arch/mips/include/asm/octeon/cvmx-spinlock.h

Source file repositories/reference/linux-study-clean/arch/mips/include/asm/octeon/cvmx-spinlock.h

File Facts

System
Linux kernel
Corpus path
arch/mips/include/asm/octeon/cvmx-spinlock.h
Extension
.h
Size
6385 bytes
Lines
233
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __CVMX_SPINLOCK_H__
#define __CVMX_SPINLOCK_H__

#include <asm/octeon/cvmx-asm.h>

/* Spinlocks for Octeon */

/* define these to enable recursive spinlock debugging */
/*#define CVMX_SPINLOCK_DEBUG */

/**
 * Spinlocks for Octeon CVMX
 */
typedef struct {
	volatile uint32_t value;
} cvmx_spinlock_t;

/* note - macros not expanded in inline ASM, so values hardcoded */
#define	 CVMX_SPINLOCK_UNLOCKED_VAL  0
#define	 CVMX_SPINLOCK_LOCKED_VAL    1

#define CVMX_SPINLOCK_UNLOCKED_INITIALIZER  {CVMX_SPINLOCK_UNLOCKED_VAL}

/**
 * Initialize a spinlock
 *
 * @lock:   Lock to initialize
 */
static inline void cvmx_spinlock_init(cvmx_spinlock_t *lock)
{
	lock->value = CVMX_SPINLOCK_UNLOCKED_VAL;
}

/**
 * Return non-zero if the spinlock is currently locked
 *
 * @lock:   Lock to check
 * Returns Non-zero if locked
 */
static inline int cvmx_spinlock_locked(cvmx_spinlock_t *lock)
{
	return lock->value != CVMX_SPINLOCK_UNLOCKED_VAL;
}

/**
 * Releases lock
 *
 * @lock:   pointer to lock structure
 */
static inline void cvmx_spinlock_unlock(cvmx_spinlock_t *lock)
{
	CVMX_SYNCWS;
	lock->value = 0;
	CVMX_SYNCWS;
}

/**
 * Attempts to take the lock, but does not spin if lock is not available.
 * May take some time to acquire the lock even if it is available
 * due to the ll/sc not succeeding.
 *
 * @lock:   pointer to lock structure
 *
 * Returns 0: lock successfully taken
 *	   1: lock not taken, held by someone else
 * These return values match the Linux semantics.
 */

static inline unsigned int cvmx_spinlock_trylock(cvmx_spinlock_t *lock)
{
	unsigned int tmp;

	__asm__ __volatile__(".set noreorder	     \n"
			     "1: ll   %[tmp], %[val] \n"
			/* if lock held, fail immediately */
			     "	 bnez %[tmp], 2f     \n"
			     "	 li   %[tmp], 1	     \n"
			     "	 sc   %[tmp], %[val] \n"
			     "	 beqz %[tmp], 1b     \n"
			     "	 li   %[tmp], 0	     \n"
			     "2:		     \n"
			     ".set reorder	     \n" :
			[val] "+m"(lock->value), [tmp] "=&r"(tmp)
			     : : "memory");

	return tmp != 0;		/* normalize to 0 or 1 */
}

/**
 * Gets lock, spins until lock is taken

Annotation

Implementation Notes