arch/riscv/include/asm/atomic.h

/*
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Copyright (C) 2012 Regents of the University of California
 * Copyright (C) 2017 SiFive
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#ifndef _ASM_RISCV_ATOMIC_H
#define _ASM_RISCV_ATOMIC_H

#ifdef CONFIG_GENERIC_ATOMIC64
# include <asm-generic/atomic64.h>
#else
# if (__riscv_xlen < 64)
#  error "64-bit atomics require XLEN to be at least 64"
# endif
#endif

#include <asm/cmpxchg.h>
#include <asm/barrier.h>

#define ATOMIC_INIT(i)	{ (i) }

#define __atomic_acquire_fence()					\
	__asm__ __volatile__(RISCV_ACQUIRE_BARRIER "" ::: "memory")

#define __atomic_release_fence()					\
	__asm__ __volatile__(RISCV_RELEASE_BARRIER "" ::: "memory");

static __always_inline int atomic_read(const atomic_t *v)
{
	return READ_ONCE(v->counter);
}
static __always_inline void atomic_set(atomic_t *v, int i)
{
	WRITE_ONCE(v->counter, i);
}

#ifndef CONFIG_GENERIC_ATOMIC64
#define ATOMIC64_INIT(i) { (i) }
static __always_inline long atomic64_read(const atomic64_t *v)
{
	return READ_ONCE(v->counter);
}
static __always_inline void atomic64_set(atomic64_t *v, long i)
{
	WRITE_ONCE(v->counter, i);
}
#endif

/*
 * First, the atomic ops that have no ordering constraints and therefor don't
 * have the AQ or RL bits set.  These don't return anything, so there's only
 * one version to worry about.
 */
#define ATOMIC_OP(op, asm_op, I, asm_type, c_type, prefix)		\
static __always_inline							\
void atomic##prefix##_##op(c_type i, atomic##prefix##_t *v)		\
{									\
	__asm__ __volatile__ (						\
		"	amo" #asm_op "." #asm_type " zero, %1, %0"	\
		: "+A" (v->counter)					\
		: "r" (I)						\
		: "memory");						\
}									\

#ifdef CONFIG_GENERIC_ATOMIC64
#define ATOMIC_OPS(op, asm_op, I)					\
        ATOMIC_OP (op, asm_op, I, w,  int,   )
#else
#define ATOMIC_OPS(op, asm_op, I)					\
        ATOMIC_OP (op, asm_op, I, w,  int,   )				\
        ATOMIC_OP (op, asm_op, I, d, long, 64)
#endif

ATOMIC_OPS(add, add,  i)
ATOMIC_OPS(sub, add, -i)
ATOMIC_OPS(and, and,  i)
ATOMIC_OPS( or,  or,  i)
ATOMIC_OPS(xor, xor,  i)

#undef ATOMIC_OP
#undef ATOMIC_OPS

/*
 * Atomic ops that have ordered, relaxed, acquire, and release variants.
 * There's two flavors of these: the arithmatic ops have both fetch and return
 * versions, while the logical ops only have fetch versions.
 */
#define ATOMIC_FETCH_OP(op, asm_op, I, asm_type, c_type, prefix)	\
static __always_inline							\
c_type atomic##prefix##_fetch_##op##_relaxed(c_type i,			\
					     atomic##prefix##_t *v)	\
{									\
	register c_type ret;						\
	__asm__ __volatile__ (						\
		"	amo" #asm_op "." #asm_type " %1, %2, %0"	\
		: "+A" (v->counter), "=r" (ret)				\
		: "r" (I)						\
		: "memory");						\
	return ret;							\
}									\
static __always_inline							\
c_type atomic##prefix##_fetch_##op(c_type i, atomic##prefix##_t *v)	\
{									\
	register c_type ret;						\
	__asm__ __volatile__ (						\
		"	amo" #asm_op "." #asm_type ".aqrl  %1, %2, %0"	\
		: "+A" (v->counter), "=r" (ret)				\
		: "r" (I)						\
		: "memory");						\
	return ret;							\
}

#define ATOMIC_OP_RETURN(op, asm_op, c_op, I, asm_type, c_type, prefix)	\
static __always_inline							\
c_type atomic##prefix##_##op##_return_relaxed(c_type i,			\
					      atomic##prefix##_t *v)	\
{									\
        return atomic##prefix##_fetch_##op##_relaxed(i, v) c_op I;	\
}									\
static __always_inline							\
c_type atomic##prefix##_##op##_return(c_type i, atomic##prefix##_t *v)	\
{									\
        return atomic##prefix##_fetch_##op(i, v) c_op I;		\
}

#ifdef CONFIG_GENERIC_ATOMIC64
#define ATOMIC_OPS(op, asm_op, c_op, I)					\
        ATOMIC_FETCH_OP( op, asm_op,       I, w,  int,   )		\
        ATOMIC_OP_RETURN(op, asm_op, c_op, I, w,  int,   )
#else
#define ATOMIC_OPS(op, asm_op, c_op, I)					\
        ATOMIC_FETCH_OP( op, asm_op,       I, w,  int,   )		\
        ATOMIC_OP_RETURN(op, asm_op, c_op, I, w,  int,   )		\
        ATOMIC_FETCH_OP( op, asm_op,       I, d, long, 64)		\
        ATOMIC_OP_RETURN(op, asm_op, c_op, I, d, long, 64)
#endif

ATOMIC_OPS(add, add, +,  i)
ATOMIC_OPS(sub, add, +, -i)

#define atomic_add_return_relaxed	atomic_add_return_relaxed
#define atomic_sub_return_relaxed	atomic_sub_return_relaxed
#define atomic_add_return		atomic_add_return
#define atomic_sub_return		atomic_sub_return

#define atomic_fetch_add_relaxed	atomic_fetch_add_relaxed
#define atomic_fetch_sub_relaxed	atomic_fetch_sub_relaxed
#define atomic_fetch_add		atomic_fetch_add
#define atomic_fetch_sub		atomic_fetch_sub

#ifndef CONFIG_GENERIC_ATOMIC64
#define atomic64_add_return_relaxed	atomic64_add_return_relaxed
#define atomic64_sub_return_relaxed	atomic64_sub_return_relaxed
#define atomic64_add_return		atomic64_add_return
#define atomic64_sub_return		atomic64_sub_return

#define atomic64_fetch_add_relaxed	atomic64_fetch_add_relaxed
#define atomic64_fetch_sub_relaxed	atomic64_fetch_sub_relaxed
#define atomic64_fetch_add		atomic64_fetch_add
#define atomic64_fetch_sub		atomic64_fetch_sub
#endif

#undef ATOMIC_OPS

#ifdef CONFIG_GENERIC_ATOMIC64
#define ATOMIC_OPS(op, asm_op, I)					\
        ATOMIC_FETCH_OP(op, asm_op, I, w,  int,   )
#else
#define ATOMIC_OPS(op, asm_op, I)					\
        ATOMIC_FETCH_OP(op, asm_op, I, w,  int,   )			\
        ATOMIC_FETCH_OP(op, asm_op, I, d, long, 64)
#endif

ATOMIC_OPS(and, and, i)
ATOMIC_OPS( or,  or, i)
ATOMIC_OPS(xor, xor, i)

#define atomic_fetch_and_relaxed	atomic_fetch_and_relaxed
#define atomic_fetch_or_relaxed		atomic_fetch_or_relaxed
#define atomic_fetch_xor_relaxed	atomic_fetch_xor_relaxed
#define atomic_fetch_and		atomic_fetch_and
#define atomic_fetch_or			atomic_fetch_or
#define atomic_fetch_xor		atomic_fetch_xor

#ifndef CONFIG_GENERIC_ATOMIC64
#define atomic64_fetch_and_relaxed	atomic64_fetch_and_relaxed
#define atomic64_fetch_or_relaxed	atomic64_fetch_or_relaxed
#define atomic64_fetch_xor_relaxed	atomic64_fetch_xor_relaxed
#define atomic64_fetch_and		atomic64_fetch_and
#define atomic64_fetch_or		atomic64_fetch_or
#define atomic64_fetch_xor		atomic64_fetch_xor
#endif

#undef ATOMIC_OPS

#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN

/* This is required to provide a full barrier on success. */
static __always_inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
       int prev, rc;

	__asm__ __volatile__ (
		"0:	lr.w     %[p],  %[c]\n"
		"	beq      %[p],  %[u], 1f\n"
		"	add      %[rc], %[p], %[a]\n"
		"	sc.w.rl  %[rc], %[rc], %[c]\n"
		"	bnez     %[rc], 0b\n"
		"	fence    rw, rw\n"
		"1:\n"
		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
		: [a]"r" (a), [u]"r" (u)
		: "memory");
	return prev;
}
#define atomic_fetch_add_unless atomic_fetch_add_unless

#ifndef CONFIG_GENERIC_ATOMIC64
static __always_inline long atomic64_fetch_add_unless(atomic64_t *v, long a, long u)
{
       long prev, rc;

	__asm__ __volatile__ (
		"0:	lr.d     %[p],  %[c]\n"
		"	beq      %[p],  %[u], 1f\n"
		"	add      %[rc], %[p], %[a]\n"
		"	sc.d.rl  %[rc], %[rc], %[c]\n"
		"	bnez     %[rc], 0b\n"
		"	fence    rw, rw\n"
		"1:\n"
		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
		: [a]"r" (a), [u]"r" (u)
		: "memory");
	return prev;
}
#define atomic64_fetch_add_unless atomic64_fetch_add_unless
#endif

/*
 * atomic_{cmp,}xchg is required to have exactly the same ordering semantics as
 * {cmp,}xchg and the operations that return, so they need a full barrier.
 */
#define ATOMIC_OP(c_t, prefix, size)					\
static __always_inline							\
c_t atomic##prefix##_xchg_relaxed(atomic##prefix##_t *v, c_t n)		\
{									\
	return __xchg_relaxed(&(v->counter), n, size);			\
}									\
static __always_inline							\
c_t atomic##prefix##_xchg_acquire(atomic##prefix##_t *v, c_t n)		\
{									\
	return __xchg_acquire(&(v->counter), n, size);			\
}									\
static __always_inline							\
c_t atomic##prefix##_xchg_release(atomic##prefix##_t *v, c_t n)		\
{									\
	return __xchg_release(&(v->counter), n, size);			\
}									\
static __always_inline							\
c_t atomic##prefix##_xchg(atomic##prefix##_t *v, c_t n)			\
{									\
	return __xchg(&(v->counter), n, size);				\
}									\
static __always_inline							\
c_t atomic##prefix##_cmpxchg_relaxed(atomic##prefix##_t *v,		\
				     c_t o, c_t n)			\
{									\
	return __cmpxchg_relaxed(&(v->counter), o, n, size);		\
}									\
static __always_inline							\
c_t atomic##prefix##_cmpxchg_acquire(atomic##prefix##_t *v,		\
				     c_t o, c_t n)			\
{									\
	return __cmpxchg_acquire(&(v->counter), o, n, size);		\
}									\
static __always_inline							\
c_t atomic##prefix##_cmpxchg_release(atomic##prefix##_t *v,		\
				     c_t o, c_t n)			\
{									\
	return __cmpxchg_release(&(v->counter), o, n, size);		\
}									\
static __always_inline							\
c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n)	\
{									\
	return __cmpxchg(&(v->counter), o, n, size);			\
}

#ifdef CONFIG_GENERIC_ATOMIC64
#define ATOMIC_OPS()							\
	ATOMIC_OP( int,   , 4)
#else
#define ATOMIC_OPS()							\
	ATOMIC_OP( int,   , 4)						\
	ATOMIC_OP(long, 64, 8)
#endif

ATOMIC_OPS()

#define atomic_xchg_relaxed atomic_xchg_relaxed
#define atomic_xchg_acquire atomic_xchg_acquire
#define atomic_xchg_release atomic_xchg_release
#define atomic_xchg atomic_xchg
#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
#define atomic_cmpxchg_acquire atomic_cmpxchg_acquire
#define atomic_cmpxchg_release atomic_cmpxchg_release
#define atomic_cmpxchg atomic_cmpxchg

#undef ATOMIC_OPS
#undef ATOMIC_OP

static __always_inline int atomic_sub_if_positive(atomic_t *v, int offset)
{
       int prev, rc;

	__asm__ __volatile__ (
		"0:	lr.w     %[p],  %[c]\n"
		"	sub      %[rc], %[p], %[o]\n"
		"	bltz     %[rc], 1f\n"
		"	sc.w.rl  %[rc], %[rc], %[c]\n"
		"	bnez     %[rc], 0b\n"
		"	fence    rw, rw\n"
		"1:\n"
		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
		: [o]"r" (offset)
		: "memory");
	return prev - offset;
}

#define atomic_dec_if_positive(v)	atomic_sub_if_positive(v, 1)

#ifndef CONFIG_GENERIC_ATOMIC64
static __always_inline long atomic64_sub_if_positive(atomic64_t *v, int offset)
{
       long prev, rc;

	__asm__ __volatile__ (
		"0:	lr.d     %[p],  %[c]\n"
		"	sub      %[rc], %[p], %[o]\n"
		"	bltz     %[rc], 1f\n"
		"	sc.d.rl  %[rc], %[rc], %[c]\n"
		"	bnez     %[rc], 0b\n"
		"	fence    rw, rw\n"
		"1:\n"
		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
		: [o]"r" (offset)
		: "memory");
	return prev - offset;
}

#define atomic64_dec_if_positive(v)	atomic64_sub_if_positive(v, 1)
#endif

#endif /* _ASM_RISCV_ATOMIC_H */