data TLB */ + mcr p15, 0, r0, c8, c7, 0 + CPWAIT r0 + + /* drain write and fill buffers */ + mcr p15, 0, r0, c7, c10, 4 + CPWAIT r0 + + /* move flash to 0x50000000 */ + ldr r2, =IXP425_EXP_CFG0 + ldr r1, [r2] + bic r1, r1, #0x80000000 + str r1, [r2] + + nop + nop + nop + nop + nop + nop + + /* invalidate I & Data TLB */ + mcr p15, 0, r0, c8, c7, 0 + CPWAIT r0 + + /* enable I cache */ + mrc p15, 0, r0, c1, c0, 0 + orr r0, r0, #MMU_Control_I + mcr p15, 0, r0, c1, c0, 0 + CPWAIT r0 + + mrs r0,cpsr /* set the cpu to SVC32 mode */ + bic r0,r0,#0x1f /* (superviser mode, M=10011) */ + orr r0,r0,#0x13 + msr cpsr,r0 + +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, _armboot_end + 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 + + /* Set up the stack */ + +stack_setup: + + ldr r0, _uboot_reloc /* upper 128 KiB: relocated uboot */ + sub r0, r0, #CFG_MALLOC_LEN /* malloc area */ + /* FIXME: bdinfo should be here */ + sub sp, r0, #12 /* leave 3 words for abort-stack */ + +clear_bss: + + ldr r0, _bss_start /* find start of bss segment */ + add r0, r0, #4 /* start at first byte of bss */ + ldr r1, _bss_end /* stop here */ + mov r2, #0x00000000 /* clear */ + +clbss_l:str r2, [r0] /* clear loop... */ + add r0, r0, #4 + cmp r0, r1 + bne clbss_l + + + ldr pc, _start_armboot + +_start_armboot: .word start_armboot + + + + +/****************************************************************************/ +/* */ +/* 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 + + /* use bad_save_user_regs for abort/prefetch/undef/swi ... */ + + .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, _armboot_end + add r2, r2, #CONFIG_STACKSIZE + sub r2, r2, #8 + 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 + + + /* use irq_save_user_regs / irq_restore_user_regs for */ + /* IRQ/FIQ handling */ + + .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, _armboot_end @ setup our mode stack + add r13, r13, #CONFIG_STACKSIZE @ resides at top of normal stack + sub r13, r13, #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 + 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 + irq_save_user_regs /* someone ought to write a more */ + bl do_fiq /* effiction fiq_save_user_regs */ + 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 + +/****************************************************************************/ +/* */ +/* Reset function: Use Watchdog to reset */ +/* */ +/****************************************************************************/ + + .align 5 +.globl reset_cpu + +reset_cpu: + ldr r1, =0x482e + ldr r2, =IXP425_OSWK + str r1, [r2] + ldr r1, =0x0fff + ldr r2, =IXP425_OSWT + str r1, [r2] + ldr r1, =0x5 + ldr r2, =IXP425_OSWE + str r1, [r2] + b reset_endless + + +reset_endless: + + b reset_endless |