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 .globl _TEXT_BASE
  71 _TEXT_BASE:
  72 #if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
  73         .word   CONFIG_SPL_TEXT_BASE
  74 #else
  75         .word   CONFIG_SYS_TEXT_BASE
  76 #endif
  77
  78 /*
  79  * These are defined in the board-specific linker script.
  80  * Subtracting _start from them lets the linker put their
  81  * relative position in the executable instead of leaving
  82  * them null.
  83  */
  84 .globl _bss_start_ofs
  85 _bss_start_ofs:
  86         .word __bss_start - _start
  87
  88 .globl _bss_end_ofs
  89 _bss_end_ofs:
  90         .word __bss_end - _start
  91
  92 .globl _end_ofs
  93 _end_ofs:
  94         .word _end - _start
  95
  96 #ifdef CONFIG_USE_IRQ
  97 /* IRQ stack memory (calculated at run-time) */
  98 .globl IRQ_STACK_START
  99 IRQ_STACK_START:
 100         .word   0x0badc0de
 101
 102 /* IRQ stack memory (calculated at run-time) */
 103 .globl FIQ_STACK_START
 104 FIQ_STACK_START:
 105         .word 0x0badc0de
 106 #endif
 107
 108 /* IRQ stack memory (calculated at run-time) + 8 bytes */
 109 .globl IRQ_STACK_START_IN
 110 IRQ_STACK_START_IN:
 111         .word   0x0badc0de
 112
 113 /*
 114  * the actual reset code
 115  */
 116
 117 reset:
 118         /*
 119          * set the cpu to SVC32 mode
 120          */
 121         mrs     r0,cpsr
 122         bic     r0,r0,#0x1f
 123         orr     r0,r0,#0xd3
 124         msr     cpsr,r0
 125
 126         /*
 127          * we do sys-critical inits only at reboot,
 128          * not when booting from ram!
 129          */
 130 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 131         bl      cpu_init_crit
 132 #endif
 133
 134         bl      _main
 135
 136 /*------------------------------------------------------------------------------*/
 137
 138         .globl  c_runtime_cpu_setup
 139 c_runtime_cpu_setup:
 140
 141         mov     pc, lr
 142
 143 /*
 144  *************************************************************************
 145  *
 146  * CPU_init_critical registers
 147  *
 148  * setup important registers
 149  * setup memory timing
 150  *
 151  *************************************************************************
 152  */
 153
 154 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 155 cpu_init_crit:
 156
 157         mov     ip, lr
 158         /*
 159          * before relocating, we have to setup RAM timing
 160          * because memory timing is board-dependent, you will
 161          * find a lowlevel_init.S in your board directory.
 162          */
 163         bl      lowlevel_init
 164         mov     lr, ip
 165
 166         mov     pc, lr
 167 #endif /* CONFIG_SKIP_LOWLEVEL_INIT */
 168
 169
 170 #ifndef CONFIG_SPL_BUILD
 171 /*
 172  *************************************************************************
 173  *
 174  * Interrupt handling
 175  *
 176  *************************************************************************
 177  */
 178
 179 @
 180 @ IRQ stack frame.
 181 @
 182 #define S_FRAME_SIZE    72
 183
 184 #define S_OLD_R0        68
 185 #define S_PSR           64
 186 #define S_PC            60
 187 #define S_LR            56
 188 #define S_SP            52
 189
 190 #define S_IP            48
 191 #define S_FP            44
 192 #define S_R10           40
 193 #define S_R9            36
 194 #define S_R8            32
 195 #define S_R7            28
 196 #define S_R6            24
 197 #define S_R5            20
 198 #define S_R4            16
 199 #define S_R3            12
 200 #define S_R2            8
 201 #define S_R1            4
 202 #define S_R0            0
 203
 204 #define MODE_SVC 0x13
 205 #define I_BIT    0x80
 206
 207 /*
 208  * use bad_save_user_regs for abort/prefetch/undef/swi ...
 209  * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
 210  */
 211
 212         .macro  bad_save_user_regs
 213         sub     sp, sp, #S_FRAME_SIZE
 214         stmia   sp, {r0 - r12}                  @ Calling r0-r12
 215         add     r8, sp, #S_PC
 216
 217         ldr     r2, IRQ_STACK_START_IN
 218         ldmia   r2, {r2 - r4}                   @ get pc, cpsr, old_r0
 219         add     r0, sp, #S_FRAME_SIZE           @ restore sp_SVC
 220
 221         add     r5, sp, #S_SP
 222         mov     r1, lr
 223         stmia   r5, {r0 - r4}                   @ save sp_SVC, lr_SVC, pc, cpsr, old_r
 224         mov     r0, sp
 225         .endm
 226
 227         .macro  irq_save_user_regs
 228         sub     sp, sp, #S_FRAME_SIZE
 229         stmia   sp, {r0 - r12}                  @ Calling r0-r12
 230         add     r8, sp, #S_PC
 231         stmdb   r8, {sp, lr}^                   @ Calling SP, LR
 232         str     lr, [r8, #0]                    @ Save calling PC
 233         mrs     r6, spsr
 234         str     r6, [r8, #4]                    @ Save CPSR
 235         str     r0, [r8, #8]                    @ Save OLD_R0
 236         mov     r0, sp
 237         .endm
 238
 239         .macro  irq_restore_user_regs
 240         ldmia   sp, {r0 - lr}^                  @ Calling r0 - lr
 241         mov     r0, r0
 242         ldr     lr, [sp, #S_PC]                 @ Get PC
 243         add     sp, sp, #S_FRAME_SIZE
 244         subs    pc, lr, #4                      @ return & move spsr_svc into cpsr
 245         .endm
 246
 247         .macro get_bad_stack
 248         ldr     r13, IRQ_STACK_START_IN         @ setup our mode stack
 249
 250         str     lr, [r13]                       @ save caller lr / spsr
 251         mrs     lr, spsr
 252         str     lr, [r13, #4]
 253
 254         mov     r13, #MODE_SVC                  @ prepare SVC-Mode
 255         msr     spsr_c, r13
 256         mov     lr, pc
 257         movs    pc, lr
 258         .endm
 259
 260         .macro get_irq_stack                    @ setup IRQ stack
 261         ldr     sp, IRQ_STACK_START
 262         .endm
 263
 264         .macro get_fiq_stack                    @ setup FIQ stack
 265         ldr     sp, FIQ_STACK_START
 266         .endm
 267
 268 /*
 269  * exception handlers
 270  */
 271         .align  5
 272 undefined_instruction:
 273         get_bad_stack
 274         bad_save_user_regs
 275         bl      do_undefined_instruction
 276
 277         .align  5
 278 software_interrupt:
 279         get_bad_stack
 280         bad_save_user_regs
 281         bl      do_software_interrupt
 282
 283         .align  5
 284 prefetch_abort:
 285         get_bad_stack
 286         bad_save_user_regs
 287         bl      do_prefetch_abort
 288
 289         .align  5
 290 data_abort:
 291         get_bad_stack
 292         bad_save_user_regs
 293         bl      do_data_abort
 294
 295         .align  5
 296 not_used:
 297         get_bad_stack
 298         bad_save_user_regs
 299         bl      do_not_used
 300
 301 #ifdef CONFIG_USE_IRQ
 302
 303         .align  5
 304 irq:
 305         get_irq_stack
 306         irq_save_user_regs
 307         bl      do_irq
 308         irq_restore_user_regs
 309
 310         .align  5
 311 fiq:
 312         get_fiq_stack
 313         /* someone ought to write a more effiction fiq_save_user_regs */
 314         irq_save_user_regs
 315         bl      do_fiq
 316         irq_restore_user_regs
 317
 318 #else
 319
 320         .align  5
 321 irq:
 322         get_bad_stack
 323         bad_save_user_regs
 324         bl      do_irq
 325
 326         .align  5
 327 fiq:
 328         get_bad_stack
 329         bad_save_user_regs
 330         bl      do_fiq
 331
 332 #endif
 333 #endif /* CONFIG_SPL_BUILD */