spinlock.h

/* spinlock.h: 64-bit Sparc spinlock support.
 *
 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
 */

#ifndef __SPARC64_SPINLOCK_H
#define __SPARC64_SPINLOCK_H

#include <linux/config.h>
#include <linux/threads.h>	/* For NR_CPUS */

#ifndef __ASSEMBLY__

/* To get debugging spinlocks which detect and catch
 * deadlock situations, set CONFIG_DEBUG_SPINLOCK
 * and rebuild your kernel.
 */

/* All of these locking primitives are expected to work properly
 * even in an RMO memory model, which currently is what the kernel
 * runs in.
 *
 * There is another issue.  Because we play games to save cycles
 * in the non-contention case, we need to be extra careful about
 * branch targets into the "spinning" code.  They live in their
 * own section, but the newer V9 branches have a shorter range
 * than the traditional 32-bit sparc branch variants.  The rule
 * is that the branches that go into and out of the spinner sections
 * must be pre-V9 branches.
 */

#ifndef CONFIG_DEBUG_SPINLOCK

typedef struct {
	volatile unsigned char lock;
#ifdef CONFIG_PREEMPT
	unsigned int break_lock;
#endif
} spinlock_t;
#define SPIN_LOCK_UNLOCKED	(spinlock_t) {0,}

#define spin_lock_init(lp)	do { *(lp)= SPIN_LOCK_UNLOCKED; } while(0)
#define spin_is_locked(lp)  ((lp)->lock != 0)

#define spin_unlock_wait(lp)	\
do {	membar("#LoadLoad");	\
} while(lp->lock)

static inline void _raw_spin_lock(spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__(
"1:	ldstub		[%1], %0\n"
"	brnz,pn		%0, 2f\n"
"	 membar		#StoreLoad | #StoreStore\n"
"	.subsection	2\n"
"2:	ldub		[%1], %0\n"
"	brnz,pt		%0, 2b\n"
"	 membar		#LoadLoad\n"
"	ba,a,pt		%%xcc, 1b\n"
"	.previous"
	: "=&r" (tmp)
	: "r" (lock)
	: "memory");
}

static inline int _raw_spin_trylock(spinlock_t *lock)
{
	unsigned long result;

	__asm__ __volatile__(
"	ldstub		[%1], %0\n"
"	membar		#StoreLoad | #StoreStore"
	: "=r" (result)
	: "r" (lock)
	: "memory");

	return (result == 0UL);
}

static inline void _raw_spin_unlock(spinlock_t *lock)
{
	__asm__ __volatile__(
"	membar		#StoreStore | #LoadStore\n"
"	stb		%%g0, [%0]"
	: /* No outputs */
	: "r" (lock)
	: "memory");
}

static inline void _raw_spin_lock_flags(spinlock_t *lock, unsigned long flags)
{
	unsigned long tmp1, tmp2;

	__asm__ __volatile__(
"1:	ldstub		[%2], %0\n"
"	brnz,pn		%0, 2f\n"
"	membar		#StoreLoad | #StoreStore\n"
"	.subsection	2\n"
"2:	rdpr		%%pil, %1\n"
"	wrpr		%3, %%pil\n"
"3:	ldub		[%2], %0\n"
"	brnz,pt		%0, 3b\n"
"	membar		#LoadLoad\n"
"	ba,pt		%%xcc, 1b\n"
"	wrpr		%1, %%pil\n"
"	.previous"
	: "=&r" (tmp1), "=&r" (tmp2)
	: "r"(lock), "r"(flags)
	: "memory");
}

#else /* !(CONFIG_DEBUG_SPINLOCK) */

typedef struct {
	volatile unsigned char lock;
	unsigned int owner_pc, owner_cpu;
#ifdef CONFIG_PREEMPT
	unsigned int break_lock;
#endif
} spinlock_t;
#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0, 0, 0xff }
#define spin_lock_init(lp)	do { *(lp)= SPIN_LOCK_UNLOCKED; } while(0)
#define spin_is_locked(__lock)	((__lock)->lock != 0)
#define spin_unlock_wait(__lock)	\
do { \
	membar("#LoadLoad"); \
} while((__lock)->lock)

extern void _do_spin_lock (spinlock_t *lock, char *str);
extern void _do_spin_unlock (spinlock_t *lock);
extern int _do_spin_trylock (spinlock_t *lock);

#define _raw_spin_trylock(lp)	_do_spin_trylock(lp)
#define _raw_spin_lock(lock)	_do_spin_lock(lock, "spin_lock")
#define _raw_spin_unlock(lock)	_do_spin_unlock(lock)
#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)

#endif /* CONFIG_DEBUG_SPINLOCK */

/* Multi-reader locks, these are much saner than the 32-bit Sparc ones... */

#ifndef CONFIG_DEBUG_SPINLOCK

typedef struct {
	volatile unsigned int lock;
#ifdef CONFIG_PREEMPT
	unsigned int break_lock;
#endif
} rwlock_t;
#define RW_LOCK_UNLOCKED	{0,}
#define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while(0)

static void inline __read_lock(rwlock_t *lock)
{
	unsigned long tmp1, tmp2;

	__asm__ __volatile__ (
"1:	ldsw		[%2], %0\n"
"	brlz,pn		%0, 2f\n"
"4:	 add		%0, 1, %1\n"
"	cas		[%2], %0, %1\n"
"	cmp		%0, %1\n"
"	bne,pn		%%icc, 1b\n"
"	 membar		#StoreLoad | #StoreStore\n"
"	.subsection	2\n"
"2:	ldsw		[%2], %0\n"
"	brlz,pt		%0, 2b\n"
"	 membar		#LoadLoad\n"
"	ba,a,pt		%%xcc, 4b\n"
"	.previous"
	: "=&r" (tmp1), "=&r" (tmp2)
	: "r" (lock)
	: "memory");
}

static void inline __read_unlock(rwlock_t *lock)
{
	unsigned long tmp1, tmp2;

	__asm__ __volatile__(
"	membar	#StoreLoad | #LoadLoad\n"
"1:	lduw	[%2], %0\n"
"	sub	%0, 1, %1\n"
"	cas	[%2], %0, %1\n"
"	cmp	%0, %1\n"
"	bne,pn	%%xcc, 1b\n"
"	 nop"
	: "=&r" (tmp1), "=&r" (tmp2)
	: "r" (lock)
	: "memory");
}

static void inline __write_lock(rwlock_t *lock)
{
	unsigned long mask, tmp1, tmp2;

	mask = 0x80000000UL;

	__asm__ __volatile__(
"1:	lduw		[%2], %0\n"
"	brnz,pn		%0, 2f\n"
"4:	 or		%0, %3, %1\n"
"	cas		[%2], %0, %1\n"
"	cmp		%0, %1\n"
"	bne,pn		%%icc, 1b\n"
"	 membar		#StoreLoad | #StoreStore\n"
"	.subsection	2\n"
"2:	lduw		[%2], %0\n"
"	brnz,pt		%0, 2b\n"
"	 membar		#LoadLoad\n"
"	ba,a,pt		%%xcc, 4b\n"
"	.previous"
	: "=&r" (tmp1), "=&r" (tmp2)
	: "r" (lock), "r" (mask)
	: "memory");
}

static void inline __write_unlock(rwlock_t *lock)
{
	__asm__ __volatile__(
"	membar		#LoadStore | #StoreStore\n"
"	stw		%%g0, [%0]"
	: /* no outputs */
	: "r" (lock)
	: "memory");
}

static int inline __write_trylock(rwlock_t *lock)
{
	unsigned long mask, tmp1, tmp2, result;

	mask = 0x80000000UL;

	__asm__ __volatile__(
"	mov		0, %2\n"
"1:	lduw		[%3], %0\n"
"	brnz,pn		%0, 2f\n"
"	 or		%0, %4, %1\n"
"	cas		[%3], %0, %1\n"
"	cmp		%0, %1\n"
"	bne,pn		%%icc, 1b\n"
"	 membar		#StoreLoad | #StoreStore\n"
"	mov		1, %2\n"
"2:"
	: "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)
	: "r" (lock), "r" (mask)
	: "memory");

	return result;
}

#define _raw_read_lock(p)	__read_lock(p)
#define _raw_read_unlock(p)	__read_unlock(p)
#define _raw_write_lock(p)	__write_lock(p)
#define _raw_write_unlock(p)	__write_unlock(p)
#define _raw_write_trylock(p)	__write_trylock(p)

#else /* !(CONFIG_DEBUG_SPINLOCK) */

typedef struct {
	volatile unsigned long lock;
	unsigned int writer_pc, writer_cpu;
	unsigned int reader_pc[NR_CPUS];
#ifdef CONFIG_PREEMPT
	unsigned int break_lock;
#endif
} rwlock_t;
#define RW_LOCK_UNLOCKED	(rwlock_t) { 0, 0, 0xff, { } }
#define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while(0)

extern void _do_read_lock(rwlock_t *rw, char *str);
extern void _do_read_unlock(rwlock_t *rw, char *str);
extern void _do_write_lock(rwlock_t *rw, char *str);
extern void _do_write_unlock(rwlock_t *rw);
extern int _do_write_trylock(rwlock_t *rw, char *str);

#define _raw_read_lock(lock) \
do {	unsigned long flags; \
	local_irq_save(flags); \
	_do_read_lock(lock, "read_lock"); \
	local_irq_restore(flags); \
} while(0)

#define _raw_read_unlock(lock) \
do {	unsigned long flags; \
	local_irq_save(flags); \
	_do_read_unlock(lock, "read_unlock"); \
	local_irq_restore(flags); \
} while(0)

#define _raw_write_lock(lock) \
do {	unsigned long flags; \
	local_irq_save(flags); \
	_do_write_lock(lock, "write_lock"); \
	local_irq_restore(flags); \
} while(0)

#define _raw_write_unlock(lock) \
do {	unsigned long flags; \
	local_irq_save(flags); \
	_do_write_unlock(lock); \
	local_irq_restore(flags); \
} while(0)

#define _raw_write_trylock(lock) \
({	unsigned long flags; \
	int val; \
	local_irq_save(flags); \
	val = _do_write_trylock(lock, "write_trylock"); \
	local_irq_restore(flags); \
	val; \
})

#endif /* CONFIG_DEBUG_SPINLOCK */

#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
#define read_can_lock(rw)	(!((rw)->lock & 0x80000000UL))
#define write_can_lock(rw)	(!(rw)->lock)

#endif /* !(__ASSEMBLY__) */

#endif /* !(__SPARC64_SPINLOCK_H) */