[PATCH 4/7] microblaze: Add SMP implementation of xchg and cmpxchg

Michal Simek
2020-02-12T15:42:44Z

From: Stefan Asserhall <stefan.asserhall@xilinx.com>

Microblaze support only 32bit loads and stores that's why only 4 byte
operations are supported by SMP.

Signed-off-by: Stefan Asserhall <stefan.asserhall@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

arch/microblaze/include/asm/cmpxchg.h | 87 +++++++++++++++++++++++++++
1 file changed, 87 insertions(+)

diff --git a/arch/microblaze/include/asm/cmpxchg.h b/arch/microblaze/include/asm/cmpxchg.h
index 3523b51aab36..0c24ac37df7f 100644
--- a/arch/microblaze/include/asm/cmpxchg.h
+++ b/arch/microblaze/include/asm/cmpxchg.h
@@ -4,6 +4,93 @@

#ifndef CONFIG_SMP
# include <asm-generic/cmpxchg.h>
+#else
+
+extern void __xchg_called_with_bad_pointer(void);
+
+static inline unsigned long __xchg_u32(volatile void *p, unsigned long val)
+{
+ unsigned long prev, temp;
+
+ __asm__ __volatile__ (
+ /* load conditional address in %3 to %0 */
+ "1: lwx %0, %3, r0;\n"
+ /* attempt store of new value */
+ " swx %4, %3, r0;\n"
+ /* checking msr carry flag */
+ " addic %1, r0, 0;\n"
+ /* store failed (MSR[C] set)? try again */
+ " bnei %1, 1b;\n"
+ /* Outputs: result value */
+ : "=&r" (prev), "=&r" (temp), "+m" (*(volatile unsigned int *)p)
+ /* Inputs: counter address */
+ : "r" (p), "r" (val)
+ : "cc", "memory"
+ );
+
+ return prev;
+}
+
+static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
+ int size)
+{
+ if (size == 4)
+ return __xchg_u32(ptr, x);
+
+ __xchg_called_with_bad_pointer();
+ return x;
+}
+
+#define xchg(ptr, x) ({ \
+ ((__typeof__(*(ptr))) \
+ __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
+})
+
+static inline unsigned long __cmpxchg_u32(volatile unsigned int *p,
+ unsigned long old, unsigned long new)
+{
+ int result, tmp;
+
+ __asm__ __volatile__ (
+ /* load conditional address in %3 to %0 */
+ "1: lwx %0, %3, r0;\n"
+ /* compare loaded value with old value */
+ " cmp %2, %0, %4;\n"
+ /* not equal to old value, write old value */
+ " bnei %2, 2f;\n"
+ /* attempt store of new value*/
+ " swx %5, %3, r0;\n"
+ /* checking msr carry flag */
+ " addic %2, r0, 0;\n"
+ /* store failed (MSR[C] set)? try again */
+ " bnei %2, 1b;\n"
+ "2: "
+ /* Outputs : result value */
+ : "=&r" (result), "+m" (*p), "=&r" (tmp)
+ /* Inputs : counter address, old, new */
+ : "r" (p), "r" (old), "r" (new), "r" (&tmp)
+ : "cc", "memory"
+ );
+
+ return result;
+}
+
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+ unsigned long new, unsigned int size)
+{
+ if (size == 4)
+ return __cmpxchg_u32(ptr, old, new);
+
+ __xchg_called_with_bad_pointer();
+ return old;
+}
+
+#define cmpxchg(ptr, o, n) ({ \
+ ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr)))); \
+})
+
+
#endif

#endif /* _ASM_MICROBLAZE_CMPXCHG_H */
--
2.25.0