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-grb.h b/include/asm-sh/cmpxchg-grb.h
new file mode 100644
index 0000000..e2681ab
--- /dev/null
+++ b/include/asm-sh/cmpxchg-grb.h
@@ -0,0 +1,70 @@
+#ifndef __ASM_SH_CMPXCHG_GRB_H
+#define __ASM_SH_CMPXCHG_GRB_H
+
+static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
+{
+ unsigned long retval;
+
+ __asm__ __volatile__ (
+ " .align 2 \n\t"
+ " mova 1f, r0 \n\t" /* r0 = end point */
+ " nop \n\t"
+ " mov r15, r1 \n\t" /* r1 = saved sp */
+ " mov #-4, r15 \n\t" /* LOGIN */
+ " mov.l @%1, %0 \n\t" /* load old value */
+ " mov.l %2, @%1 \n\t" /* store new value */
+ "1: mov r1, r15 \n\t" /* LOGOUT */
+ : "=&r" (retval),
+ "+r" (m)
+ : "r" (val)
+ : "memory", "r0", "r1");
+
+ return retval;
+}
+
+static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
+{
+ unsigned long retval;
+
+ __asm__ __volatile__ (
+ " .align 2 \n\t"
+ " mova 1f, r0 \n\t" /* r0 = end point */
+ " mov r15, r1 \n\t" /* r1 = saved sp */
+ " mov #-6, r15 \n\t" /* LOGIN */
+ " mov.b @%1, %0 \n\t" /* load old value */
+ " extu.b %0, %0 \n\t" /* extend as unsigned */
+ " mov.b %2, @%1 \n\t" /* store new value */
+ "1: mov r1, r15 \n\t" /* LOGOUT */
+ : "=&r" (retval),
+ "+r" (m)
+ : "r" (val)
+ : "memory" , "r0", "r1");
+
+ return retval;
+}
+
+static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
+ unsigned long new)
+{
+ unsigned long retval;
+
+ __asm__ __volatile__ (
+ " .align 2 \n\t"
+ " mova 1f, r0 \n\t" /* r0 = end point */
+ " nop \n\t"
+ " mov r15, r1 \n\t" /* r1 = saved sp */
+ " mov #-8, r15 \n\t" /* LOGIN */
+ " mov.l @%1, %0 \n\t" /* load old value */
+ " cmp/eq %0, %2 \n\t"
+ " bf 1f \n\t" /* if not equal */
+ " mov.l %2, @%1 \n\t" /* store new value */
+ "1: mov r1, r15 \n\t" /* LOGOUT */
+ : "=&r" (retval),
+ "+r" (m)
+ : "r" (new)
+ : "memory" , "r0", "r1", "t");
+
+ return retval;
+}
+
+#endif /* __ASM_SH_CMPXCHG_GRB_H */