1 files changed, 165 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h
new file mode 100644
index 000000000000..b3b394ffaf7e
--- /dev/null
+++ b/arch/riscv/include/asm/spinlock.h
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2015 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ *
+ *   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, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RISCV_SPINLOCK_H
+#define _ASM_RISCV_SPINLOCK_H
+
+#include <linux/kernel.h>
+#include <asm/current.h>
+
+/*
+ * Simple spin lock operations.  These provide no fairness guarantees.
+ */
+
+/* FIXME: Replace this with a ticket lock, like MIPS. */
+
+#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
+#define arch_spin_is_locked(x)	((x)->lock != 0)
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+	__asm__ __volatile__ (
+		"amoswap.w.rl x0, x0, %0"
+		: "=A" (lock->lock)
+		:: "memory");
+}
+
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+	int tmp = 1, busy;
+
+	__asm__ __volatile__ (
+		"amoswap.w.aq %0, %2, %1"
+		: "=r" (busy), "+A" (lock->lock)
+		: "r" (tmp)
+		: "memory");
+
+	return !busy;
+}
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+	while (1) {
+		if (arch_spin_is_locked(lock))
+			continue;
+
+		if (arch_spin_trylock(lock))
+			break;
+	}
+}
+
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+	smp_rmb();
+	do {
+		cpu_relax();
+	} while (arch_spin_is_locked(lock));
+	smp_acquire__after_ctrl_dep();
+}
+
+/***********************************************************/
+
+static inline int arch_read_can_lock(arch_rwlock_t *lock)
+{
+	return lock->lock >= 0;
+}
+
+static inline int arch_write_can_lock(arch_rwlock_t *lock)
+{
+	return lock->lock == 0;
+}
+
+static inline void arch_read_lock(arch_rwlock_t *lock)
+{
+	int tmp;
+
+	__asm__ __volatile__(
+		"1:	lr.w	%1, %0\n"
+		"	bltz	%1, 1b\n"
+		"	addi	%1, %1, 1\n"
+		"	sc.w.aq	%1, %1, %0\n"
+		"	bnez	%1, 1b\n"
+		: "+A" (lock->lock), "=&r" (tmp)
+		:: "memory");
+}
+
+static inline void arch_write_lock(arch_rwlock_t *lock)
+{
+	int tmp;
+
+	__asm__ __volatile__(
+		"1:	lr.w	%1, %0\n"
+		"	bnez	%1, 1b\n"
+		"	li	%1, -1\n"
+		"	sc.w.aq	%1, %1, %0\n"
+		"	bnez	%1, 1b\n"
+		: "+A" (lock->lock), "=&r" (tmp)
+		:: "memory");
+}
+
+static inline int arch_read_trylock(arch_rwlock_t *lock)
+{
+	int busy;
+
+	__asm__ __volatile__(
+		"1:	lr.w	%1, %0\n"
+		"	bltz	%1, 1f\n"
+		"	addi	%1, %1, 1\n"
+		"	sc.w.aq	%1, %1, %0\n"
+		"	bnez	%1, 1b\n"
+		"1:\n"
+		: "+A" (lock->lock), "=&r" (busy)
+		:: "memory");
+
+	return !busy;
+}
+
+static inline int arch_write_trylock(arch_rwlock_t *lock)
+{
+	int busy;
+
+	__asm__ __volatile__(
+		"1:	lr.w	%1, %0\n"
+		"	bnez	%1, 1f\n"
+		"	li	%1, -1\n"
+		"	sc.w.aq	%1, %1, %0\n"
+		"	bnez	%1, 1b\n"
+		"1:\n"
+		: "+A" (lock->lock), "=&r" (busy)
+		:: "memory");
+
+	return !busy;
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *lock)
+{
+	__asm__ __volatile__(
+		"amoadd.w.rl x0, %1, %0"
+		: "+A" (lock->lock)
+		: "r" (-1)
+		: "memory");
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *lock)
+{
+	__asm__ __volatile__ (
+		"amoswap.w.rl x0, x0, %0"
+		: "=A" (lock->lock)
+		:: "memory");
+}
+
+#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
+#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
+
+#endif /* _ASM_RISCV_SPINLOCK_H */