/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <asm/spinlock_types.h>
#include <asm/processor.h>
#include <asm/barrier.h>
#define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__)
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(x) \
do { while (arch_spin_is_locked(x)) cpu_relax(); } while (0)
#ifdef CONFIG_ARC_HAS_LLSC
/*
* A normal LLOCK/SCOND based system, w/o need for livelock workaround
*/
#ifndef CONFIG_ARC_STAR_9000923308
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int val;
smp_mb();
__asm__ __volatile__(
"1: llock %[val], [%[slock]] \n"
" breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */
" scond %[LOCKED], [%[slock]] \n" /* acquire */
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [slock] "r" (&(lock->slock)),
[LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned int val, got_it = 0;
smp_mb();
__asm__ __volatile__(
"1: llock %[val], [%[slock]] \n"
" breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */
" scond %[LOCKED], [%[slock]] \n" /* acquire */
" bnz 1b \n"
" mov %[got_it], 1 \n"
"4: \n"
" \n"
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
: [slock] "r" (&(lock->slock)),
[LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
smp_mb();
lock->slock = __ARCH_SPIN_LOCK_UNLOCKED__;
smp_mb();
}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
* Unfair locking as Writers could be starved indefinitely by Reader(s)
*/
static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned int val;
smp_mb();
/*
* zero means writer holds the lock exclusively, deny Reader.
* Otherwise grant lock to first/subseq reader
*
* if (rw->counter > 0) {
* rw->counter--;
* ret = 1;
* }
*/
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */
" sub %[val], %[val], 1 \n" /* reader lock */
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [rwlock] "r" (&(rw->counter)),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned int val, got_it = 0;
smp_mb();
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */
" sub %[val], %[val], 1 \n" /* counter-- */
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n" /* retry if collided with someone */
" mov %[got_it], 1 \n"
" \n"
"4: ; --- done --- \n"
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
: [rwlock] "r" (&(rw->counter)),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
unsigned int val;
smp_mb();
/*
* If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
* deny writer. Otherwise if unlocked grant to writer
* Hence the claim that Linux rwlocks are unfair to writers.
* (can be starved for an indefinite time by readers).
*
* if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
* rw->counter = 0;
* ret = 1;
* }
*/
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */
" mov %[val], %[WR_LOCKED] \n"
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [rwlock] "r" (&(rw->counter)),
[UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned int val, got_it = 0;
smp_mb();
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */
" mov %[val], %[WR_LOCKED] \n"
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n" /* retry if collided with someone */
" mov %[got_it], 1 \n"
" \n"
"4: ; --- done --- \n"
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
: [rwlock] "r" (&(rw->counter)),
[UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned int val;
smp_mb();
/*
* rw->counter++;
*/
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" add %[val], %[val], 1 \n"
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [rwlock] "r" (&(rw->counter))
: "memory", "cc");
smp_mb();
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
smp_mb();
rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
smp_mb();
}
#else /* CONFIG_ARC_STAR_9000923308 */
/*
* HS38x4 could get into a LLOCK/SCOND livelock in case of multiple overlapping
* coherency transactions in the SCU. The exclusive line state keeps rotating
* among contenting cores leading to a never ending cycle. So break the cycle
* by deferring the retry of failed exclusive access (SCOND). The actual delay
* needed is function of number of contending cores as well as the unrelated
* coherency traffic from other cores. To keep the code simple, start off with
* small delay of 1 which would suffice most cases and in case of contention
* double the delay. Eventually the delay is sufficient such that the coherency
* pipeline is drained, thus a subsequent exclusive access would succeed.
*/
#define SCOND_FAIL_RETRY_VAR_DEF \
unsigned int delay, tmp; \
#define SCOND_FAIL_RETRY_ASM \
" ; --- scond fail delay --- \n" \
" mov %[tmp], %[delay] \n" /* tmp = delay */ \
"2: brne.d %[tmp], 0, 2b \n" /* while (tmp != 0) */ \
" sub %[tmp], %[tmp], 1 \n" /* tmp-- */ \
" rol %[delay], %[delay] \n" /* delay *= 2 */ \
" b 1b \n" /* start over */ \
" \n" \
"4: ; --- done --- \n" \
#define SCOND_FAIL_RETRY_VARS \
,[delay] "=&r" (delay), [tmp] "=&r" (tmp) \
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int val;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[slock]] \n"
" breq %[val], %[LOCKED], 0b \n" /* spin while LOCKED */
" scond %[LOCKED], [%[slock]] \n" /* acquire */
" bz 4f \n" /* done */
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val)
SCOND_FAIL_RETRY_VARS
: [slock] "r" (&(lock->slock)),
[LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned int val, got_it = 0;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[slock]] \n"
" breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */
" scond %[LOCKED], [%[slock]] \n" /* acquire */
" bz.d 4f \n"
" mov.z %[got_it], 1 \n" /* got it */
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
SCOND_FAIL_RETRY_VARS
: [slock] "r" (&(lock->slock)),
[LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
smp_mb();
lock->slock = __ARCH_SPIN_LOCK_UNLOCKED__;
smp_mb();
}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
* Unfair locking as Writers could be starved indefinitely by Reader(s)
*/
static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned int val;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
/*
* zero means writer holds the lock exclusively, deny Reader.
* Otherwise grant lock to first/subseq reader
*
* if (rw->counter > 0) {
* rw->counter--;
* ret = 1;
* }
*/
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
" brls %[val], %[WR_LOCKED], 0b\n" /* <= 0: spin while write locked */
" sub %[val], %[val], 1 \n" /* reader lock */
" scond %[val], [%[rwlock]] \n"
" bz 4f \n" /* done */
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val)
SCOND_FAIL_RETRY_VARS
: [rwlock] "r" (&(rw->counter)),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned int val, got_it = 0;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
" brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */
" sub %[val], %[val], 1 \n" /* counter-- */
" scond %[val], [%[rwlock]] \n"
" bz.d 4f \n"
" mov.z %[got_it], 1 \n" /* got it */
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
SCOND_FAIL_RETRY_VARS
: [rwlock] "r" (&(rw->counter)),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
unsigned int val;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
/*
* If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
* deny writer. Otherwise if unlocked grant to writer
* Hence the claim that Linux rwlocks are unfair to writers.
* (can be starved for an indefinite time by readers).
*
* if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
* rw->counter = 0;
* ret = 1;
* }
*/
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
" brne %[val], %[UNLOCKED], 0b \n" /* while !UNLOCKED spin */
" mov %[val], %[WR_LOCKED] \n"
" scond %[val], [%[rwlock]] \n"
" bz 4f \n"
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val)
SCOND_FAIL_RETRY_VARS
: [rwlock] "r" (&(rw->counter)),
[UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned int val, got_it = 0;
SCOND_FAIL_RETRY_VAR_DEF;
smp_mb();
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
" brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */
" mov %[val], %[WR_LOCKED] \n"
" scond %[val], [%[rwlock]] \n"
" bz.d 4f \n"
" mov.z %[got_it], 1 \n" /* got it */
" \n"
SCOND_FAIL_RETRY_ASM
: [val] "=&r" (val),
[got_it] "+&r" (got_it)
SCOND_FAIL_RETRY_VARS
: [rwlock] "r" (&(rw->counter)),
[UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
[WR_LOCKED] "ir" (0)
: "memory", "cc");
smp_mb();
return got_it;
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned int val;
smp_mb();
/*
* rw->counter++;
*/
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" add %[val], %[val], 1 \n"
" scond %[val], [%[rwlock]] \n"
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [rwlock] "r" (&(rw->counter))
: "memory", "cc");
smp_mb();
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
unsigned int val;
smp_mb();
/*
* rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
*/
__asm__ __volatile__(
"1: llock %[val], [%[rwlock]] \n"
" scond %[UNLOCKED], [%[rwlock]]\n"
" bnz 1b \n"
" \n"
: [val] "=&r" (val)
: [rwlock] "r" (&(rw->counter)),
[UNLOCKED] "r" (__ARCH_RW_LOCK_UNLOCKED__)
: "memory", "cc");
smp_mb();
}
#undef SCOND_FAIL_RETRY_VAR_DEF
#undef SCOND_FAIL_RETRY_ASM
#undef SCOND_FAIL_RETRY_VARS
#endif /* CONFIG_ARC_STAR_9000923308 */
#else /* !CONFIG_ARC_HAS_LLSC */
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int val = __ARCH_SPIN_LOCK_LOCKED__;
/*
* This smp_mb() is technically superfluous, we only need the one
* after the lock for providing the ACQUIRE semantics.
* However doing the "right" thing was regressing hackbench
* so keeping this, pending further investigation
*/
smp_mb();
__asm__ __volatile__(
"1: ex %0, [%1] \n"
" breq %0, %2, 1b \n"
: "+&r" (val)
: "r"(&(lock->slock)), "ir"(__ARCH_SPIN_LOCK_LOCKED__)
: "memory");
/*
* ACQUIRE barrier to ensure load/store after taking the lock
* don't "bleed-up" out of the critical section (leak-in is allowed)
* http://www.spinics.net/lists/kernel/msg2010409.html
*
* ARCv2 only has load-load, store-store and all-all barrier
* thus need the full all-all barrier
*/
smp_mb();
}
/* 1 - lock taken successfully */
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned int val = __ARCH_SPIN_LOCK_LOCKED__;
smp_mb();
__asm__ __volatile__(
"1: ex %0, [%1] \n"
: "+r" (val)
: "r"(&(lock->slock))
: "memory");
smp_mb();
return (val == __ARCH_SPIN_LOCK_UNLOCKED__);
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned int val = __ARCH_SPIN_LOCK_UNLOCKED__;
/*
* RELEASE barrier: given the instructions avail on ARCv2, full barrier
* is the only option
*/
smp_mb();
__asm__ __volatile__(
" ex %0, [%1] \n"
: "+r" (val)
: "r"(&(lock->slock))
: "memory");
/*
* superfluous, but keeping for now - see pairing version in
* arch_spin_lock above
*/
smp_mb();
}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
* Unfair locking as Writers could be starved indefinitely by Reader(s)
*
* The spinlock itself is contained in @counter and access to it is
* serialized with @lock_mutex.
*/
/* 1 - lock taken successfully */
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
int ret = 0;
arch_spin_lock(&(rw->lock_mutex));
/*
* zero means writer holds the lock exclusively, deny Reader.
* Otherwise grant lock to first/subseq reader
*/
if (rw->counter > 0) {
rw->counter--;
ret = 1;
}
arch_spin_unlock(&(rw->lock_mutex));
smp_mb();
return ret;
}
/* 1 - lock taken successfully */
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
int ret = 0;
arch_spin_lock(&(rw->lock_mutex));
/*
* If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
* deny writer. Otherwise if unlocked grant to writer
* Hence the claim that Linux rwlocks are unfair to writers.
* (can be starved for an indefinite time by readers).
*/
if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
rw->counter = 0;
ret = 1;
}
arch_spin_unlock(&(rw->lock_mutex));
return ret;
}
static inline void arch_read_lock(arch_rwlock_t *rw)
{
while (!arch_read_trylock(rw))
cpu_relax();
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
while (!arch_write_trylock(rw))
cpu_relax();
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
arch_spin_lock(&(rw->lock_mutex));
rw->counter++;
arch_spin_unlock(&(rw->lock_mutex));
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
arch_spin_lock(&(rw->lock_mutex));
rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
arch_spin_unlock(&(rw->lock_mutex));
}
#endif
#define arch_read_can_lock(x) ((x)->counter > 0)
#define arch_write_can_lock(x) ((x)->counter == __ARCH_RW_LOCK_UNLOCKED__)
#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 */
