Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 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 | #else |
| 128 | |
| 129 | /* |
| 130 | * Overkill warning ... |
| 131 | */ |
| 132 | #define mtc0_tlbw_hazard() \ |
| 133 | __asm__ __volatile__( \ |
| 134 | ".set noreorder\n\t" \ |
| 135 | "nop; nop; nop; nop; nop; nop;\n\t" \ |
| 136 | ".set reorder\n\t") |
| 137 | |
| 138 | #define tlbw_use_hazard() \ |
| 139 | __asm__ __volatile__( \ |
| 140 | ".set noreorder\n\t" \ |
| 141 | "nop; nop; nop; nop; nop; nop;\n\t" \ |
| 142 | ".set reorder\n\t") |
| 143 | |
| 144 | #endif |
| 145 | |
| 146 | /* |
| 147 | * mtc0->mfc0 hazard |
| 148 | * The 24K has a 2 cycle mtc0/mfc0 execution hazard. |
| 149 | * It is a MIPS32R2 processor so ehb will clear the hazard. |
| 150 | */ |
| 151 | |
| 152 | #ifdef CONFIG_CPU_MIPSR2 |
| 153 | /* |
| 154 | * Use a macro for ehb unless explicit support for MIPSR2 is enabled |
| 155 | */ |
| 156 | __asm__( |
| 157 | " .macro\tirq_enable_hazard \n\t" |
| 158 | " _ehb \n\t" |
| 159 | " .endm \n\t" |
| 160 | " \n\t" |
| 161 | " .macro\tirq_disable_hazard \n\t" |
| 162 | " _ehb \n\t" |
| 163 | " .endm"); |
| 164 | |
| 165 | #define irq_enable_hazard() \ |
| 166 | __asm__ __volatile__( \ |
| 167 | "_ehb\t\t\t\t# irq_enable_hazard") |
| 168 | |
| 169 | #define irq_disable_hazard() \ |
| 170 | __asm__ __volatile__( \ |
| 171 | "_ehb\t\t\t\t# irq_disable_hazard") |
| 172 | |
| 173 | #elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000) |
| 174 | |
| 175 | /* |
| 176 | * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer. |
| 177 | */ |
| 178 | |
| 179 | __asm__( |
| 180 | " .macro\tirq_enable_hazard \n\t" |
| 181 | " .endm \n\t" |
| 182 | " \n\t" |
| 183 | " .macro\tirq_disable_hazard \n\t" |
| 184 | " .endm"); |
| 185 | |
| 186 | #define irq_enable_hazard() do { } while (0) |
| 187 | #define irq_disable_hazard() do { } while (0) |
| 188 | |
| 189 | #else |
| 190 | |
| 191 | /* |
| 192 | * Default for classic MIPS processors. Assume worst case hazards but don't |
| 193 | * care about the irq_enable_hazard - sooner or later the hardware will |
| 194 | * enable it and we don't care when exactly. |
| 195 | */ |
| 196 | |
| 197 | __asm__( |
| 198 | " # \n\t" |
| 199 | " # There is a hazard but we do not care \n\t" |
| 200 | " # \n\t" |
| 201 | " .macro\tirq_enable_hazard \n\t" |
| 202 | " .endm \n\t" |
| 203 | " \n\t" |
| 204 | " .macro\tirq_disable_hazard \n\t" |
| 205 | " _ssnop; _ssnop; _ssnop \n\t" |
| 206 | " .endm"); |
| 207 | |
| 208 | #define irq_enable_hazard() do { } while (0) |
| 209 | #define irq_disable_hazard() \ |
| 210 | __asm__ __volatile__( \ |
| 211 | "_ssnop; _ssnop; _ssnop;\t\t# irq_disable_hazard") |
| 212 | |
| 213 | #endif |
| 214 | |
| 215 | #endif /* __ASSEMBLY__ */ |
| 216 | |
| 217 | #endif /* _ASM_HAZARDS_H */ |