Merge remote-tracking branch 'lts/linux-4.4.y' into linux-linaro-lsk-v4.4

[firefly-linux-kernel-4.4.55.git] / arch / arm64 / include / asm / spinlock.h

diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 499e8de33a0004c42c170de2fc007d3224908ac3..53ee219e76a735a8824df8b8b472ffb9febef29e 100644 (file)
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -26,9 +26,28 @@
  * The memory barriers are implicit with the load-acquire and store-release
  * instructions.
  */
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+       unsigned int tmp;
+       arch_spinlock_t lockval;
 
-#define arch_spin_unlock_wait(lock) \
-       do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
+       asm volatile(
+"      sevl\n"
+"1:    wfe\n"
+"2:    ldaxr   %w0, %2\n"
+"      eor     %w1, %w0, %w0, ror #16\n"
+"      cbnz    %w1, 1b\n"
+       ARM64_LSE_ATOMIC_INSN(
+       /* LL/SC */
+"      stxr    %w1, %w0, %2\n"
+"      cbnz    %w1, 2b\n", /* Serialise against any concurrent lockers */
+       /* LSE atomics */
+"      nop\n"
+"      nop\n")
+       : "=&r" (lockval), "=&r" (tmp), "+Q" (*lock)
+       :
+       : "memory");
+}
 
 #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)