1efe4ce3ca
This implements kernel-level atomic rollback built on top of gUSA, as an alternative non-IRQ based atomicity method. This is generally a faster method for platforms that are lacking the LL/SC pairs that SH-4A and later use, and is only supportable on legacy cores. Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
90 lines
2.0 KiB
C
90 lines
2.0 KiB
C
#ifndef __ASM_SH_ATOMIC_H
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#define __ASM_SH_ATOMIC_H
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/*
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* Atomic operations that C can't guarantee us. Useful for
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* resource counting etc..
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*
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*/
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typedef struct { volatile int counter; } atomic_t;
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#define ATOMIC_INIT(i) ( (atomic_t) { (i) } )
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#define atomic_read(v) ((v)->counter)
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#define atomic_set(v,i) ((v)->counter = (i))
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#include <linux/compiler.h>
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#include <asm/system.h>
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#if defined(CONFIG_GUSA_RB)
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#include <asm/atomic-grb.h>
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#elif defined(CONFIG_CPU_SH4A)
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#include <asm/atomic-llsc.h>
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#else
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#include <asm/atomic-irq.h>
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#endif
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#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
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#define atomic_dec_return(v) atomic_sub_return(1,(v))
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#define atomic_inc_return(v) atomic_add_return(1,(v))
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/*
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* atomic_inc_and_test - increment and test
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1
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* and returns true if the result is zero, or false for all
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* other cases.
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*/
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#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
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#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (v)) == 0)
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#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
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#define atomic_inc(v) atomic_add(1,(v))
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#define atomic_dec(v) atomic_sub(1,(v))
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#ifndef CONFIG_GUSA_RB
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static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
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{
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int ret;
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unsigned long flags;
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local_irq_save(flags);
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ret = v->counter;
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if (likely(ret == old))
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v->counter = new;
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local_irq_restore(flags);
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return ret;
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}
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static inline int atomic_add_unless(atomic_t *v, int a, int u)
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{
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int ret;
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unsigned long flags;
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local_irq_save(flags);
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ret = v->counter;
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if (ret != u)
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v->counter += a;
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local_irq_restore(flags);
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return ret != u;
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}
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#endif
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#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
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#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
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/* Atomic operations are already serializing on SH */
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#define smp_mb__before_atomic_dec() barrier()
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#define smp_mb__after_atomic_dec() barrier()
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#define smp_mb__before_atomic_inc() barrier()
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#define smp_mb__after_atomic_inc() barrier()
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#include <asm-generic/atomic.h>
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#endif /* __ASM_SH_ATOMIC_H */
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