diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/xtensa/include/asm/spinlock.h | 188 |
1 files changed, 187 insertions, 1 deletions
diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h index 8ff23649581b..03975906b36f 100644 --- a/arch/xtensa/include/asm/spinlock.h +++ b/arch/xtensa/include/asm/spinlock.h @@ -11,6 +11,192 @@ #ifndef _XTENSA_SPINLOCK_H #define _XTENSA_SPINLOCK_H -#include <linux/spinlock.h> +/* + * spinlock + * + * There is at most one owner of a spinlock. There are not different + * types of spinlock owners like there are for rwlocks (see below). + * + * When trying to obtain a spinlock, the function "spins" forever, or busy- + * waits, until the lock is obtained. When spinning, presumably some other + * owner will soon give up the spinlock making it available to others. Use + * the trylock functions to avoid spinning forever. + * + * possible values: + * + * 0 nobody owns the spinlock + * 1 somebody owns the spinlock + */ + +#define __raw_spin_is_locked(x) ((x)->slock != 0) +#define __raw_spin_unlock_wait(lock) \ + do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0) + +#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock) + +static inline void __raw_spin_lock(raw_spinlock_t *lock) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " wsr %0, scompare1\n" + "1: movi %0, 1\n" + " s32c1i %0, %1, 0\n" + " bnez %0, 1b\n" + : "=&a" (tmp) + : "a" (&lock->slock) + : "memory"); +} + +/* Returns 1 if the lock is obtained, 0 otherwise. */ + +static inline int __raw_spin_trylock(raw_spinlock_t *lock) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " wsr %0, scompare1\n" + " movi %0, 1\n" + " s32c1i %0, %1, 0\n" + : "=&a" (tmp) + : "a" (&lock->slock) + : "memory"); + + return tmp == 0 ? 1 : 0; +} + +static inline void __raw_spin_unlock(raw_spinlock_t *lock) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " s32ri %0, %1, 0\n" + : "=&a" (tmp) + : "a" (&lock->slock) + : "memory"); +} + +/* + * rwlock + * + * Read-write locks are really a more flexible spinlock. They allow + * multiple readers but only one writer. Write ownership is exclusive + * (i.e., all other readers and writers are blocked from ownership while + * there is a write owner). These rwlocks are unfair to writers. Writers + * can be starved for an indefinite time by readers. + * + * possible values: + * + * 0 nobody owns the rwlock + * >0 one or more readers own the rwlock + * (the positive value is the actual number of readers) + * 0x80000000 one writer owns the rwlock, no other writers, no readers + */ + +#define __raw_write_can_lock(x) ((x)->lock == 0) + +static inline void __raw_write_lock(raw_rwlock_t *rw) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " wsr %0, scompare1\n" + "1: movi %0, 1\n" + " slli %0, %0, 31\n" + " s32c1i %0, %1, 0\n" + " bnez %0, 1b\n" + : "=&a" (tmp) + : "a" (&rw->lock) + : "memory"); +} + +/* Returns 1 if the lock is obtained, 0 otherwise. */ + +static inline int __raw_write_trylock(raw_rwlock_t *rw) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " wsr %0, scompare1\n" + " movi %0, 1\n" + " slli %0, %0, 31\n" + " s32c1i %0, %1, 0\n" + : "=&a" (tmp) + : "a" (&rw->lock) + : "memory"); + + return tmp == 0 ? 1 : 0; +} + +static inline void __raw_write_unlock(raw_rwlock_t *rw) +{ + unsigned long tmp; + + __asm__ __volatile__( + " movi %0, 0\n" + " s32ri %0, %1, 0\n" + : "=&a" (tmp) + : "a" (&rw->lock) + : "memory"); +} + +static inline void __raw_read_lock(raw_rwlock_t *rw) +{ + unsigned long tmp; + unsigned long result; + + __asm__ __volatile__( + "1: l32i %1, %2, 0\n" + " bltz %1, 1b\n" + " wsr %1, scompare1\n" + " addi %0, %1, 1\n" + " s32c1i %0, %2, 0\n" + " bne %0, %1, 1b\n" + : "=&a" (result), "=&a" (tmp) + : "a" (&rw->lock) + : "memory"); +} + +/* Returns 1 if the lock is obtained, 0 otherwise. */ + +static inline int __raw_read_trylock(raw_rwlock_t *rw) +{ + unsigned long result; + unsigned long tmp; + + __asm__ __volatile__( + " l32i %1, %2, 0\n" + " addi %0, %1, 1\n" + " bltz %0, 1f\n" + " wsr %1, scompare1\n" + " s32c1i %0, %2, 0\n" + " sub %0, %0, %1\n" + "1:\n" + : "=&a" (result), "=&a" (tmp) + : "a" (&rw->lock) + : "memory"); + + return result == 0; +} + +static inline void __raw_read_unlock(raw_rwlock_t *rw) +{ + unsigned long tmp1, tmp2; + + __asm__ __volatile__( + "1: l32i %1, %2, 0\n" + " addi %0, %1, -1\n" + " wsr %1, scompare1\n" + " s32c1i %0, %2, 0\n" + " bne %0, %1, 1b\n" + : "=&a" (tmp1), "=&a" (tmp2) + : "a" (&rw->lock) + : "memory"); +} #endif /* _XTENSA_SPINLOCK_H */ |