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Diffstat (limited to 'arch/tile/include/asm/barrier.h')
| -rw-r--r-- | arch/tile/include/asm/barrier.h | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/arch/tile/include/asm/barrier.h b/arch/tile/include/asm/barrier.h new file mode 100644 index 00000000000..990a217a0b7 --- /dev/null +++ b/arch/tile/include/asm/barrier.h @@ -0,0 +1,148 @@ +/* + * Copyright 2010 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#ifndef _ASM_TILE_BARRIER_H +#define _ASM_TILE_BARRIER_H + +#ifndef __ASSEMBLY__ + +#include <linux/types.h> +#include <arch/chip.h> +#include <arch/spr_def.h> +#include <asm/timex.h> + +/* + * read_barrier_depends - Flush all pending reads that subsequents reads + * depend on. + * + * No data-dependent reads from memory-like regions are ever reordered + * over this barrier. All reads preceding this primitive are guaranteed + * to access memory (but not necessarily other CPUs' caches) before any + * reads following this primitive that depend on the data return by + * any of the preceding reads. This primitive is much lighter weight than + * rmb() on most CPUs, and is never heavier weight than is + * rmb(). + * + * These ordering constraints are respected by both the local CPU + * and the compiler. + * + * Ordering is not guaranteed by anything other than these primitives, + * not even by data dependencies. See the documentation for + * memory_barrier() for examples and URLs to more information. + * + * For example, the following code would force ordering (the initial + * value of "a" is zero, "b" is one, and "p" is "&a"): + * + * <programlisting> + * CPU 0 CPU 1 + * + * b = 2; + * memory_barrier(); + * p = &b; q = p; + * read_barrier_depends(); + * d = *q; + * </programlisting> + * + * because the read of "*q" depends on the read of "p" and these + * two reads are separated by a read_barrier_depends(). However, + * the following code, with the same initial values for "a" and "b": + * + * <programlisting> + * CPU 0 CPU 1 + * + * a = 2; + * memory_barrier(); + * b = 3; y = b; + * read_barrier_depends(); + * x = a; + * </programlisting> + * + * does not enforce ordering, since there is no data dependency between + * the read of "a" and the read of "b". Therefore, on some CPUs, such + * as Alpha, "y" could be set to 3 and "x" to 0. Use rmb() + * in cases like this where there are no data dependencies. + */ +#define read_barrier_depends() do { } while (0) + +#define __sync() __insn_mf() + +#if !CHIP_HAS_MF_WAITS_FOR_VICTIMS() +#include <hv/syscall_public.h> +/* + * Issue an uncacheable load to each memory controller, then + * wait until those loads have completed. + */ +static inline void __mb_incoherent(void) +{ + long clobber_r10; + asm volatile("swint2" + : "=R10" (clobber_r10) + : "R10" (HV_SYS_fence_incoherent) + : "r0", "r1", "r2", "r3", "r4", + "r5", "r6", "r7", "r8", "r9", + "r11", "r12", "r13", "r14", + "r15", "r16", "r17", "r18", "r19", + "r20", "r21", "r22", "r23", "r24", + "r25", "r26", "r27", "r28", "r29"); +} +#endif + +/* Fence to guarantee visibility of stores to incoherent memory. */ +static inline void +mb_incoherent(void) +{ + __insn_mf(); + +#if !CHIP_HAS_MF_WAITS_FOR_VICTIMS() + { +#if CHIP_HAS_TILE_WRITE_PENDING() + const unsigned long WRITE_TIMEOUT_CYCLES = 400; + unsigned long start = get_cycles_low(); + do { + if (__insn_mfspr(SPR_TILE_WRITE_PENDING) == 0) + return; + } while ((get_cycles_low() - start) < WRITE_TIMEOUT_CYCLES); +#endif /* CHIP_HAS_TILE_WRITE_PENDING() */ + (void) __mb_incoherent(); + } +#endif /* CHIP_HAS_MF_WAITS_FOR_VICTIMS() */ +} + +#define fast_wmb() __sync() +#define fast_rmb() __sync() +#define fast_mb() __sync() +#define fast_iob() mb_incoherent() + +#define wmb() fast_wmb() +#define rmb() fast_rmb() +#define mb() fast_mb() +#define iob() fast_iob() + +#ifdef CONFIG_SMP +#define smp_mb() mb() +#define smp_rmb() rmb() +#define smp_wmb() wmb() +#define smp_read_barrier_depends() read_barrier_depends() +#else +#define smp_mb() barrier() +#define smp_rmb() barrier() +#define smp_wmb() barrier() +#define smp_read_barrier_depends() do { } while (0) +#endif + +#define set_mb(var, value) \ + do { var = value; mb(); } while (0) + +#endif /* !__ASSEMBLY__ */ +#endif /* _ASM_TILE_BARRIER_H */ |