arch/ppc/cpu/ppc4xx/dcr.S

   1 /*
   2  * (C) Copyright 2001
   3  * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   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 as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23 #include <config.h>
  24
  25 #if defined(CONFIG_4xx) && defined(CONFIG_CMD_SETGETDCR)
  26
  27 #include <ppc4xx.h>
  28
  29 #define _LINUX_CONFIG_H 1       /* avoid reading Linux autoconf.h file  */
  30
  31 #include <ppc_asm.tmpl>
  32 #include <ppc_defs.h>
  33
  34 #include <asm/cache.h>
  35 #include <asm/mmu.h>
  36
  37 #define _ASMLANGUAGE
  38
  39 /*****************************************************************************
  40  *
  41  *  XXX - DANGER
  42  *        These routines make use of self modifying code.  DO NOT CALL THEM
  43  *        UNTIL THEY ARE RELOCATED TO RAM.  Additionally, I do not
  44  *        recommend them for use in anything other than an interactive
  45  *        debugging environment.  This is mainly due to performance reasons.
  46  *
  47  ****************************************************************************/
  48
  49 /*
  50  * static void _create_MFDCR(unsigned short dcrn)
  51  *
  52  * Builds a 'mfdcr' instruction for get_dcr
  53  * function.
  54  */
  55                 .section ".text"
  56                 .align 2
  57                 .type    _create_MFDCR,@function
  58 _create_MFDCR:
  59                 /*
  60                  * Build up a 'mfdcr' instruction formatted as follows:
  61                  *
  62                  *  OPCD |   RT   |    DCRF      |     XO       | CR |
  63                  * ---------------|--------------|--------------|----|
  64                  * 0   5 | 6   10 | 11        20 | 21        30 | 31 |
  65                  *       |        |    DCRN      |              |    |
  66                  *   31  |  %r3   | (5..9|0..4)  |      323     |  0 |
  67                  *
  68                  * Where:
  69                  *      OPCD = opcode - 31
  70                  *      RT   = destination register - %r3 return register
  71                  *      DCRF = DCRN # with upper and lower halves swapped
  72                  *      XO   = extended opcode - 323
  73                  *      CR   = CR[CR0] NOT undefined - 0
  74                  */
  75                 rlwinm  r0, r3, 27, 27, 31      /* OPCD = 31 */
  76                 rlwinm  r3, r3, 5, 22, 26
  77                 or      r3, r3, r0
  78                 slwi    r3, r3, 10
  79                 oris    r3, r3, 0x3e30          /* RT = %r3 */
  80                 ori     r3, r3, 323             /* XO = 323 */
  81                 slwi    r3, r3, 1               /* CR = 0 */
  82
  83                 mflr    r4
  84                 stw     r3, 0(r4)               /* Store instr in get_dcr() */
  85                 dcbst   r0, r4                  /* Make sure val is written out */
  86                 sync                            /* Wait for write to complete */
  87                 icbi    r0, r4                  /* Make sure old instr is dumped */
  88                 isync                           /* Wait for icbi to complete */
  89
  90                 blr
  91 .Lfe1:          .size    _create_MFDCR,.Lfe1-_create_MFDCR
  92 /* end _create_MFDCR() */
  93
  94 /*
  95  * static void _create_MTDCR(unsigned short dcrn, unsigned long value)
  96  *
  97  * Builds a 'mtdcr' instruction for set_dcr
  98  * function.
  99  */
 100                 .section ".text"
 101                 .align 2
 102                 .type    _create_MTDCR,@function
 103 _create_MTDCR:
 104                 /*
 105                  * Build up a 'mtdcr' instruction formatted as follows:
 106                  *
 107                  *  OPCD |   RS   |    DCRF      |     XO       | CR |
 108                  * ---------------|--------------|--------------|----|
 109                  * 0   5 | 6   10 | 11        20 | 21        30 | 31 |
 110                  *       |        |    DCRN      |              |    |
 111                  *   31  |  %r3   | (5..9|0..4)  |      451     |  0 |
 112                  *
 113                  * Where:
 114                  *      OPCD = opcode - 31
 115                  *      RS   = source register - %r4
 116                  *      DCRF = dest. DCRN # with upper and lower halves swapped
 117                  *      XO   = extended opcode - 451
 118                  *      CR   = CR[CR0] NOT undefined - 0
 119                  */
 120                 rlwinm  r0, r3, 27, 27, 31      /* OPCD = 31 */
 121                 rlwinm  r3, r3, 5, 22, 26
 122                 or      r3, r3, r0
 123                 slwi    r3, r3, 10
 124                 oris    r3, r3, 0x3e40          /* RS = %r4 */
 125                 ori     r3, r3, 451             /* XO = 451 */
 126                 slwi    r3, r3, 1               /* CR = 0 */
 127
 128                 mflr    r5
 129                 stw     r3, 0(r5)               /* Store instr in set_dcr() */
 130                 dcbst   r0, r5                  /* Make sure val is written out */
 131                 sync                            /* Wait for write to complete */
 132                 icbi    r0, r5                  /* Make sure old instr is dumped */
 133                 isync                           /* Wait for icbi to complete */
 134
 135                 blr
 136 .Lfe2:          .size    _create_MTDCR,.Lfe2-_create_MTDCR
 137 /* end _create_MTDCR() */
 138
 139
 140 /*
 141  * unsigned long get_dcr(unsigned short dcrn)
 142  *
 143  * Return a given DCR's value.
 144  */
 145                 /* */
 146                 /* XXX - This is self modifying code, hence */
 147                 /* it is in the data section. */
 148                 /* */
 149                 .section ".data"
 150                 .align  2
 151                 .globl  get_dcr
 152                 .type   get_dcr,@function
 153 get_dcr:
 154                 mflr    r0                      /* Get link register */
 155                 stwu    r1, -32(r1)             /* Save back chain and move SP */
 156                 stw     r0, +36(r1)             /* Save link register */
 157
 158                 bl      _create_MFDCR           /* Build following instruction */
 159                 /* XXX - we build this instuction up on the fly. */
 160                 .long   0                       /* Get DCR's value */
 161
 162                 lwz     r0, +36(r1)             /* Get saved link register */
 163                 mtlr    r0                      /* Restore link register */
 164                 addi    r1, r1, +32             /* Remove frame from stack */
 165                 blr                             /* Return to calling function */
 166 .Lfe3:          .size   get_dcr,.Lfe3-get_dcr
 167 /* end get_dcr() */
 168
 169
 170 /*
 171  * unsigned void set_dcr(unsigned short dcrn, unsigned long value)
 172  *
 173  * Return a given DCR's value.
 174  */
 175                 /*
 176                  * XXX - This is self modifying code, hence
 177                  * it is in the data section.
 178                  */
 179                 .section ".data"
 180                 .align  2
 181                 .globl  set_dcr
 182                 .type   set_dcr,@function
 183 set_dcr:
 184                 mflr    r0                      /* Get link register */
 185                 stwu    r1, -32(r1)             /* Save back chain and move SP */
 186                 stw     r0, +36(r1)             /* Save link register */
 187
 188                 bl      _create_MTDCR           /* Build following instruction */
 189                 /* XXX - we build this instuction up on the fly. */
 190                 .long   0                       /* Set DCR's value */
 191
 192                 lwz     r0, +36(r1)             /* Get saved link register */
 193                 mtlr    r0                      /* Restore link register */
 194                 addi    r1, r1, +32             /* Remove frame from stack */
 195                 blr                             /* Return to calling function */
 196 .Lfe4:          .size   set_dcr,.Lfe4-set_dcr
 197 /* end set_dcr() */
 198 #endif