sh: GUSA atomic rollback support.
This implements kernel-level atomic rollback built on top of gUSA,
as an alternative non-IRQ based atomicity method. This is generally
a faster method for platforms that are lacking the LL/SC pairs that
SH-4A and later use, and is only supportable on legacy cores.
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/cmpxchg-irq.h b/include/asm-sh/cmpxchg-irq.h
new file mode 100644
index 0000000..43049ec
--- /dev/null
+++ b/include/asm-sh/cmpxchg-irq.h
@@ -0,0 +1,40 @@
+#ifndef __ASM_SH_CMPXCHG_IRQ_H
+#define __ASM_SH_CMPXCHG_IRQ_H
+
+static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
+{
+ unsigned long flags, retval;
+
+ local_irq_save(flags);
+ retval = *m;
+ *m = val;
+ local_irq_restore(flags);
+ return retval;
+}
+
+static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
+{
+ unsigned long flags, retval;
+
+ local_irq_save(flags);
+ retval = *m;
+ *m = val & 0xff;
+ local_irq_restore(flags);
+ return retval;
+}
+
+static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
+ unsigned long new)
+{
+ __u32 retval;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ retval = *m;
+ if (retval == old)
+ *m = new;
+ local_irq_restore(flags); /* implies memory barrier */
+ return retval;
+}
+
+#endif /* __ASM_SH_CMPXCHG_IRQ_H */