- 根目录:
- arch
- mips
- include
- asm
- spinlock.h
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1999, 2000, 06 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
*/
#ifndef _ASM_SPINLOCK_H
#define _ASM_SPINLOCK_H
#include <linux/compiler.h>
#include <asm/barrier.h>
#include <asm/compiler.h>
#include <asm/war.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* These are fair FIFO ticket locks
*
* (the type definitions are in asm/spinlock_types.h)
*/
/*
* Ticket locks are conceptually two parts, one indicating the current head of
* the queue, and the other indicating the current tail. The lock is acquired
* by atomically noting the tail and incrementing it by one (thus adding
* ourself to the queue and noting our position), then waiting until the head
* becomes equal to the the initial value of the tail.
*/
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
u32 counters = ACCESS_ONCE(lock->lock);
return ((counters >> 16) ^ counters) & 0xffff;
}
static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
return lock.h.serving_now == lock.h.ticket;
}
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(x) \
while (arch_spin_is_locked(x)) { cpu_relax(); }
static inline int arch_spin_is_contended(arch_spinlock_t *lock)
{
u32 counters = ACCESS_ONCE(lock->lock);
return (((counters >> 16) - counters) & 0xffff) > 1;
}
#define arch_spin_is_contended arch_spin_is_contended
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
int my_ticket;
int tmp;
int inc = 0x10000;
if (R10000_LLSC_WAR) {
__asm__ __volatile__ (
" .set push # arch_spin_lock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" addu %[my_ticket], %[ticket], %[inc] \n"
" sc %[my_ticket], %[ticket_ptr] \n"
" beqzl %[my_ticket], 1b \n"
" nop \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[ticket], %[ticket], 0xffff \n"
" bne %[ticket], %[my_ticket], 4f \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
"2: \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0xffff \n"
" sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
" \n"
" lhu %[ticket], %[serving_now_ptr] \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
" b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[serving_now_ptr] "+m" (lock->h.serving_now),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (my_ticket)
: [inc] "r" (inc));
} else {
__asm__ __volatile__ (
" .set push # arch_spin_lock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" addu %[my_ticket], %[ticket], %[inc] \n"
" sc %[my_ticket], %[ticket_ptr] \n"
" beqz %[my_ticket], 1b \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[ticket], %[ticket], 0xffff \n"
" bne %[ticket], %[my_ticket], 4f \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
"2: \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0xffff \n"
" sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
" \n"
" lhu %[ticket], %[serving_now_ptr] \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
" b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[serving_now_ptr] "+m" (lock->h.serving_now),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (my_ticket)
: [inc] "r" (inc));
}
smp_llsc_mb();
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned int serving_now = lock->h.serving_now + 1;
wmb();
lock->h.serving_now = (u16)serving_now;
nudge_writes();
}
static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
{
int tmp, tmp2, tmp3;
int inc = 0x10000;
if (R10000_LLSC_WAR) {
__asm__ __volatile__ (
" .set push # arch_spin_trylock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[now_serving], %[ticket], 0xffff \n"
" bne %[my_ticket], %[now_serving], 3f \n"
" addu %[ticket], %[ticket], %[inc] \n"
" sc %[ticket], %[ticket_ptr] \n"
" beqzl %[ticket], 1b \n"
" li %[ticket], 1 \n"
"2: \n"
" .subsection 2 \n"
"3: b 2b \n"
" li %[ticket], 0 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (tmp2),
[now_serving] "=&r" (tmp3)
: [inc] "r" (inc));
} else {
__asm__ __volatile__ (
" .set push # arch_spin_trylock \n"
" .set noreorder \n"
" \n"
"1: ll %[ticket], %[ticket_ptr] \n"
" srl %[my_ticket], %[ticket], 16 \n"
" andi %[now_serving], %[ticket], 0xffff \n"
" bne %[my_ticket], %[now_serving], 3f \n"
" addu %[ticket], %[ticket], %[inc] \n"
" sc %[ticket], %[ticket_ptr] \n"
" beqz %[ticket], 1b \n"
" li %[ticket], 1 \n"
"2: \n"
" .subsection 2 \n"
"3: b 2b \n"
" li %[ticket], 0 \n"
" .previous \n"
" .set pop \n"
: [ticket_ptr] "+" GCC_OFF_SMALL_ASM() (lock->lock),
[ticket] "=&r" (tmp),
[my_ticket] "=&r" (tmp2),
[now_serving] "=&r" (tmp3)
: [inc] "r" (inc));
}
smp_llsc_mb();
return tmp;
}
/*
* 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.
*/
/*
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_read_can_lock(rw) ((rw)->lock >= 0)
/*
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_write_can_lock(rw) (!(rw)->lock)
static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned int tmp;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_read_lock \n"
"1: ll %1, %2 \n"
" bltz %1, 1b \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
" .set reorder \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_lock \n"
" bltz %1, 1b \n"
" addu %1, 1 \n"
"2: sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
smp_llsc_mb();
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned int tmp;
smp_mb__before_llsc();
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_unlock \n"
" addiu %1, -1 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_read_unlock \n"
" addiu %1, -1 \n"
" sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
unsigned int tmp;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_write_lock \n"
"1: ll %1, %2 \n"
" bnez %1, 1b \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
" .set reorder \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
"1: ll %1, %2 # arch_write_lock \n"
" bnez %1, 1b \n"
" lui %1, 0x8000 \n"
"2: sc %1, %0 \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
}
smp_llsc_mb();
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
smp_mb__before_llsc();
__asm__ __volatile__(
" # arch_write_unlock \n"
" sw $0, %0 \n"
: "=m" (rw->lock)
: "m" (rw->lock)
: "memory");
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned int tmp;
int ret;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_read_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bltz %1, 2f \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" .set reorder \n"
" beqzl %1, 1b \n"
" nop \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
__asm__ __volatile__(
" .set noreorder # arch_read_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bltz %1, 2f \n"
" addu %1, 1 \n"
" sc %1, %0 \n"
" beqz %1, 1b \n"
" nop \n"
" .set reorder \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
}
return ret;
}
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned int tmp;
int ret;
if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set noreorder # arch_write_trylock \n"
" li %2, 0 \n"
"1: ll %1, %3 \n"
" bnez %1, 2f \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" beqzl %1, 1b \n"
" nop \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
" .set reorder \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} else {
do {
__asm__ __volatile__(
" ll %1, %3 # arch_write_trylock \n"
" li %2, 0 \n"
" bnez %1, 2f \n"
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" li %2, 1 \n"
"2: \n"
: "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp),
"=&r" (ret)
: GCC_OFF_SMALL_ASM() (rw->lock)
: "memory");
} while (unlikely(!tmp));
smp_llsc_mb();
}
return ret;
}
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
#endif /* _ASM_SPINLOCK_H */