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[wrt350n-kernel.git] / include / asm-mips / hazards.h

/*
 * 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) 2003, 04, 07 Ralf Baechle <ralf@linux-mips.org>
 * Copyright (C) MIPS Technologies, Inc.
 *   written by Ralf Baechle <ralf@linux-mips.org>
 */
#ifndef _ASM_HAZARDS_H
#define _ASM_HAZARDS_H


#ifdef __ASSEMBLY__
#define ASMMACRO(name, code...) .macro name; code; .endm
#else

#define ASMMACRO(name, code...)                                         \
__asm__(".macro " #name "; " #code "; .endm");                          \
                                                                        \
static inline void name(void)                                           \
{                                                                       \
        __asm__ __volatile__ (#name);                                   \
}

/*
 * MIPS R2 instruction hazard barrier.   Needs to be called as a subroutine.
 */
extern void mips_ihb(void);

#endif

ASMMACRO(_ssnop,
         sll    $0, $0, 1
        )

ASMMACRO(_ehb,
         sll    $0, $0, 3
        )

/*
 * TLB hazards
 */
#if defined(CONFIG_CPU_MIPSR2)

/*
 * MIPSR2 defines ehb for hazard avoidance
 */

ASMMACRO(mtc0_tlbw_hazard,
         _ehb
        )
ASMMACRO(tlbw_use_hazard,
         _ehb
        )
ASMMACRO(tlb_probe_hazard,
         _ehb
        )
ASMMACRO(irq_enable_hazard,
         _ehb
        )
ASMMACRO(irq_disable_hazard,
        _ehb
        )
ASMMACRO(back_to_back_c0_hazard,
         _ehb
        )
/*
 * gcc has a tradition of misscompiling the previous construct using the
 * address of a label as argument to inline assembler.  Gas otoh has the
 * annoying difference between la and dla which are only usable for 32-bit
 * rsp. 64-bit code, so can't be used without conditional compilation.
 * The alterantive is switching the assembler to 64-bit code which happens
 * to work right even for 32-bit code ...
 */
#define instruction_hazard()                                            \
do {                                                                    \
        unsigned long tmp;                                              \
                                                                        \
        __asm__ __volatile__(                                           \
        "       .set    mips64r2                                \n"     \
        "       dla     %0, 1f                                  \n"     \
        "       jr.hb   %0                                      \n"     \
        "       .set    mips0                                   \n"     \
        "1:                                                     \n"     \
        : "=r" (tmp));                                                  \
} while (0)

#elif defined(CONFIG_CPU_R10000)

/*
 * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
 */

ASMMACRO(mtc0_tlbw_hazard,
        )
ASMMACRO(tlbw_use_hazard,
        )
ASMMACRO(tlb_probe_hazard,
        )
ASMMACRO(irq_enable_hazard,
        )
ASMMACRO(irq_disable_hazard,
        )
ASMMACRO(back_to_back_c0_hazard,
        )
#define instruction_hazard() do { } while (0)

#elif defined(CONFIG_CPU_RM9000)

/*
 * RM9000 hazards.  When the JTLB is updated by tlbwi or tlbwr, a subsequent
 * use of the JTLB for instructions should not occur for 4 cpu cycles and use
 * for data translations should not occur for 3 cpu cycles.
 */

ASMMACRO(mtc0_tlbw_hazard,
         _ssnop; _ssnop; _ssnop; _ssnop
        )
ASMMACRO(tlbw_use_hazard,
         _ssnop; _ssnop; _ssnop; _ssnop
        )
ASMMACRO(tlb_probe_hazard,
         _ssnop; _ssnop; _ssnop; _ssnop
        )
ASMMACRO(irq_enable_hazard,
        )
ASMMACRO(irq_disable_hazard,
        )
ASMMACRO(back_to_back_c0_hazard,
        )
#define instruction_hazard() do { } while (0)

#elif defined(CONFIG_CPU_SB1)

/*
 * Mostly like R4000 for historic reasons
 */
ASMMACRO(mtc0_tlbw_hazard,
        )
ASMMACRO(tlbw_use_hazard,
        )
ASMMACRO(tlb_probe_hazard,
        )
ASMMACRO(irq_enable_hazard,
        )
ASMMACRO(irq_disable_hazard,
         _ssnop; _ssnop; _ssnop
        )
ASMMACRO(back_to_back_c0_hazard,
        )
#define instruction_hazard() do { } while (0)

#else

/*
 * Finally the catchall case for all other processors including R4000, R4400,
 * R4600, R4700, R5000, RM7000, NEC VR41xx etc.
 *
 * The taken branch will result in a two cycle penalty for the two killed
 * instructions on R4000 / R4400.  Other processors only have a single cycle
 * hazard so this is nice trick to have an optimal code for a range of
 * processors.
 */
ASMMACRO(mtc0_tlbw_hazard,
        nop; nop
        )
ASMMACRO(tlbw_use_hazard,
        nop; nop; nop
        )
ASMMACRO(tlb_probe_hazard,
         nop; nop; nop
        )
ASMMACRO(irq_enable_hazard,
         _ssnop; _ssnop; _ssnop;
        )
ASMMACRO(irq_disable_hazard,
        nop; nop; nop
        )
ASMMACRO(back_to_back_c0_hazard,
         _ssnop; _ssnop; _ssnop;
        )
#define instruction_hazard() do { } while (0)

#endif


/* FPU hazards */

#if defined(CONFIG_CPU_SB1)
ASMMACRO(enable_fpu_hazard,
         .set   push;
         .set   mips64;
         .set   noreorder;
         _ssnop;
         bnezl  $0,.+4;
         _ssnop;
         .set   pop
)
ASMMACRO(disable_fpu_hazard,
)

#elif defined(CONFIG_CPU_MIPSR2)
ASMMACRO(enable_fpu_hazard,
         _ehb
)
ASMMACRO(disable_fpu_hazard,
         _ehb
)
#else
ASMMACRO(enable_fpu_hazard,
         nop; nop; nop; nop
)
ASMMACRO(disable_fpu_hazard,
         _ehb
)
#endif

#endif /* _ASM_HAZARDS_H */