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/*
* arch/ubicom32/include/asm/ubicom32-common.h
* Ubicom32 atomic lock operations.
*
* (C) Copyright 2009, Ubicom, Inc.
*
* This file is part of the Ubicom32 Linux Kernel Port.
*
* The Ubicom32 Linux Kernel Port is free software: you can redistribute
* it and/or modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, either version 2 of the
* License, or (at your option) any later version.
*
* The Ubicom32 Linux Kernel Port 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 the Ubicom32 Linux Kernel Port. If not,
* see <http://www.gnu.org/licenses/>.
*
* Ubicom32 implementation derived from (with many thanks):
* arch/m68knommu
* arch/blackfin
* arch/parisc
*/
#ifndef _ASM_UBICOM32_UBICOM32_COMMON_H
#define _ASM_UBICOM32_UBICOM32_COMMON_H
#define S(arg) #arg
#define D(arg) S(arg)
/*
* scratchpad1 is owned by the LDSR.
*
* The upper bits provide 16 global spinlocks. Acquiring one of these
* global spinlocks synchornizes across multiple threads and prevents
* the LDSR from delivering any interrupts while the lock is held.
* Use these locks only when absolutely required.
*
* The lower 16 bits of scratchpad1 are used as per thread interrupt
* enable/disable bits. These bits will prevent a thread from receiving
* any interrupts.
*
* Bit Usage:
* - MT_EN_LOCK_BIT - Protects writes to MT_EN, so code can read current value
* then write a new value atomically (profiler for example)
* - ATOMIC_LOCK_BIT - Used to provide general purpose atomic handling.
* - LDSR_LOCK_BIT - Used by the LDSR exclusively to provide protection.
* - DCCR_LOCK_BIT - Used to limit access to the DCCR cache control peripheral
* - ICCR_LOCK_BIT - Used to limit access to the ICCR cache control peripheral
* - LSB 16 bits - Used by the LDSR to represent thread enable/disable bits.
*/
#define MT_EN_LOCK_BIT 31
#define ATOMIC_LOCK_BIT 30
#define LDSR_LOCK_BIT 29
#define PCI_LOCK_BIT 28
#define ICCR_LOCK_BIT 27
#define DCCR_LOCK_BIT 26
#if !defined(__ASSEMBLY__)
#define UBICOM32_TRYLOCK(bit) \
asm volatile ( \
" move.4 %0, #0 \n\t" \
" bset scratchpad1, scratchpad1, #"D(bit)" \n\t" \
" jmpne.f 1f \n\t" \
" move.4 %0, #1 \n\t" \
"1: \n\t" \
: "=r" (ret) \
: \
: "cc", "memory" \
) \
#define UBICOM32_UNLOCK(bit) \
asm volatile ( \
" bclr scratchpad1, scratchpad1, #"D(bit)" \n\t" \
: \
: \
: "cc", "memory" \
) \
#define UBICOM32_LOCK(bit) \
asm volatile ( \
"1: bset scratchpad1, scratchpad1, #"D(bit)" \n\t" \
" jmpne.f 1b \n\t" \
: \
: \
: "cc", "memory" \
) \
/*
* __atomic_lock_trylock()
* Attempt to acquire the lock, return TRUE if acquired.
*/
static inline int __atomic_lock_trylock(void)
{
int ret;
UBICOM32_TRYLOCK(ATOMIC_LOCK_BIT);
return ret;
}
/*
* __atomic_lock_release()
* Release the global atomic lock.
*
* Note: no one is suspended waiting since this lock is a spinning lock.
*/
static inline void __atomic_lock_release(void)
{
UBICOM32_UNLOCK(ATOMIC_LOCK_BIT);
}
/*
* __atomic_lock_acquire()
* Acquire the global atomic lock, spin if not available.
*/
static inline void __atomic_lock_acquire(void)
{
UBICOM32_LOCK(ATOMIC_LOCK_BIT);
}
#else /* __ASSEMBLY__ */
#include <asm/ubicom32-common-asm.h>
#endif /* __ASSEMBLY__ */
#endif /* _ASM_UBICOM32_UBICOM32_COMMON_H */
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