diff options
author | James Hogan <james.hogan@imgtec.com> | 2012-10-09 11:00:24 +0100 |
---|---|---|
committer | James Hogan <james.hogan@imgtec.com> | 2013-03-02 20:09:50 +0000 |
commit | 6006c0d8ce9441dd1363bf14f18a8e28d3588460 (patch) | |
tree | 786183053c89e11b3058b8a16f7953744b819340 /arch/metag/include/asm/cmpxchg_irq.h | |
parent | 9b802d1f43978869fcd98e92b854fd8785cefee7 (diff) |
metag: Atomics, locks and bitops
Add header files to implement Meta hardware thread locks (used by some
other atomic operations), atomics, spinlocks, and bitops.
There are 2 main types of atomic primitives for metag (in addition to
IRQs off on UP):
- LOCK instructions provide locking between hardware threads.
- LNKGET/LNKSET instructions provide load-linked/store-conditional
operations allowing for lighter weight atomics on Meta2
LOCK instructions allow for hardware threads to acquire voluntary or
exclusive hardware thread locks:
- LOCK0 releases exclusive and voluntary lock from the running hardware
thread.
- LOCK1 acquires the voluntary hardware lock, blocking until it becomes
available.
- LOCK2 implies LOCK1, and additionally acquires the exclusive hardware
lock, blocking all other hardware threads from executing.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Diffstat (limited to 'arch/metag/include/asm/cmpxchg_irq.h')
-rw-r--r-- | arch/metag/include/asm/cmpxchg_irq.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/metag/include/asm/cmpxchg_irq.h b/arch/metag/include/asm/cmpxchg_irq.h new file mode 100644 index 00000000000..649573168b0 --- /dev/null +++ b/arch/metag/include/asm/cmpxchg_irq.h @@ -0,0 +1,42 @@ +#ifndef __ASM_METAG_CMPXCHG_IRQ_H +#define __ASM_METAG_CMPXCHG_IRQ_H + +#include <linux/irqflags.h> + +static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val) +{ + unsigned long flags, retval; + + local_irq_save(flags); + retval = *m; + *m = val; + local_irq_restore(flags); + return retval; +} + +static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val) +{ + unsigned long flags, retval; + + local_irq_save(flags); + retval = *m; + *m = val & 0xff; + local_irq_restore(flags); + return retval; +} + +static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old, + unsigned long new) +{ + __u32 retval; + unsigned long flags; + + local_irq_save(flags); + retval = *m; + if (retval == old) + *m = new; + local_irq_restore(flags); /* implies memory barrier */ + return retval; +} + +#endif /* __ASM_METAG_CMPXCHG_IRQ_H */ |