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) 2006 by Ralf Baechle (ralf@linux-mips.org) 7 */ 8 #ifndef __ASM_BARRIER_H 9 #define __ASM_BARRIER_H 10 11 #include <asm/addrspace.h> 12 13 /* 14 * Sync types defined by the MIPS architecture (document MD00087 table 6.5) 15 * These values are used with the sync instruction to perform memory barriers. 16 * Types of ordering guarantees available through the SYNC instruction: 17 * - Completion Barriers 18 * - Ordering Barriers 19 * As compared to the completion barrier, the ordering barrier is a 20 * lighter-weight operation as it does not require the specified instructions 21 * before the SYNC to be already completed. Instead it only requires that those 22 * specified instructions which are subsequent to the SYNC in the instruction 23 * stream are never re-ordered for processing ahead of the specified 24 * instructions which are before the SYNC in the instruction stream. 25 * This potentially reduces how many cycles the barrier instruction must stall 26 * before it completes. 27 * Implementations that do not use any of the non-zero values of stype to define 28 * different barriers, such as ordering barriers, must make those stype values 29 * act the same as stype zero. 30 */ 31 32 /* 33 * Completion barriers: 34 * - Every synchronizable specified memory instruction (loads or stores or both) 35 * that occurs in the instruction stream before the SYNC instruction must be 36 * already globally performed before any synchronizable specified memory 37 * instructions that occur after the SYNC are allowed to be performed, with 38 * respect to any other processor or coherent I/O module. 39 * 40 * - The barrier does not guarantee the order in which instruction fetches are 41 * performed. 42 * 43 * - A stype value of zero will always be defined such that it performs the most 44 * complete set of synchronization operations that are defined.This means 45 * stype zero always does a completion barrier that affects both loads and 46 * stores preceding the SYNC instruction and both loads and stores that are 47 * subsequent to the SYNC instruction. Non-zero values of stype may be defined 48 * by the architecture or specific implementations to perform synchronization 49 * behaviors that are less complete than that of stype zero. If an 50 * implementation does not use one of these non-zero values to define a 51 * different synchronization behavior, then that non-zero value of stype must 52 * act the same as stype zero completion barrier. This allows software written 53 * for an implementation with a lighter-weight barrier to work on another 54 * implementation which only implements the stype zero completion barrier. 55 * 56 * - A completion barrier is required, potentially in conjunction with SSNOP (in 57 * Release 1 of the Architecture) or EHB (in Release 2 of the Architecture), 58 * to guarantee that memory reference results are visible across operating 59 * mode changes. For example, a completion barrier is required on some 60 * implementations on entry to and exit from Debug Mode to guarantee that 61 * memory effects are handled correctly. 62 */ 63 64 /* 65 * stype 0 - A completion barrier that affects preceding loads and stores and 66 * subsequent loads and stores. 67 * Older instructions which must reach the load/store ordering point before the 68 * SYNC instruction completes: Loads, Stores 69 * Younger instructions which must reach the load/store ordering point only 70 * after the SYNC instruction completes: Loads, Stores 71 * Older instructions which must be globally performed when the SYNC instruction 72 * completes: Loads, Stores 73 */ 74 #define STYPE_SYNC 0x0 75 76 /* 77 * Ordering barriers: 78 * - Every synchronizable specified memory instruction (loads or stores or both) 79 * that occurs in the instruction stream before the SYNC instruction must 80 * reach a stage in the load/store datapath after which no instruction 81 * re-ordering is possible before any synchronizable specified memory 82 * instruction which occurs after the SYNC instruction in the instruction 83 * stream reaches the same stage in the load/store datapath. 84 * 85 * - If any memory instruction before the SYNC instruction in program order, 86 * generates a memory request to the external memory and any memory 87 * instruction after the SYNC instruction in program order also generates a 88 * memory request to external memory, the memory request belonging to the 89 * older instruction must be globally performed before the time the memory 90 * request belonging to the younger instruction is globally performed. 91 * 92 * - The barrier does not guarantee the order in which instruction fetches are 93 * performed. 94 */ 95 96 /* 97 * stype 0x10 - An ordering barrier that affects preceding loads and stores and 98 * subsequent loads and stores. 99 * Older instructions which must reach the load/store ordering point before the 100 * SYNC instruction completes: Loads, Stores 101 * Younger instructions which must reach the load/store ordering point only 102 * after the SYNC instruction completes: Loads, Stores 103 * Older instructions which must be globally performed when the SYNC instruction 104 * completes: N/A 105 */ 106 #define STYPE_SYNC_MB 0x10 107 108 109 #ifdef CONFIG_CPU_HAS_SYNC 110 #define __sync() \ 111 __asm__ __volatile__( \ 112 ".set push\n\t" \ 113 ".set noreorder\n\t" \ 114 ".set mips2\n\t" \ 115 "sync\n\t" \ 116 ".set pop" \ 117 : /* no output */ \ 118 : /* no input */ \ 119 : "memory") 120 #else 121 #define __sync() do { } while(0) 122 #endif 123 124 #define __fast_iob() \ 125 __asm__ __volatile__( \ 126 ".set push\n\t" \ 127 ".set noreorder\n\t" \ 128 "lw $0,%0\n\t" \ 129 "nop\n\t" \ 130 ".set pop" \ 131 : /* no output */ \ 132 : "m" (*(int *)CKSEG1) \ 133 : "memory") 134 #ifdef CONFIG_CPU_CAVIUM_OCTEON 135 # define OCTEON_SYNCW_STR ".set push\n.set arch=octeon\nsyncw\nsyncw\n.set pop\n" 136 # define __syncw() __asm__ __volatile__(OCTEON_SYNCW_STR : : : "memory") 137 138 # define fast_wmb() __syncw() 139 # define fast_rmb() barrier() 140 # define fast_mb() __sync() 141 # define fast_iob() do { } while (0) 142 #else /* ! CONFIG_CPU_CAVIUM_OCTEON */ 143 # define fast_wmb() __sync() 144 # define fast_rmb() __sync() 145 # define fast_mb() __sync() 146 # ifdef CONFIG_SGI_IP28 147 # define fast_iob() \ 148 __asm__ __volatile__( \ 149 ".set push\n\t" \ 150 ".set noreorder\n\t" \ 151 "lw $0,%0\n\t" \ 152 "sync\n\t" \ 153 "lw $0,%0\n\t" \ 154 ".set pop" \ 155 : /* no output */ \ 156 : "m" (*(int *)CKSEG1ADDR(0x1fa00004)) \ 157 : "memory") 158 # else 159 # define fast_iob() \ 160 do { \ 161 __sync(); \ 162 __fast_iob(); \ 163 } while (0) 164 # endif 165 #endif /* CONFIG_CPU_CAVIUM_OCTEON */ 166 167 #ifdef CONFIG_CPU_HAS_WB 168 169 #include <asm/wbflush.h> 170 171 #define mb() wbflush() 172 #define iob() wbflush() 173 174 #else /* !CONFIG_CPU_HAS_WB */ 175 176 #define mb() fast_mb() 177 #define iob() fast_iob() 178 179 #endif /* !CONFIG_CPU_HAS_WB */ 180 181 #define wmb() fast_wmb() 182 #define rmb() fast_rmb() 183 184 #if defined(CONFIG_WEAK_ORDERING) 185 # ifdef CONFIG_CPU_CAVIUM_OCTEON 186 # define __smp_mb() __sync() 187 # define __smp_rmb() barrier() 188 # define __smp_wmb() __syncw() 189 # else 190 # define __smp_mb() __asm__ __volatile__("sync" : : :"memory") 191 # define __smp_rmb() __asm__ __volatile__("sync" : : :"memory") 192 # define __smp_wmb() __asm__ __volatile__("sync" : : :"memory") 193 # endif 194 #else 195 #define __smp_mb() barrier() 196 #define __smp_rmb() barrier() 197 #define __smp_wmb() barrier() 198 #endif 199 200 #if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP) 201 #define __WEAK_LLSC_MB " sync \n" 202 #else 203 #define __WEAK_LLSC_MB " \n" 204 #endif 205 206 #define smp_llsc_mb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory") 207 208 #ifdef CONFIG_CPU_CAVIUM_OCTEON 209 #define smp_mb__before_llsc() smp_wmb() 210 #define __smp_mb__before_llsc() __smp_wmb() 211 /* Cause previous writes to become visible on all CPUs as soon as possible */ 212 #define nudge_writes() __asm__ __volatile__(".set push\n\t" \ 213 ".set arch=octeon\n\t" \ 214 "syncw\n\t" \ 215 ".set pop" : : : "memory") 216 #else 217 #define smp_mb__before_llsc() smp_llsc_mb() 218 #define __smp_mb__before_llsc() smp_llsc_mb() 219 #define nudge_writes() mb() 220 #endif 221 222 #define __smp_mb__before_atomic() __smp_mb__before_llsc() 223 #define __smp_mb__after_atomic() smp_llsc_mb() 224 225 #include <asm-generic/barrier.h> 226 227 #endif /* __ASM_BARRIER_H */ 228