root/arch/mips/include/asm/atomic.h
/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 * But use these as seldom as possible since they are much more slower
 * than regular operations.
 *
 * 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) 1996, 97, 99, 2000, 03, 04, 06 by Ralf Baechle
 */
#ifndef _ASM_ATOMIC_H
#define _ASM_ATOMIC_H

#include <linux/irqflags.h>
#include <linux/types.h>
#include <asm/asm.h>
#include <asm/barrier.h>
#include <asm/compiler.h>
#include <asm/cpu-features.h>
#include <asm/cmpxchg.h>
#include <asm/sync.h>

#define ATOMIC_OPS(pfx, type)                                           \
static __always_inline type arch_##pfx##_read(const pfx##_t *v)         \
{                                                                       \
        return READ_ONCE(v->counter);                                   \
}                                                                       \
                                                                        \
static __always_inline void arch_##pfx##_set(pfx##_t *v, type i)        \
{                                                                       \
        WRITE_ONCE(v->counter, i);                                      \
}                                                                       \

ATOMIC_OPS(atomic, int)

#ifdef CONFIG_64BIT
# define ATOMIC64_INIT(i)       { (i) }
ATOMIC_OPS(atomic64, s64)
#endif

#define ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc)                  \
static __inline__ void arch_##pfx##_##op(type i, pfx##_t * v)           \
{                                                                       \
        type temp;                                                      \
                                                                        \
        if (!kernel_uses_llsc) {                                        \
                unsigned long flags;                                    \
                                                                        \
                raw_local_irq_save(flags);                              \
                v->counter c_op i;                                      \
                raw_local_irq_restore(flags);                           \
                return;                                                 \
        }                                                               \
                                                                        \
        __asm__ __volatile__(                                           \
        "       .set    push                                    \n"     \
        "       .set    " MIPS_ISA_LEVEL "                      \n"     \
        "       " __SYNC(full, loongson3_war) "                 \n"     \
        "1:     " #ll " %0, %1          # " #pfx "_" #op "      \n"     \
        "       " #asm_op " %0, %2                              \n"     \
        "       " #sc " %0, %1                                  \n"     \
        "\t" __stringify(SC_BEQZ) "     %0, 1b                  \n"     \
        "       .set    pop                                     \n"     \
        : "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter)            \
        : "Ir" (i) : __LLSC_CLOBBER);                                   \
}

#define ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc)           \
static __inline__ type                                                  \
arch_##pfx##_##op##_return_relaxed(type i, pfx##_t * v)                 \
{                                                                       \
        type temp, result;                                              \
                                                                        \
        if (!kernel_uses_llsc) {                                        \
                unsigned long flags;                                    \
                                                                        \
                raw_local_irq_save(flags);                              \
                result = v->counter;                                    \
                result c_op i;                                          \
                v->counter = result;                                    \
                raw_local_irq_restore(flags);                           \
                return result;                                          \
        }                                                               \
                                                                        \
        __asm__ __volatile__(                                           \
        "       .set    push                                    \n"     \
        "       .set    " MIPS_ISA_LEVEL "                      \n"     \
        "       " __SYNC(full, loongson3_war) "                 \n"     \
        "1:     " #ll " %1, %2          # " #pfx "_" #op "_return\n"    \
        "       " #asm_op " %0, %1, %3                          \n"     \
        "       " #sc " %0, %2                                  \n"     \
        "\t" __stringify(SC_BEQZ) "     %0, 1b                  \n"     \
        "       " #asm_op " %0, %1, %3                          \n"     \
        "       .set    pop                                     \n"     \
        : "=&r" (result), "=&r" (temp),                                 \
          "+" GCC_OFF_SMALL_ASM() (v->counter)                          \
        : "Ir" (i) : __LLSC_CLOBBER);                                   \
                                                                        \
        return result;                                                  \
}

#define ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)            \
static __inline__ type                                                  \
arch_##pfx##_fetch_##op##_relaxed(type i, pfx##_t * v)                  \
{                                                                       \
        int temp, result;                                               \
                                                                        \
        if (!kernel_uses_llsc) {                                        \
                unsigned long flags;                                    \
                                                                        \
                raw_local_irq_save(flags);                              \
                result = v->counter;                                    \
                v->counter c_op i;                                      \
                raw_local_irq_restore(flags);                           \
                return result;                                          \
        }                                                               \
                                                                        \
        __asm__ __volatile__(                                           \
        "       .set    push                                    \n"     \
        "       .set    " MIPS_ISA_LEVEL "                      \n"     \
        "       " __SYNC(full, loongson3_war) "                 \n"     \
        "1:     " #ll " %1, %2          # " #pfx "_fetch_" #op "\n"     \
        "       " #asm_op " %0, %1, %3                          \n"     \
        "       " #sc " %0, %2                                  \n"     \
        "\t" __stringify(SC_BEQZ) "     %0, 1b                  \n"     \
        "       .set    pop                                     \n"     \
        "       move    %0, %1                                  \n"     \
        : "=&r" (result), "=&r" (temp),                                 \
          "+" GCC_OFF_SMALL_ASM() (v->counter)                          \
        : "Ir" (i) : __LLSC_CLOBBER);                                   \
                                                                        \
        return result;                                                  \
}

#undef ATOMIC_OPS
#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc)                 \
        ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc)                  \
        ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc)           \
        ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)

ATOMIC_OPS(atomic, add, int, +=, addu, ll, sc)
ATOMIC_OPS(atomic, sub, int, -=, subu, ll, sc)

#define arch_atomic_add_return_relaxed  arch_atomic_add_return_relaxed
#define arch_atomic_sub_return_relaxed  arch_atomic_sub_return_relaxed
#define arch_atomic_fetch_add_relaxed   arch_atomic_fetch_add_relaxed
#define arch_atomic_fetch_sub_relaxed   arch_atomic_fetch_sub_relaxed

#ifdef CONFIG_64BIT
ATOMIC_OPS(atomic64, add, s64, +=, daddu, lld, scd)
ATOMIC_OPS(atomic64, sub, s64, -=, dsubu, lld, scd)
# define arch_atomic64_add_return_relaxed       arch_atomic64_add_return_relaxed
# define arch_atomic64_sub_return_relaxed       arch_atomic64_sub_return_relaxed
# define arch_atomic64_fetch_add_relaxed        arch_atomic64_fetch_add_relaxed
# define arch_atomic64_fetch_sub_relaxed        arch_atomic64_fetch_sub_relaxed
#endif /* CONFIG_64BIT */

#undef ATOMIC_OPS
#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc)                 \
        ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc)                  \
        ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)

ATOMIC_OPS(atomic, and, int, &=, and, ll, sc)
ATOMIC_OPS(atomic, or, int, |=, or, ll, sc)
ATOMIC_OPS(atomic, xor, int, ^=, xor, ll, sc)

#define arch_atomic_fetch_and_relaxed   arch_atomic_fetch_and_relaxed
#define arch_atomic_fetch_or_relaxed    arch_atomic_fetch_or_relaxed
#define arch_atomic_fetch_xor_relaxed   arch_atomic_fetch_xor_relaxed

#ifdef CONFIG_64BIT
ATOMIC_OPS(atomic64, and, s64, &=, and, lld, scd)
ATOMIC_OPS(atomic64, or, s64, |=, or, lld, scd)
ATOMIC_OPS(atomic64, xor, s64, ^=, xor, lld, scd)
# define arch_atomic64_fetch_and_relaxed        arch_atomic64_fetch_and_relaxed
# define arch_atomic64_fetch_or_relaxed         arch_atomic64_fetch_or_relaxed
# define arch_atomic64_fetch_xor_relaxed        arch_atomic64_fetch_xor_relaxed
#endif

#undef ATOMIC_OPS
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP

/*
 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically test @v and subtract @i if @v is greater or equal than @i.
 * The function returns the old value of @v minus @i.
 */
#define ATOMIC_SIP_OP(pfx, type, op, ll, sc)                            \
static __inline__ type arch_##pfx##_sub_if_positive(type i, pfx##_t * v)        \
{                                                                       \
        type temp, result;                                              \
                                                                        \
        smp_mb__before_atomic();                                        \
                                                                        \
        if (!kernel_uses_llsc) {                                        \
                unsigned long flags;                                    \
                                                                        \
                raw_local_irq_save(flags);                              \
                result = v->counter;                                    \
                result -= i;                                            \
                if (result >= 0)                                        \
                        v->counter = result;                            \
                raw_local_irq_restore(flags);                           \
                smp_mb__after_atomic();                                 \
                return result;                                          \
        }                                                               \
                                                                        \
        __asm__ __volatile__(                                           \
        "       .set    push                                    \n"     \
        "       .set    " MIPS_ISA_LEVEL "                      \n"     \
        "       " __SYNC(full, loongson3_war) "                 \n"     \
        "1:     " #ll " %1, %2          # atomic_sub_if_positive\n"     \
        "       .set    pop                                     \n"     \
        "       " #op " %0, %1, %3                              \n"     \
        "       move    %1, %0                                  \n"     \
        "       bltz    %0, 2f                                  \n"     \
        "       .set    push                                    \n"     \
        "       .set    " MIPS_ISA_LEVEL "                      \n"     \
        "       " #sc " %1, %2                                  \n"     \
        "       " __stringify(SC_BEQZ) "        %1, 1b          \n"     \
        "2:     " __SYNC(full, loongson3_war) "                 \n"     \
        "       .set    pop                                     \n"     \
        : "=&r" (result), "=&r" (temp),                                 \
          "+" GCC_OFF_SMALL_ASM() (v->counter)                          \
        : "Ir" (i)                                                      \
        : __LLSC_CLOBBER);                                              \
                                                                        \
        /*                                                              \
         * In the Loongson3 workaround case we already have a           \
         * completion barrier at 2: above, which is needed due to the   \
         * bltz that can branch to code outside of the LL/SC loop. As   \
         * such, we don't need to emit another barrier here.            \
         */                                                             \
        if (__SYNC_loongson3_war == 0)                                  \
                smp_mb__after_atomic();                                 \
                                                                        \
        return result;                                                  \
}

ATOMIC_SIP_OP(atomic, int, subu, ll, sc)
#define arch_atomic_dec_if_positive(v)  arch_atomic_sub_if_positive(1, v)

#ifdef CONFIG_64BIT
ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
#define arch_atomic64_dec_if_positive(v)        arch_atomic64_sub_if_positive(1, v)
#endif

#undef ATOMIC_SIP_OP

#endif /* _ASM_ATOMIC_H */