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linux-headers-6.8.0-83
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arch
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sparc
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spinlock_32.h
/* SPDX-License-Identifier: GPL-2.0 */ /* spinlock.h: 32-bit Sparc spinlock support. * * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu) */ #ifndef __SPARC_SPINLOCK_H #define __SPARC_SPINLOCK_H #ifndef __ASSEMBLY__ #include <asm/psr.h> #include <asm/barrier.h> #include <asm/processor.h> /* for cpu_relax */ #define arch_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0) static inline void arch_spin_lock(arch_spinlock_t *lock) { __asm__ __volatile__( "\n1:\n\t" "ldstub [%0], %%g2\n\t" "orcc %%g2, 0x0, %%g0\n\t" "bne,a 2f\n\t" " ldub [%0], %%g2\n\t" ".subsection 2\n" "2:\n\t" "orcc %%g2, 0x0, %%g0\n\t" "bne,a 2b\n\t" " ldub [%0], %%g2\n\t" "b,a 1b\n\t" ".previous\n" : /* no outputs */ : "r" (lock) : "g2", "memory", "cc"); } static inline int arch_spin_trylock(arch_spinlock_t *lock) { unsigned int result; __asm__ __volatile__("ldstub [%1], %0" : "=r" (result) : "r" (lock) : "memory"); return (result == 0); } static inline void arch_spin_unlock(arch_spinlock_t *lock) { __asm__ __volatile__("stb %%g0, [%0]" : : "r" (lock) : "memory"); } /* 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. * * XXX This might create some problems with my dual spinlock * XXX scheme, deadlocks etc. -DaveM * * Sort of like atomic_t's on Sparc, but even more clever. * * ------------------------------------ * | 24-bit counter | wlock | arch_rwlock_t * ------------------------------------ * 31 8 7 0 * * wlock signifies the one writer is in or somebody is updating * counter. For a writer, if he successfully acquires the wlock, * but counter is non-zero, he has to release the lock and wait, * till both counter and wlock are zero. * * Unfortunately this scheme limits us to ~16,000,000 cpus. */ static inline void __arch_read_lock(arch_rwlock_t *rw) { register arch_rwlock_t *lp asm("g1"); lp = rw; __asm__ __volatile__( "mov %%o7, %%g4\n\t" "call ___rw_read_enter\n\t" " ldstub [%%g1 + 3], %%g2\n" : /* no outputs */ : "r" (lp) : "g2", "g4", "memory", "cc"); } #define arch_read_lock(lock) \ do { unsigned long flags; \ local_irq_save(flags); \ __arch_read_lock(lock); \ local_irq_restore(flags); \ } while(0) static inline void __arch_read_unlock(arch_rwlock_t *rw) { register arch_rwlock_t *lp asm("g1"); lp = rw; __asm__ __volatile__( "mov %%o7, %%g4\n\t" "call ___rw_read_exit\n\t" " ldstub [%%g1 + 3], %%g2\n" : /* no outputs */ : "r" (lp) : "g2", "g4", "memory", "cc"); } #define arch_read_unlock(lock) \ do { unsigned long flags; \ local_irq_save(flags); \ __arch_read_unlock(lock); \ local_irq_restore(flags); \ } while(0) static inline void arch_write_lock(arch_rwlock_t *rw) { register arch_rwlock_t *lp asm("g1"); lp = rw; __asm__ __volatile__( "mov %%o7, %%g4\n\t" "call ___rw_write_enter\n\t" " ldstub [%%g1 + 3], %%g2\n" : /* no outputs */ : "r" (lp) : "g2", "g4", "memory", "cc"); *(volatile __u32 *)&lp->lock = ~0U; } static inline void arch_write_unlock(arch_rwlock_t *lock) { __asm__ __volatile__( " st %%g0, [%0]" : /* no outputs */ : "r" (lock) : "memory"); } static inline int arch_write_trylock(arch_rwlock_t *rw) { unsigned int val; __asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&rw->lock) : "memory"); if (val == 0) { val = rw->lock & ~0xff; if (val) ((volatile u8*)&rw->lock)[3] = 0; else *(volatile u32*)&rw->lock = ~0U; } return (val == 0); } static inline int __arch_read_trylock(arch_rwlock_t *rw) { register arch_rwlock_t *lp asm("g1"); register int res asm("o0"); lp = rw; __asm__ __volatile__( "mov %%o7, %%g4\n\t" "call ___rw_read_try\n\t" " ldstub [%%g1 + 3], %%g2\n" : "=r" (res) : "r" (lp) : "g2", "g4", "memory", "cc"); return res; } #define arch_read_trylock(lock) \ ({ unsigned long flags; \ int res; \ local_irq_save(flags); \ res = __arch_read_trylock(lock); \ local_irq_restore(flags); \ res; \ }) #endif /* !(__ASSEMBLY__) */ #endif /* __SPARC_SPINLOCK_H */
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