arch/s390/include/asm/spinlock.h

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999
   4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   5  *
   6  *  Derived from "include/asm-i386/spinlock.h"
   7  */
   8
   9 #ifndef __ASM_SPINLOCK_H
  10 #define __ASM_SPINLOCK_H
  11
  12 #include <linux/smp.h>
  13
  14 #define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)
  15
  16 extern int spin_retry;
  17
  18 static inline int
  19 _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new)
  20 {
  21         return __sync_bool_compare_and_swap(lock, old, new);
  22 }
  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  * (the type definitions are in asm/spinlock_types.h)
  31  */
  32
  33 void arch_lock_relax(unsigned int cpu);
  34
  35 void arch_spin_lock_wait(arch_spinlock_t *);
  36 int arch_spin_trylock_retry(arch_spinlock_t *);
  37 void arch_spin_lock_wait_flags(arch_spinlock_t *, unsigned long flags);
  38
  39 static inline void arch_spin_relax(arch_spinlock_t *lock)
  40 {
  41         arch_lock_relax(lock->lock);
  42 }
  43
  44 static inline u32 arch_spin_lockval(int cpu)
  45 {
  46         return ~cpu;
  47 }
  48
  49 static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
  50 {
  51         return lock.lock == 0;
  52 }
  53
  54 static inline int arch_spin_is_locked(arch_spinlock_t *lp)
  55 {
  56         return ACCESS_ONCE(lp->lock) != 0;
  57 }
  58
  59 static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
  60 {
  61         barrier();
  62         return likely(arch_spin_value_unlocked(*lp) &&
  63                       _raw_compare_and_swap(&lp->lock, 0, SPINLOCK_LOCKVAL));
  64 }
  65
  66 static inline void arch_spin_lock(arch_spinlock_t *lp)
  67 {
  68         if (!arch_spin_trylock_once(lp))
  69                 arch_spin_lock_wait(lp);
  70 }
  71
  72 static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
  73                                         unsigned long flags)
  74 {
  75         if (!arch_spin_trylock_once(lp))
  76                 arch_spin_lock_wait_flags(lp, flags);
  77 }
  78
  79 static inline int arch_spin_trylock(arch_spinlock_t *lp)
  80 {
  81         if (!arch_spin_trylock_once(lp))
  82                 return arch_spin_trylock_retry(lp);
  83         return 1;
  84 }
  85
  86 static inline void arch_spin_unlock(arch_spinlock_t *lp)
  87 {
  88         typecheck(unsigned int, lp->lock);
  89         asm volatile(
  90                 "st     %1,%0\n"
  91                 : "+Q" (lp->lock)
  92                 : "d" (0)
  93                 : "cc", "memory");
  94 }
  95
  96 static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
  97 {
  98         while (arch_spin_is_locked(lock))
  99                 arch_spin_relax(lock);
 100 }
 101
 102 /*
 103  * Read-write spinlocks, allowing multiple readers
 104  * but only one writer.
 105  *
 106  * NOTE! it is quite common to have readers in interrupts
 107  * but no interrupt writers. For those circumstances we
 108  * can "mix" irq-safe locks - any writer needs to get a
 109  * irq-safe write-lock, but readers can get non-irqsafe
 110  * read-locks.
 111  */
 112
 113 /**
 114  * read_can_lock - would read_trylock() succeed?
 115  * @lock: the rwlock in question.
 116  */
 117 #define arch_read_can_lock(x) ((int)(x)->lock >= 0)
 118
 119 /**
 120  * write_can_lock - would write_trylock() succeed?
 121  * @lock: the rwlock in question.
 122  */
 123 #define arch_write_can_lock(x) ((x)->lock == 0)
 124
 125 extern int _raw_read_trylock_retry(arch_rwlock_t *lp);
 126 extern int _raw_write_trylock_retry(arch_rwlock_t *lp);
 127
 128 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 129 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
 130
 131 static inline int arch_read_trylock_once(arch_rwlock_t *rw)
 132 {
 133         unsigned int old = ACCESS_ONCE(rw->lock);
 134         return likely((int) old >= 0 &&
 135                       _raw_compare_and_swap(&rw->lock, old, old + 1));
 136 }
 137
 138 static inline int arch_write_trylock_once(arch_rwlock_t *rw)
 139 {
 140         unsigned int old = ACCESS_ONCE(rw->lock);
 141         return likely(old == 0 &&
 142                       _raw_compare_and_swap(&rw->lock, 0, 0x80000000));
 143 }
 144
 145 #ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
 146
 147 #define __RAW_OP_OR     "lao"
 148 #define __RAW_OP_AND    "lan"
 149 #define __RAW_OP_ADD    "laa"
 150
 151 #define __RAW_LOCK(ptr, op_val, op_string)              \
 152 ({                                                      \
 153         unsigned int old_val;                           \
 154                                                         \
 155         typecheck(unsigned int *, ptr);                 \
 156         asm volatile(                                   \
 157                 op_string "     %0,%2,%1\n"             \
 158                 "bcr    14,0\n"                         \
 159                 : "=d" (old_val), "+Q" (*ptr)           \
 160                 : "d" (op_val)                          \
 161                 : "cc", "memory");                      \
 162         old_val;                                        \
 163 })
 164
 165 #define __RAW_UNLOCK(ptr, op_val, op_string)            \
 166 ({                                                      \
 167         unsigned int old_val;                           \
 168                                                         \
 169         typecheck(unsigned int *, ptr);                 \
 170         asm volatile(                                   \
 171                 op_string "     %0,%2,%1\n"             \
 172                 : "=d" (old_val), "+Q" (*ptr)           \
 173                 : "d" (op_val)                          \
 174                 : "cc", "memory");                      \
 175         old_val;                                        \
 176 })
 177
 178 extern void _raw_read_lock_wait(arch_rwlock_t *lp);
 179 extern void _raw_write_lock_wait(arch_rwlock_t *lp, unsigned int prev);
 180
 181 static inline void arch_read_lock(arch_rwlock_t *rw)
 182 {
 183         unsigned int old;
 184
 185         old = __RAW_LOCK(&rw->lock, 1, __RAW_OP_ADD);
 186         if ((int) old < 0)
 187                 _raw_read_lock_wait(rw);
 188 }
 189
 190 static inline void arch_read_unlock(arch_rwlock_t *rw)
 191 {
 192         __RAW_UNLOCK(&rw->lock, -1, __RAW_OP_ADD);
 193 }
 194
 195 static inline void arch_write_lock(arch_rwlock_t *rw)
 196 {
 197         unsigned int old;
 198
 199         old = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
 200         if (old != 0)
 201                 _raw_write_lock_wait(rw, old);
 202         rw->owner = SPINLOCK_LOCKVAL;
 203 }
 204
 205 static inline void arch_write_unlock(arch_rwlock_t *rw)
 206 {
 207         rw->owner = 0;
 208         __RAW_UNLOCK(&rw->lock, 0x7fffffff, __RAW_OP_AND);
 209 }
 210
 211 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 212
 213 extern void _raw_read_lock_wait(arch_rwlock_t *lp);
 214 extern void _raw_write_lock_wait(arch_rwlock_t *lp);
 215
 216 static inline void arch_read_lock(arch_rwlock_t *rw)
 217 {
 218         if (!arch_read_trylock_once(rw))
 219                 _raw_read_lock_wait(rw);
 220 }
 221
 222 static inline void arch_read_unlock(arch_rwlock_t *rw)
 223 {
 224         unsigned int old;
 225
 226         do {
 227                 old = ACCESS_ONCE(rw->lock);
 228         } while (!_raw_compare_and_swap(&rw->lock, old, old - 1));
 229 }
 230
 231 static inline void arch_write_lock(arch_rwlock_t *rw)
 232 {
 233         if (!arch_write_trylock_once(rw))
 234                 _raw_write_lock_wait(rw);
 235         rw->owner = SPINLOCK_LOCKVAL;
 236 }
 237
 238 static inline void arch_write_unlock(arch_rwlock_t *rw)
 239 {
 240         typecheck(unsigned int, rw->lock);
 241
 242         rw->owner = 0;
 243         asm volatile(
 244                 "st     %1,%0\n"
 245                 : "+Q" (rw->lock)
 246                 : "d" (0)
 247                 : "cc", "memory");
 248 }
 249
 250 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 251
 252 static inline int arch_read_trylock(arch_rwlock_t *rw)
 253 {
 254         if (!arch_read_trylock_once(rw))
 255                 return _raw_read_trylock_retry(rw);
 256         return 1;
 257 }
 258
 259 static inline int arch_write_trylock(arch_rwlock_t *rw)
 260 {
 261         if (!arch_write_trylock_once(rw) && !_raw_write_trylock_retry(rw))
 262                 return 0;
 263         rw->owner = SPINLOCK_LOCKVAL;
 264         return 1;
 265 }
 266
 267 static inline void arch_read_relax(arch_rwlock_t *rw)
 268 {
 269         arch_lock_relax(rw->owner);
 270 }
 271
 272 static inline void arch_write_relax(arch_rwlock_t *rw)
 273 {
 274         arch_lock_relax(rw->owner);
 275 }
 276
 277 #endif /* __ASM_SPINLOCK_H */