1 /* 2 * Generic barrier definitions, originally based on MN10300 definitions. 3 * 4 * It should be possible to use these on really simple architectures, 5 * but it serves more as a starting point for new ports. 6 * 7 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 8 * Written by David Howells (dhowells@redhat.com) 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public Licence 12 * as published by the Free Software Foundation; either version 13 * 2 of the Licence, or (at your option) any later version. 14 */ 15 #ifndef __ASM_GENERIC_BARRIER_H 16 #define __ASM_GENERIC_BARRIER_H 17 18 #ifndef __ASSEMBLY__ 19 20 #include <linux/compiler.h> 21 22 #ifndef nop 23 #define nop() asm volatile ("nop") 24 #endif 25 26 /* 27 * Force strict CPU ordering. And yes, this is required on UP too when we're 28 * talking to devices. 29 * 30 * Fall back to compiler barriers if nothing better is provided. 31 */ 32 33 #ifndef mb 34 #define mb() barrier() 35 #endif 36 37 #ifndef rmb 38 #define rmb() mb() 39 #endif 40 41 #ifndef wmb 42 #define wmb() mb() 43 #endif 44 45 #ifndef dma_rmb 46 #define dma_rmb() rmb() 47 #endif 48 49 #ifndef dma_wmb 50 #define dma_wmb() wmb() 51 #endif 52 53 #ifndef read_barrier_depends 54 #define read_barrier_depends() do { } while (0) 55 #endif 56 57 #ifdef CONFIG_SMP 58 59 #ifndef smp_mb 60 #define smp_mb() mb() 61 #endif 62 63 #ifndef smp_rmb 64 #define smp_rmb() rmb() 65 #endif 66 67 #ifndef smp_wmb 68 #define smp_wmb() wmb() 69 #endif 70 71 #ifndef smp_read_barrier_depends 72 #define smp_read_barrier_depends() read_barrier_depends() 73 #endif 74 75 #else /* !CONFIG_SMP */ 76 77 #ifndef smp_mb 78 #define smp_mb() barrier() 79 #endif 80 81 #ifndef smp_rmb 82 #define smp_rmb() barrier() 83 #endif 84 85 #ifndef smp_wmb 86 #define smp_wmb() barrier() 87 #endif 88 89 #ifndef smp_read_barrier_depends 90 #define smp_read_barrier_depends() do { } while (0) 91 #endif 92 93 #endif /* CONFIG_SMP */ 94 95 #ifndef smp_store_mb 96 #define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } while (0) 97 #endif 98 99 #ifndef smp_mb__before_atomic 100 #define smp_mb__before_atomic() smp_mb() 101 #endif 102 103 #ifndef smp_mb__after_atomic 104 #define smp_mb__after_atomic() smp_mb() 105 #endif 106 107 #define smp_store_release(p, v) \ 108 do { \ 109 compiletime_assert_atomic_type(*p); \ 110 smp_mb(); \ 111 WRITE_ONCE(*p, v); \ 112 } while (0) 113 114 #define smp_load_acquire(p) \ 115 ({ \ 116 typeof(*p) ___p1 = READ_ONCE(*p); \ 117 compiletime_assert_atomic_type(*p); \ 118 smp_mb(); \ 119 ___p1; \ 120 }) 121 122 #endif /* !__ASSEMBLY__ */ 123 #endif /* __ASM_GENERIC_BARRIER_H */ 124