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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/xtensa/include/asm/spinlock.h
Initial import
Diffstat (limited to 'arch/xtensa/include/asm/spinlock.h')
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diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h
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+++ b/arch/xtensa/include/asm/spinlock.h
@@ -0,0 +1,205 @@
+/*
+ * include/asm-xtensa/spinlock.h
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2005 Tensilica Inc.
+ */
+
+#ifndef _XTENSA_SPINLOCK_H
+#define _XTENSA_SPINLOCK_H
+
+/*
+ * spinlock
+ *
+ * There is at most one owner of a spinlock. There are not different
+ * types of spinlock owners like there are for rwlocks (see below).
+ *
+ * When trying to obtain a spinlock, the function "spins" forever, or busy-
+ * waits, until the lock is obtained. When spinning, presumably some other
+ * owner will soon give up the spinlock making it available to others. Use
+ * the trylock functions to avoid spinning forever.
+ *
+ * possible values:
+ *
+ * 0 nobody owns the spinlock
+ * 1 somebody owns the spinlock
+ */
+
+#define arch_spin_is_locked(x) ((x)->slock != 0)
+#define arch_spin_unlock_wait(lock) \
+ do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
+
+#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " wsr %0, scompare1\n"
+ "1: movi %0, 1\n"
+ " s32c1i %0, %1, 0\n"
+ " bnez %0, 1b\n"
+ : "=&a" (tmp)
+ : "a" (&lock->slock)
+ : "memory");
+}
+
+/* Returns 1 if the lock is obtained, 0 otherwise. */
+
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " wsr %0, scompare1\n"
+ " movi %0, 1\n"
+ " s32c1i %0, %1, 0\n"
+ : "=&a" (tmp)
+ : "a" (&lock->slock)
+ : "memory");
+
+ return tmp == 0 ? 1 : 0;
+}
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " s32ri %0, %1, 0\n"
+ : "=&a" (tmp)
+ : "a" (&lock->slock)
+ : "memory");
+}
+
+/*
+ * rwlock
+ *
+ * Read-write locks are really a more flexible spinlock. They allow
+ * multiple readers but only one writer. Write ownership is exclusive
+ * (i.e., all other readers and writers are blocked from ownership while
+ * there is a write owner). These rwlocks are unfair to writers. Writers
+ * can be starved for an indefinite time by readers.
+ *
+ * possible values:
+ *
+ * 0 nobody owns the rwlock
+ * >0 one or more readers own the rwlock
+ * (the positive value is the actual number of readers)
+ * 0x80000000 one writer owns the rwlock, no other writers, no readers
+ */
+
+#define arch_write_can_lock(x) ((x)->lock == 0)
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " wsr %0, scompare1\n"
+ "1: movi %0, 1\n"
+ " slli %0, %0, 31\n"
+ " s32c1i %0, %1, 0\n"
+ " bnez %0, 1b\n"
+ : "=&a" (tmp)
+ : "a" (&rw->lock)
+ : "memory");
+}
+
+/* Returns 1 if the lock is obtained, 0 otherwise. */
+
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " wsr %0, scompare1\n"
+ " movi %0, 1\n"
+ " slli %0, %0, 31\n"
+ " s32c1i %0, %1, 0\n"
+ : "=&a" (tmp)
+ : "a" (&rw->lock)
+ : "memory");
+
+ return tmp == 0 ? 1 : 0;
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " movi %0, 0\n"
+ " s32ri %0, %1, 0\n"
+ : "=&a" (tmp)
+ : "a" (&rw->lock)
+ : "memory");
+}
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+ unsigned long tmp;
+ unsigned long result;
+
+ __asm__ __volatile__(
+ "1: l32i %1, %2, 0\n"
+ " bltz %1, 1b\n"
+ " wsr %1, scompare1\n"
+ " addi %0, %1, 1\n"
+ " s32c1i %0, %2, 0\n"
+ " bne %0, %1, 1b\n"
+ : "=&a" (result), "=&a" (tmp)
+ : "a" (&rw->lock)
+ : "memory");
+}
+
+/* Returns 1 if the lock is obtained, 0 otherwise. */
+
+static inline int arch_read_trylock(arch_rwlock_t *rw)
+{
+ unsigned long result;
+ unsigned long tmp;
+
+ __asm__ __volatile__(
+ " l32i %1, %2, 0\n"
+ " addi %0, %1, 1\n"
+ " bltz %0, 1f\n"
+ " wsr %1, scompare1\n"
+ " s32c1i %0, %2, 0\n"
+ " sub %0, %0, %1\n"
+ "1:\n"
+ : "=&a" (result), "=&a" (tmp)
+ : "a" (&rw->lock)
+ : "memory");
+
+ return result == 0;
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+ unsigned long tmp1, tmp2;
+
+ __asm__ __volatile__(
+ "1: l32i %1, %2, 0\n"
+ " addi %0, %1, -1\n"
+ " wsr %1, scompare1\n"
+ " s32c1i %0, %2, 0\n"
+ " bne %0, %1, 1b\n"
+ : "=&a" (tmp1), "=&a" (tmp2)
+ : "a" (&rw->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 /* _XTENSA_SPINLOCK_H */