include/asm-mips/hazards.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2003, 2004 Ralf Baechle
   7  */
   8 #ifndef _ASM_HAZARDS_H
   9 #define _ASM_HAZARDS_H
  10
  11 #include <linux/config.h>
  12
  13 #ifdef __ASSEMBLY__
  14
  15         .macro  _ssnop
  16         sll     $0, $0, 1
  17         .endm
  18
  19         .macro  _ehb
  20         sll     $0, $0, 3
  21         .endm
  22
  23 /*
  24  * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
  25  * use of the JTLB for instructions should not occur for 4 cpu cycles and use
  26  * for data translations should not occur for 3 cpu cycles.
  27  */
  28 #ifdef CONFIG_CPU_RM9000
  29
  30         .macro  mtc0_tlbw_hazard
  31         .set    push
  32         .set    mips32
  33         _ssnop; _ssnop; _ssnop; _ssnop
  34         .set    pop
  35         .endm
  36
  37         .macro  tlbw_eret_hazard
  38         .set    push
  39         .set    mips32
  40         _ssnop; _ssnop; _ssnop; _ssnop
  41         .set    pop
  42         .endm
  43
  44 #else
  45
  46 /*
  47  * The taken branch will result in a two cycle penalty for the two killed
  48  * instructions on R4000 / R4400.  Other processors only have a single cycle
  49  * hazard so this is nice trick to have an optimal code for a range of
  50  * processors.
  51  */
  52         .macro  mtc0_tlbw_hazard
  53         b       . + 8
  54         .endm
  55
  56         .macro  tlbw_eret_hazard
  57         .endm
  58 #endif
  59
  60 /*
  61  * mtc0->mfc0 hazard
  62  * The 24K has a 2 cycle mtc0/mfc0 execution hazard.
  63  * It is a MIPS32R2 processor so ehb will clear the hazard.
  64  */
  65
  66 #ifdef CONFIG_CPU_MIPSR2
  67 /*
  68  * Use a macro for ehb unless explicit support for MIPSR2 is enabled
  69  */
  70
  71 #define irq_enable_hazard
  72         _ehb
  73
  74 #define irq_disable_hazard
  75         _ehb
  76
  77 #elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000)
  78
  79 /*
  80  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
  81  */
  82
  83 #define irq_enable_hazard
  84
  85 #define irq_disable_hazard
  86
  87 #else
  88
  89 /*
  90  * Classic MIPS needs 1 - 3 nops or ssnops
  91  */
  92 #define irq_enable_hazard
  93 #define irq_disable_hazard                                              \
  94         _ssnop; _ssnop; _ssnop
  95
  96 #endif
  97
  98 #else /* __ASSEMBLY__ */
  99
 100 __asm__(
 101         "       .macro  _ssnop                                  \n\t"
 102         "       sll     $0, $2, 1                               \n\t"
 103         "       .endm                                           \n\t"
 104         "                                                       \n\t"
 105         "       .macro  _ehb                                    \n\t"
 106         "       sll     $0, $0, 3                               \n\t"
 107         "       .endm                                           \n\t");
 108
 109 #ifdef CONFIG_CPU_RM9000
 110 /*
 111  * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
 112  * use of the JTLB for instructions should not occur for 4 cpu cycles and use
 113  * for data translations should not occur for 3 cpu cycles.
 114  */
 115
 116 #define mtc0_tlbw_hazard()                                              \
 117         __asm__ __volatile__(                                           \
 118                 ".set\tmips32\n\t"                                      \
 119                 "_ssnop; _ssnop; _ssnop; _ssnop\n\t"                    \
 120                 ".set\tmips0")
 121
 122 #define tlbw_use_hazard()                                               \
 123         __asm__ __volatile__(                                           \
 124                 ".set\tmips32\n\t"                                      \
 125                 "_ssnop; _ssnop; _ssnop; _ssnop\n\t"                    \
 126                 ".set\tmips0")
 127
 128 #define back_to_back_c0_hazard()        do { } while (0)
 129
 130 #else
 131
 132 /*
 133  * Overkill warning ...
 134  */
 135 #define mtc0_tlbw_hazard()                                              \
 136         __asm__ __volatile__(                                           \
 137                 ".set noreorder\n\t"                                    \
 138                 "nop; nop; nop; nop; nop; nop;\n\t"                     \
 139                 ".set reorder\n\t")
 140
 141 #define tlbw_use_hazard()                                               \
 142         __asm__ __volatile__(                                           \
 143                 ".set noreorder\n\t"                                    \
 144                 "nop; nop; nop; nop; nop; nop;\n\t"                     \
 145                 ".set reorder\n\t")
 146
 147 #define back_to_back_c0_hazard()                                        \
 148         __asm__ __volatile__(                                           \
 149         "       .set noreorder                          \n"             \
 150         "       nop; nop; nop                           \n"             \
 151         "       .set reorder                            \n")
 152
 153 #endif
 154
 155 /*
 156  * mtc0->mfc0 hazard
 157  * The 24K has a 2 cycle mtc0/mfc0 execution hazard.
 158  * It is a MIPS32R2 processor so ehb will clear the hazard.
 159  */
 160
 161 #ifdef CONFIG_CPU_MIPSR2
 162 /*
 163  * Use a macro for ehb unless explicit support for MIPSR2 is enabled
 164  */
 165 __asm__(
 166         "       .macro\tirq_enable_hazard                       \n\t"
 167         "       _ehb                                            \n\t"
 168         "       .endm                                           \n\t"
 169         "                                                       \n\t"
 170         "       .macro\tirq_disable_hazard                      \n\t"
 171         "       _ehb                                            \n\t"
 172         "       .endm");
 173
 174 #define irq_enable_hazard()                                             \
 175         __asm__ __volatile__(                                           \
 176         "_ehb\t\t\t\t# irq_enable_hazard")
 177
 178 #define irq_disable_hazard()                                            \
 179         __asm__ __volatile__(                                           \
 180         "_ehb\t\t\t\t# irq_disable_hazard")
 181
 182 #define back_to_back_c0_hazard()                                        \
 183         __asm__ __volatile__(                                           \
 184         "_ehb\t\t\t\t# back_to_back_c0_hazard")
 185
 186 #elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000)
 187
 188 /*
 189  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
 190  */
 191
 192 __asm__(
 193         "       .macro\tirq_enable_hazard                       \n\t"
 194         "       .endm                                           \n\t"
 195         "                                                       \n\t"
 196         "       .macro\tirq_disable_hazard                      \n\t"
 197         "       .endm");
 198
 199 #define irq_enable_hazard()     do { } while (0)
 200 #define irq_disable_hazard()    do { } while (0)
 201
 202 #define back_to_back_c0_hazard()        do { } while (0)
 203
 204 #else
 205
 206 /*
 207  * Default for classic MIPS processors.  Assume worst case hazards but don't
 208  * care about the irq_enable_hazard - sooner or later the hardware will
 209  * enable it and we don't care when exactly.
 210  */
 211
 212 __asm__(
 213         "       #                                               \n\t"
 214         "       # There is a hazard but we do not care          \n\t"
 215         "       #                                               \n\t"
 216         "       .macro\tirq_enable_hazard                       \n\t"
 217         "       .endm                                           \n\t"
 218         "                                                       \n\t"
 219         "       .macro\tirq_disable_hazard                      \n\t"
 220         "       _ssnop; _ssnop; _ssnop                          \n\t"
 221         "       .endm");
 222
 223 #define irq_enable_hazard()     do { } while (0)
 224 #define irq_disable_hazard()                                            \
 225         __asm__ __volatile__(                                           \
 226         "_ssnop; _ssnop; _ssnop;\t\t# irq_disable_hazard")
 227
 228 #define back_to_back_c0_hazard()                                        \
 229         __asm__ __volatile__(                                           \
 230         "       .set noreorder                          \n"             \
 231         "       nop; nop; nop                           \n"             \
 232         "       .set reorder                            \n")
 233
 234 #endif
 235
 236 #endif /* __ASSEMBLY__ */
 237
 238 #endif /* _ASM_HAZARDS_H */