/*
 *  include/asm-s390/spinlock.h
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  Derived from "include/asm-i386/spinlock.h"
 */

#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H

#ifndef __SMP__

/*
 * Your basic spinlocks, allowing only a single CPU anywhere
 *
 * Gcc-2.7.x has a nasty bug with empty initializers.
 */
#if (__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
typedef struct { } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { }
#else
  typedef struct { int gcc_is_buggy; } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#endif

#define spin_lock_init(lock)	do { } while(0)
#define spin_lock(lock)		do { } while(0)
#define spin_trylock(lock)	do { } while(0)
#define spin_unlock(lock)	do { } while(0)
#define spin_lock_irq(lock)	cli()
#define spin_unlock_irq(lock)	sti()

#define spin_lock_irqsave(lock, flags) \
	do { save_flags(flags); cli(); } while (0)
#define spin_unlock_irqrestore(lock, flags) \
	restore_flags(flags)

/*
 * Read-write spinlocks, allowing multiple readers
 * but only one writer.
 *
 * NOTE! it is quite common to have readers in interrupts
 * but no interrupt writers. For those circumstances we
 * can "mix" irq-safe locks - any writer needs to get a
 * irq-safe write-lock, but readers can get non-irqsafe
 * read-locks.
 *
 * Gcc-2.7.x has a nasty bug with empty initializers.
 */
#if (__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
  typedef struct { } rwlock_t;
  #define RW_LOCK_UNLOCKED (rwlock_t) { }
#else
  typedef struct { int gcc_is_buggy; } rwlock_t;
  #define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
#endif

#define read_lock(lock)		do { } while(0)
#define read_unlock(lock)	do { } while(0)
#define write_lock(lock)	do { } while(0)
#define write_unlock(lock)	do { } while(0)
#define read_lock_irq(lock)	cli()
#define read_unlock_irq(lock)	sti()
#define write_lock_irq(lock)	cli()
#define write_unlock_irq(lock)	sti()

#define read_lock_irqsave(lock, flags)	\
	do { save_flags(flags); cli(); } while (0)
#define read_unlock_irqrestore(lock, flags) \
	restore_flags(flags)
#define write_lock_irqsave(lock, flags)	\
	do { save_flags(flags); cli(); } while (0)
#define write_unlock_irqrestore(lock, flags) \
	restore_flags(flags)

#else /* __SMP__ */

/* Simple spin lock operations.  There are two variants, one clears IRQ's
 * on the local processor, one does not.
 *
 * We make no fairness assumptions. They have a cost.
 */

typedef struct {
	volatile unsigned long lock;
} spinlock_t;

#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#define spin_lock_init(lp) do { (lp)->lock = 0; } while(0)
#define spin_unlock_wait(lp)	do { barrier(); } while((lp)->lock)

extern inline void spin_lock(spinlock_t *lp)
{
	__asm__ __volatile("    lhi   1,-1\n"
			   "0:  slr   0,0\n"
			   "    cs    0,1,%1\n"
			   "    jl    0b"
			   : "=m" (lp->lock)
			   : "0" (lp->lock) : "0", "1");
}

extern inline int spin_trylock(spinlock_t *lp)
{
	unsigned long result;
	__asm__ __volatile("    slr   %1,%1\n"
			   "    lhi   0,-1\n"
			   "0:  cs    %1,0,%0"
			   : "=m" (lp->lock), "=&d" (result)
			   : "0" (lp->lock) : "0");
	return !result;
}



extern inline void spin_unlock(spinlock_t *lp)
{
	__asm__ __volatile("    xc 0(4,%0),0(%0)\n"
                           "    bcr 15,0"
			   : /* no output */ : "a" (lp) );
}
		
#define spin_lock_irq(lock) \
	do { __cli(); spin_lock(lock); } while (0)
#define spin_unlock_irq(lock) \
	do { spin_unlock(lock); __sti(); } while (0)

#define spin_lock_irqsave(lock, flags) \
	do { __save_flags(flags); __cli(); spin_lock(lock); } while (0)
#define spin_unlock_irqrestore(lock, flags) \
	do { spin_unlock(lock); __restore_flags(flags); } while (0)

/*
 * Read-write spinlocks, allowing multiple readers
 * but only one writer.
 *
 * NOTE! it is quite common to have readers in interrupts
 * but no interrupt writers. For those circumstances we
 * can "mix" irq-safe locks - any writer needs to get a
 * irq-safe write-lock, but readers can get non-irqsafe
 * read-locks.
 */
typedef struct {
	volatile unsigned long lock;
	volatile unsigned long owner_pc;
} rwlock_t;

#define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 }

extern void _read_lock(rwlock_t *rw);
extern void _read_unlock(rwlock_t *rw);
extern void _write_lock(rwlock_t *rw);
extern void _write_unlock(rwlock_t *rw);

#define read_lock(rw)   \
        asm volatile("   l     2,%0\n"   \
                     "0: sll   2,1\n"    \
                     "   srl   2,1\n"     /* clear high (=write) bit */ \
                     "   lr    3,2\n"    \
                     "   ahi   3,1\n"     /* one more reader */ \
                     "   cs    2,3,%0\n"  /* try to write new value */ \
                     "   jl    0b"       \
                     : "+m" ((rw)->lock) : : "2", "3" );

#define read_unlock(rw) \
        asm volatile("   l     2,%0\n"   \
                     "0: lr    3,2\n"    \
                     "   ahi   3,-1\n"    /* one less reader */ \
                     "   cs    2,3,%0\n" \
                     "   jl    0b"       \
                     : "+m" ((rw)->lock) : : "2", "3" );

#define write_lock(rw) \
        asm volatile("   lhi   3,1\n"    \
                     "   sll   3,31\n"    /* new lock value = 0x80000000 */ \
                     "0: slr   2,2\n"     /* old lock value must be 0 */ \
                     "   cs    2,3,%0\n" \
                     "   jl    0b"       \
                     : "+m" ((rw)->lock) : : "2", "3" );

#define write_unlock(rw) \
        asm volatile("   slr   3,3\n"     /* new lock value = 0 */ \
                     "0: lhi   2,1\n"    \
                     "   sll   2,31\n"    /* old lock value must be 0x80000000 */ \
                     "   cs    2,3,%0\n" \
                     "   jl    0b"       \
                     : "+m" ((rw)->lock) : : "2", "3" );

#define read_lock_irq(lock)	do { __cli(); read_lock(lock); } while (0)
#define read_unlock_irq(lock)	do { read_unlock(lock); __sti(); } while (0)
#define write_lock_irq(lock)	do { __cli(); write_lock(lock); } while (0)
#define write_unlock_irq(lock)	do { write_unlock(lock); __sti(); } while (0)

#define read_lock_irqsave(lock, flags)	\
	do { __save_flags(flags); __cli(); read_lock(lock); } while (0)
#define read_unlock_irqrestore(lock, flags) \
	do { read_unlock(lock); __restore_flags(flags); } while (0)
#define write_lock_irqsave(lock, flags)	\
	do { __save_flags(flags); __cli(); write_lock(lock); } while (0)
#define write_unlock_irqrestore(lock, flags) \
	do { write_unlock(lock); __restore_flags(flags); } while (0)

#endif /* SMP */
#endif /* __ASM_SPINLOCK_H */









