Initial revision
diff --git a/cpu/arm920t/start.S b/cpu/arm920t/start.S
new file mode 100644
index 0000000..a858dfa
--- /dev/null
+++ b/cpu/arm920t/start.S
@@ -0,0 +1,475 @@
+/*
+ * 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 <gj@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 <config.h>
+#include <version.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
+ 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
+ *
+ *************************************************************************
+ */
+
+/*
+ * CFG_MEM_END is in the board dependent config-file (configs/config_BOARD.h)
+ */
+_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
+
+/*
+ * _armboot_real_end is the first usable RAM address behind armboot
+ * and the various stacks
+ */
+.globl _armboot_real_end
+_armboot_real_end:
+ .word 0x0badc0de
+
+#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:
+ /*
+ * set the cpu to SVC32 mode
+ */
+ mrs r0,cpsr
+ bic r0,r0,#0x1f
+ orr r0,r0,#0xd3
+ msr cpsr,r0
+
+/* turn off the watchdog */
+#if defined(CONFIG_S3C2400)
+#define pWTCON 0x15300000
+/* Interupt-Controller base addresses */
+#define INTMSK 0x14400008
+/* clock divisor register */
+#define CLKDIVN 0x14800014
+#elif defined(CONFIG_S3C2410)
+#define pWTCON 0x53000000
+/* Interupt-Controller base addresses */
+#define INTMSK 0x4A000008
+#define INTSUBMSK 0x4A00001C
+/* clock divisor register */
+#define CLKDIVN 0x4C000014
+#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]
+
+ /*
+ * we do sys-critical inits only at reboot,
+ * not when booting from ram!
+ */
+#ifdef CONFIG_INIT_CRITICAL
+ bl cpu_init_crit
+#endif
+
+relocate:
+ /*
+ * relocate armboot to RAM
+ */
+ adr r0, _start /* r0 <- current position of code */
+ ldr r2, _armboot_start
+ ldr r3, _armboot_end
+ sub r2, r3, r2 /* r2 <- size of armboot */
+ ldr r1, _TEXT_BASE /* r1 <- destination address */
+ add r2, r0, r2 /* r2 <- source end address */
+
+ /*
+ * r0 = source address
+ * r1 = target address
+ * r2 = source end address
+ */
+copy_loop:
+ ldmia r0!, {r3-r10}
+ stmia r1!, {r3-r10}
+ cmp r0, r2
+ ble copy_loop
+
+#if 0
+ /* try doing this stuff after the relocation */
+ 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, =INTMR
+ str r1, [r0]
+
+ /* FCLK:HCLK:PCLK = 1:2:4 */
+ /* default FCLK is 120 MHz ! */
+ ldr r0, =CLKDIVN
+ mov r1, #3
+ str r1, [r0]
+ /* END stuff after relocation */
+#endif
+
+ /* set up the stack */
+ ldr r0, _armboot_end
+ add r0, r0, #CONFIG_STACKSIZE
+ sub sp, r0, #12 /* leave 3 words for abort-stack */
+
+ ldr pc, _start_armboot
+
+_start_armboot: .word start_armboot
+
+
+/*
+ *************************************************************************
+ *
+ * CPU_init_critical registers
+ *
+ * setup important registers
+ * setup memory timing
+ *
+ *************************************************************************
+ */
+
+
+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 memsetup.S in your board directory.
+ */
+ mov ip, lr
+ bl memsetup
+ mov lr, ip
+
+ 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, _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
+
+ .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
+ 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
+
+ .align 5
+.globl reset_cpu
+reset_cpu:
+#ifdef CONFIG_S3C2400
+ bl disable_interrupts
+ ldr r1, _rWTCON
+ ldr r2, _rWTCNT
+ /* Disable watchdog */
+ mov r3, #0x0000
+ str r3, [r1]
+ /* Initialize watchdog timer count register */
+ mov r3, #0x0001
+ str r3, [r2]
+ /* Enable watchdog timer; assert reset at timer timeout */
+ mov r3, #0x0021
+ str r3, [r1]
+_loop_forever:
+ b _loop_forever
+_rWTCON:
+ .word 0x15300000
+_rWTCNT:
+ .word 0x15300008
+#else /* ! CONFIG_S3C2400 */
+ mov ip, #0
+ mcr p15, 0, ip, c7, c7, 0 @ invalidate cache
+ mcr p15, 0, ip, c8, c7, 0 @ flush TLB (v4)
+ mrc p15, 0, ip, c1, c0, 0 @ get ctrl register
+ bic ip, ip, #0x000f @ ............wcam
+ bic ip, ip, #0x2100 @ ..v....s........
+ mcr p15, 0, ip, c1, c0, 0 @ ctrl register
+ mov pc, r0
+#endif /* CONFIG_S3C2400 */