/* * Spinlock support for the Hexagon architecture * * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. * * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and * only version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. */ #ifndef _ASM_SPINLOCK_H #define _ASM_SPINLOCK_H #include <asm/irqflags.h> /* * This file is pulled in for SMP builds. * Really need to check all the barrier stuff for "true" SMP */ /* * Read locks: * - load the lock value * - increment it * - if the lock value is still negative, go back and try again. * - unsuccessful store is unsuccessful. Go back and try again. Loser. * - successful store new lock value if positive -> lock acquired */ static inline void arch_read_lock(arch_rwlock_t *lock) { __asm__ __volatile__( "1: R6 = memw_locked(%0);\n" " { P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n" " { if !P3 jump 1b; }\n" " memw_locked(%0,P3) = R6;\n" " { if !P3 jump 1b; }\n" : : "r" (&lock->lock) : "memory", "r6", "p3" ); } static inline void arch_read_unlock(arch_rwlock_t *lock) { __asm__ __volatile__( "1: R6 = memw_locked(%0);\n" " R6 = add(R6,#-1);\n" " memw_locked(%0,P3) = R6\n" " if !P3 jump 1b;\n" : : "r" (&lock->lock) : "memory", "r6", "p3" ); } /* I think this returns 0 on fail, 1 on success. */ static inline int arch_read_trylock(arch_rwlock_t *lock) { int temp; __asm__ __volatile__( " R6 = memw_locked(%1);\n" " { %0 = #0; P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n" " { if !P3 jump 1f; }\n" " memw_locked(%1,P3) = R6;\n" " { %0 = P3 }\n" "1:\n" : "=&r" (temp) : "r" (&lock->lock) : "memory", "r6", "p3" ); return temp; } static inline int arch_read_can_lock(arch_rwlock_t *rwlock) { return rwlock->lock == 0; } static inline int arch_write_can_lock(arch_rwlock_t *rwlock) { return rwlock->lock == 0; } /* Stuffs a -1 in the lock value? */ static inline void arch_write_lock(arch_rwlock_t *lock) { __asm__ __volatile__( "1: R6 = memw_locked(%0)\n" " { P3 = cmp.eq(R6,#0); R6 = #-1;}\n" " { if !P3 jump 1b; }\n" " memw_locked(%0,P3) = R6;\n" " { if !P3 jump 1b; }\n" : : "r" (&lock->lock) : "memory", "r6", "p3" ); } static inline int arch_write_trylock(arch_rwlock_t *lock) { int temp; __asm__ __volatile__( " R6 = memw_locked(%1)\n" " { %0 = #0; P3 = cmp.eq(R6,#0); R6 = #-1;}\n" " { if !P3 jump 1f; }\n" " memw_locked(%1,P3) = R6;\n" " %0 = P3;\n" "1:\n" : "=&r" (temp) : "r" (&lock->lock) : "memory", "r6", "p3" ); return temp; } static inline void arch_write_unlock(arch_rwlock_t *lock) { smp_mb(); lock->lock = 0; } static inline void arch_spin_lock(arch_spinlock_t *lock) { __asm__ __volatile__( "1: R6 = memw_locked(%0);\n" " P3 = cmp.eq(R6,#0);\n" " { if !P3 jump 1b; R6 = #1; }\n" " memw_locked(%0,P3) = R6;\n" " { if !P3 jump 1b; }\n" : : "r" (&lock->lock) : "memory", "r6", "p3" ); } static inline void arch_spin_unlock(arch_spinlock_t *lock) { smp_mb(); lock->lock = 0; } static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock) { int temp; __asm__ __volatile__( " R6 = memw_locked(%1);\n" " P3 = cmp.eq(R6,#0);\n" " { if !P3 jump 1f; R6 = #1; %0 = #0; }\n" " memw_locked(%1,P3) = R6;\n" " %0 = P3;\n" "1:\n" : "=&r" (temp) : "r" (&lock->lock) : "memory", "r6", "p3" ); return temp; } /* * SMP spinlocks are intended to allow only a single CPU at the lock */ #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) #define arch_spin_unlock_wait(lock) \ do {while (arch_spin_is_locked(lock)) cpu_relax(); } while (0) #define arch_spin_is_locked(x) ((x)->lock != 0) #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) #endif