1// See LICENSE for license details.
2
3#ifndef _RISCV_ATOMIC_H
4#define _RISCV_ATOMIC_H
5
6#include "config.h"
7#include "encoding.h"
8
9// Currently, interrupts are always disabled in M-mode.
10#define disable_irqsave() (0)
11#define enable_irqrestore(flags) ((void) (flags))
12
13typedef struct { int lock; } spinlock_t;
14#define SPINLOCK_INIT {0}
15
16#define mb() asm volatile ("fence" ::: "memory")
17#define atomic_set(ptr, val) (*(volatile typeof(*(ptr)) *)(ptr) = val)
18#define atomic_read(ptr) (*(volatile typeof(*(ptr)) *)(ptr))
19
20#ifdef __riscv_atomic
21# define atomic_add(ptr, inc) __sync_fetch_and_add(ptr, inc)
22# define atomic_or(ptr, inc) __sync_fetch_and_or(ptr, inc)
23# define atomic_swap(ptr, swp) __sync_lock_test_and_set(ptr, swp)
24# define atomic_cas(ptr, cmp, swp) __sync_val_compare_and_swap(ptr, cmp, swp)
25#else
26# define atomic_binop(ptr, inc, op) ({ \
27  long flags = disable_irqsave(); \
28  typeof(*(ptr)) res = atomic_read(ptr); \
29  atomic_set(ptr, op); \
30  enable_irqrestore(flags); \
31  res; })
32# define atomic_add(ptr, inc) atomic_binop(ptr, inc, res + (inc))
33# define atomic_or(ptr, inc) atomic_binop(ptr, inc, res | (inc))
34# define atomic_swap(ptr, inc) atomic_binop(ptr, inc, (inc))
35# define atomic_cas(ptr, cmp, swp) ({ \
36  long flags = disable_irqsave(); \
37  typeof(*(ptr)) res = *(volatile typeof(*(ptr)) *)(ptr); \
38  if (res == (cmp)) *(volatile typeof(ptr))(ptr) = (swp); \
39  enable_irqrestore(flags); \
40  res; })
41#endif
42
43static inline int spinlock_trylock(spinlock_t* lock)
44{
45  int res = atomic_swap(&lock->lock, -1);
46  mb();
47  return res;
48}
49
50static inline void spinlock_lock(spinlock_t* lock)
51{
52  do
53  {
54    while (atomic_read(&lock->lock))
55      ;
56  } while (spinlock_trylock(lock));
57}
58
59static inline void spinlock_unlock(spinlock_t* lock)
60{
61  mb();
62  atomic_set(&lock->lock,0);
63}
64
65static inline long spinlock_lock_irqsave(spinlock_t* lock)
66{
67  long flags = disable_irqsave();
68  spinlock_lock(lock);
69  return flags;
70}
71
72static inline void spinlock_unlock_irqrestore(spinlock_t* lock, long flags)
73{
74  spinlock_unlock(lock);
75  enable_irqrestore(flags);
76}
77
78#endif
79