1 /* 2 * Queued spinlock 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P. 15 * 16 * Authors: Waiman Long <[email protected]> 17 */ 18 #ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H 19 #define __ASM_GENERIC_QSPINLOCK_TYPES_H 20 21 /* 22 * Including atomic.h with PARAVIRT on will cause compilation errors because 23 * of recursive header file incluson via paravirt_types.h. So don't include 24 * it if PARAVIRT is on. 25 */ 26 #ifndef CONFIG_PARAVIRT 27 #include <linux/types.h> 28 #include <linux/atomic.h> 29 #endif 30 31 typedef struct qspinlock { 32 atomic_t val; 33 } arch_spinlock_t; 34 35 /* 36 * Initializier 37 */ 38 #define __ARCH_SPIN_LOCK_UNLOCKED { ATOMIC_INIT(0) } 39 40 /* 41 * Bitfields in the atomic value: 42 * 43 * When NR_CPUS < 16K 44 * 0- 7: locked byte 45 * 8: pending 46 * 9-15: not used 47 * 16-17: tail index 48 * 18-31: tail cpu (+1) 49 * 50 * When NR_CPUS >= 16K 51 * 0- 7: locked byte 52 * 8: pending 53 * 9-10: tail index 54 * 11-31: tail cpu (+1) 55 */ 56 #define _Q_SET_MASK(type) (((1U << _Q_ ## type ## _BITS) - 1)\ 57 << _Q_ ## type ## _OFFSET) 58 #define _Q_LOCKED_OFFSET 0 59 #define _Q_LOCKED_BITS 8 60 #define _Q_LOCKED_MASK _Q_SET_MASK(LOCKED) 61 62 #define _Q_PENDING_OFFSET (_Q_LOCKED_OFFSET + _Q_LOCKED_BITS) 63 #if CONFIG_NR_CPUS < (1U << 14) 64 #define _Q_PENDING_BITS 8 65 #else 66 #define _Q_PENDING_BITS 1 67 #endif 68 #define _Q_PENDING_MASK _Q_SET_MASK(PENDING) 69 70 #define _Q_TAIL_IDX_OFFSET (_Q_PENDING_OFFSET + _Q_PENDING_BITS) 71 #define _Q_TAIL_IDX_BITS 2 72 #define _Q_TAIL_IDX_MASK _Q_SET_MASK(TAIL_IDX) 73 74 #define _Q_TAIL_CPU_OFFSET (_Q_TAIL_IDX_OFFSET + _Q_TAIL_IDX_BITS) 75 #define _Q_TAIL_CPU_BITS (32 - _Q_TAIL_CPU_OFFSET) 76 #define _Q_TAIL_CPU_MASK _Q_SET_MASK(TAIL_CPU) 77 78 #define _Q_TAIL_OFFSET _Q_TAIL_IDX_OFFSET 79 #define _Q_TAIL_MASK (_Q_TAIL_IDX_MASK | _Q_TAIL_CPU_MASK) 80 81 #define _Q_LOCKED_VAL (1U << _Q_LOCKED_OFFSET) 82 #define _Q_PENDING_VAL (1U << _Q_PENDING_OFFSET) 83 84 #endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */ 85