David Daney | 58f0777 | 2008-12-23 15:22:14 -0800 | [diff] [blame] | 1 | /***********************license start*************** |
| 2 | * Author: Cavium Networks |
| 3 | * |
| 4 | * Contact: support@caviumnetworks.com |
| 5 | * This file is part of the OCTEON SDK |
| 6 | * |
| 7 | * Copyright (c) 2003-2008 Cavium Networks |
| 8 | * |
| 9 | * This file is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License, Version 2, as |
| 11 | * published by the Free Software Foundation. |
| 12 | * |
| 13 | * This file is distributed in the hope that it will be useful, but |
| 14 | * AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty |
| 15 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or |
| 16 | * NONINFRINGEMENT. See the GNU General Public License for more |
| 17 | * details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with this file; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 22 | * or visit http://www.gnu.org/licenses/. |
| 23 | * |
| 24 | * This file may also be available under a different license from Cavium. |
| 25 | * Contact Cavium Networks for more information |
| 26 | ***********************license end**************************************/ |
| 27 | |
| 28 | /** |
| 29 | * Implementation of spinlocks for Octeon CVMX. Although similar in |
| 30 | * function to Linux kernel spinlocks, they are not compatible. |
| 31 | * Octeon CVMX spinlocks are only used to synchronize with the boot |
| 32 | * monitor and other non-Linux programs running in the system. |
| 33 | */ |
| 34 | |
| 35 | #ifndef __CVMX_SPINLOCK_H__ |
| 36 | #define __CVMX_SPINLOCK_H__ |
| 37 | |
| 38 | #include "cvmx-asm.h" |
| 39 | |
| 40 | /* Spinlocks for Octeon */ |
| 41 | |
| 42 | /* define these to enable recursive spinlock debugging */ |
| 43 | /*#define CVMX_SPINLOCK_DEBUG */ |
| 44 | |
| 45 | /** |
| 46 | * Spinlocks for Octeon CVMX |
| 47 | */ |
| 48 | typedef struct { |
| 49 | volatile uint32_t value; |
| 50 | } cvmx_spinlock_t; |
| 51 | |
| 52 | /* note - macros not expanded in inline ASM, so values hardcoded */ |
| 53 | #define CVMX_SPINLOCK_UNLOCKED_VAL 0 |
| 54 | #define CVMX_SPINLOCK_LOCKED_VAL 1 |
| 55 | |
| 56 | #define CVMX_SPINLOCK_UNLOCKED_INITIALIZER {CVMX_SPINLOCK_UNLOCKED_VAL} |
| 57 | |
| 58 | /** |
| 59 | * Initialize a spinlock |
| 60 | * |
| 61 | * @lock: Lock to initialize |
| 62 | */ |
| 63 | static inline void cvmx_spinlock_init(cvmx_spinlock_t *lock) |
| 64 | { |
| 65 | lock->value = CVMX_SPINLOCK_UNLOCKED_VAL; |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * Return non-zero if the spinlock is currently locked |
| 70 | * |
| 71 | * @lock: Lock to check |
| 72 | * Returns Non-zero if locked |
| 73 | */ |
| 74 | static inline int cvmx_spinlock_locked(cvmx_spinlock_t *lock) |
| 75 | { |
| 76 | return lock->value != CVMX_SPINLOCK_UNLOCKED_VAL; |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * Releases lock |
| 81 | * |
| 82 | * @lock: pointer to lock structure |
| 83 | */ |
| 84 | static inline void cvmx_spinlock_unlock(cvmx_spinlock_t *lock) |
| 85 | { |
| 86 | CVMX_SYNCWS; |
| 87 | lock->value = 0; |
| 88 | CVMX_SYNCWS; |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * Attempts to take the lock, but does not spin if lock is not available. |
| 93 | * May take some time to acquire the lock even if it is available |
| 94 | * due to the ll/sc not succeeding. |
| 95 | * |
| 96 | * @lock: pointer to lock structure |
| 97 | * |
| 98 | * Returns 0: lock successfully taken |
| 99 | * 1: lock not taken, held by someone else |
| 100 | * These return values match the Linux semantics. |
| 101 | */ |
| 102 | |
| 103 | static inline unsigned int cvmx_spinlock_trylock(cvmx_spinlock_t *lock) |
| 104 | { |
| 105 | unsigned int tmp; |
| 106 | |
| 107 | __asm__ __volatile__(".set noreorder \n" |
| 108 | "1: ll %[tmp], %[val] \n" |
| 109 | /* if lock held, fail immediately */ |
| 110 | " bnez %[tmp], 2f \n" |
| 111 | " li %[tmp], 1 \n" |
| 112 | " sc %[tmp], %[val] \n" |
| 113 | " beqz %[tmp], 1b \n" |
| 114 | " li %[tmp], 0 \n" |
| 115 | "2: \n" |
| 116 | ".set reorder \n" : |
| 117 | [val] "+m"(lock->value), [tmp] "=&r"(tmp) |
| 118 | : : "memory"); |
| 119 | |
| 120 | return tmp != 0; /* normalize to 0 or 1 */ |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Gets lock, spins until lock is taken |
| 125 | * |
| 126 | * @lock: pointer to lock structure |
| 127 | */ |
| 128 | static inline void cvmx_spinlock_lock(cvmx_spinlock_t *lock) |
| 129 | { |
| 130 | unsigned int tmp; |
| 131 | |
| 132 | __asm__ __volatile__(".set noreorder \n" |
| 133 | "1: ll %[tmp], %[val] \n" |
| 134 | " bnez %[tmp], 1b \n" |
| 135 | " li %[tmp], 1 \n" |
| 136 | " sc %[tmp], %[val] \n" |
| 137 | " beqz %[tmp], 1b \n" |
| 138 | " nop \n" |
| 139 | ".set reorder \n" : |
| 140 | [val] "+m"(lock->value), [tmp] "=&r"(tmp) |
| 141 | : : "memory"); |
| 142 | |
| 143 | } |
| 144 | |
| 145 | /** ******************************************************************** |
| 146 | * Bit spinlocks |
| 147 | * These spinlocks use a single bit (bit 31) of a 32 bit word for locking. |
| 148 | * The rest of the bits in the word are left undisturbed. This enables more |
| 149 | * compact data structures as only 1 bit is consumed for the lock. |
| 150 | * |
| 151 | */ |
| 152 | |
| 153 | /** |
| 154 | * Gets lock, spins until lock is taken |
| 155 | * Preserves the low 31 bits of the 32 bit |
| 156 | * word used for the lock. |
| 157 | * |
| 158 | * |
| 159 | * @word: word to lock bit 31 of |
| 160 | */ |
| 161 | static inline void cvmx_spinlock_bit_lock(uint32_t *word) |
| 162 | { |
| 163 | unsigned int tmp; |
| 164 | unsigned int sav; |
| 165 | |
| 166 | __asm__ __volatile__(".set noreorder \n" |
| 167 | ".set noat \n" |
| 168 | "1: ll %[tmp], %[val] \n" |
| 169 | " bbit1 %[tmp], 31, 1b \n" |
| 170 | " li $at, 1 \n" |
| 171 | " ins %[tmp], $at, 31, 1 \n" |
| 172 | " sc %[tmp], %[val] \n" |
| 173 | " beqz %[tmp], 1b \n" |
| 174 | " nop \n" |
| 175 | ".set at \n" |
| 176 | ".set reorder \n" : |
| 177 | [val] "+m"(*word), [tmp] "=&r"(tmp), [sav] "=&r"(sav) |
| 178 | : : "memory"); |
| 179 | |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | * Attempts to get lock, returns immediately with success/failure |
| 184 | * Preserves the low 31 bits of the 32 bit |
| 185 | * word used for the lock. |
| 186 | * |
| 187 | * |
| 188 | * @word: word to lock bit 31 of |
| 189 | * Returns 0: lock successfully taken |
| 190 | * 1: lock not taken, held by someone else |
| 191 | * These return values match the Linux semantics. |
| 192 | */ |
| 193 | static inline unsigned int cvmx_spinlock_bit_trylock(uint32_t *word) |
| 194 | { |
| 195 | unsigned int tmp; |
| 196 | |
| 197 | __asm__ __volatile__(".set noreorder\n\t" |
| 198 | ".set noat\n" |
| 199 | "1: ll %[tmp], %[val] \n" |
| 200 | /* if lock held, fail immediately */ |
| 201 | " bbit1 %[tmp], 31, 2f \n" |
| 202 | " li $at, 1 \n" |
| 203 | " ins %[tmp], $at, 31, 1 \n" |
| 204 | " sc %[tmp], %[val] \n" |
| 205 | " beqz %[tmp], 1b \n" |
| 206 | " li %[tmp], 0 \n" |
| 207 | "2: \n" |
| 208 | ".set at \n" |
| 209 | ".set reorder \n" : |
| 210 | [val] "+m"(*word), [tmp] "=&r"(tmp) |
| 211 | : : "memory"); |
| 212 | |
| 213 | return tmp != 0; /* normalize to 0 or 1 */ |
| 214 | } |
| 215 | |
| 216 | /** |
| 217 | * Releases bit lock |
| 218 | * |
| 219 | * Unconditionally clears bit 31 of the lock word. Note that this is |
| 220 | * done non-atomically, as this implementation assumes that the rest |
| 221 | * of the bits in the word are protected by the lock. |
| 222 | * |
| 223 | * @word: word to unlock bit 31 in |
| 224 | */ |
| 225 | static inline void cvmx_spinlock_bit_unlock(uint32_t *word) |
| 226 | { |
| 227 | CVMX_SYNCWS; |
| 228 | *word &= ~(1UL << 31); |
| 229 | CVMX_SYNCWS; |
| 230 | } |
| 231 | |
| 232 | #endif /* __CVMX_SPINLOCK_H__ */ |