^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) /* SPDX-License-Identifier: GPL-2.0 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) #ifndef __ASM_SPINLOCK_H
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) #define __ASM_SPINLOCK_H
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) #include <asm/barrier.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) #include <asm/ldcw.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) #include <asm/processor.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <asm/spinlock_types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) static inline int arch_spin_is_locked(arch_spinlock_t *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) volatile unsigned int *a = __ldcw_align(x);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) return READ_ONCE(*a) == 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) static inline void arch_spin_lock(arch_spinlock_t *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) volatile unsigned int *a;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) a = __ldcw_align(x);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) while (__ldcw(a) == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) while (*a == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) static inline void arch_spin_lock_flags(arch_spinlock_t *x,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) unsigned long flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) volatile unsigned int *a;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) a = __ldcw_align(x);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) while (__ldcw(a) == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) while (*a == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) if (flags & PSW_SM_I) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) local_irq_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) local_irq_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) #define arch_spin_lock_flags arch_spin_lock_flags
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) static inline void arch_spin_unlock(arch_spinlock_t *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) volatile unsigned int *a;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) a = __ldcw_align(x);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) /* Release with ordered store. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) __asm__ __volatile__("stw,ma %0,0(%1)" : : "r"(1), "r"(a) : "memory");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) static inline int arch_spin_trylock(arch_spinlock_t *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) volatile unsigned int *a;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) a = __ldcw_align(x);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) return __ldcw(a) != 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * Read-write spinlocks, allowing multiple readers but only one writer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * Unfair locking as Writers could be starved indefinitely by Reader(s)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) * The spinlock itself is contained in @counter and access to it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) * serialized with @lock_mutex.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) /* 1 - lock taken successfully */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) static inline int arch_read_trylock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) int ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) arch_spin_lock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) * zero means writer holds the lock exclusively, deny Reader.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) * Otherwise grant lock to first/subseq reader
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) if (rw->counter > 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) rw->counter--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) ret = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) arch_spin_unlock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) /* 1 - lock taken successfully */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) static inline int arch_write_trylock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) int ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) arch_spin_lock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) * deny writer. Otherwise if unlocked grant to writer
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) * Hence the claim that Linux rwlocks are unfair to writers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * (can be starved for an indefinite time by readers).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) rw->counter = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) ret = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) arch_spin_unlock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) static inline void arch_read_lock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) while (!arch_read_trylock(rw))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) cpu_relax();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) static inline void arch_write_lock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) while (!arch_write_trylock(rw))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) cpu_relax();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) static inline void arch_read_unlock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) arch_spin_lock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) rw->counter++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) arch_spin_unlock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) static inline void arch_write_unlock(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) arch_spin_lock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) arch_spin_unlock(&(rw->lock_mutex));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) #endif /* __ASM_SPINLOCK_H */
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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