1 files changed, 188 insertions, 0 deletions
diff --git a/arch/sparc/include/asm/spinlock_32.h b/arch/sparc/include/asm/spinlock_32.h
new file mode 100644
index 000000000..bc5aa6f61
--- /dev/null
+++ b/arch/sparc/include/asm/spinlock_32.h
@@ -0,0 +1,188 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* spinlock.h: 32-bit Sparc spinlock support.
+ *
+ * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#ifndef __SPARC_SPINLOCK_H
+#define __SPARC_SPINLOCK_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/psr.h>
+#include <asm/barrier.h>
+#include <asm/processor.h> /* for cpu_relax */
+
+#define arch_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0)
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+	__asm__ __volatile__(
+	"\n1:\n\t"
+	"ldstub	[%0], %%g2\n\t"
+	"orcc	%%g2, 0x0, %%g0\n\t"
+	"bne,a	2f\n\t"
+	" ldub	[%0], %%g2\n\t"
+	".subsection	2\n"
+	"2:\n\t"
+	"orcc	%%g2, 0x0, %%g0\n\t"
+	"bne,a	2b\n\t"
+	" ldub	[%0], %%g2\n\t"
+	"b,a	1b\n\t"
+	".previous\n"
+	: /* no outputs */
+	: "r" (lock)
+	: "g2", "memory", "cc");
+}
+
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+	unsigned int result;
+	__asm__ __volatile__("ldstub [%1], %0"
+			     : "=r" (result)
+			     : "r" (lock)
+			     : "memory");
+	return (result == 0);
+}
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+	__asm__ __volatile__("stb %%g0, [%0]" : : "r" (lock) : "memory");
+}
+
+/* Read-write spinlocks, allowing multiple readers
+ * but only one writer.
+ *
+ * NOTE! it is quite common to have readers in interrupts
+ * but no interrupt writers. For those circumstances we
+ * can "mix" irq-safe locks - any writer needs to get a
+ * irq-safe write-lock, but readers can get non-irqsafe
+ * read-locks.
+ *
+ * XXX This might create some problems with my dual spinlock
+ * XXX scheme, deadlocks etc. -DaveM
+ *
+ * Sort of like atomic_t's on Sparc, but even more clever.
+ *
+ *	------------------------------------
+ *	| 24-bit counter           | wlock |  arch_rwlock_t
+ *	------------------------------------
+ *	 31                       8 7     0
+ *
+ * wlock signifies the one writer is in or somebody is updating
+ * counter. For a writer, if he successfully acquires the wlock,
+ * but counter is non-zero, he has to release the lock and wait,
+ * till both counter and wlock are zero.
+ *
+ * Unfortunately this scheme limits us to ~16,000,000 cpus.
+ */
+static inline void __arch_read_lock(arch_rwlock_t *rw)
+{
+	register arch_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_enter\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+}
+
+#define arch_read_lock(lock) \
+do {	unsigned long flags; \
+	local_irq_save(flags); \
+	__arch_read_lock(lock); \
+	local_irq_restore(flags); \
+} while(0)
+
+static inline void __arch_read_unlock(arch_rwlock_t *rw)
+{
+	register arch_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_exit\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+}
+
+#define arch_read_unlock(lock) \
+do {	unsigned long flags; \
+	local_irq_save(flags); \
+	__arch_read_unlock(lock); \
+	local_irq_restore(flags); \
+} while(0)
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+	register arch_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_write_enter\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+	*(volatile __u32 *)&lp->lock = ~0U;
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *lock)
+{
+	__asm__ __volatile__(
+"	st		%%g0, [%0]"
+	: /* no outputs */
+	: "r" (lock)
+	: "memory");
+}
+
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+	unsigned int val;
+
+	__asm__ __volatile__("ldstub [%1 + 3], %0"
+			     : "=r" (val)
+			     : "r" (&rw->lock)
+			     : "memory");
+
+	if (val == 0) {
+		val = rw->lock & ~0xff;
+		if (val)
+			((volatile u8*)&rw->lock)[3] = 0;
+		else
+			*(volatile u32*)&rw->lock = ~0U;
+	}
+
+	return (val == 0);
+}
+
+static inline int __arch_read_trylock(arch_rwlock_t *rw)
+{
+	register arch_rwlock_t *lp asm("g1");
+	register int res asm("o0");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_try\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: "=r" (res)
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+	return res;
+}
+
+#define arch_read_trylock(lock) \
+({	unsigned long flags; \
+	int res; \
+	local_irq_save(flags); \
+	res = __arch_read_trylock(lock); \
+	local_irq_restore(flags); \
+	res; \
+})
+
+#endif /* !(__ASSEMBLY__) */
+
+#endif /* __SPARC_SPINLOCK_H */