include/asm-mips/spinlock.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1999, 2000, 06 by Ralf Baechle
   7  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   8  */
   9 #ifndef _ASM_SPINLOCK_H
  10 #define _ASM_SPINLOCK_H
  11
  12 #include <asm/barrier.h>
  13 #include <asm/war.h>
  14
  15 /*
  16  * Your basic SMP spinlocks, allowing only a single CPU anywhere
  17  */
  18
  19 #define __raw_spin_is_locked(x)       ((x)->lock != 0)
  20 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
  21 #define __raw_spin_unlock_wait(x) \
  22         do { cpu_relax(); } while ((x)->lock)
  23
  24 /*
  25  * Simple spin lock operations.  There are two variants, one clears IRQ's
  26  * on the local processor, one does not.
  27  *
  28  * We make no fairness assumptions.  They have a cost.
  29  */
  30
  31 static inline void __raw_spin_lock(raw_spinlock_t *lock)
  32 {
  33         unsigned int tmp;
  34
  35         if (R10000_LLSC_WAR) {
  36                 __asm__ __volatile__(
  37                 "       .set    noreorder       # __raw_spin_lock       \n"
  38                 "1:     ll      %1, %2                                  \n"
  39                 "       bnez    %1, 1b                                  \n"
  40                 "        li     %1, 1                                   \n"
  41                 "       sc      %1, %0                                  \n"
  42                 "       beqzl   %1, 1b                                  \n"
  43                 "        nop                                            \n"
  44                 "       .set    reorder                                 \n"
  45                 : "=m" (lock->lock), "=&r" (tmp)
  46                 : "m" (lock->lock)
  47                 : "memory");
  48         } else {
  49                 __asm__ __volatile__(
  50                 "       .set    noreorder       # __raw_spin_lock       \n"
  51                 "1:     ll      %1, %2                                  \n"
  52                 "       bnez    %1, 1b                                  \n"
  53                 "        li     %1, 1                                   \n"
  54                 "       sc      %1, %0                                  \n"
  55                 "       beqz    %1, 1b                                  \n"
  56                 "        nop                                            \n"
  57                 "       .set    reorder                                 \n"
  58                 : "=m" (lock->lock), "=&r" (tmp)
  59                 : "m" (lock->lock)
  60                 : "memory");
  61         }
  62
  63         smp_mb();
  64 }
  65
  66 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  67 {
  68         smp_mb();
  69
  70         __asm__ __volatile__(
  71         "       .set    noreorder       # __raw_spin_unlock     \n"
  72         "       sw      $0, %0                                  \n"
  73         "       .set\treorder                                   \n"
  74         : "=m" (lock->lock)
  75         : "m" (lock->lock)
  76         : "memory");
  77 }
  78
  79 static inline unsigned int __raw_spin_trylock(raw_spinlock_t *lock)
  80 {
  81         unsigned int temp, res;
  82
  83         if (R10000_LLSC_WAR) {
  84                 __asm__ __volatile__(
  85                 "       .set    noreorder       # __raw_spin_trylock    \n"
  86                 "1:     ll      %0, %3                                  \n"
  87                 "       ori     %2, %0, 1                               \n"
  88                 "       sc      %2, %1                                  \n"
  89                 "       beqzl   %2, 1b                                  \n"
  90                 "        nop                                            \n"
  91                 "       andi    %2, %0, 1                               \n"
  92                 "       .set    reorder"
  93                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
  94                 : "m" (lock->lock)
  95                 : "memory");
  96         } else {
  97                 __asm__ __volatile__(
  98                 "       .set    noreorder       # __raw_spin_trylock    \n"
  99                 "1:     ll      %0, %3                                  \n"
 100                 "       ori     %2, %0, 1                               \n"
 101                 "       sc      %2, %1                                  \n"
 102                 "       beqz    %2, 1b                                  \n"
 103                 "        andi   %2, %0, 1                               \n"
 104                 "       .set    reorder"
 105                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
 106                 : "m" (lock->lock)
 107                 : "memory");
 108         }
 109
 110         smp_mb();
 111
 112         return res == 0;
 113 }
 114
 115 /*
 116  * Read-write spinlocks, allowing multiple readers but only one writer.
 117  *
 118  * NOTE! it is quite common to have readers in interrupts but no interrupt
 119  * writers. For those circumstances we can "mix" irq-safe locks - any writer
 120  * needs to get a irq-safe write-lock, but readers can get non-irqsafe
 121  * read-locks.
 122  */
 123
 124 /*
 125  * read_can_lock - would read_trylock() succeed?
 126  * @lock: the rwlock in question.
 127  */
 128 #define __raw_read_can_lock(rw) ((rw)->lock >= 0)
 129
 130 /*
 131  * write_can_lock - would write_trylock() succeed?
 132  * @lock: the rwlock in question.
 133  */
 134 #define __raw_write_can_lock(rw)        (!(rw)->lock)
 135
 136 static inline void __raw_read_lock(raw_rwlock_t *rw)
 137 {
 138         unsigned int tmp;
 139
 140         if (R10000_LLSC_WAR) {
 141                 __asm__ __volatile__(
 142                 "       .set    noreorder       # __raw_read_lock       \n"
 143                 "1:     ll      %1, %2                                  \n"
 144                 "       bltz    %1, 1b                                  \n"
 145                 "        addu   %1, 1                                   \n"
 146                 "       sc      %1, %0                                  \n"
 147                 "       beqzl   %1, 1b                                  \n"
 148                 "        nop                                            \n"
 149                 "       .set    reorder                                 \n"
 150                 : "=m" (rw->lock), "=&r" (tmp)
 151                 : "m" (rw->lock)
 152                 : "memory");
 153         } else {
 154                 __asm__ __volatile__(
 155                 "       .set    noreorder       # __raw_read_lock       \n"
 156                 "1:     ll      %1, %2                                  \n"
 157                 "       bltz    %1, 1b                                  \n"
 158                 "        addu   %1, 1                                   \n"
 159                 "       sc      %1, %0                                  \n"
 160                 "       beqz    %1, 1b                                  \n"
 161                 "        nop                                            \n"
 162                 "       .set    reorder                                 \n"
 163                 : "=m" (rw->lock), "=&r" (tmp)
 164                 : "m" (rw->lock)
 165                 : "memory");
 166         }
 167
 168         smp_mb();
 169 }
 170
 171 /* Note the use of sub, not subu which will make the kernel die with an
 172    overflow exception if we ever try to unlock an rwlock that is already
 173    unlocked or is being held by a writer.  */
 174 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 175 {
 176         unsigned int tmp;
 177
 178         smp_mb();
 179
 180         if (R10000_LLSC_WAR) {
 181                 __asm__ __volatile__(
 182                 "1:     ll      %1, %2          # __raw_read_unlock     \n"
 183                 "       sub     %1, 1                                   \n"
 184                 "       sc      %1, %0                                  \n"
 185                 "       beqzl   %1, 1b                                  \n"
 186                 : "=m" (rw->lock), "=&r" (tmp)
 187                 : "m" (rw->lock)
 188                 : "memory");
 189         } else {
 190                 __asm__ __volatile__(
 191                 "       .set    noreorder       # __raw_read_unlock     \n"
 192                 "1:     ll      %1, %2                                  \n"
 193                 "       sub     %1, 1                                   \n"
 194                 "       sc      %1, %0                                  \n"
 195                 "       beqz    %1, 1b                                  \n"
 196                 "        nop                                            \n"
 197                 "       .set    reorder                                 \n"
 198                 : "=m" (rw->lock), "=&r" (tmp)
 199                 : "m" (rw->lock)
 200                 : "memory");
 201         }
 202 }
 203
 204 static inline void __raw_write_lock(raw_rwlock_t *rw)
 205 {
 206         unsigned int tmp;
 207
 208         if (R10000_LLSC_WAR) {
 209                 __asm__ __volatile__(
 210                 "       .set    noreorder       # __raw_write_lock      \n"
 211                 "1:     ll      %1, %2                                  \n"
 212                 "       bnez    %1, 1b                                  \n"
 213                 "        lui    %1, 0x8000                              \n"
 214                 "       sc      %1, %0                                  \n"
 215                 "       beqzl   %1, 1b                                  \n"
 216                 "        nop                                            \n"
 217                 "       .set    reorder                                 \n"
 218                 : "=m" (rw->lock), "=&r" (tmp)
 219                 : "m" (rw->lock)
 220                 : "memory");
 221         } else {
 222                 __asm__ __volatile__(
 223                 "       .set    noreorder       # __raw_write_lock      \n"
 224                 "1:     ll      %1, %2                                  \n"
 225                 "       bnez    %1, 1b                                  \n"
 226                 "        lui    %1, 0x8000                              \n"
 227                 "       sc      %1, %0                                  \n"
 228                 "       beqz    %1, 1b                                  \n"
 229                 "        nop                                            \n"
 230                 "       .set    reorder                                 \n"
 231                 : "=m" (rw->lock), "=&r" (tmp)
 232                 : "m" (rw->lock)
 233                 : "memory");
 234         }
 235
 236         smp_mb();
 237 }
 238
 239 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 240 {
 241         smp_mb();
 242
 243         __asm__ __volatile__(
 244         "                               # __raw_write_unlock    \n"
 245         "       sw      $0, %0                                  \n"
 246         : "=m" (rw->lock)
 247         : "m" (rw->lock)
 248         : "memory");
 249 }
 250
 251 static inline int __raw_read_trylock(raw_rwlock_t *rw)
 252 {
 253         unsigned int tmp;
 254         int ret;
 255
 256         if (R10000_LLSC_WAR) {
 257                 __asm__ __volatile__(
 258                 "       .set    noreorder       # __raw_read_trylock    \n"
 259                 "       li      %2, 0                                   \n"
 260                 "1:     ll      %1, %3                                  \n"
 261                 "       bnez    %1, 2f                                  \n"
 262                 "        addu   %1, 1                                   \n"
 263                 "       sc      %1, %0                                  \n"
 264                 "       .set    reorder                                 \n"
 265                 "       beqzl   %1, 1b                                  \n"
 266                 "        nop                                            \n"
 267                 __WEAK_ORDERING_MB
 268                 "       li      %2, 1                                   \n"
 269                 "2:                                                     \n"
 270                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 271                 : "m" (rw->lock)
 272                 : "memory");
 273         } else {
 274                 __asm__ __volatile__(
 275                 "       .set    noreorder       # __raw_read_trylock    \n"
 276                 "       li      %2, 0                                   \n"
 277                 "1:     ll      %1, %3                                  \n"
 278                 "       bnez    %1, 2f                                  \n"
 279                 "        addu   %1, 1                                   \n"
 280                 "       sc      %1, %0                                  \n"
 281                 "       beqz    %1, 1b                                  \n"
 282                 "        nop                                            \n"
 283                 "       .set    reorder                                 \n"
 284                 __WEAK_ORDERING_MB
 285                 "       li      %2, 1                                   \n"
 286                 "2:                                                     \n"
 287                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 288                 : "m" (rw->lock)
 289                 : "memory");
 290         }
 291
 292         return ret;
 293 }
 294
 295 static inline int __raw_write_trylock(raw_rwlock_t *rw)
 296 {
 297         unsigned int tmp;
 298         int ret;
 299
 300         if (R10000_LLSC_WAR) {
 301                 __asm__ __volatile__(
 302                 "       .set    noreorder       # __raw_write_trylock   \n"
 303                 "       li      %2, 0                                   \n"
 304                 "1:     ll      %1, %3                                  \n"
 305                 "       bnez    %1, 2f                                  \n"
 306                 "        lui    %1, 0x8000                              \n"
 307                 "       sc      %1, %0                                  \n"
 308                 "       beqzl   %1, 1b                                  \n"
 309                 "        nop                                            \n"
 310                 __WEAK_ORDERING_MB
 311                 "       li      %2, 1                                   \n"
 312                 "       .set    reorder                                 \n"
 313                 "2:                                                     \n"
 314                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 315                 : "m" (rw->lock)
 316                 : "memory");
 317         } else {
 318                 __asm__ __volatile__(
 319                 "       .set    noreorder       # __raw_write_trylock   \n"
 320                 "       li      %2, 0                                   \n"
 321                 "1:     ll      %1, %3                                  \n"
 322                 "       bnez    %1, 2f                                  \n"
 323                 "       lui     %1, 0x8000                              \n"
 324                 "       sc      %1, %0                                  \n"
 325                 "       beqz    %1, 1b                                  \n"
 326                 "        nop                                            \n"
 327                 __WEAK_ORDERING_MB
 328                 "       li      %2, 1                                   \n"
 329                 "       .set    reorder                                 \n"
 330                 "2:                                                     \n"
 331                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 332                 : "m" (rw->lock)
 333                 : "memory");
 334         }
 335
 336         return ret;
 337 }
 338
 339
 340 #define _raw_spin_relax(lock)   cpu_relax()
 341 #define _raw_read_relax(lock)   cpu_relax()
 342 #define _raw_write_relax(lock)  cpu_relax()
 343
 344 #endif /* _ASM_SPINLOCK_H */