compat: add linux/atmoic.h

This include is needed by some drivers.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/include/linux/atomic.h b/include/linux/atomic.h
new file mode 100644 (file)
index 0000000..378b748
--- /dev/null
+++ b/include/linux/atomic.h
@@ -0,0 +1,46 @@
+#ifndef _COMPAT_LINUX_ATOMIC_H
+#define _COMPAT_LINUX_ATOMIC_H 1
+
+#include <linux/version.h>
+
+#if (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,36))
+#include_next <linux/atomic.h>
+#else
+
+#include <asm/atomic.h>
+
+/**
+ * atomic_inc_not_zero_hint - increment if not null
+ * @v: pointer of type atomic_t
+ * @hint: probable value of the atomic before the increment
+ *
+ * This version of atomic_inc_not_zero() gives a hint of probable
+ * value of the atomic. This helps processor to not read the memory
+ * before doing the atomic read/modify/write cycle, lowering
+ * number of bus transactions on some arches.
+ *
+ * Returns: 0 if increment was not done, 1 otherwise.
+ */
+#ifndef atomic_inc_not_zero_hint
+static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
+{
+       int val, c = hint;
+
+       /* sanity test, should be removed by compiler if hint is a constant */
+       if (!hint)
+               return atomic_inc_not_zero(v);
+
+       do {
+               val = atomic_cmpxchg(v, c, c + 1);
+               if (val == c)
+                       return 1;
+               c = val;
+       } while (c);
+
+       return 0;
+}
+#endif
+
+#endif /* (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,36)) */
+
+#endif /* _COMPAT_LINUX_ATOMIC_H */