asm-generic: add generic atomic.h and io.h

atomic.h and io.h are based on the mn10300 architecture,
which is already pretty generic and can be used by
other architectures that do not have hardware support
for atomic operations or out-of-order I/O access.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 165 insertions, 0 deletions

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
new file mode 100644
index 00000000000..c99c64dc5f3
--- /dev/null
+++ b/include/asm-generic/atomic.h
@@ -0,0 +1,165 @@
+/*
+ * Generic C implementation of atomic counter operations
+ * Originally implemented for MN10300.
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef __ASM_GENERIC_ATOMIC_H
+#define __ASM_GENERIC_ATOMIC_H
+
+#ifdef CONFIG_SMP
+#error not SMP safe
+#endif
+
+/*
+ * Atomic operations that C can't guarantee us.  Useful for
+ * resource counting etc..
+ */
+
+#define ATOMIC_INIT(i)  { (i) }
+
+#ifdef __KERNEL__
+
+/**
+ * atomic_read - read atomic variable
+ * @v: pointer of type atomic_t
+ *
+ * Atomically reads the value of @v.  Note that the guaranteed
+ * useful range of an atomic_t is only 24 bits.
+ */
+#define atomic_read(v)  ((v)->counter)
+
+/**
+ * atomic_set - set atomic variable
+ * @v: pointer of type atomic_t
+ * @i: required value
+ *
+ * Atomically sets the value of @v to @i.  Note that the guaranteed
+ * useful range of an atomic_t is only 24 bits.
+ */
+#define atomic_set(v, i) (((v)->counter) = (i))
+
+#include <asm/system.h>
+
+/**
+ * atomic_add_return - add integer to atomic variable
+ * @i: integer value to add
+ * @v: pointer of type atomic_t
+ *
+ * Atomically adds @i to @v and returns the result
+ * Note that the guaranteed useful range of an atomic_t is only 24 bits.
+ */
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+        unsigned long flags;
+        int temp;
+
+        local_irq_save(flags);
+        temp = v->counter;
+        temp += i;
+        v->counter = temp;
+        local_irq_restore(flags);
+
+        return temp;
+}
+
+/**
+ * atomic_sub_return - subtract integer from atomic variable
+ * @i: integer value to subtract
+ * @v: pointer of type atomic_t
+ *
+ * Atomically subtracts @i from @v and returns the result
+ * Note that the guaranteed useful range of an atomic_t is only 24 bits.
+ */
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+        unsigned long flags;
+        int temp;
+
+        local_irq_save(flags);
+        temp = v->counter;
+        temp -= i;
+        v->counter = temp;
+        local_irq_restore(flags);
+
+        return temp;
+}
+
+static inline int atomic_add_negative(int i, atomic_t *v)
+{
+        return atomic_add_return(i, v) < 0;
+}
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+        atomic_add_return(i, v);
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+        atomic_sub_return(i, v);
+}
+
+static inline void atomic_inc(atomic_t *v)
+{
+        atomic_add_return(1, v);
+}
+
+static inline void atomic_dec(atomic_t *v)
+{
+        atomic_sub_return(1, v);
+}
+
+#define atomic_dec_return(v)            atomic_sub_return(1, (v))
+#define atomic_inc_return(v)            atomic_add_return(1, (v))
+
+#define atomic_sub_and_test(i, v)       (atomic_sub_return((i), (v)) == 0)
+#define atomic_dec_and_test(v)          (atomic_sub_return(1, (v)) == 0)
+#define atomic_inc_and_test(v)          (atomic_add_return(1, (v)) == 0)
+
+#define atomic_add_unless(v, a, u)                              \
+({                                                              \
+        int c, old;                                             \
+        c = atomic_read(v);                                     \
+        while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+                c = old;                                        \
+        c != (u);                                               \
+})
+
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+        unsigned long flags;
+
+        mask = ~mask;
+        local_irq_save(flags);
+        *addr &= mask;
+        local_irq_restore(flags);
+}
+
+#define atomic_xchg(ptr, v)             (xchg(&(ptr)->counter, (v)))
+#define atomic_cmpxchg(v, old, new)     (cmpxchg(&((v)->counter), (old), (new)))
+
+#define cmpxchg_local(ptr, o, n)                                               \
+        ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
+                        (unsigned long)(n), sizeof(*(ptr))))
+
+#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+
+/* Assume that atomic operations are already serializing */
+#define smp_mb__before_atomic_dec()     barrier()
+#define smp_mb__after_atomic_dec()      barrier()
+#define smp_mb__before_atomic_inc()     barrier()
+#define smp_mb__after_atomic_inc()      barrier()
+
+#include <asm-generic/atomic-long.h>
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_GENERIC_ATOMIC_H */