| 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 */ |
| 129 | |
