arch/xtensa/include/asm/atomic.h

   1 /*
   2  * include/asm-xtensa/atomic.h
   3  *
   4  * Atomic operations that C can't guarantee us.  Useful for resource counting..
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 2001 - 2008 Tensilica Inc.
  11  */
  12
  13 #ifndef _XTENSA_ATOMIC_H
  14 #define _XTENSA_ATOMIC_H
  15
  16 #include <linux/stringify.h>
  17 #include <linux/types.h>
  18
  19 #ifdef __KERNEL__
  20 #include <asm/processor.h>
  21 #include <asm/cmpxchg.h>
  22 #include <asm/barrier.h>
  23
  24 #define ATOMIC_INIT(i)  { (i) }
  25
  26 /*
  27  * This Xtensa implementation assumes that the right mechanism
  28  * for exclusion is for locking interrupts to level EXCM_LEVEL.
  29  *
  30  * Locking interrupts looks like this:
  31  *
  32  *    rsil a15, TOPLEVEL
  33  *    <code>
  34  *    wsr  a15, PS
  35  *    rsync
  36  *
  37  * Note that a15 is used here because the register allocation
  38  * done by the compiler is not guaranteed and a window overflow
  39  * may not occur between the rsil and wsr instructions. By using
  40  * a15 in the rsil, the machine is guaranteed to be in a state
  41  * where no register reference will cause an overflow.
  42  */
  43
  44 /**
  45  * atomic_read - read atomic variable
  46  * @v: pointer of type atomic_t
  47  *
  48  * Atomically reads the value of @v.
  49  */
  50 #define atomic_read(v)          READ_ONCE((v)->counter)
  51
  52 /**
  53  * atomic_set - set atomic variable
  54  * @v: pointer of type atomic_t
  55  * @i: required value
  56  *
  57  * Atomically sets the value of @v to @i.
  58  */
  59 #define atomic_set(v,i)         WRITE_ONCE((v)->counter, (i))
  60
  61 #if XCHAL_HAVE_S32C1I
  62 #define ATOMIC_OP(op)                                                   \
  63 static inline void atomic_##op(int i, atomic_t * v)                     \
  64 {                                                                       \
  65         unsigned long tmp;                                              \
  66         int result;                                                     \
  67                                                                         \
  68         __asm__ __volatile__(                                           \
  69                         "1:     l32i    %1, %3, 0\n"                    \
  70                         "       wsr     %1, scompare1\n"                \
  71                         "       " #op " %0, %1, %2\n"                   \
  72                         "       s32c1i  %0, %3, 0\n"                    \
  73                         "       bne     %0, %1, 1b\n"                   \
  74                         : "=&a" (result), "=&a" (tmp)                   \
  75                         : "a" (i), "a" (v)                              \
  76                         : "memory"                                      \
  77                         );                                              \
  78 }                                                                       \
  79
  80 #define ATOMIC_OP_RETURN(op)                                            \
  81 static inline int atomic_##op##_return(int i, atomic_t * v)             \
  82 {                                                                       \
  83         unsigned long tmp;                                              \
  84         int result;                                                     \
  85                                                                         \
  86         __asm__ __volatile__(                                           \
  87                         "1:     l32i    %1, %3, 0\n"                    \
  88                         "       wsr     %1, scompare1\n"                \
  89                         "       " #op " %0, %1, %2\n"                   \
  90                         "       s32c1i  %0, %3, 0\n"                    \
  91                         "       bne     %0, %1, 1b\n"                   \
  92                         "       " #op " %0, %0, %2\n"                   \
  93                         : "=&a" (result), "=&a" (tmp)                   \
  94                         : "a" (i), "a" (v)                              \
  95                         : "memory"                                      \
  96                         );                                              \
  97                                                                         \
  98         return result;                                                  \
  99 }
 100
 101 #else /* XCHAL_HAVE_S32C1I */
 102
 103 #define ATOMIC_OP(op)                                                   \
 104 static inline void atomic_##op(int i, atomic_t * v)                     \
 105 {                                                                       \
 106         unsigned int vval;                                              \
 107                                                                         \
 108         __asm__ __volatile__(                                           \
 109                         "       rsil    a15, "__stringify(TOPLEVEL)"\n"\
 110                         "       l32i    %0, %2, 0\n"                    \
 111                         "       " #op " %0, %0, %1\n"                   \
 112                         "       s32i    %0, %2, 0\n"                    \
 113                         "       wsr     a15, ps\n"                      \
 114                         "       rsync\n"                                \
 115                         : "=&a" (vval)                                  \
 116                         : "a" (i), "a" (v)                              \
 117                         : "a15", "memory"                               \
 118                         );                                              \
 119 }                                                                       \
 120
 121 #define ATOMIC_OP_RETURN(op)                                            \
 122 static inline int atomic_##op##_return(int i, atomic_t * v)             \
 123 {                                                                       \
 124         unsigned int vval;                                              \
 125                                                                         \
 126         __asm__ __volatile__(                                           \
 127                         "       rsil    a15,"__stringify(TOPLEVEL)"\n"  \
 128                         "       l32i    %0, %2, 0\n"                    \
 129                         "       " #op " %0, %0, %1\n"                   \
 130                         "       s32i    %0, %2, 0\n"                    \
 131                         "       wsr     a15, ps\n"                      \
 132                         "       rsync\n"                                \
 133                         : "=&a" (vval)                                  \
 134                         : "a" (i), "a" (v)                              \
 135                         : "a15", "memory"                               \
 136                         );                                              \
 137                                                                         \
 138         return vval;                                                    \
 139 }
 140
 141 #endif /* XCHAL_HAVE_S32C1I */
 142
 143 #define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
 144
 145 ATOMIC_OPS(add)
 146 ATOMIC_OPS(sub)
 147
 148 ATOMIC_OP(and)
 149 ATOMIC_OP(or)
 150 ATOMIC_OP(xor)
 151
 152 #undef ATOMIC_OPS
 153 #undef ATOMIC_OP_RETURN
 154 #undef ATOMIC_OP
 155
 156 /**
 157  * atomic_sub_and_test - subtract value from variable and test result
 158  * @i: integer value to subtract
 159  * @v: pointer of type atomic_t
 160  *
 161  * Atomically subtracts @i from @v and returns
 162  * true if the result is zero, or false for all
 163  * other cases.
 164  */
 165 #define atomic_sub_and_test(i,v) (atomic_sub_return((i),(v)) == 0)
 166
 167 /**
 168  * atomic_inc - increment atomic variable
 169  * @v: pointer of type atomic_t
 170  *
 171  * Atomically increments @v by 1.
 172  */
 173 #define atomic_inc(v) atomic_add(1,(v))
 174
 175 /**
 176  * atomic_inc - increment atomic variable
 177  * @v: pointer of type atomic_t
 178  *
 179  * Atomically increments @v by 1.
 180  */
 181 #define atomic_inc_return(v) atomic_add_return(1,(v))
 182
 183 /**
 184  * atomic_dec - decrement atomic variable
 185  * @v: pointer of type atomic_t
 186  *
 187  * Atomically decrements @v by 1.
 188  */
 189 #define atomic_dec(v) atomic_sub(1,(v))
 190
 191 /**
 192  * atomic_dec_return - decrement atomic variable
 193  * @v: pointer of type atomic_t
 194  *
 195  * Atomically decrements @v by 1.
 196  */
 197 #define atomic_dec_return(v) atomic_sub_return(1,(v))
 198
 199 /**
 200  * atomic_dec_and_test - decrement and test
 201  * @v: pointer of type atomic_t
 202  *
 203  * Atomically decrements @v by 1 and
 204  * returns true if the result is 0, or false for all other
 205  * cases.
 206  */
 207 #define atomic_dec_and_test(v) (atomic_sub_return(1,(v)) == 0)
 208
 209 /**
 210  * atomic_inc_and_test - increment and test
 211  * @v: pointer of type atomic_t
 212  *
 213  * Atomically increments @v by 1
 214  * and returns true if the result is zero, or false for all
 215  * other cases.
 216  */
 217 #define atomic_inc_and_test(v) (atomic_add_return(1,(v)) == 0)
 218
 219 /**
 220  * atomic_add_negative - add and test if negative
 221  * @v: pointer of type atomic_t
 222  * @i: integer value to add
 223  *
 224  * Atomically adds @i to @v and returns true
 225  * if the result is negative, or false when
 226  * result is greater than or equal to zero.
 227  */
 228 #define atomic_add_negative(i,v) (atomic_add_return((i),(v)) < 0)
 229
 230 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 231 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 232
 233 /**
 234  * __atomic_add_unless - add unless the number is a given value
 235  * @v: pointer of type atomic_t
 236  * @a: the amount to add to v...
 237  * @u: ...unless v is equal to u.
 238  *
 239  * Atomically adds @a to @v, so long as it was not @u.
 240  * Returns the old value of @v.
 241  */
 242 static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
 243 {
 244         int c, old;
 245         c = atomic_read(v);
 246         for (;;) {
 247                 if (unlikely(c == (u)))
 248                         break;
 249                 old = atomic_cmpxchg((v), c, c + (a));
 250                 if (likely(old == c))
 251                         break;
 252                 c = old;
 253         }
 254         return c;
 255 }
 256
 257 #endif /* __KERNEL__ */
 258
 259 #endif /* _XTENSA_ATOMIC_H */