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-rw-r--r--arch/riscv/include/asm/spinlock.h151
1 files changed, 151 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..04c71d938afd
--- /dev/null
+++ b/arch/riscv/include/asm/spinlock.h
@@ -0,0 +1,151 @@
+/*
+ * 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_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 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");
+}
+
+#endif /* _ASM_RISCV_SPINLOCK_H */