arch/powerpc/platforms/cell/spufs/spu_restore.c

   1 /*
   2  * spu_restore.c
   3  *
   4  * (C) Copyright IBM Corp. 2005
   5  *
   6  * SPU-side context restore sequence outlined in
   7  * Synergistic Processor Element Book IV
   8  *
   9  * Author: Mark Nutter <mnutter@us.ibm.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24  *
  25  */
  26
  27
  28 #ifndef LS_SIZE
  29 #define LS_SIZE                 0x40000 /* 256K (in bytes) */
  30 #endif
  31
  32 typedef unsigned int u32;
  33 typedef unsigned long long u64;
  34
  35 #include <spu_intrinsics.h>
  36 #include <asm/spu_csa.h>
  37 #include "spu_utils.h"
  38
  39 #define BR_INSTR                0x327fff80      /* br -4         */
  40 #define NOP_INSTR               0x40200000      /* nop           */
  41 #define HEQ_INSTR               0x7b000000      /* heq $0, $0    */
  42 #define STOP_INSTR              0x00000000      /* stop 0x0      */
  43 #define ILLEGAL_INSTR           0x00800000      /* illegal instr */
  44 #define RESTORE_COMPLETE        0x00003ffc      /* stop 0x3ffc   */
  45
  46 static inline void fetch_regs_from_mem(addr64 lscsa_ea)
  47 {
  48         unsigned int ls = (unsigned int)&regs_spill[0];
  49         unsigned int size = sizeof(regs_spill);
  50         unsigned int tag_id = 0;
  51         unsigned int cmd = 0x40;        /* GET */
  52
  53         spu_writech(MFC_LSA, ls);
  54         spu_writech(MFC_EAH, lscsa_ea.ui[0]);
  55         spu_writech(MFC_EAL, lscsa_ea.ui[1]);
  56         spu_writech(MFC_Size, size);
  57         spu_writech(MFC_TagID, tag_id);
  58         spu_writech(MFC_Cmd, cmd);
  59 }
  60
  61 static inline void restore_upper_240kb(addr64 lscsa_ea)
  62 {
  63         unsigned int ls = 16384;
  64         unsigned int list = (unsigned int)&dma_list[0];
  65         unsigned int size = sizeof(dma_list);
  66         unsigned int tag_id = 0;
  67         unsigned int cmd = 0x44;        /* GETL */
  68
  69         /* Restore, Step 4:
  70          *    Enqueue the GETL command (tag 0) to the MFC SPU command
  71          *    queue to transfer the upper 240 kb of LS from CSA.
  72          */
  73         spu_writech(MFC_LSA, ls);
  74         spu_writech(MFC_EAH, lscsa_ea.ui[0]);
  75         spu_writech(MFC_EAL, list);
  76         spu_writech(MFC_Size, size);
  77         spu_writech(MFC_TagID, tag_id);
  78         spu_writech(MFC_Cmd, cmd);
  79 }
  80
  81 static inline void restore_decr(void)
  82 {
  83         unsigned int offset;
  84         unsigned int decr_running;
  85         unsigned int decr;
  86
  87         /* Restore, Step 6(moved):
  88          *    If the LSCSA "decrementer running" flag is set
  89          *    then write the SPU_WrDec channel with the
  90          *    decrementer value from LSCSA.
  91          */
  92         offset = LSCSA_QW_OFFSET(decr_status);
  93         decr_running = regs_spill[offset].slot[0] & SPU_DECR_STATUS_RUNNING;
  94         if (decr_running) {
  95                 offset = LSCSA_QW_OFFSET(decr);
  96                 decr = regs_spill[offset].slot[0];
  97                 spu_writech(SPU_WrDec, decr);
  98         }
  99 }
 100
 101 static inline void write_ppu_mb(void)
 102 {
 103         unsigned int offset;
 104         unsigned int data;
 105
 106         /* Restore, Step 11:
 107          *    Write the MFC_WrOut_MB channel with the PPU_MB
 108          *    data from LSCSA.
 109          */
 110         offset = LSCSA_QW_OFFSET(ppu_mb);
 111         data = regs_spill[offset].slot[0];
 112         spu_writech(SPU_WrOutMbox, data);
 113 }
 114
 115 static inline void write_ppuint_mb(void)
 116 {
 117         unsigned int offset;
 118         unsigned int data;
 119
 120         /* Restore, Step 12:
 121          *    Write the MFC_WrInt_MB channel with the PPUINT_MB
 122          *    data from LSCSA.
 123          */
 124         offset = LSCSA_QW_OFFSET(ppuint_mb);
 125         data = regs_spill[offset].slot[0];
 126         spu_writech(SPU_WrOutIntrMbox, data);
 127 }
 128
 129 static inline void restore_fpcr(void)
 130 {
 131         unsigned int offset;
 132         vector unsigned int fpcr;
 133
 134         /* Restore, Step 13:
 135          *    Restore the floating-point status and control
 136          *    register from the LSCSA.
 137          */
 138         offset = LSCSA_QW_OFFSET(fpcr);
 139         fpcr = regs_spill[offset].v;
 140         spu_mtfpscr(fpcr);
 141 }
 142
 143 static inline void restore_srr0(void)
 144 {
 145         unsigned int offset;
 146         unsigned int srr0;
 147
 148         /* Restore, Step 14:
 149          *    Restore the SPU SRR0 data from the LSCSA.
 150          */
 151         offset = LSCSA_QW_OFFSET(srr0);
 152         srr0 = regs_spill[offset].slot[0];
 153         spu_writech(SPU_WrSRR0, srr0);
 154 }
 155
 156 static inline void restore_event_mask(void)
 157 {
 158         unsigned int offset;
 159         unsigned int event_mask;
 160
 161         /* Restore, Step 15:
 162          *    Restore the SPU_RdEventMsk data from the LSCSA.
 163          */
 164         offset = LSCSA_QW_OFFSET(event_mask);
 165         event_mask = regs_spill[offset].slot[0];
 166         spu_writech(SPU_WrEventMask, event_mask);
 167 }
 168
 169 static inline void restore_tag_mask(void)
 170 {
 171         unsigned int offset;
 172         unsigned int tag_mask;
 173
 174         /* Restore, Step 16:
 175          *    Restore the SPU_RdTagMsk data from the LSCSA.
 176          */
 177         offset = LSCSA_QW_OFFSET(tag_mask);
 178         tag_mask = regs_spill[offset].slot[0];
 179         spu_writech(MFC_WrTagMask, tag_mask);
 180 }
 181
 182 static inline void restore_complete(void)
 183 {
 184         extern void exit_fini(void);
 185         unsigned int *exit_instrs = (unsigned int *)exit_fini;
 186         unsigned int offset;
 187         unsigned int stopped_status;
 188         unsigned int stopped_code;
 189
 190         /* Restore, Step 18:
 191          *    Issue a stop-and-signal instruction with
 192          *    "good context restore" signal value.
 193          *
 194          * Restore, Step 19:
 195          *    There may be additional instructions placed
 196          *    here by the PPE Sequence for SPU Context
 197          *    Restore in order to restore the correct
 198          *    "stopped state".
 199          *
 200          *    This step is handled here by analyzing the
 201          *    LSCSA.stopped_status and then modifying the
 202          *    exit() function to behave appropriately.
 203          */
 204
 205         offset = LSCSA_QW_OFFSET(stopped_status);
 206         stopped_status = regs_spill[offset].slot[0];
 207         stopped_code = regs_spill[offset].slot[1];
 208
 209         switch (stopped_status) {
 210         case SPU_STOPPED_STATUS_P_I:
 211                 /* SPU_Status[P,I]=1.  Add illegal instruction
 212                  * followed by stop-and-signal instruction after
 213                  * end of restore code.
 214                  */
 215                 exit_instrs[0] = RESTORE_COMPLETE;
 216                 exit_instrs[1] = ILLEGAL_INSTR;
 217                 exit_instrs[2] = STOP_INSTR | stopped_code;
 218                 break;
 219         case SPU_STOPPED_STATUS_P_H:
 220                 /* SPU_Status[P,H]=1.  Add 'heq $0, $0' followed
 221                  * by stop-and-signal instruction after end of
 222                  * restore code.
 223                  */
 224                 exit_instrs[0] = RESTORE_COMPLETE;
 225                 exit_instrs[1] = HEQ_INSTR;
 226                 exit_instrs[2] = STOP_INSTR | stopped_code;
 227                 break;
 228         case SPU_STOPPED_STATUS_S_P:
 229                 /* SPU_Status[S,P]=1.  Add nop instruction
 230                  * followed by 'br -4' after end of restore
 231                  * code.
 232                  */
 233                 exit_instrs[0] = RESTORE_COMPLETE;
 234                 exit_instrs[1] = STOP_INSTR | stopped_code;
 235                 exit_instrs[2] = NOP_INSTR;
 236                 exit_instrs[3] = BR_INSTR;
 237                 break;
 238         case SPU_STOPPED_STATUS_S_I:
 239                 /* SPU_Status[S,I]=1.  Add  illegal instruction
 240                  * followed by 'br -4' after end of restore code.
 241                  */
 242                 exit_instrs[0] = RESTORE_COMPLETE;
 243                 exit_instrs[1] = ILLEGAL_INSTR;
 244                 exit_instrs[2] = NOP_INSTR;
 245                 exit_instrs[3] = BR_INSTR;
 246                 break;
 247         case SPU_STOPPED_STATUS_I:
 248                 /* SPU_Status[I]=1. Add illegal instruction followed
 249                  * by infinite loop after end of restore sequence.
 250                  */
 251                 exit_instrs[0] = RESTORE_COMPLETE;
 252                 exit_instrs[1] = ILLEGAL_INSTR;
 253                 exit_instrs[2] = NOP_INSTR;
 254                 exit_instrs[3] = BR_INSTR;
 255                 break;
 256         case SPU_STOPPED_STATUS_S:
 257                 /* SPU_Status[S]=1. Add two 'nop' instructions. */
 258                 exit_instrs[0] = RESTORE_COMPLETE;
 259                 exit_instrs[1] = NOP_INSTR;
 260                 exit_instrs[2] = NOP_INSTR;
 261                 exit_instrs[3] = BR_INSTR;
 262                 break;
 263         case SPU_STOPPED_STATUS_H:
 264                 /* SPU_Status[H]=1. Add 'heq $0, $0' instruction
 265                  * after end of restore code.
 266                  */
 267                 exit_instrs[0] = RESTORE_COMPLETE;
 268                 exit_instrs[1] = HEQ_INSTR;
 269                 exit_instrs[2] = NOP_INSTR;
 270                 exit_instrs[3] = BR_INSTR;
 271                 break;
 272         case SPU_STOPPED_STATUS_P:
 273                 /* SPU_Status[P]=1. Add stop-and-signal instruction
 274                  * after end of restore code.
 275                  */
 276                 exit_instrs[0] = RESTORE_COMPLETE;
 277                 exit_instrs[1] = STOP_INSTR | stopped_code;
 278                 break;
 279         case SPU_STOPPED_STATUS_R:
 280                 /* SPU_Status[I,S,H,P,R]=0. Add infinite loop. */
 281                 exit_instrs[0] = RESTORE_COMPLETE;
 282                 exit_instrs[1] = NOP_INSTR;
 283                 exit_instrs[2] = NOP_INSTR;
 284                 exit_instrs[3] = BR_INSTR;
 285                 break;
 286         default:
 287                 /* SPU_Status[R]=1. No additonal instructions. */
 288                 break;
 289         }
 290         spu_sync();
 291 }
 292
 293 /**
 294  * main - entry point for SPU-side context restore.
 295  *
 296  * This code deviates from the documented sequence in the
 297  * following aspects:
 298  *
 299  *      1. The EA for LSCSA is passed from PPE in the
 300  *         signal notification channels.
 301  *      2. The register spill area is pulled by SPU
 302  *         into LS, rather than pushed by PPE.
 303  *      3. All 128 registers are restored by exit().
 304  *      4. The exit() function is modified at run
 305  *         time in order to properly restore the
 306  *         SPU_Status register.
 307  */
 308 int main()
 309 {
 310         addr64 lscsa_ea;
 311
 312         lscsa_ea.ui[0] = spu_readch(SPU_RdSigNotify1);
 313         lscsa_ea.ui[1] = spu_readch(SPU_RdSigNotify2);
 314         fetch_regs_from_mem(lscsa_ea);
 315
 316         set_event_mask();               /* Step 1.  */
 317         set_tag_mask();                 /* Step 2.  */
 318         build_dma_list(lscsa_ea);       /* Step 3.  */
 319         restore_upper_240kb(lscsa_ea);  /* Step 4.  */
 320                                         /* Step 5: done by 'exit'. */
 321         enqueue_putllc(lscsa_ea);       /* Step 7. */
 322         set_tag_update();               /* Step 8. */
 323         read_tag_status();              /* Step 9. */
 324         restore_decr();                 /* moved Step 6. */
 325         read_llar_status();             /* Step 10. */
 326         write_ppu_mb();                 /* Step 11. */
 327         write_ppuint_mb();              /* Step 12. */
 328         restore_fpcr();                 /* Step 13. */
 329         restore_srr0();                 /* Step 14. */
 330         restore_event_mask();           /* Step 15. */
 331         restore_tag_mask();             /* Step 16. */
 332                                         /* Step 17. done by 'exit'. */
 333         restore_complete();             /* Step 18. */
 334
 335         return 0;
 336 }