7a2852e49f
SGI-IP28 is running in so called slow mode, when kernel is started from the PROM. PROM calls must be done in slow mode otherwise the PROM will issue an error. To get better memory performance we now switch to normal mode, when the PROM is no longer needed. Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
155 lines
4.2 KiB
C
155 lines
4.2 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2006 by Ralf Baechle (ralf@linux-mips.org)
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*/
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#ifndef __ASM_BARRIER_H
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#define __ASM_BARRIER_H
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/*
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* read_barrier_depends - Flush all pending reads that subsequents reads
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* depend on.
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*
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* No data-dependent reads from memory-like regions are ever reordered
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* over this barrier. All reads preceding this primitive are guaranteed
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* to access memory (but not necessarily other CPUs' caches) before any
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* reads following this primitive that depend on the data return by
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* any of the preceding reads. This primitive is much lighter weight than
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* rmb() on most CPUs, and is never heavier weight than is
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* rmb().
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*
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* These ordering constraints are respected by both the local CPU
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* and the compiler.
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*
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* Ordering is not guaranteed by anything other than these primitives,
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* not even by data dependencies. See the documentation for
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* memory_barrier() for examples and URLs to more information.
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*
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* For example, the following code would force ordering (the initial
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* value of "a" is zero, "b" is one, and "p" is "&a"):
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* b = 2;
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* memory_barrier();
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* p = &b; q = p;
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* read_barrier_depends();
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* d = *q;
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* </programlisting>
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*
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* because the read of "*q" depends on the read of "p" and these
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* two reads are separated by a read_barrier_depends(). However,
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* the following code, with the same initial values for "a" and "b":
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* a = 2;
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* memory_barrier();
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* b = 3; y = b;
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* read_barrier_depends();
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* x = a;
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* </programlisting>
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*
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* does not enforce ordering, since there is no data dependency between
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* the read of "a" and the read of "b". Therefore, on some CPUs, such
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* as Alpha, "y" could be set to 3 and "x" to 0. Use rmb()
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* in cases like this where there are no data dependencies.
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*/
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#define read_barrier_depends() do { } while(0)
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#define smp_read_barrier_depends() do { } while(0)
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#ifdef CONFIG_CPU_HAS_SYNC
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#define __sync() \
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__asm__ __volatile__( \
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".set push\n\t" \
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".set noreorder\n\t" \
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".set mips2\n\t" \
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"sync\n\t" \
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".set pop" \
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: /* no output */ \
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: /* no input */ \
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: "memory")
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#else
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#define __sync() do { } while(0)
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#endif
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#define __fast_iob() \
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__asm__ __volatile__( \
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".set push\n\t" \
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".set noreorder\n\t" \
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"lw $0,%0\n\t" \
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"nop\n\t" \
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".set pop" \
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: /* no output */ \
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: "m" (*(int *)CKSEG1) \
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: "memory")
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#define fast_wmb() __sync()
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#define fast_rmb() __sync()
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#define fast_mb() __sync()
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#ifdef CONFIG_SGI_IP28
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#define fast_iob() \
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__asm__ __volatile__( \
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".set push\n\t" \
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".set noreorder\n\t" \
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"lw $0,%0\n\t" \
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"sync\n\t" \
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"lw $0,%0\n\t" \
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".set pop" \
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: /* no output */ \
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: "m" (*(int *)CKSEG1ADDR(0x1fa00004)) \
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: "memory")
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#else
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#define fast_iob() \
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do { \
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__sync(); \
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__fast_iob(); \
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} while (0)
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#endif
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#ifdef CONFIG_CPU_HAS_WB
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#include <asm/wbflush.h>
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#define wmb() fast_wmb()
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#define rmb() fast_rmb()
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#define mb() wbflush()
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#define iob() wbflush()
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#else /* !CONFIG_CPU_HAS_WB */
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#define wmb() fast_wmb()
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#define rmb() fast_rmb()
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#define mb() fast_mb()
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#define iob() fast_iob()
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#endif /* !CONFIG_CPU_HAS_WB */
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#if defined(CONFIG_WEAK_ORDERING) && defined(CONFIG_SMP)
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#define __WEAK_ORDERING_MB " sync \n"
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#else
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#define __WEAK_ORDERING_MB " \n"
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#endif
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#if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP)
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#define __WEAK_LLSC_MB " sync \n"
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#else
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#define __WEAK_LLSC_MB " \n"
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#endif
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#define smp_mb() __asm__ __volatile__(__WEAK_ORDERING_MB : : :"memory")
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#define smp_rmb() __asm__ __volatile__(__WEAK_ORDERING_MB : : :"memory")
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#define smp_wmb() __asm__ __volatile__(__WEAK_ORDERING_MB : : :"memory")
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#define set_mb(var, value) \
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do { var = value; smp_mb(); } while (0)
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#define smp_llsc_mb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
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#define smp_llsc_rmb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
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#define smp_llsc_wmb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
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#endif /* __ASM_BARRIER_H */
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