target/linux/ubicom32/files/arch/ubicom32/include/asm/ubicom32-common.h

   1 /*
   2  * arch/ubicom32/include/asm/ubicom32-common.h
   3  *   Ubicom32 atomic lock operations.
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  *
   7  * This file is part of the Ubicom32 Linux Kernel Port.
   8  *
   9  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  10  * it and/or modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation, either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  * the GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with the Ubicom32 Linux Kernel Port.  If not,
  21  * see <http://www.gnu.org/licenses/>.
  22  *
  23  * Ubicom32 implementation derived from (with many thanks):
  24  *   arch/m68knommu
  25  *   arch/blackfin
  26  *   arch/parisc
  27  */
  28
  29 #ifndef _ASM_UBICOM32_UBICOM32_COMMON_H
  30 #define _ASM_UBICOM32_UBICOM32_COMMON_H
  31
  32 #define S(arg) #arg
  33 #define D(arg) S(arg)
  34 /*
  35  * scratchpad1 is owned by the LDSR.
  36  *
  37  * The upper bits provide 16 global spinlocks.  Acquiring one of these
  38  * global spinlocks synchornizes across multiple threads and prevents
  39  * the LDSR from delivering any interrupts while the lock is held.
  40  * Use these locks only when absolutely required.
  41  *
  42  * The lower 16 bits of scratchpad1 are used as per thread interrupt
  43  * enable/disable bits.  These bits will prevent a thread from receiving
  44  * any interrupts.
  45  *
  46  * Bit Usage:
  47  * - MT_EN_LOCK_BIT   - Protects writes to MT_EN, so code can read current value
  48  *                      then write a new value atomically (profiler for example)
  49  * - ATOMIC_LOCK_BIT - Used to provide general purpose atomic handling.
  50  * - LDSR_LOCK_BIT   - Used by the LDSR exclusively to provide protection.
  51  * - DCCR_LOCK_BIT   - Used to limit access to the DCCR cache control peripheral
  52  * - ICCR_LOCK_BIT   - Used to limit access to the ICCR cache control peripheral
  53  * - LSB 16 bits     - Used by the LDSR to represent thread enable/disable bits.
  54  */
  55 #define MT_EN_LOCK_BIT  31
  56 #define ATOMIC_LOCK_BIT 30
  57 #define LDSR_LOCK_BIT   29
  58 #define PCI_LOCK_BIT    28
  59 #define ICCR_LOCK_BIT   27
  60 #define DCCR_LOCK_BIT   26
  61
  62 #if !defined(__ASSEMBLY__)
  63
  64 #define UBICOM32_TRYLOCK(bit) \
  65         asm volatile (                                                \
  66         "       move.4 %0, #0                                   \n\t" \
  67         "       bset scratchpad1, scratchpad1, #"D(bit)"        \n\t" \
  68         "       jmpne.f 1f                                      \n\t" \
  69         "       move.4 %0, #1                                   \n\t" \
  70         "1:                                                     \n\t" \
  71                 : "=r" (ret)                                          \
  72                 :                                                     \
  73                 : "cc", "memory"                                      \
  74         )                                                             \
  75
  76 #define UBICOM32_UNLOCK(bit) \
  77         asm volatile (                                                \
  78         "       bclr scratchpad1, scratchpad1, #"D(bit)"        \n\t" \
  79                 :                                                     \
  80                 :                                                     \
  81                 : "cc", "memory"                                      \
  82         )                                                             \
  83
  84 #define UBICOM32_LOCK(bit) \
  85         asm volatile (                                                \
  86         "1:     bset scratchpad1, scratchpad1, #"D(bit)"        \n\t" \
  87         "       jmpne.f 1b                                      \n\t" \
  88                 :                                                     \
  89                 :                                                     \
  90                 : "cc", "memory"                                      \
  91         )                                                             \
  92
  93 /*
  94  * __atomic_lock_trylock()
  95  *      Attempt to acquire the lock, return TRUE if acquired.
  96  */
  97 static inline int __atomic_lock_trylock(void)
  98 {
  99         int ret;
 100         UBICOM32_TRYLOCK(ATOMIC_LOCK_BIT);
 101         return ret;
 102 }
 103
 104 /*
 105  * __atomic_lock_release()
 106  *      Release the global atomic lock.
 107  *
 108  * Note: no one is suspended waiting since this lock is a spinning lock.
 109  */
 110 static inline void __atomic_lock_release(void)
 111 {
 112         UBICOM32_UNLOCK(ATOMIC_LOCK_BIT);
 113 }
 114
 115 /*
 116  * __atomic_lock_acquire()
 117  *      Acquire the global atomic lock, spin if not available.
 118  */
 119 static inline void __atomic_lock_acquire(void)
 120 {
 121         UBICOM32_LOCK(ATOMIC_LOCK_BIT);
 122 }
 123 #else /* __ASSEMBLY__ */
 124
 125 #include <asm/ubicom32-common-asm.h>
 126
 127 #endif /* __ASSEMBLY__ */
 128 #endif /* _ASM_UBICOM32_UBICOM32_COMMON_H */