/* spinlock.h: 64-bit Sparc spinlock support.
*
* Copyright (C) 1997 David S. Miller ([email protected])
*/

#ifndef __SPARC64_SPINLOCK_H
#define __SPARC64_SPINLOCK_H

#ifndef __ASSEMBLY__

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

/* 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.
*/

#define arch_spin_is_locked(lp) ((lp)->lock != 0)

#define arch_spin_unlock_wait(lp) \
do { rmb(); \
} while((lp)->lock)

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned long tmp;

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

static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned long result;

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

return (result == 0UL);
}

static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
__asm__ __volatile__(
" stb %%g0, [%0]"
: /* No outputs */
: "r" (lock)
: "memory");
}

static inline void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
{
unsigned long tmp1, tmp2;

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

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

static void inline arch_read_lock(arch_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"
" nop\n"
" .subsection 2\n"
"2: ldsw [%2], %0\n"
" brlz,pt %0, 2b\n"
" nop\n"
" ba,a,pt %%xcc, 4b\n"
" .previous"
: "=&r" (tmp1), "=&r" (tmp2)
: "r" (lock)
: "memory");
}

static int inline arch_read_trylock(arch_rwlock_t *lock)
{
int tmp1, tmp2;

__asm__ __volatile__ (
"1: ldsw [%2], %0\n"
" brlz,a,pn %0, 2f\n"
" mov 0, %0\n"
" add %0, 1, %1\n"
" cas [%2], %0, %1\n"
" cmp %0, %1\n"
" bne,pn %%icc, 1b\n"
" mov 1, %0\n"
"2:"
: "=&r" (tmp1), "=&r" (tmp2)
: "r" (lock)
: "memory");

return tmp1;
}

static void inline arch_read_unlock(arch_rwlock_t *lock)
{
unsigned long tmp1, tmp2;

__asm__ __volatile__(
"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 arch_write_lock(arch_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"
" nop\n"
" .subsection 2\n"
"2: lduw [%2], %0\n"
" brnz,pt %0, 2b\n"
" nop\n"
" ba,a,pt %%xcc, 4b\n"
" .previous"
: "=&r" (tmp1), "=&r" (tmp2)
: "r" (lock), "r" (mask)
: "memory");
}

static void inline arch_write_unlock(arch_rwlock_t *lock)
{
__asm__ __volatile__(
" stw %%g0, [%0]"
: /* no outputs */
: "r" (lock)
: "memory");
}

static int inline arch_write_trylock(arch_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"
" nop\n"
" mov 1, %2\n"
"2:"
: "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)
: "r" (lock), "r" (mask)
: "memory");

return result;
}

#define arch_read_lock_flags(p, f) arch_read_lock(p)
#define arch_write_lock_flags(p, f) arch_write_lock(p)

#define arch_read_can_lock(rw) (!((rw)->lock & 0x80000000UL))
#define arch_write_can_lock(rw) (!(rw)->lock)

#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()

#endif /* !(__ASSEMBLY__) */

#endif /* !(__SPARC64_SPINLOCK_H) */