#ifndef __CB_BDK_SPINLOCK_H__
#define __CB_BDK_SPINLOCK_H__
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/**
* @file
*
* Implementation of spinlocks.
*
*
$Revision: 49448 $
*
* @addtogroup hal
* @{
*/
/**
* Spinlocks
*/
typedef union
{
uint64_t combined;
struct
{
#if __BYTE_ORDER == __BIG_ENDIAN
uint32_t ticket;
uint32_t serving;
#else
uint32_t serving;
uint32_t ticket;
#endif
} s;
} bdk_spinlock_t;
/**
* Initialize a spinlock
*
* @param lock Lock to initialize
*/
static inline void bdk_spinlock_init(bdk_spinlock_t *lock)
{
asm volatile ("str xzr, [%[b]]"
: "+m" (lock->combined)
: [b] "r" (&lock->combined)
: "memory");
}
/**
* Releases lock
*
* @param lock pointer to lock structure
*/
static inline void bdk_spinlock_unlock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
static inline void bdk_spinlock_unlock(bdk_spinlock_t *lock)
{
/* Implies a release */
asm volatile ("stlr %w[v], [%[b]]"
: "+m" (lock->s.serving)
: [v] "r" (lock->s.serving + 1), [b] "r" (&lock->s.serving)
: "memory");
}
/**
* Gets lock, spins until lock is taken
*
* @param lock pointer to lock structure
*/
static inline void bdk_spinlock_lock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
static inline void bdk_spinlock_lock(bdk_spinlock_t *lock)
{
uint64_t combined;
uint32_t ticket;
uint32_t serving;
asm volatile (
"mov %x[serving], 1<<32 \n"
"ldadda %x[serving], %x[combined], [%[ptr]] \n"
"and %x[serving], %x[combined], 0xffffffff \n"
"lsr %x[ticket], %x[combined], 32 \n"
"cmp %x[ticket], %x[serving] \n"
"b.eq 1f \n"
"sevl \n"
"2: wfe \n"
"ldxr %w[serving], [%[ptr2]] \n"
"cmp %x[ticket], %x[serving] \n"
"b.ne 2b \n"
"1: \n"
: [serving] "=&r" (serving), [ticket] "=&r" (ticket), [combined] "=&r" (combined), "+m" (lock->combined)
: [ptr] "r" (&lock->combined), [ptr2] "r" (&lock->s.serving)
: "memory"
);
}
/**
* Trys to get the lock, failing if we can't get it immediately
*
* @param lock pointer to lock structure
*/
static inline int bdk_spinlock_trylock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
static inline int bdk_spinlock_trylock(bdk_spinlock_t *lock)
{
uint64_t combined = *(volatile uint64_t *)&lock->combined;
uint32_t ticket = combined >> 32;
uint32_t serving = (uint32_t)combined;
if (ticket != serving)
return -1;
uint64_t new_combined = combined + (1ull << 32);
bool success = bdk_atomic_compare_and_store64(&lock->combined, combined, new_combined);
return success ? 0 : -1;
}
/** @} */
#endif /* !__CB_BDK_SPINLOCK_H__ */