asm/octeon/cvmx-spinlock.h

0001 /***********************license start***************
0002  * Author: Cavium Networks
0003  *
0004  * Contact: support@caviumnetworks.com
0005  * This file is part of the OCTEON SDK
0006  *
0007  * Copyright (c) 2003-2008 Cavium Networks
0008  *
0009  * This file is free software; you can redistribute it and/or modify
0010  * it under the terms of the GNU General Public License, Version 2, as
0011  * published by the Free Software Foundation.
0012  *
0013  * This file is distributed in the hope that it will be useful, but
0014  * AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty
0015  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
0016  * NONINFRINGEMENT.  See the GNU General Public License for more
0017  * details.
0018  *
0019  * You should have received a copy of the GNU General Public License
0020  * along with this file; if not, write to the Free Software
0021  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
0022  * or visit http://www.gnu.org/licenses/.
0023  *
0024  * This file may also be available under a different license from Cavium.
0025  * Contact Cavium Networks for more information
0026  ***********************license end**************************************/
0027
0028 /**
0029  * Implementation of spinlocks for Octeon CVMX.  Although similar in
0030  * function to Linux kernel spinlocks, they are not compatible.
0031  * Octeon CVMX spinlocks are only used to synchronize with the boot
0032  * monitor and other non-Linux programs running in the system.
0033  */
0034
0035 #ifndef __CVMX_SPINLOCK_H__
0036 #define __CVMX_SPINLOCK_H__
0037
0038 #include <asm/octeon/cvmx-asm.h>
0039
0040 /* Spinlocks for Octeon */
0041
0042 /* define these to enable recursive spinlock debugging */
0043 /*#define CVMX_SPINLOCK_DEBUG */
0044
0045 /**
0046  * Spinlocks for Octeon CVMX
0047  */
0048 typedef struct {
0049     volatile uint32_t value;
0050 } cvmx_spinlock_t;
0051
0052 /* note - macros not expanded in inline ASM, so values hardcoded */
0053 #define  CVMX_SPINLOCK_UNLOCKED_VAL  0
0054 #define  CVMX_SPINLOCK_LOCKED_VAL    1
0055
0056 #define CVMX_SPINLOCK_UNLOCKED_INITIALIZER  {CVMX_SPINLOCK_UNLOCKED_VAL}
0057
0058 /**
0059  * Initialize a spinlock
0060  *
0061  * @lock:   Lock to initialize
0062  */
0063 static inline void cvmx_spinlock_init(cvmx_spinlock_t *lock)
0064 {
0065     lock->value = CVMX_SPINLOCK_UNLOCKED_VAL;
0066 }
0067
0068 /**
0069  * Return non-zero if the spinlock is currently locked
0070  *
0071  * @lock:   Lock to check
0072  * Returns Non-zero if locked
0073  */
0074 static inline int cvmx_spinlock_locked(cvmx_spinlock_t *lock)
0075 {
0076     return lock->value != CVMX_SPINLOCK_UNLOCKED_VAL;
0077 }
0078
0079 /**
0080  * Releases lock
0081  *
0082  * @lock:   pointer to lock structure
0083  */
0084 static inline void cvmx_spinlock_unlock(cvmx_spinlock_t *lock)
0085 {
0086     CVMX_SYNCWS;
0087     lock->value = 0;
0088     CVMX_SYNCWS;
0089 }
0090
0091 /**
0092  * Attempts to take the lock, but does not spin if lock is not available.
0093  * May take some time to acquire the lock even if it is available
0094  * due to the ll/sc not succeeding.
0095  *
0096  * @lock:   pointer to lock structure
0097  *
0098  * Returns 0: lock successfully taken
0099  *     1: lock not taken, held by someone else
0100  * These return values match the Linux semantics.
0101  */
0102
0103 static inline unsigned int cvmx_spinlock_trylock(cvmx_spinlock_t *lock)
0104 {
0105     unsigned int tmp;
0106
0107     __asm__ __volatile__(".set noreorder         \n"
0108                  "1: ll   %[tmp], %[val] \n"
0109             /* if lock held, fail immediately */
0110                  "   bnez %[tmp], 2f     \n"
0111                  "   li   %[tmp], 1      \n"
0112                  "   sc   %[tmp], %[val] \n"
0113                  "   beqz %[tmp], 1b     \n"
0114                  "   li   %[tmp], 0      \n"
0115                  "2:             \n"
0116                  ".set reorder       \n" :
0117             [val] "+m"(lock->value), [tmp] "=&r"(tmp)
0118                  : : "memory");
0119
0120     return tmp != 0;        /* normalize to 0 or 1 */
0121 }
0122
0123 /**
0124  * Gets lock, spins until lock is taken
0125  *
0126  * @lock:   pointer to lock structure
0127  */
0128 static inline void cvmx_spinlock_lock(cvmx_spinlock_t *lock)
0129 {
0130     unsigned int tmp;
0131
0132     __asm__ __volatile__(".set noreorder         \n"
0133                  "1: ll   %[tmp], %[val]  \n"
0134                  "   bnez %[tmp], 1b     \n"
0135                  "   li   %[tmp], 1      \n"
0136                  "   sc   %[tmp], %[val] \n"
0137                  "   beqz %[tmp], 1b     \n"
0138                  "   nop            \n"
0139                  ".set reorder       \n" :
0140             [val] "+m"(lock->value), [tmp] "=&r"(tmp)
0141             : : "memory");
0142
0143 }
0144
0145 /** ********************************************************************
0146  * Bit spinlocks
0147  * These spinlocks use a single bit (bit 31) of a 32 bit word for locking.
0148  * The rest of the bits in the word are left undisturbed.  This enables more
0149  * compact data structures as only 1 bit is consumed for the lock.
0150  *
0151  */
0152
0153 /**
0154  * Gets lock, spins until lock is taken
0155  * Preserves the low 31 bits of the 32 bit
0156  * word used for the lock.
0157  *
0158  *
0159  * @word:  word to lock bit 31 of
0160  */
0161 static inline void cvmx_spinlock_bit_lock(uint32_t *word)
0162 {
0163     unsigned int tmp;
0164     unsigned int sav;
0165
0166     __asm__ __volatile__(".set noreorder         \n"
0167                  ".set noat          \n"
0168                  "1: ll    %[tmp], %[val]  \n"
0169                  "   bbit1 %[tmp], 31, 1b    \n"
0170                  "   li    $at, 1      \n"
0171                  "   ins   %[tmp], $at, 31, 1  \n"
0172                  "   sc    %[tmp], %[val] \n"
0173                  "   beqz  %[tmp], 1b     \n"
0174                  "   nop            \n"
0175                  ".set at          \n"
0176                  ".set reorder       \n" :
0177             [val] "+m"(*word), [tmp] "=&r"(tmp), [sav] "=&r"(sav)
0178                  : : "memory");
0179
0180 }
0181
0182 /**
0183  * Attempts to get lock, returns immediately with success/failure
0184  * Preserves the low 31 bits of the 32 bit
0185  * word used for the lock.
0186  *
0187  *
0188  * @word:  word to lock bit 31 of
0189  * Returns 0: lock successfully taken
0190  *     1: lock not taken, held by someone else
0191  * These return values match the Linux semantics.
0192  */
0193 static inline unsigned int cvmx_spinlock_bit_trylock(uint32_t *word)
0194 {
0195     unsigned int tmp;
0196
0197     __asm__ __volatile__(".set noreorder\n\t"
0198                  ".set noat\n"
0199                  "1: ll    %[tmp], %[val] \n"
0200             /* if lock held, fail immediately */
0201                  "   bbit1 %[tmp], 31, 2f     \n"
0202                  "   li    $at, 1      \n"
0203                  "   ins   %[tmp], $at, 31, 1  \n"
0204                  "   sc    %[tmp], %[val] \n"
0205                  "   beqz  %[tmp], 1b     \n"
0206                  "   li    %[tmp], 0      \n"
0207                  "2:             \n"
0208                  ".set at          \n"
0209                  ".set reorder       \n" :
0210             [val] "+m"(*word), [tmp] "=&r"(tmp)
0211             : : "memory");
0212
0213     return tmp != 0;        /* normalize to 0 or 1 */
0214 }
0215
0216 /**
0217  * Releases bit lock
0218  *
0219  * Unconditionally clears bit 31 of the lock word.  Note that this is
0220  * done non-atomically, as this implementation assumes that the rest
0221  * of the bits in the word are protected by the lock.
0222  *
0223  * @word:  word to unlock bit 31 in
0224  */
0225 static inline void cvmx_spinlock_bit_unlock(uint32_t *word)
0226 {
0227     CVMX_SYNCWS;
0228     *word &= ~(1UL << 31);
0229     CVMX_SYNCWS;
0230 }
0231
0232 #endif /* __CVMX_SPINLOCK_H__ */