1 files changed, 316 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
new file mode 100644
index 000000000..3198dde87
--- /dev/null
+++ b/arch/powerpc/include/asm/spinlock.h
@@ -0,0 +1,316 @@
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+#ifdef __KERNEL__
+
+/*
+ * Simple spin lock operations.  
+ *
+ * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
+ *	Rework to support virtual processors
+ *
+ * Type of int is used as a full 64b word is not necessary.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
+#include <linux/jump_label.h>
+#include <linux/irqflags.h>
+#ifdef CONFIG_PPC64
+#include <asm/paca.h>
+#include <asm/hvcall.h>
+#endif
+#include <asm/synch.h>
+#include <asm/ppc-opcode.h>
+#include <asm/asm-405.h>
+
+#ifdef CONFIG_PPC64
+/* use 0x800000yy when locked, where yy == CPU number */
+#ifdef __BIG_ENDIAN__
+#define LOCK_TOKEN	(*(u32 *)(&get_paca()->lock_token))
+#else
+#define LOCK_TOKEN	(*(u32 *)(&get_paca()->paca_index))
+#endif
+#else
+#define LOCK_TOKEN	1
+#endif
+
+#if defined(CONFIG_PPC64) && defined(CONFIG_SMP)
+#define CLEAR_IO_SYNC	(get_paca()->io_sync = 0)
+#define SYNC_IO		do {						\
+				if (unlikely(get_paca()->io_sync)) {	\
+					mb();				\
+					get_paca()->io_sync = 0;	\
+				}					\
+			} while (0)
+#else
+#define CLEAR_IO_SYNC
+#define SYNC_IO
+#endif
+
+#ifdef CONFIG_PPC_PSERIES
+DECLARE_STATIC_KEY_FALSE(shared_processor);
+
+#define vcpu_is_preempted vcpu_is_preempted
+static inline bool vcpu_is_preempted(int cpu)
+{
+	if (!static_branch_unlikely(&shared_processor))
+		return false;
+	return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1);
+}
+#endif
+
+static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
+{
+	return lock.slock == 0;
+}
+
+static inline int arch_spin_is_locked(arch_spinlock_t *lock)
+{
+	smp_mb();
+	return !arch_spin_value_unlocked(*lock);
+}
+
+/*
+ * This returns the old value in the lock, so we succeeded
+ * in getting the lock if the return value is 0.
+ */
+static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock)
+{
+	unsigned long tmp, token;
+
+	token = LOCK_TOKEN;
+	__asm__ __volatile__(
+"1:	" PPC_LWARX(%0,0,%2,1) "\n\
+	cmpwi		0,%0,0\n\
+	bne-		2f\n\
+	stwcx.		%1,0,%2\n\
+	bne-		1b\n"
+	PPC_ACQUIRE_BARRIER
+"2:"
+	: "=&r" (tmp)
+	: "r" (token), "r" (&lock->slock)
+	: "cr0", "memory");
+
+	return tmp;
+}
+
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+	CLEAR_IO_SYNC;
+	return __arch_spin_trylock(lock) == 0;
+}
+
+/*
+ * On a system with shared processors (that is, where a physical
+ * processor is multiplexed between several virtual processors),
+ * there is no point spinning on a lock if the holder of the lock
+ * isn't currently scheduled on a physical processor.  Instead
+ * we detect this situation and ask the hypervisor to give the
+ * rest of our timeslice to the lock holder.
+ *
+ * So that we can tell which virtual processor is holding a lock,
+ * we put 0x80000000 | smp_processor_id() in the lock when it is
+ * held.  Conveniently, we have a word in the paca that holds this
+ * value.
+ */
+
+#if defined(CONFIG_PPC_SPLPAR)
+/* We only yield to the hypervisor if we are in shared processor mode */
+#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr))
+extern void __spin_yield(arch_spinlock_t *lock);
+extern void __rw_yield(arch_rwlock_t *lock);
+#else /* SPLPAR */
+#define __spin_yield(x)	barrier()
+#define __rw_yield(x)	barrier()
+#define SHARED_PROCESSOR	0
+#endif
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+	CLEAR_IO_SYNC;
+	while (1) {
+		if (likely(__arch_spin_trylock(lock) == 0))
+			break;
+		do {
+			HMT_low();
+			if (SHARED_PROCESSOR)
+				__spin_yield(lock);
+		} while (unlikely(lock->slock != 0));
+		HMT_medium();
+	}
+}
+
+static inline
+void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
+{
+	unsigned long flags_dis;
+
+	CLEAR_IO_SYNC;
+	while (1) {
+		if (likely(__arch_spin_trylock(lock) == 0))
+			break;
+		local_save_flags(flags_dis);
+		local_irq_restore(flags);
+		do {
+			HMT_low();
+			if (SHARED_PROCESSOR)
+				__spin_yield(lock);
+		} while (unlikely(lock->slock != 0));
+		HMT_medium();
+		local_irq_restore(flags_dis);
+	}
+}
+#define arch_spin_lock_flags arch_spin_lock_flags
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+	SYNC_IO;
+	__asm__ __volatile__("# arch_spin_unlock\n\t"
+				PPC_RELEASE_BARRIER: : :"memory");
+	lock->slock = 0;
+}
+
+/*
+ * 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.
+ */
+
+#ifdef CONFIG_PPC64
+#define __DO_SIGN_EXTEND	"extsw	%0,%0\n"
+#define WRLOCK_TOKEN		LOCK_TOKEN	/* it's negative */
+#else
+#define __DO_SIGN_EXTEND
+#define WRLOCK_TOKEN		(-1)
+#endif
+
+/*
+ * This returns the old value in the lock + 1,
+ * so we got a read lock if the return value is > 0.
+ */
+static inline long __arch_read_trylock(arch_rwlock_t *rw)
+{
+	long tmp;
+
+	__asm__ __volatile__(
+"1:	" PPC_LWARX(%0,0,%1,1) "\n"
+	__DO_SIGN_EXTEND
+"	addic.		%0,%0,1\n\
+	ble-		2f\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.		%0,0,%1\n\
+	bne-		1b\n"
+	PPC_ACQUIRE_BARRIER
+"2:"	: "=&r" (tmp)
+	: "r" (&rw->lock)
+	: "cr0", "xer", "memory");
+
+	return tmp;
+}
+
+/*
+ * This returns the old value in the lock,
+ * so we got the write lock if the return value is 0.
+ */
+static inline long __arch_write_trylock(arch_rwlock_t *rw)
+{
+	long tmp, token;
+
+	token = WRLOCK_TOKEN;
+	__asm__ __volatile__(
+"1:	" PPC_LWARX(%0,0,%2,1) "\n\
+	cmpwi		0,%0,0\n\
+	bne-		2f\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.		%1,0,%2\n\
+	bne-		1b\n"
+	PPC_ACQUIRE_BARRIER
+"2:"	: "=&r" (tmp)
+	: "r" (token), "r" (&rw->lock)
+	: "cr0", "memory");
+
+	return tmp;
+}
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+	while (1) {
+		if (likely(__arch_read_trylock(rw) > 0))
+			break;
+		do {
+			HMT_low();
+			if (SHARED_PROCESSOR)
+				__rw_yield(rw);
+		} while (unlikely(rw->lock < 0));
+		HMT_medium();
+	}
+}
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+	while (1) {
+		if (likely(__arch_write_trylock(rw) == 0))
+			break;
+		do {
+			HMT_low();
+			if (SHARED_PROCESSOR)
+				__rw_yield(rw);
+		} while (unlikely(rw->lock != 0));
+		HMT_medium();
+	}
+}
+
+static inline int arch_read_trylock(arch_rwlock_t *rw)
+{
+	return __arch_read_trylock(rw) > 0;
+}
+
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+	return __arch_write_trylock(rw) == 0;
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+	long tmp;
+
+	__asm__ __volatile__(
+	"# read_unlock\n\t"
+	PPC_RELEASE_BARRIER
+"1:	lwarx		%0,0,%1\n\
+	addic		%0,%0,-1\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.		%0,0,%1\n\
+	bne-		1b"
+	: "=&r"(tmp)
+	: "r"(&rw->lock)
+	: "cr0", "xer", "memory");
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+	__asm__ __volatile__("# write_unlock\n\t"
+				PPC_RELEASE_BARRIER: : :"memory");
+	rw->lock = 0;
+}
+
+#define arch_spin_relax(lock)	__spin_yield(lock)
+#define arch_read_relax(lock)	__rw_yield(lock)
+#define arch_write_relax(lock)	__rw_yield(lock)
+
+/* See include/linux/spinlock.h */
+#define smp_mb__after_spinlock()   smp_mb()
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_SPINLOCK_H */