arch/arm/cpu/arm720t/start.S

   1 /*
   2  *  armboot - Startup Code for ARM720 CPU-core
   3  *
   4  *  Copyright (c) 2001  Marius Gröger <mag@sysgo.de>
   5  *  Copyright (c) 2002  Alex Züpke <azu@sysgo.de>
   6  *
   7  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 #include <asm-offsets.h>
  11 #include <config.h>
  12 #include <version.h>
  13 #include <asm/hardware.h>
  14
  15 /*
  16  *************************************************************************
  17  *
  18  * Jump vector table as in table 3.1 in [1]
  19  *
  20  *************************************************************************
  21  */
  22
  23
  24 .globl _start
  25 _start: b       reset
  26         ldr     pc, _undefined_instruction
  27         ldr     pc, _software_interrupt
  28         ldr     pc, _prefetch_abort
  29         ldr     pc, _data_abort
  30         ldr     pc, _not_used
  31         ldr     pc, _irq
  32         ldr     pc, _fiq
  33
  34 #ifdef CONFIG_SPL_BUILD
  35 _undefined_instruction: .word _undefined_instruction
  36 _software_interrupt:    .word _software_interrupt
  37 _prefetch_abort:        .word _prefetch_abort
  38 _data_abort:            .word _data_abort
  39 _not_used:              .word _not_used
  40 _irq:                   .word _irq
  41 _fiq:                   .word _fiq
  42 _pad:                   .word 0x12345678 /* now 16*4=64 */
  43 #else
  44 _undefined_instruction: .word undefined_instruction
  45 _software_interrupt:    .word software_interrupt
  46 _prefetch_abort:        .word prefetch_abort
  47 _data_abort:            .word data_abort
  48 _not_used:              .word not_used
  49 _irq:                   .word irq
  50 _fiq:                   .word fiq
  51 _pad:                   .word 0x12345678 /* now 16*4=64 */
  52 #endif  /* CONFIG_SPL_BUILD */
  53
  54         .balignl 16,0xdeadbeef
  55
  56
  57 /*
  58  *************************************************************************
  59  *
  60  * Startup Code (reset vector)
  61  *
  62  * do important init only if we don't start from RAM!
  63  * relocate armboot to ram
  64  * setup stack
  65  * jump to second stage
  66  *
  67  *************************************************************************
  68  */
  69
  70 #ifdef CONFIG_USE_IRQ
  71 /* IRQ stack memory (calculated at run-time) */
  72 .globl IRQ_STACK_START
  73 IRQ_STACK_START:
  74         .word   0x0badc0de
  75
  76 /* IRQ stack memory (calculated at run-time) */
  77 .globl FIQ_STACK_START
  78 FIQ_STACK_START:
  79         .word 0x0badc0de
  80 #endif
  81
  82 /* IRQ stack memory (calculated at run-time) + 8 bytes */
  83 .globl IRQ_STACK_START_IN
  84 IRQ_STACK_START_IN:
  85         .word   0x0badc0de
  86
  87 /*
  88  * the actual reset code
  89  */
  90
  91 reset:
  92         /*
  93          * set the cpu to SVC32 mode
  94          */
  95         mrs     r0,cpsr
  96         bic     r0,r0,#0x1f
  97         orr     r0,r0,#0xd3
  98         msr     cpsr,r0
  99
 100         /*
 101          * we do sys-critical inits only at reboot,
 102          * not when booting from ram!
 103          */
 104 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 105         bl      cpu_init_crit
 106 #endif
 107
 108         bl      _main
 109
 110 /*------------------------------------------------------------------------------*/
 111
 112         .globl  c_runtime_cpu_setup
 113 c_runtime_cpu_setup:
 114
 115         mov     pc, lr
 116
 117 /*
 118  *************************************************************************
 119  *
 120  * CPU_init_critical registers
 121  *
 122  * setup important registers
 123  * setup memory timing
 124  *
 125  *************************************************************************
 126  */
 127
 128 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 129 cpu_init_crit:
 130
 131         mov     ip, lr
 132         /*
 133          * before relocating, we have to setup RAM timing
 134          * because memory timing is board-dependent, you will
 135          * find a lowlevel_init.S in your board directory.
 136          */
 137         bl      lowlevel_init
 138         mov     lr, ip
 139
 140         mov     pc, lr
 141 #endif /* CONFIG_SKIP_LOWLEVEL_INIT */
 142
 143
 144 #ifndef CONFIG_SPL_BUILD
 145 /*
 146  *************************************************************************
 147  *
 148  * Interrupt handling
 149  *
 150  *************************************************************************
 151  */
 152
 153 @
 154 @ IRQ stack frame.
 155 @
 156 #define S_FRAME_SIZE    72
 157
 158 #define S_OLD_R0        68
 159 #define S_PSR           64
 160 #define S_PC            60
 161 #define S_LR            56
 162 #define S_SP            52
 163
 164 #define S_IP            48
 165 #define S_FP            44
 166 #define S_R10           40
 167 #define S_R9            36
 168 #define S_R8            32
 169 #define S_R7            28
 170 #define S_R6            24
 171 #define S_R5            20
 172 #define S_R4            16
 173 #define S_R3            12
 174 #define S_R2            8
 175 #define S_R1            4
 176 #define S_R0            0
 177
 178 #define MODE_SVC 0x13
 179 #define I_BIT    0x80
 180
 181 /*
 182  * use bad_save_user_regs for abort/prefetch/undef/swi ...
 183  * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
 184  */
 185
 186         .macro  bad_save_user_regs
 187         sub     sp, sp, #S_FRAME_SIZE
 188         stmia   sp, {r0 - r12}                  @ Calling r0-r12
 189         add     r8, sp, #S_PC
 190
 191         ldr     r2, IRQ_STACK_START_IN
 192         ldmia   r2, {r2 - r4}                   @ get pc, cpsr, old_r0
 193         add     r0, sp, #S_FRAME_SIZE           @ restore sp_SVC
 194
 195         add     r5, sp, #S_SP
 196         mov     r1, lr
 197         stmia   r5, {r0 - r4}                   @ save sp_SVC, lr_SVC, pc, cpsr, old_r
 198         mov     r0, sp
 199         .endm
 200
 201         .macro  irq_save_user_regs
 202         sub     sp, sp, #S_FRAME_SIZE
 203         stmia   sp, {r0 - r12}                  @ Calling r0-r12
 204         add     r8, sp, #S_PC
 205         stmdb   r8, {sp, lr}^                   @ Calling SP, LR
 206         str     lr, [r8, #0]                    @ Save calling PC
 207         mrs     r6, spsr
 208         str     r6, [r8, #4]                    @ Save CPSR
 209         str     r0, [r8, #8]                    @ Save OLD_R0
 210         mov     r0, sp
 211         .endm
 212
 213         .macro  irq_restore_user_regs
 214         ldmia   sp, {r0 - lr}^                  @ Calling r0 - lr
 215         mov     r0, r0
 216         ldr     lr, [sp, #S_PC]                 @ Get PC
 217         add     sp, sp, #S_FRAME_SIZE
 218         subs    pc, lr, #4                      @ return & move spsr_svc into cpsr
 219         .endm
 220
 221         .macro get_bad_stack
 222         ldr     r13, IRQ_STACK_START_IN         @ setup our mode stack
 223
 224         str     lr, [r13]                       @ save caller lr / spsr
 225         mrs     lr, spsr
 226         str     lr, [r13, #4]
 227
 228         mov     r13, #MODE_SVC                  @ prepare SVC-Mode
 229         msr     spsr_c, r13
 230         mov     lr, pc
 231         movs    pc, lr
 232         .endm
 233
 234         .macro get_irq_stack                    @ setup IRQ stack
 235         ldr     sp, IRQ_STACK_START
 236         .endm
 237
 238         .macro get_fiq_stack                    @ setup FIQ stack
 239         ldr     sp, FIQ_STACK_START
 240         .endm
 241
 242 /*
 243  * exception handlers
 244  */
 245         .align  5
 246 undefined_instruction:
 247         get_bad_stack
 248         bad_save_user_regs
 249         bl      do_undefined_instruction
 250
 251         .align  5
 252 software_interrupt:
 253         get_bad_stack
 254         bad_save_user_regs
 255         bl      do_software_interrupt
 256
 257         .align  5
 258 prefetch_abort:
 259         get_bad_stack
 260         bad_save_user_regs
 261         bl      do_prefetch_abort
 262
 263         .align  5
 264 data_abort:
 265         get_bad_stack
 266         bad_save_user_regs
 267         bl      do_data_abort
 268
 269         .align  5
 270 not_used:
 271         get_bad_stack
 272         bad_save_user_regs
 273         bl      do_not_used
 274
 275 #ifdef CONFIG_USE_IRQ
 276
 277         .align  5
 278 irq:
 279         get_irq_stack
 280         irq_save_user_regs
 281         bl      do_irq
 282         irq_restore_user_regs
 283
 284         .align  5
 285 fiq:
 286         get_fiq_stack
 287         /* someone ought to write a more effiction fiq_save_user_regs */
 288         irq_save_user_regs
 289         bl      do_fiq
 290         irq_restore_user_regs
 291
 292 #else
 293
 294         .align  5
 295 irq:
 296         get_bad_stack
 297         bad_save_user_regs
 298         bl      do_irq
 299
 300         .align  5
 301 fiq:
 302         get_bad_stack
 303         bad_save_user_regs
 304         bl      do_fiq
 305
 306 #endif
 307 #endif /* CONFIG_SPL_BUILD */