max80_fw/rv32/atomic.h

/*
 * Hacked atomics with hpa-specific lw.l/sw.u instructions
 */

#ifndef ATOMIC_H
#define ATOMIC_H

#include "compiler.h"

typedef uint32_t atomic_t;

#define lw_l(x) ({							\
	    volatile atomic_t *__p = (volatile atomic_t *)(x);		\
	    atomic_t __v;						\
	    asm inline volatile("lw.l %0,%1"				\
				: "=r" (__v), "+m" (*__p)		\
				: : "memory");				\
	    (typeof(*(x))) __v;						\
	})

static inline void _sw_u(volatile atomic_t *__p, atomic_t __v)
{
    asm inline volatile("sw.u %1,%0"
			: "+m" (*__p) : "r" (__v)
			: "memory");
}

#define sw_u(x,v) _sw_u((volatile atomic_t *)(x), (v))

/* Simple barrier-enforcing accessors */

static inline atomic_t atomic_get(const volatile atomic_t *_p)
{
    atomic_t _v;
    asm inline volatile("lw %0,%1" : "=r" (_v) : "m" (*_p) : "memory");
    return _v;
}

static inline void atomic_set(volatile atomic_t *_p, atomic_t _v)
{
    asm inline volatile("sw %1,%0" : "=m" (*_p) : "r" (_v) : "memory");
}

static inline atomic_t atomic_swap(volatile atomic_t *_p, atomic_t _v)
{
    atomic_t _o = lw_l(_p);
    sw_u(_p, _v);
    return _o;
}

/* These functions all do read-modify-write returning the old or new values */
#define ATOMIC_OP2_RET(name, op, ret)					\
    static inline atomic_t						\
    atomic_ ## name (volatile atomic_t *_p, atomic_t _v)		\
{									\
    atomic_t _o = lw_l(_p);						\
    atomic_t _n = _o op _v;						\
    sw_u(_p, _n);							\
    return ret;								\
}

#define ATOMIC_OP2(name, op)			\
    ATOMIC_OP2_RET(name, op, _n)		\
    ATOMIC_OP2_RET(xchg_ ## name, op, _o)

ATOMIC_OP2(add, +)
ATOMIC_OP2(sub, -)
ATOMIC_OP2(and, &)
ATOMIC_OP2(or, |)
ATOMIC_OP2(xor, ^)

static inline atomic_t atomic_xchg_and_xor(volatile atomic_t *_p, atomic_t _va, atomic_t _vx)
{
    atomic_t _o = lw_l(_p);
    atomic_t _n = (_o & _va) ^ _vx;
    sw_u(_p, _n);
    return _o;
}

#endif /* ATOMIC_H */