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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H

#include <asm/barrier.h>
#include <asm/ldcw.h>
#include <asm/processor.h>
#include <asm/spinlock_types.h>

static inline int arch_spin_is_locked(arch_spinlock_t *x)
{
	volatile unsigned int *a = __ldcw_align(x);
	return *a == 0;
}

#define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0)

static inline void arch_spin_lock_flags(arch_spinlock_t *x,
					 unsigned long flags)
{
	volatile unsigned int *a;

	a = __ldcw_align(x);
	while (__ldcw(a) == 0)
		while (*a == 0)
			if (flags & PSW_SM_I) {
				local_irq_enable();
				cpu_relax();
				local_irq_disable();
			} else
				cpu_relax();
}
#define arch_spin_lock_flags arch_spin_lock_flags

static inline void arch_spin_unlock(arch_spinlock_t *x)
{
	volatile unsigned int *a;

	a = __ldcw_align(x);
	mb();
	*a = 1;
}

static inline int arch_spin_trylock(arch_spinlock_t *x)
{
	volatile unsigned int *a;
	int ret;

	a = __ldcw_align(x);
        ret = __ldcw(a) != 0;

	return ret;
}

/*
 * Read-write spinlocks, allowing multiple readers but only one writer.
 * Linux rwlocks are unfair to writers; they can be starved for an indefinite
 * time by readers.  With care, they can also be taken in interrupt context.
 *
 * In the PA-RISC implementation, we have a spinlock and a counter.
 * Readers use the lock to serialise their access to the counter (which
 * records how many readers currently hold the lock).
 * Writers hold the spinlock, preventing any readers or other writers from
 * grabbing the rwlock.
 */

/* Note that we have to ensure interrupts are disabled in case we're
 * interrupted by some other code that wants to grab the same read lock */
static  __inline__ void arch_read_lock(arch_rwlock_t *rw)
{
	unsigned long flags;
	local_irq_save(flags);
	arch_spin_lock_flags(&rw->lock, flags);
	rw->counter++;
	arch_spin_unlock(&rw->lock);
	local_irq_restore(flags);
}

/* Note that we have to ensure interrupts are disabled in case we're
 * interrupted by some other code that wants to grab the same read lock */
static  __inline__ void arch_read_unlock(arch_rwlock_t *rw)
{
	unsigned long flags;
	local_irq_save(flags);
	arch_spin_lock_flags(&rw->lock, flags);
	rw->counter--;
	arch_spin_unlock(&rw->lock);
	local_irq_restore(flags);
}

/* Note that we have to ensure interrupts are disabled in case we're
 * interrupted by some other code that wants to grab the same read lock */
static __inline__ int arch_read_trylock(arch_rwlock_t *rw)
{
	unsigned long flags;
 retry:
	local_irq_save(flags);
	if (arch_spin_trylock(&rw->lock)) {
		rw->counter++;
		arch_spin_unlock(&rw->lock);
		local_irq_restore(flags);
		return 1;
	}

	local_irq_restore(flags);
	/* If write-locked, we fail to acquire the lock */
	if (rw->counter < 0)
		return 0;

	/* Wait until we have a realistic chance at the lock */
	while (arch_spin_is_locked(&rw->lock) && rw->counter >= 0)
		cpu_relax();

	goto retry;
}

/* Note that we have to ensure interrupts are disabled in case we're
 * interrupted by some other code that wants to read_trylock() this lock */
static __inline__ void arch_write_lock(arch_rwlock_t *rw)
{
	unsigned long flags;
retry:
	local_irq_save(flags);
	arch_spin_lock_flags(&rw->lock, flags);

	if (rw->counter != 0) {
		arch_spin_unlock(&rw->lock);
		local_irq_restore(flags);

		while (rw->counter != 0)
			cpu_relax();

		goto retry;
	}

	rw->counter = -1; /* mark as write-locked */
	mb();
	local_irq_restore(flags);
}

static __inline__ void arch_write_unlock(arch_rwlock_t *rw)
{
	rw->counter = 0;
	arch_spin_unlock(&rw->lock);
}

/* Note that we have to ensure interrupts are disabled in case we're
 * interrupted by some other code that wants to read_trylock() this lock */
static __inline__ int arch_write_trylock(arch_rwlock_t *rw)
{
	unsigned long flags;
	int result = 0;

	local_irq_save(flags);
	if (arch_spin_trylock(&rw->lock)) {
		if (rw->counter == 0) {
			rw->counter = -1;
			result = 1;
		} else {
			/* Read-locked.  Oh well. */
			arch_spin_unlock(&rw->lock);
		}
	}
	local_irq_restore(flags);

	return result;
}

#endif /* __ASM_SPINLOCK_H */

Filemanager

Name Type Size Permission Actions
Kbuild File 610 B 0644
agp.h File 596 B 0644
asm-offsets.h File 35 B 0644
asmregs.h File 3.04 KB 0644
assembly.h File 12.94 KB 0644
atomic.h File 8.24 KB 0644
barrier.h File 2.44 KB 0644
bitops.h File 5.89 KB 0644
bug.h File 2.35 KB 0644
bugs.h File 340 B 0644
cache.h File 1.59 KB 0644
cacheflush.h File 4.06 KB 0644
checksum.h File 5.48 KB 0644
cmpxchg.h File 3.62 KB 0644
compat.h File 6.52 KB 0644
compat_ucontext.h File 591 B 0644
delay.h File 533 B 0644
dma-mapping.h File 2.42 KB 0644
dma.h File 5.71 KB 0644
dwarf.h File 602 B 0644
eisa_bus.h File 702 B 0644
eisa_eeprom.h File 4.42 KB 0644
elf.h File 14.31 KB 0644
fb.h File 403 B 0644
fixmap.h File 1.15 KB 0644
floppy.h File 6.61 KB 0644
ftrace.h File 379 B 0644
futex.h File 2.66 KB 0644
grfioctl.h File 4.68 KB 0644
hardirq.h File 1.3 KB 0644
hardware.h File 4.1 KB 0644
hash.h File 5.07 KB 0644
hugetlb.h File 1.67 KB 0644
ide.h File 1.09 KB 0644
io.h File 8.14 KB 0644
irq.h File 1.23 KB 0644
irqflags.h File 1.02 KB 0644
kbdleds.h File 477 B 0644
kmap_types.h File 221 B 0644
ldcw.h File 2.15 KB 0644
led.h File 1.33 KB 0644
linkage.h File 759 B 0644
machdep.h File 349 B 0644
mckinley.h File 270 B 0644
mmu.h File 195 B 0644
mmu_context.h File 2.08 KB 0644
mmzone.h File 1.51 KB 0644
module.h File 527 B 0644
page.h File 5.42 KB 0644
parisc-device.h File 1.92 KB 0644
parport.h File 358 B 0644
pci.h File 6.57 KB 0644
pdc.h File 3.93 KB 0644
pdc_chassis.h File 15.06 KB 0644
pdcpat.h File 15 KB 0644
perf.h File 1.89 KB 0644
perf_event.h File 152 B 0644
pgalloc.h File 4.22 KB 0644
pgtable.h File 18.92 KB 0644
prefetch.h File 1.12 KB 0644
processor.h File 9.86 KB 0644
psw.h File 2.39 KB 0644
ptrace.h File 803 B 0644
ropes.h File 9.73 KB 0644
rt_sigframe.h File 745 B 0644
runway.h File 320 B 0644
sections.h File 283 B 0644
serial.h File 124 B 0644
shmparam.h File 263 B 0644
signal.h File 841 B 0644
smp.h File 1.25 KB 0644
socket.h File 311 B 0644
special_insns.h File 1015 B 0644
spinlock.h File 4.02 KB 0644
spinlock_types.h File 483 B 0644
string.h File 247 B 0644
superio.h File 3.25 KB 0644
switch_to.h File 332 B 0644
syscall.h File 1.4 KB 0644
termios.h File 1.72 KB 0644
thread_info.h File 3.15 KB 0644
timex.h File 372 B 0644
tlb.h File 672 B 0644
tlbflush.h File 2.63 KB 0644
topology.h File 900 B 0644
traps.h File 468 B 0644
uaccess.h File 6.55 KB 0644
ucontext.h File 327 B 0644
unaligned.h File 472 B 0644
unistd.h File 5.47 KB 0644
unwind.h File 2.56 KB 0644