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| -rw-r--r-- | arch/mips/include/asm/barrier.h | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h new file mode 100644 index 000000000..a5eb1bb19 --- /dev/null +++ b/arch/mips/include/asm/barrier.h @@ -0,0 +1,227 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2006 by Ralf Baechle (ralf@linux-mips.org) + */ +#ifndef __ASM_BARRIER_H +#define __ASM_BARRIER_H + +#include <asm/addrspace.h> + +/* + * Sync types defined by the MIPS architecture (document MD00087 table 6.5) + * These values are used with the sync instruction to perform memory barriers. + * Types of ordering guarantees available through the SYNC instruction: + * - Completion Barriers + * - Ordering Barriers + * As compared to the completion barrier, the ordering barrier is a + * lighter-weight operation as it does not require the specified instructions + * before the SYNC to be already completed. Instead it only requires that those + * specified instructions which are subsequent to the SYNC in the instruction + * stream are never re-ordered for processing ahead of the specified + * instructions which are before the SYNC in the instruction stream. + * This potentially reduces how many cycles the barrier instruction must stall + * before it completes. + * Implementations that do not use any of the non-zero values of stype to define + * different barriers, such as ordering barriers, must make those stype values + * act the same as stype zero. + */ + +/* + * Completion barriers: + * - Every synchronizable specified memory instruction (loads or stores or both) + * that occurs in the instruction stream before the SYNC instruction must be + * already globally performed before any synchronizable specified memory + * instructions that occur after the SYNC are allowed to be performed, with + * respect to any other processor or coherent I/O module. + * + * - The barrier does not guarantee the order in which instruction fetches are + * performed. + * + * - A stype value of zero will always be defined such that it performs the most + * complete set of synchronization operations that are defined.This means + * stype zero always does a completion barrier that affects both loads and + * stores preceding the SYNC instruction and both loads and stores that are + * subsequent to the SYNC instruction. Non-zero values of stype may be defined + * by the architecture or specific implementations to perform synchronization + * behaviors that are less complete than that of stype zero. If an + * implementation does not use one of these non-zero values to define a + * different synchronization behavior, then that non-zero value of stype must + * act the same as stype zero completion barrier. This allows software written + * for an implementation with a lighter-weight barrier to work on another + * implementation which only implements the stype zero completion barrier. + * + * - A completion barrier is required, potentially in conjunction with SSNOP (in + * Release 1 of the Architecture) or EHB (in Release 2 of the Architecture), + * to guarantee that memory reference results are visible across operating + * mode changes. For example, a completion barrier is required on some + * implementations on entry to and exit from Debug Mode to guarantee that + * memory effects are handled correctly. + */ + +/* + * stype 0 - A completion barrier that affects preceding loads and stores and + * subsequent loads and stores. + * Older instructions which must reach the load/store ordering point before the + * SYNC instruction completes: Loads, Stores + * Younger instructions which must reach the load/store ordering point only + * after the SYNC instruction completes: Loads, Stores + * Older instructions which must be globally performed when the SYNC instruction + * completes: Loads, Stores + */ +#define STYPE_SYNC 0x0 + +/* + * Ordering barriers: + * - Every synchronizable specified memory instruction (loads or stores or both) + * that occurs in the instruction stream before the SYNC instruction must + * reach a stage in the load/store datapath after which no instruction + * re-ordering is possible before any synchronizable specified memory + * instruction which occurs after the SYNC instruction in the instruction + * stream reaches the same stage in the load/store datapath. + * + * - If any memory instruction before the SYNC instruction in program order, + * generates a memory request to the external memory and any memory + * instruction after the SYNC instruction in program order also generates a + * memory request to external memory, the memory request belonging to the + * older instruction must be globally performed before the time the memory + * request belonging to the younger instruction is globally performed. + * + * - The barrier does not guarantee the order in which instruction fetches are + * performed. + */ + +/* + * stype 0x10 - An ordering barrier that affects preceding loads and stores and + * subsequent loads and stores. + * Older instructions which must reach the load/store ordering point before the + * SYNC instruction completes: Loads, Stores + * Younger instructions which must reach the load/store ordering point only + * after the SYNC instruction completes: Loads, Stores + * Older instructions which must be globally performed when the SYNC instruction + * completes: N/A + */ +#define STYPE_SYNC_MB 0x10 + + +#ifdef CONFIG_CPU_HAS_SYNC +#define __sync() \ + __asm__ __volatile__( \ + ".set push\n\t" \ + ".set noreorder\n\t" \ + ".set mips2\n\t" \ + "sync\n\t" \ + ".set pop" \ + : /* no output */ \ + : /* no input */ \ + : "memory") +#else +#define __sync() do { } while(0) +#endif + +#define __fast_iob() \ + __asm__ __volatile__( \ + ".set push\n\t" \ + ".set noreorder\n\t" \ + "lw $0,%0\n\t" \ + "nop\n\t" \ + ".set pop" \ + : /* no output */ \ + : "m" (*(int *)CKSEG1) \ + : "memory") +#ifdef CONFIG_CPU_CAVIUM_OCTEON +# define OCTEON_SYNCW_STR ".set push\n.set arch=octeon\nsyncw\nsyncw\n.set pop\n" +# define __syncw() __asm__ __volatile__(OCTEON_SYNCW_STR : : : "memory") + +# define fast_wmb() __syncw() +# define fast_rmb() barrier() +# define fast_mb() __sync() +# define fast_iob() do { } while (0) +#else /* ! CONFIG_CPU_CAVIUM_OCTEON */ +# define fast_wmb() __sync() +# define fast_rmb() __sync() +# define fast_mb() __sync() +# ifdef CONFIG_SGI_IP28 +# define fast_iob() \ + __asm__ __volatile__( \ + ".set push\n\t" \ + ".set noreorder\n\t" \ + "lw $0,%0\n\t" \ + "sync\n\t" \ + "lw $0,%0\n\t" \ + ".set pop" \ + : /* no output */ \ + : "m" (*(int *)CKSEG1ADDR(0x1fa00004)) \ + : "memory") +# else +# define fast_iob() \ + do { \ + __sync(); \ + __fast_iob(); \ + } while (0) +# endif +#endif /* CONFIG_CPU_CAVIUM_OCTEON */ + +#ifdef CONFIG_CPU_HAS_WB + +#include <asm/wbflush.h> + +#define mb() wbflush() +#define iob() wbflush() + +#else /* !CONFIG_CPU_HAS_WB */ + +#define mb() fast_mb() +#define iob() fast_iob() + +#endif /* !CONFIG_CPU_HAS_WB */ + +#define wmb() fast_wmb() +#define rmb() fast_rmb() + +#if defined(CONFIG_WEAK_ORDERING) +# ifdef CONFIG_CPU_CAVIUM_OCTEON +# define __smp_mb() __sync() +# define __smp_rmb() barrier() +# define __smp_wmb() __syncw() +# else +# define __smp_mb() __asm__ __volatile__("sync" : : :"memory") +# define __smp_rmb() __asm__ __volatile__("sync" : : :"memory") +# define __smp_wmb() __asm__ __volatile__("sync" : : :"memory") +# endif +#else +#define __smp_mb() barrier() +#define __smp_rmb() barrier() +#define __smp_wmb() barrier() +#endif + +#if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP) +#define __WEAK_LLSC_MB " sync \n" +#else +#define __WEAK_LLSC_MB " \n" +#endif + +#define smp_llsc_mb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory") + +#ifdef CONFIG_CPU_CAVIUM_OCTEON +#define smp_mb__before_llsc() smp_wmb() +#define __smp_mb__before_llsc() __smp_wmb() +/* Cause previous writes to become visible on all CPUs as soon as possible */ +#define nudge_writes() __asm__ __volatile__(".set push\n\t" \ + ".set arch=octeon\n\t" \ + "syncw\n\t" \ + ".set pop" : : : "memory") +#else +#define smp_mb__before_llsc() smp_llsc_mb() +#define __smp_mb__before_llsc() smp_llsc_mb() +#define nudge_writes() mb() +#endif + +#define __smp_mb__before_atomic() __smp_mb__before_llsc() +#define __smp_mb__after_atomic() smp_llsc_mb() + +#include <asm-generic/barrier.h> + +#endif /* __ASM_BARRIER_H */ |