src/start.S

   1 /*
   2  *      <start.S>
   3  *
   4  *     BIOS start code for Open Hack'Ware.
   5  *
   6  *   Copyright (C) 2004-2005 Jocelyn Mayer (l_indien@magic.fr)
   7  *
   8  *   This program is free software; you can redistribute it and/or
   9  *   modify it under the terms of the GNU General Public License V2
  10  *   as published by the Free Software Foundation
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #define ASSEMBLY_CODE
  23 #include "bios.h"
  24
  25 .section .start, "ax"
  26 .align 2
  27
  28 .globl _start
  29 _start:
  30         /* Save our stack pointer */
  31         lis    r11, saved_params@h                           ;
  32         ori    r11, r11, saved_params@l                      ;
  33         stw    r1, 0(r11)                                    ;
  34         /* Fill space from _bss_start to _ram_start with zeroes */
  35         lis    r11, _bss_start@h                             ;
  36         ori    r11, r11, _bss_start@l                        ;
  37         lis    r12, _ram_start@h                             ;
  38         ori    r12, r12, _ram_start@l                        ;
  39         subf   r12, r11, r12                                 ;
  40         srawi  r12, r12, 2                                   ;
  41         cmpi   0, r12, 0                                     ;
  42         beq    _bss_done                                     ;
  43         mtctr  r12                                           ;
  44         subi   r11, r11, 4                                   ;
  45         li     r12, 0                                        ;
  46 _bss_loop:
  47         stwu   r12, 4(r11)                                   ;
  48         bdnz   _bss_loop                                     ;
  49 _bss_done:
  50         /* Now, we have a real C environment: call main */
  51         bl     main                                          ;
  52         /* If we return, stop */
  53 .globl bug
  54 bug:
  55         li     r0, 0x80                                      ;
  56         mtlr   r0                                            ;
  57         blr                                                  ;
  58 _return_loop:
  59         b      _return_loop                                  ;
  60
  61 .section .data
  62 .align 2
  63 saved_params:
  64         .long 0x00000000 /* OF stack     */
  65         .long 0x00000000 /* client stack */
  66         .long 0x00000000 /* client link  */
  67
  68 .section .text
  69 .align 2
  70
  71 .globl transfer_handler
  72 transfer_handler:
  73         /* Build a new stack room and launch loaded image
  74          * void transfer_handler (void *residual, void *load_addr,
  75          *                        void *OF_entry, void *bootinfos,
  76          *                        void *cmdline, void *unused,
  77          *                        void *nip, void *stack_base);
  78          */
  79         mfmsr  r0                                            ;
  80         mtspr  SRR1, r0                                      ;
  81         mtspr  SRR0, r9                                      ;
  82         li     r0, 0                                         ;
  83         mr     r1, r10                                       ;
  84         stw    r1, -16(r1)                                   ;
  85         stwu   r0, -4(r1)                                    ;
  86         stwu   r0, -4(r1)                                    ;
  87         stwu   r0, -4(r1)                                    ;
  88         stwu   r0, -4(r1)                                    ;
  89         /* Skip frame pointer */
  90         stwu   r0, -8(r1)                                    ;
  91         stwu   r0, -4(r1)                                    ;
  92         stwu   r0, -4(r1)                                    ;
  93         rfi                                                  ;
  94         /* Should never return, but who knows... */
  95         bl     bug                                           ;
  96
  97 .globl  OF_entry
  98 OF_entry:
  99         /* Save the stack pointer and get our own one */
 100         lis    r11, saved_params@h                           ;
 101         ori    r11, r11, saved_params@l                      ;
 102         mflr   r12                                           ;
 103         stw    r12, 8(r11)                                   ;
 104         stw    r1, 4(r11)                                    ;
 105         lwz    r1, 0(r11)                                    ;
 106         bl     OF_client_entry                               ;
 107         lis    r11, saved_params@h                           ;
 108         ori    r11, r11, saved_params@l                      ;
 109         lwz    r12, 8(r11)                                   ;
 110         mtlr   r12                                           ;
 111         lwz    r1, 4(r11)                                    ;
 112         blr                                                  ;
 113
 114         /* PPC helpers */
 115 .globl mfmsr
 116 mfmsr:
 117         /* uint32_t mfmsr (void); */
 118         mfmsr  r3                                            ;
 119         blr                                                  ;
 120 .globl mtmsr
 121 mtmsr:
 122         /* void mtmsr (uint32_t msr); */
 123         lis    r0, _mtmsr_rfi@h                              ;
 124         ori    r0, r0, _mtmsr_rfi@l                          ;
 125         mtspr  26, r0                                        ;
 126         mtspr  27, r3                                        ;
 127         rfi                                                  ;
 128 _mtmsr_rfi:
 129         blr                                                  ;
 130 .globl MMU_on
 131 MMU_on:
 132         /* void MMU_on (void); */
 133         stwu   r1, -16(r1)                                   ;
 134         mflr   r0                                            ;
 135         stw    r0, 20(r1)                                    ;
 136         mfmsr  r3                                            ;
 137         ori    r3, r3, 0x30                                  ;
 138         bl     mtmsr                                         ;
 139         lwz    r0, 20(r1)                                    ;
 140         mtlr   r0                                            ;
 141         addi   r1, r1, 16                                    ;
 142         blr                                                  ;
 143
 144 .globl MMU_off
 145 MMU_off:
 146         /* void MMU_off (void); */
 147         stwu   r1, -16(r1)                                   ;
 148         mflr   r0                                            ;
 149         stw    r0, 20(r1)                                    ;
 150         mfmsr  r3                                            ;
 151         andi.  r3, r3, 0xFFCF                                ;
 152         bl     mtmsr                                         ;
 153         lwz    r0, 20(r1)                                    ;
 154         mtlr   r0                                            ;
 155         addi   r1, r1, 16                                    ;
 156         blr                                                  ;
 157
 158 .globl mfpvr
 159 mfpvr:
 160         /* uint32_t mfpvr (void); */
 161         mfpvr  r3                                            ;
 162         blr                                                  ;
 163
 164 .globl mftb
 165 mftb:
 166         /* void mftb (uint32_t *tb); */
 167         stwu   r1, -16(r1)                                   ;
 168         stw    r11, 12(r1)                                   ;
 169         stw    r12,  8(r1)                                   ;
 170         /* No need to save lr */
 171 _tb_loop:
 172         mftbu  r11                                           ;
 173         mftb   r12                                           ;
 174         mftbu  r0                                            ;
 175         cmpw   r0, r11                                       ;
 176         bne    _tb_loop                                      ;
 177         stw    r11,  0(r3)                                   ;
 178         stw    r12,  4(r3)                                   ;
 179         lwz    r12,  8(r1)                                   ;
 180         lwz    r11, 12(r1)                                   ;
 181         addi   r1, r1, 16                                    ;
 182         blr                                                  ;
 183
 184         /* IO helpers */
 185 .globl inb
 186 inb:
 187         /* uint32_t inb (uint16_t port); */
 188         stwu   r1, -16(r1)                                   ;
 189         stw    r11, 12(r1)                                   ;
 190         lis    r11, isa_io_base@h                            ;
 191         ori    r11, r11, isa_io_base@l                       ;
 192         lwz    r11, 0(r11)                                   ;
 193         add    r3, r3, r11                                   ;
 194         lbz    r3, 0(r3)                                     ;
 195         eieio                                                ;
 196         lwz    r11, 12(r1)                                   ;
 197         addi   r1, r1, 16                                    ;
 198         blr                                                  ;
 199
 200 .globl outb
 201 outb:
 202         /* void outb (uint16_t port, uint32_t val); */
 203         stwu   r1, -16(r1)                                   ;
 204         stw    r11, 12(r1)                                   ;
 205         lis    r11, isa_io_base@h                            ;
 206         ori    r11, r11, isa_io_base@l                       ;
 207         lwz    r11, 0(r11)                                   ;
 208         add    r3, r3, r11                                   ;
 209         eieio                                                ;
 210         stb    r4, 0(r3)                                     ;
 211         lwz    r11, 12(r1)                                   ;
 212         addi   r1, r1, 16                                    ;
 213         blr                                                  ;
 214
 215 .globl inw
 216 inw:
 217         /* uint32_t inw (uint16_t port); */
 218         stwu   r1, -16(r1)                                   ;
 219         stw    r11, 12(r1)                                   ;
 220         lis    r11, isa_io_base@h                            ;
 221         ori    r11, r11, isa_io_base@l                       ;
 222         lwz    r11, 0(r11)                                   ;
 223         add    r3, r3, r11                                   ;
 224         lhbrx  r3, 0, r3                                     ;
 225         eieio                                                ;
 226         lwz    r11, 12(r1)                                   ;
 227         addi   r1, r1, 16                                    ;
 228         blr                                                  ;
 229
 230 .globl outw
 231 outw:
 232         /* void outw (uint16_t port, uint32_t val); */
 233         stwu   r1, -16(r1)                                   ;
 234         stw    r11, 12(r1)                                   ;
 235         lis    r11, isa_io_base@h                            ;
 236         ori    r11, r11, isa_io_base@l                       ;
 237         lwz    r11, 0(r11)                                   ;
 238         add    r3, r3, r11                                   ;
 239         eieio                                                ;
 240         sthbrx r4, 0, r3                                     ;
 241         lwz    r11, 12(r1)                                   ;
 242         addi   r1, r1, 16                                    ;
 243         blr                                                  ;
 244
 245 .globl inl
 246 inl:
 247         /* uint32_t inl (uint16_t port); */
 248         stwu   r1, -16(r1)                                   ;
 249         stw    r11, 12(r1)                                   ;
 250         lis    r11, isa_io_base@h                            ;
 251         ori    r11, r11, isa_io_base@l                       ;
 252         lwz    r11, 0(r11)                                   ;
 253         add    r3, r3, r11                                   ;
 254         lwbrx  r3, 0, r3                                     ;
 255         eieio                                                ;
 256         lwz    r11, 12(r1)                                   ;
 257         addi   r1, r1, 16                                    ;
 258         blr                                                  ;
 259
 260 .globl outl
 261 outl:
 262         /* void outl (uint16_t port, uint32_t val); */
 263         stwu   r1, -16(r1)                                   ;
 264         stw    r11, 12(r1)                                   ;
 265         lis    r11, isa_io_base@h                            ;
 266         ori    r11, r11, isa_io_base@l                       ;
 267         lwz    r11, 0(r11)                                   ;
 268         add    r3, r3, r11                                   ;
 269         eieio                                                ;
 270         stwbrx r4, 0, r3                                     ;
 271         lwz    r11, 12(r1)                                   ;
 272         addi   r1, r1, 16                                    ;
 273         blr                                                  ;
 274
 275 .globl eieio
 276 eieio:
 277         eieio                                                ;
 278         blr                                                  ;
 279
 280         /* Misc helpers */
 281 .globl ldswap16
 282 ldswap16:
 283         /* uint16_t ldswap16 (uint16_t *addr); */
 284         lhbrx  r3, 0, r3                                     ;
 285         blr                                                  ;
 286
 287 .globl stswap16
 288 stswap16:
 289         /* void stswap16 (void *addr, uint16_t val); */
 290         sthbrx r4, 0, r3                                     ;
 291         blr                                                  ;
 292
 293 .globl ldswap32
 294 ldswap32:
 295         /* uint32_t ldswap32 (uint32_t *addr); */
 296         lwbrx  r3, 0, r3                                     ;
 297         blr                                                  ;
 298
 299 .globl stswap32
 300 stswap32:
 301         /* void stswap32 (void *addr, uint32_t val); */
 302         stwbrx r4, 0, r3                                     ;
 303         blr                                                  ;
 304
 305 .globl mul64
 306 mul64:
 307         /* void mul64 (uint32_t *ret, uint32_t a, uint32_t b); */
 308         mulhwu r0, r4, r5                                    ;
 309         stw    r0, 0(r3)                                     ;
 310         mullw  r0, r4, r5                                    ;
 311         stw    r0, 4(r3)                                     ;
 312         blr                                                  ;
 313
 314 .globl add64
 315 add64:
 316         /* void add64 (uint32_t *ret, uint32_t *a, uint32_t *b); */
 317         stwu   r1, -16(r1)                                   ;
 318         stw    r11, 12(r1)                                   ;
 319         stw    r12,  8(r1)                                   ;
 320         lwz    r11,  4(r4)                                   ;
 321         lwz    r12,  4(r5)                                   ;
 322         addc   r0, r11, r12                                  ;
 323         stw    r0,   4(r3)                                   ;
 324         lwz    r11,  0(r4)                                   ;
 325         lwz    r12,  0(r5)                                   ;
 326         adde   r0, r11, r12                                  ;
 327         stw    r0,   0(r3)                                   ;
 328         lwz    r12,  8(r1)                                   ;
 329         lwz    r11,  4(r1)                                   ;
 330         addi   r1, r1, 16                                    ;
 331         blr                                                  ;
 332
 333 .globl setjmp
 334 setjmp:
 335         /* int setjmp (jmp_buf env); */
 336         /* save gprs */
 337         stmw   r0, 0(r3)                                     ;
 338         /* save lr, ctr, xer and ccr */
 339         mflr   r0                                            ;
 340         stw    r0, 0x80(r3)                                  ;
 341         mfctr  r0                                            ;
 342         stw    r0, 0x84(r3)                                  ;
 343         mfxer  r0                                            ;
 344         stw    r0, 0x88(r3)                                  ;
 345         mfcr   r0                                            ;
 346         stw    r0, 0x8C(r3)                                  ;
 347         /* return 0 */
 348         li     r3, 0                                         ;
 349         blr                                                  ;
 350
 351 .globl longjmp
 352 longjmp:
 353         /* void longjmp (jmp_buf env, int val); */
 354         /* Let's pretend env is our stack */
 355         mr     r1, r3                                        ;
 356         /* Be sure we won't return 0 */
 357         cmpi   0, r4, 0                                      ;
 358         bne    _longjmp_cont                                 ;
 359         addi   r4, r4, 1                                     ;
 360 _longjmp_cont:
 361         /* Store return value in jmp_buf */
 362         stw    r4, 0x0C(r1)                                  ;
 363         /* restore lr, ctr, xer and ccr */
 364         lwz    r0, 0x80(r1)                                  ;
 365         mtlr   r0                                            ;
 366         lwz    r0, 0x84(r1)                                  ;
 367         mtctr  r0                                            ;
 368         lwz    r0, 0x88(r1)                                  ;
 369         mtxer  r0                                            ;
 370         lwz    r0, 0x8C(r1)                                  ;
 371         mtcr   r0                                            ;
 372         /* Restore r2 to r31 */
 373         lmw    r2, 0x08(r1)                                  ;
 374         /* Restore r0 (could forget it...) */
 375         lwz    r0, 0x00(r1)                                  ;
 376         /* Restore stack */
 377         lwz    r1, 0x04(r1)                                  ;
 378         /* Return */
 379         blr                                                  ;