Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * Spin and read/write lock operations.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  *   Rework to support virtual processors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/spinlock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/export.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/smp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) /* waiting for a spinlock... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #if defined(CONFIG_PPC_SPLPAR)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <asm/hvcall.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include <asm/smp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) void splpar_spin_yield(arch_spinlock_t *lock)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	unsigned int lock_value, holder_cpu, yield_count;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	lock_value = lock->slock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 	if (lock_value == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 	holder_cpu = lock_value & 0xffff;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 	BUG_ON(holder_cpu >= NR_CPUS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 	yield_count = yield_count_of(holder_cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 	if ((yield_count & 1) == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 		return;		/* virtual cpu is currently running */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 	rmb();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 	if (lock->slock != lock_value)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 		return;		/* something has changed */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 	yield_to_preempted(holder_cpu, yield_count);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) EXPORT_SYMBOL_GPL(splpar_spin_yield);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42)  * Waiting for a read lock or a write lock on a rwlock...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)  * This turns out to be the same for read and write locks, since
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)  * we only know the holder if it is write-locked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) void splpar_rw_yield(arch_rwlock_t *rw)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	int lock_value;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	unsigned int holder_cpu, yield_count;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	lock_value = rw->lock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 	if (lock_value >= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 		return;		/* no write lock at present */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	holder_cpu = lock_value & 0xffff;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	BUG_ON(holder_cpu >= NR_CPUS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 	yield_count = yield_count_of(holder_cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 	if ((yield_count & 1) == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 		return;		/* virtual cpu is currently running */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 	rmb();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 	if (rw->lock != lock_value)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 		return;		/* something has changed */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) 	yield_to_preempted(holder_cpu, yield_count);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) #endif