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 Ralf Baechle (ralf@linux-mips.org)
   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, 2f                                  \n"
  53                 "        li     %1, 1                                   \n"
  54                 "       sc      %1, %0                                  \n"
  55                 "       beqz    %1, 2f                                  \n"
  56                 "        nop                                            \n"
  57                 "       .subsection 2                                   \n"
  58                 "2:     ll      %1, %2                                  \n"
  59                 "       bnez    %1, 2b                                  \n"
  60                 "        li     %1, 1                                   \n"
  61                 "       b       1b                                      \n"
  62                 "        nop                                            \n"
  63                 "       .previous                                       \n"
  64                 "       .set    reorder                                 \n"
  65                 : "=m" (lock->lock), "=&r" (tmp)
  66                 : "m" (lock->lock)
  67                 : "memory");
  68         }
  69
  70         smp_mb();
  71 }
  72
  73 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  74 {
  75         smp_mb();
  76
  77         __asm__ __volatile__(
  78         "       .set    noreorder       # __raw_spin_unlock     \n"
  79         "       sw      $0, %0                                  \n"
  80         "       .set\treorder                                   \n"
  81         : "=m" (lock->lock)
  82         : "m" (lock->lock)
  83         : "memory");
  84 }
  85
  86 static inline unsigned int __raw_spin_trylock(raw_spinlock_t *lock)
  87 {
  88         unsigned int temp, res;
  89
  90         if (R10000_LLSC_WAR) {
  91                 __asm__ __volatile__(
  92                 "       .set    noreorder       # __raw_spin_trylock    \n"
  93                 "1:     ll      %0, %3                                  \n"
  94                 "       ori     %2, %0, 1                               \n"
  95                 "       sc      %2, %1                                  \n"
  96                 "       beqzl   %2, 1b                                  \n"
  97                 "        nop                                            \n"
  98                 "       andi    %2, %0, 1                               \n"
  99                 "       .set    reorder"
 100                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
 101                 : "m" (lock->lock)
 102                 : "memory");
 103         } else {
 104                 __asm__ __volatile__(
 105                 "       .set    noreorder       # __raw_spin_trylock    \n"
 106                 "1:     ll      %0, %3                                  \n"
 107                 "       ori     %2, %0, 1                               \n"
 108                 "       sc      %2, %1                                  \n"
 109                 "       beqz    %2, 2f                                  \n"
 110                 "        andi   %2, %0, 1                               \n"
 111                 "       .subsection 2                                   \n"
 112                 "2:     b       1b                                      \n"
 113                 "        nop                                            \n"
 114                 "       .previous                                       \n"
 115                 "       .set    reorder"
 116                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
 117                 : "m" (lock->lock)
 118                 : "memory");
 119         }
 120
 121         smp_mb();
 122
 123         return res == 0;
 124 }
 125
 126 /*
 127  * Read-write spinlocks, allowing multiple readers but only one writer.
 128  *
 129  * NOTE! it is quite common to have readers in interrupts but no interrupt
 130  * writers. For those circumstances we can "mix" irq-safe locks - any writer
 131  * needs to get a irq-safe write-lock, but readers can get non-irqsafe
 132  * read-locks.
 133  */
 134
 135 /*
 136  * read_can_lock - would read_trylock() succeed?
 137  * @lock: the rwlock in question.
 138  */
 139 #define __raw_read_can_lock(rw) ((rw)->lock >= 0)
 140
 141 /*
 142  * write_can_lock - would write_trylock() succeed?
 143  * @lock: the rwlock in question.
 144  */
 145 #define __raw_write_can_lock(rw)        (!(rw)->lock)
 146
 147 static inline void __raw_read_lock(raw_rwlock_t *rw)
 148 {
 149         unsigned int tmp;
 150
 151         if (R10000_LLSC_WAR) {
 152                 __asm__ __volatile__(
 153                 "       .set    noreorder       # __raw_read_lock       \n"
 154                 "1:     ll      %1, %2                                  \n"
 155                 "       bltz    %1, 1b                                  \n"
 156                 "        addu   %1, 1                                   \n"
 157                 "       sc      %1, %0                                  \n"
 158                 "       beqzl   %1, 1b                                  \n"
 159                 "        nop                                            \n"
 160                 "       .set    reorder                                 \n"
 161                 : "=m" (rw->lock), "=&r" (tmp)
 162                 : "m" (rw->lock)
 163                 : "memory");
 164         } else {
 165                 __asm__ __volatile__(
 166                 "       .set    noreorder       # __raw_read_lock       \n"
 167                 "1:     ll      %1, %2                                  \n"
 168                 "       bltz    %1, 2f                                  \n"
 169                 "        addu   %1, 1                                   \n"
 170                 "       sc      %1, %0                                  \n"
 171                 "       beqz    %1, 1b                                  \n"
 172                 "        nop                                            \n"
 173                 "       .subsection 2                                   \n"
 174                 "2:     ll      %1, %2                                  \n"
 175                 "       bltz    %1, 2b                                  \n"
 176                 "        addu   %1, 1                                   \n"
 177                 "       b       1b                                      \n"
 178                 "        nop                                            \n"
 179                 "       .previous                                       \n"
 180                 "       .set    reorder                                 \n"
 181                 : "=m" (rw->lock), "=&r" (tmp)
 182                 : "m" (rw->lock)
 183                 : "memory");
 184         }
 185
 186         smp_mb();
 187 }
 188
 189 /* Note the use of sub, not subu which will make the kernel die with an
 190    overflow exception if we ever try to unlock an rwlock that is already
 191    unlocked or is being held by a writer.  */
 192 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 193 {
 194         unsigned int tmp;
 195
 196         smp_mb();
 197
 198         if (R10000_LLSC_WAR) {
 199                 __asm__ __volatile__(
 200                 "1:     ll      %1, %2          # __raw_read_unlock     \n"
 201                 "       sub     %1, 1                                   \n"
 202                 "       sc      %1, %0                                  \n"
 203                 "       beqzl   %1, 1b                                  \n"
 204                 : "=m" (rw->lock), "=&r" (tmp)
 205                 : "m" (rw->lock)
 206                 : "memory");
 207         } else {
 208                 __asm__ __volatile__(
 209                 "       .set    noreorder       # __raw_read_unlock     \n"
 210                 "1:     ll      %1, %2                                  \n"
 211                 "       sub     %1, 1                                   \n"
 212                 "       sc      %1, %0                                  \n"
 213                 "       beqz    %1, 2f                                  \n"
 214                 "        nop                                            \n"
 215                 "       .subsection 2                                   \n"
 216                 "2:     b       1b                                      \n"
 217                 "        nop                                            \n"
 218                 "       .previous                                       \n"
 219                 "       .set    reorder                                 \n"
 220                 : "=m" (rw->lock), "=&r" (tmp)
 221                 : "m" (rw->lock)
 222                 : "memory");
 223         }
 224 }
 225
 226 static inline void __raw_write_lock(raw_rwlock_t *rw)
 227 {
 228         unsigned int tmp;
 229
 230         if (R10000_LLSC_WAR) {
 231                 __asm__ __volatile__(
 232                 "       .set    noreorder       # __raw_write_lock      \n"
 233                 "1:     ll      %1, %2                                  \n"
 234                 "       bnez    %1, 1b                                  \n"
 235                 "        lui    %1, 0x8000                              \n"
 236                 "       sc      %1, %0                                  \n"
 237                 "       beqzl   %1, 1b                                  \n"
 238                 "        nop                                            \n"
 239                 "       .set    reorder                                 \n"
 240                 : "=m" (rw->lock), "=&r" (tmp)
 241                 : "m" (rw->lock)
 242                 : "memory");
 243         } else {
 244                 __asm__ __volatile__(
 245                 "       .set    noreorder       # __raw_write_lock      \n"
 246                 "1:     ll      %1, %2                                  \n"
 247                 "       bnez    %1, 2f                                  \n"
 248                 "        lui    %1, 0x8000                              \n"
 249                 "       sc      %1, %0                                  \n"
 250                 "       beqz    %1, 2f                                  \n"
 251                 "        nop                                            \n"
 252                 "       .subsection 2                                   \n"
 253                 "2:     ll      %1, %2                                  \n"
 254                 "       bnez    %1, 2b                                  \n"
 255                 "        lui    %1, 0x8000                              \n"
 256                 "       b       1b                                      \n"
 257                 "        nop                                            \n"
 258                 "       .previous                                       \n"
 259                 "       .set    reorder                                 \n"
 260                 : "=m" (rw->lock), "=&r" (tmp)
 261                 : "m" (rw->lock)
 262                 : "memory");
 263         }
 264
 265         smp_mb();
 266 }
 267
 268 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 269 {
 270         smp_mb();
 271
 272         __asm__ __volatile__(
 273         "                               # __raw_write_unlock    \n"
 274         "       sw      $0, %0                                  \n"
 275         : "=m" (rw->lock)
 276         : "m" (rw->lock)
 277         : "memory");
 278 }
 279
 280 static inline int __raw_read_trylock(raw_rwlock_t *rw)
 281 {
 282         unsigned int tmp;
 283         int ret;
 284
 285         if (R10000_LLSC_WAR) {
 286                 __asm__ __volatile__(
 287                 "       .set    noreorder       # __raw_read_trylock    \n"
 288                 "       li      %2, 0                                   \n"
 289                 "1:     ll      %1, %3                                  \n"
 290                 "       bltz    %1, 2f                                  \n"
 291                 "        addu   %1, 1                                   \n"
 292                 "       sc      %1, %0                                  \n"
 293                 "       .set    reorder                                 \n"
 294                 "       beqzl   %1, 1b                                  \n"
 295                 "        nop                                            \n"
 296                 __WEAK_ORDERING_MB
 297                 "       li      %2, 1                                   \n"
 298                 "2:                                                     \n"
 299                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 300                 : "m" (rw->lock)
 301                 : "memory");
 302         } else {
 303                 __asm__ __volatile__(
 304                 "       .set    noreorder       # __raw_read_trylock    \n"
 305                 "       li      %2, 0                                   \n"
 306                 "1:     ll      %1, %3                                  \n"
 307                 "       bltz    %1, 2f                                  \n"
 308                 "        addu   %1, 1                                   \n"
 309                 "       sc      %1, %0                                  \n"
 310                 "       beqz    %1, 1b                                  \n"
 311                 "        nop                                            \n"
 312                 "       .set    reorder                                 \n"
 313                 __WEAK_ORDERING_MB
 314                 "       li      %2, 1                                   \n"
 315                 "2:                                                     \n"
 316                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 317                 : "m" (rw->lock)
 318                 : "memory");
 319         }
 320
 321         return ret;
 322 }
 323
 324 static inline int __raw_write_trylock(raw_rwlock_t *rw)
 325 {
 326         unsigned int tmp;
 327         int ret;
 328
 329         if (R10000_LLSC_WAR) {
 330                 __asm__ __volatile__(
 331                 "       .set    noreorder       # __raw_write_trylock   \n"
 332                 "       li      %2, 0                                   \n"
 333                 "1:     ll      %1, %3                                  \n"
 334                 "       bnez    %1, 2f                                  \n"
 335                 "        lui    %1, 0x8000                              \n"
 336                 "       sc      %1, %0                                  \n"
 337                 "       beqzl   %1, 1b                                  \n"
 338                 "        nop                                            \n"
 339                 __WEAK_ORDERING_MB
 340                 "       li      %2, 1                                   \n"
 341                 "       .set    reorder                                 \n"
 342                 "2:                                                     \n"
 343                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 344                 : "m" (rw->lock)
 345                 : "memory");
 346         } else {
 347                 __asm__ __volatile__(
 348                 "       .set    noreorder       # __raw_write_trylock   \n"
 349                 "       li      %2, 0                                   \n"
 350                 "1:     ll      %1, %3                                  \n"
 351                 "       bnez    %1, 2f                                  \n"
 352                 "       lui     %1, 0x8000                              \n"
 353                 "       sc      %1, %0                                  \n"
 354                 "       beqz    %1, 3f                                  \n"
 355                 "        li     %2, 1                                   \n"
 356                 "2:                                                     \n"
 357                 __WEAK_ORDERING_MB
 358                 "       .subsection 2                                   \n"
 359                 "3:     b       1b                                      \n"
 360                 "        li     %2, 0                                   \n"
 361                 "       .previous                                       \n"
 362                 "       .set    reorder                                 \n"
 363                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 364                 : "m" (rw->lock)
 365                 : "memory");
 366         }
 367
 368         return ret;
 369 }
 370
 371
 372 #define _raw_spin_relax(lock)   cpu_relax()
 373 #define _raw_read_relax(lock)   cpu_relax()
 374 #define _raw_write_relax(lock)  cpu_relax()
 375
 376 #endif /* _ASM_SPINLOCK_H */