ARM: atomic.h: move generic implementation to asm-generic

For easier code-sharing, the UBIFS code still uses the Linux atomic
accessors.  Make porting it to sandbox easier, by providing these
functions for all platforms.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 99 insertions, 0 deletions

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
new file mode 100644
index 0000000000..6357b66a53
--- /dev/null
+++ b/include/asm-generic/atomic.h
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  based on linux/include/asm-arm/atomic.h
+ *
+ *  Copyright (c) 1996 Russell King.
+ */
+
+#ifndef __ASM_GENERIC_ATOMIC_H
+#define __ASM_GENERIC_ATOMIC_H
+
+#ifdef CONFIG_SMP
+#error SMP not supported
+#endif
+
+typedef struct { volatile int counter; } atomic_t;
+
+#define ATOMIC_INIT(i)	{ (i) }
+
+#define atomic_read(v)	((v)->counter)
+#define atomic_set(v,i)	(((v)->counter) = (i))
+
+static inline void atomic_add(int i, volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter += i;
+	local_irq_restore(flags);
+}
+
+static inline void atomic_sub(int i, volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter -= i;
+	local_irq_restore(flags);
+}
+
+static inline void atomic_inc(volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter += 1;
+	local_irq_restore(flags);
+}
+
+static inline void atomic_dec(volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter -= 1;
+	local_irq_restore(flags);
+}
+
+static inline int atomic_dec_and_test(volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+	int val;
+
+	local_irq_save(flags);
+	val = v->counter;
+	v->counter = val -= 1;
+	local_irq_restore(flags);
+
+	return val == 0;
+}
+
+static inline int atomic_add_negative(int i, volatile atomic_t *v)
+{
+	unsigned long flags = 0;
+	int val;
+
+	local_irq_save(flags);
+	val = v->counter;
+	v->counter = val += i;
+	local_irq_restore(flags);
+
+	return val < 0;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	*addr &= ~mask;
+	local_irq_restore(flags);
+}
+
+/* Atomic operations are already serializing on ARM */
+#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()
+
+#endif