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 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 <linux/config.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                 "       sync                                            \n"
  45                 "       .set    reorder                                 \n"
  46                 : "=m" (lock->lock), "=&r" (tmp)
  47                 : "m" (lock->lock)
  48                 : "memory");
  49         } else {
  50                 __asm__ __volatile__(
  51                 "       .set    noreorder       # __raw_spin_lock       \n"
  52                 "1:     ll      %1, %2                                  \n"
  53                 "       bnez    %1, 1b                                  \n"
  54                 "        li     %1, 1                                   \n"
  55                 "       sc      %1, %0                                  \n"
  56                 "       beqz    %1, 1b                                  \n"
  57                 "        sync                                           \n"
  58                 "       .set    reorder                                 \n"
  59                 : "=m" (lock->lock), "=&r" (tmp)
  60                 : "m" (lock->lock)
  61                 : "memory");
  62         }
  63 }
  64
  65 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  66 {
  67         __asm__ __volatile__(
  68         "       .set    noreorder       # __raw_spin_unlock     \n"
  69         "       sync                                            \n"
  70         "       sw      $0, %0                                  \n"
  71         "       .set\treorder                                   \n"
  72         : "=m" (lock->lock)
  73         : "m" (lock->lock)
  74         : "memory");
  75 }
  76
  77 static inline unsigned int __raw_spin_trylock(raw_spinlock_t *lock)
  78 {
  79         unsigned int temp, res;
  80
  81         if (R10000_LLSC_WAR) {
  82                 __asm__ __volatile__(
  83                 "       .set    noreorder       # __raw_spin_trylock    \n"
  84                 "1:     ll      %0, %3                                  \n"
  85                 "       ori     %2, %0, 1                               \n"
  86                 "       sc      %2, %1                                  \n"
  87                 "       beqzl   %2, 1b                                  \n"
  88                 "        nop                                            \n"
  89                 "       andi    %2, %0, 1                               \n"
  90                 "       sync                                            \n"
  91                 "       .set    reorder"
  92                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
  93                 : "m" (lock->lock)
  94                 : "memory");
  95         } else {
  96                 __asm__ __volatile__(
  97                 "       .set    noreorder       # __raw_spin_trylock    \n"
  98                 "1:     ll      %0, %3                                  \n"
  99                 "       ori     %2, %0, 1                               \n"
 100                 "       sc      %2, %1                                  \n"
 101                 "       beqz    %2, 1b                                  \n"
 102                 "        andi   %2, %0, 1                               \n"
 103                 "       sync                                            \n"
 104                 "       .set    reorder"
 105                 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
 106                 : "m" (lock->lock)
 107                 : "memory");
 108         }
 109
 110         return res == 0;
 111 }
 112
 113 /*
 114  * Read-write spinlocks, allowing multiple readers but only one writer.
 115  *
 116  * NOTE! it is quite common to have readers in interrupts but no interrupt
 117  * writers. For those circumstances we can "mix" irq-safe locks - any writer
 118  * needs to get a irq-safe write-lock, but readers can get non-irqsafe
 119  * read-locks.
 120  */
 121
 122 static inline void __raw_read_lock(raw_rwlock_t *rw)
 123 {
 124         unsigned int tmp;
 125
 126         if (R10000_LLSC_WAR) {
 127                 __asm__ __volatile__(
 128                 "       .set    noreorder       # __raw_read_lock       \n"
 129                 "1:     ll      %1, %2                                  \n"
 130                 "       bltz    %1, 1b                                  \n"
 131                 "        addu   %1, 1                                   \n"
 132                 "       sc      %1, %0                                  \n"
 133                 "       beqzl   %1, 1b                                  \n"
 134                 "        nop                                            \n"
 135                 "       sync                                            \n"
 136                 "       .set    reorder                                 \n"
 137                 : "=m" (rw->lock), "=&r" (tmp)
 138                 : "m" (rw->lock)
 139                 : "memory");
 140         } else {
 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                 "       beqz    %1, 1b                                  \n"
 148                 "        sync                                           \n"
 149                 "       .set    reorder                                 \n"
 150                 : "=m" (rw->lock), "=&r" (tmp)
 151                 : "m" (rw->lock)
 152                 : "memory");
 153         }
 154 }
 155
 156 /* Note the use of sub, not subu which will make the kernel die with an
 157    overflow exception if we ever try to unlock an rwlock that is already
 158    unlocked or is being held by a writer.  */
 159 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 160 {
 161         unsigned int tmp;
 162
 163         if (R10000_LLSC_WAR) {
 164                 __asm__ __volatile__(
 165                 "1:     ll      %1, %2          # __raw_read_unlock     \n"
 166                 "       sub     %1, 1                                   \n"
 167                 "       sc      %1, %0                                  \n"
 168                 "       beqzl   %1, 1b                                  \n"
 169                 "       sync                                            \n"
 170                 : "=m" (rw->lock), "=&r" (tmp)
 171                 : "m" (rw->lock)
 172                 : "memory");
 173         } else {
 174                 __asm__ __volatile__(
 175                 "       .set    noreorder       # __raw_read_unlock     \n"
 176                 "1:     ll      %1, %2                                  \n"
 177                 "       sub     %1, 1                                   \n"
 178                 "       sc      %1, %0                                  \n"
 179                 "       beqz    %1, 1b                                  \n"
 180                 "        sync                                           \n"
 181                 "       .set    reorder                                 \n"
 182                 : "=m" (rw->lock), "=&r" (tmp)
 183                 : "m" (rw->lock)
 184                 : "memory");
 185         }
 186 }
 187
 188 static inline void __raw_write_lock(raw_rwlock_t *rw)
 189 {
 190         unsigned int tmp;
 191
 192         if (R10000_LLSC_WAR) {
 193                 __asm__ __volatile__(
 194                 "       .set    noreorder       # __raw_write_lock      \n"
 195                 "1:     ll      %1, %2                                  \n"
 196                 "       bnez    %1, 1b                                  \n"
 197                 "        lui    %1, 0x8000                              \n"
 198                 "       sc      %1, %0                                  \n"
 199                 "       beqzl   %1, 1b                                  \n"
 200                 "        nop                                            \n"
 201                 "       sync                                            \n"
 202                 "       .set    reorder                                 \n"
 203                 : "=m" (rw->lock), "=&r" (tmp)
 204                 : "m" (rw->lock)
 205                 : "memory");
 206         } else {
 207                 __asm__ __volatile__(
 208                 "       .set    noreorder       # __raw_write_lock      \n"
 209                 "1:     ll      %1, %2                                  \n"
 210                 "       bnez    %1, 1b                                  \n"
 211                 "        lui    %1, 0x8000                              \n"
 212                 "       sc      %1, %0                                  \n"
 213                 "       beqz    %1, 1b                                  \n"
 214                 "        nop                                            \n"
 215                 "       sync                                            \n"
 216                 "       .set    reorder                                 \n"
 217                 : "=m" (rw->lock), "=&r" (tmp)
 218                 : "m" (rw->lock)
 219                 : "memory");
 220         }
 221 }
 222
 223 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 224 {
 225         __asm__ __volatile__(
 226         "       sync                    # __raw_write_unlock    \n"
 227         "       sw      $0, %0                                  \n"
 228         : "=m" (rw->lock)
 229         : "m" (rw->lock)
 230         : "memory");
 231 }
 232
 233 #define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
 234
 235 static inline int __raw_write_trylock(raw_rwlock_t *rw)
 236 {
 237         unsigned int tmp;
 238         int ret;
 239
 240         if (R10000_LLSC_WAR) {
 241                 __asm__ __volatile__(
 242                 "       .set    noreorder       # __raw_write_trylock   \n"
 243                 "       li      %2, 0                                   \n"
 244                 "1:     ll      %1, %3                                  \n"
 245                 "       bnez    %1, 2f                                  \n"
 246                 "        lui    %1, 0x8000                              \n"
 247                 "       sc      %1, %0                                  \n"
 248                 "       beqzl   %1, 1b                                  \n"
 249                 "        nop                                            \n"
 250                 "       sync                                            \n"
 251                 "       li      %2, 1                                   \n"
 252                 "       .set    reorder                                 \n"
 253                 "2:                                                     \n"
 254                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 255                 : "m" (rw->lock)
 256                 : "memory");
 257         } else {
 258                 __asm__ __volatile__(
 259                 "       .set    noreorder       # __raw_write_trylock   \n"
 260                 "       li      %2, 0                                   \n"
 261                 "1:     ll      %1, %3                                  \n"
 262                 "       bnez    %1, 2f                                  \n"
 263                 "       lui     %1, 0x8000                              \n"
 264                 "       sc      %1, %0                                  \n"
 265                 "       beqz    %1, 1b                                  \n"
 266                 "        sync                                           \n"
 267                 "       li      %2, 1                                   \n"
 268                 "       .set    reorder                                 \n"
 269                 "2:                                                     \n"
 270                 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
 271                 : "m" (rw->lock)
 272                 : "memory");
 273         }
 274
 275         return ret;
 276 }
 277
 278 #endif /* _ASM_SPINLOCK_H */