include/asm-m68k/semaphore.h

   1 #ifndef _M68K_SEMAPHORE_H
   2 #define _M68K_SEMAPHORE_H
   3
   4 #define RW_LOCK_BIAS             0x01000000
   5
   6 #ifndef __ASSEMBLY__
   7
   8 #include <linux/linkage.h>
   9 #include <linux/wait.h>
  10 #include <linux/spinlock.h>
  11
  12 #include <asm/system.h>
  13 #include <asm/atomic.h>
  14
  15 /*
  16  * Interrupt-safe semaphores..
  17  *
  18  * (C) Copyright 1996 Linus Torvalds
  19  *
  20  * m68k version by Andreas Schwab
  21  */
  22
  23
  24 struct semaphore {
  25         atomic_t count;
  26         atomic_t waking;
  27         wait_queue_head_t wait;
  28 #if WAITQUEUE_DEBUG
  29         long __magic;
  30 #endif
  31 };
  32
  33 #if WAITQUEUE_DEBUG
  34 # define __SEM_DEBUG_INIT(name) \
  35                 , (long)&(name).__magic
  36 #else
  37 # define __SEM_DEBUG_INIT(name)
  38 #endif
  39
  40 #define __SEMAPHORE_INITIALIZER(name,count) \
  41 { ATOMIC_INIT(count), ATOMIC_INIT(0), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
  42         __SEM_DEBUG_INIT(name) }
  43
  44 #define __MUTEX_INITIALIZER(name) \
  45         __SEMAPHORE_INITIALIZER(name,1)
  46
  47 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  48         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  49
  50 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  51 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  52
  53 extern inline void sema_init (struct semaphore *sem, int val)
  54 {
  55         *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
  56 }
  57
  58 static inline void init_MUTEX (struct semaphore *sem)
  59 {
  60         sema_init(sem, 1);
  61 }
  62
  63 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  64 {
  65         sema_init(sem, 0);
  66 }
  67
  68 asmlinkage void __down_failed(void /* special register calling convention */);
  69 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  70 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  71 asmlinkage void __up_wakeup(void /* special register calling convention */);
  72
  73 asmlinkage void __down(struct semaphore * sem);
  74 asmlinkage int  __down_interruptible(struct semaphore * sem);
  75 asmlinkage int  __down_trylock(struct semaphore * sem);
  76 asmlinkage void __up(struct semaphore * sem);
  77
  78 /*
  79  * This is ugly, but we want the default case to fall through.
  80  * "down_failed" is a special asm handler that calls the C
  81  * routine that actually waits. See arch/m68k/lib/semaphore.S
  82  */
  83 extern inline void down(struct semaphore * sem)
  84 {
  85         register struct semaphore *sem1 __asm__ ("%a1") = sem;
  86
  87 #if WAITQUEUE_DEBUG
  88         CHECK_MAGIC(sem->__magic);
  89 #endif
  90
  91         __asm__ __volatile__(
  92                 "| atomic down operation\n\t"
  93                 "subql #1,%0@\n\t"
  94                 "jmi 2f\n\t"
  95                 "1:\n"
  96                 ".section .text.lock,\"ax\"\n"
  97                 ".even\n"
  98                 "2:\tpea 1b\n\t"
  99                 "jbra __down_failed\n"
 100                 ".previous"
 101                 : /* no outputs */
 102                 : "a" (sem1)
 103                 : "memory");
 104 }
 105
 106 extern inline int down_interruptible(struct semaphore * sem)
 107 {
 108         register struct semaphore *sem1 __asm__ ("%a1") = sem;
 109         register int result __asm__ ("%d0");
 110
 111 #if WAITQUEUE_DEBUG
 112         CHECK_MAGIC(sem->__magic);
 113 #endif
 114
 115         __asm__ __volatile__(
 116                 "| atomic interruptible down operation\n\t"
 117                 "subql #1,%1@\n\t"
 118                 "jmi 2f\n\t"
 119                 "clrl %0\n"
 120                 "1:\n"
 121                 ".section .text.lock,\"ax\"\n"
 122                 ".even\n"
 123                 "2:\tpea 1b\n\t"
 124                 "jbra __down_failed_interruptible\n"
 125                 ".previous"
 126                 : "=d" (result)
 127                 : "a" (sem1)
 128                 : "%d0", "memory");
 129         return result;
 130 }
 131
 132 extern inline int down_trylock(struct semaphore * sem)
 133 {
 134         register struct semaphore *sem1 __asm__ ("%a1") = sem;
 135         register int result __asm__ ("%d0");
 136
 137 #if WAITQUEUE_DEBUG
 138         CHECK_MAGIC(sem->__magic);
 139 #endif
 140
 141         __asm__ __volatile__(
 142                 "| atomic down trylock operation\n\t"
 143                 "subql #1,%1@\n\t"
 144                 "jmi 2f\n\t"
 145                 "clrl %0\n"
 146                 "1:\n"
 147                 ".section .text.lock,\"ax\"\n"
 148                 ".even\n"
 149                 "2:\tpea 1b\n\t"
 150                 "jbra __down_failed_trylock\n"
 151                 ".previous"
 152                 : "=d" (result)
 153                 : "a" (sem1)
 154                 : "%d0", "memory");
 155         return result;
 156 }
 157
 158 /*
 159  * Note! This is subtle. We jump to wake people up only if
 160  * the semaphore was negative (== somebody was waiting on it).
 161  * The default case (no contention) will result in NO
 162  * jumps for both down() and up().
 163  */
 164 extern inline void up(struct semaphore * sem)
 165 {
 166         register struct semaphore *sem1 __asm__ ("%a1") = sem;
 167
 168 #if WAITQUEUE_DEBUG
 169         CHECK_MAGIC(sem->__magic);
 170 #endif
 171
 172         __asm__ __volatile__(
 173                 "| atomic up operation\n\t"
 174                 "addql #1,%0@\n\t"
 175                 "jle 2f\n"
 176                 "1:\n"
 177                 ".section .text.lock,\"ax\"\n"
 178                 ".even\n"
 179                 "2:\t"
 180                 "pea 1b\n\t"
 181                 "jbra __up_wakeup\n"
 182                 ".previous"
 183                 : /* no outputs */
 184                 : "a" (sem1)
 185                 : "memory");
 186 }
 187
 188
 189 /* rw mutexes (should that be mutices? =) -- throw rw
 190  * spinlocks and semaphores together, and this is what we
 191  * end up with...
 192  *
 193  * m68k version by Roman Zippel
 194  */
 195
 196 struct rw_semaphore {
 197         atomic_t                count;
 198         volatile unsigned char  write_bias_granted;
 199         volatile unsigned char  read_bias_granted;
 200         volatile unsigned char  pad1;
 201         volatile unsigned char  pad2;
 202         wait_queue_head_t       wait;
 203         wait_queue_head_t       write_bias_wait;
 204 #if WAITQUEUE_DEBUG
 205         long                    __magic;
 206         atomic_t                readers;
 207         atomic_t                writers;
 208 #endif
 209 };
 210
 211 #if WAITQUEUE_DEBUG
 212 #define __RWSEM_DEBUG_INIT      , ATOMIC_INIT(0), ATOMIC_INIT(0)
 213 #else
 214 #define __RWSEM_DEBUG_INIT      /* */
 215 #endif
 216
 217 #define __RWSEM_INITIALIZER(name,count) \
 218 { ATOMIC_INIT(count), 0, 0, 0, 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \
 219         __WAIT_QUEUE_HEAD_INITIALIZER((name).write_bias_wait) \
 220         __SEM_DEBUG_INIT(name) __RWSEM_DEBUG_INIT }
 221
 222 #define __DECLARE_RWSEM_GENERIC(name,count) \
 223         struct rw_semaphore name = __RWSEM_INITIALIZER(name,count)
 224
 225 #define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS)
 226 #define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS-1)
 227 #define DECLARE_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,0)
 228
 229 extern inline void init_rwsem(struct rw_semaphore *sem)
 230 {
 231         atomic_set(&sem->count, RW_LOCK_BIAS);
 232         sem->read_bias_granted = 0;
 233         sem->write_bias_granted = 0;
 234         init_waitqueue_head(&sem->wait);
 235         init_waitqueue_head(&sem->write_bias_wait);
 236 #if WAITQUEUE_DEBUG
 237         sem->__magic = (long)&sem->__magic;
 238         atomic_set(&sem->readers, 0);
 239         atomic_set(&sem->writers, 0);
 240 #endif
 241 }
 242
 243 extern inline void down_read(struct rw_semaphore *sem)
 244 {
 245         register struct rw_semaphore *__sem __asm__ ("%a1") = sem;
 246
 247 #if WAITQUEUE_DEBUG
 248         if (sem->__magic != (long)&sem->__magic)
 249                 BUG();
 250 #endif
 251         __asm__ __volatile__(
 252                 "| atomic down_read operation\n\t"
 253                 "subql #1,%0@\n\t"
 254                 "jmi 2f\n"
 255                 "1:\n"
 256                 ".section .text.lock,\"ax\"\n"
 257                 ".even\n"
 258                 "2:\n\t"
 259                 "pea 1b\n\t"
 260                 "jbra __down_read_failed\n"
 261                 ".previous"
 262                 : /* no outputs */
 263                 : "a" (__sem)
 264                 : "memory");
 265 #if WAITQUEUE_DEBUG
 266         if (sem->write_bias_granted)
 267                 BUG();
 268         if (atomic_read(&sem->writers))
 269                 BUG();
 270         atomic_inc(&sem->readers);
 271 #endif
 272 }
 273
 274 extern inline void down_write(struct rw_semaphore *sem)
 275 {
 276         register struct rw_semaphore *__sem __asm__ ("%a1") = sem;
 277
 278 #if WAITQUEUE_DEBUG
 279         if (sem->__magic != (long)&sem->__magic)
 280                 BUG();
 281 #endif
 282         __asm__ __volatile__(
 283                 "| atomic down_write operation\n\t"
 284                 "subl %1,%0@\n\t"
 285                 "jne 2f\n"
 286                 "1:\n"
 287                 ".section .text.lock,\"ax\"\n"
 288                 ".even\n"
 289                 "2:\n\t"
 290                 "pea 1b\n\t"
 291                 "jbra __down_write_failed\n"
 292                 ".previous"
 293                 : /* no outputs */
 294                 : "a" (__sem), "id" (RW_LOCK_BIAS)
 295                 : "memory");
 296 #if WAITQUEUE_DEBUG
 297         if (atomic_read(&sem->writers))
 298                 BUG();
 299         if (atomic_read(&sem->readers))
 300                 BUG();
 301         if (sem->read_bias_granted)
 302                 BUG();
 303         if (sem->write_bias_granted)
 304                 BUG();
 305         atomic_inc(&sem->writers);
 306 #endif
 307 }
 308
 309 /* When a reader does a release, the only significant
 310  * case is when there was a writer waiting, and we've
 311  * bumped the count to 0: we must wake the writer up.
 312  */
 313 extern inline void __up_read(struct rw_semaphore *sem)
 314 {
 315         register struct rw_semaphore *__sem __asm__ ("%a1") = sem;
 316
 317         __asm__ __volatile__(
 318                 "| atomic up_read operation\n\t"
 319                 "addql #1,%0@\n\t"
 320                 "jeq 2f\n"
 321                 "1:\n"
 322                 ".section .text.lock,\"ax\"\n"
 323                 ".even\n"
 324                 "2:\n\t"
 325                 "pea 1b\n\t"
 326                 "jbra __rwsem_wake\n"
 327                 ".previous"
 328                 : /* no outputs */
 329                 : "a" (__sem)
 330                 : "memory");
 331 }
 332
 333 extern inline void up_read(struct rw_semaphore *sem)
 334 {
 335 #if WAITQUEUE_DEBUG
 336         if (sem->write_bias_granted)
 337                 BUG();
 338         if (atomic_read(&sem->writers))
 339                 BUG();
 340         atomic_dec(&sem->readers);
 341 #endif
 342         __up_read(sem);
 343 }
 344
 345 /* releasing the writer is easy -- just release it and
 346  * wake up any sleepers.
 347  */
 348 extern inline void __up_write(struct rw_semaphore *sem)
 349 {
 350         register struct rw_semaphore *__sem __asm__ ("%a1") = sem;
 351
 352         __asm__ __volatile__(
 353                 "| atomic up_write operation\n\t"
 354                 "addl %1,%0@\n\t"
 355                 "jcs 2f\n"
 356                 "1:\n"
 357                 ".section .text.lock,\"ax\"\n"
 358                 ".even\n"
 359                 "2:\n\t"
 360                 "pea 1b\n\t"
 361                 "jbra __rwsem_wake\n"
 362                 ".previous"
 363                 : /* no outputs */
 364                 : "a" (__sem), "id" (RW_LOCK_BIAS)
 365                 : "memory");
 366 }
 367
 368 extern inline void up_write(struct rw_semaphore *sem)
 369 {
 370 #if WAITQUEUE_DEBUG
 371         if (sem->read_bias_granted)
 372                 BUG();
 373         if (sem->write_bias_granted)
 374                 BUG();
 375         if (atomic_read(&sem->readers))
 376                 BUG();
 377         if (atomic_read(&sem->writers) != 1)
 378                 BUG();
 379         atomic_dec(&sem->writers);
 380 #endif
 381         __up_write(sem);
 382 }
 383 #endif /* __ASSEMBLY__ */
 384
 385 #endif