Blackfin: flush caches on SMP when one core calls another via IPI

Sometimes a SMP system will randomly panic at boot.  This is due to caches
being out of sync when one core tries to signal the other.  So when one
core calls another via IPI, flush the data caches.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/mach-common/smp.c

@@ -122,9 +122,17 @@ static void ipi_call_function(unsigned int cpu, struct ipi_message *msg)
 	wait = msg->call_struct.wait;
 	cpu_clear(cpu, msg->call_struct.pending);
 	func(info);
-	if (wait)
+	if (wait) {
+#ifdef __ARCH_SYNC_CORE_DCACHE
+		/*
+		 * 'wait' usually means synchronization between CPUs.
+		 * Invalidate D cache in case shared data was changed
+		 * by func() to ensure cache coherence.
+		 */
+		resync_core_dcache();
+#endif
 		cpu_clear(cpu, msg->call_struct.waitmask);
-	else
+	} else
 		kfree(msg);
 }
 
@@ -219,6 +227,13 @@ int smp_call_function(void (*func)(void *info), void *info, int wait)
 			blackfin_dcache_invalidate_range(
 				(unsigned long)(&msg->call_struct.waitmask),
 				(unsigned long)(&msg->call_struct.waitmask));
+#ifdef __ARCH_SYNC_CORE_DCACHE
+		/*
+		 * Invalidate D cache in case shared data was changed by
+		 * other processors to ensure cache coherence.
+		 */
+		resync_core_dcache();
+#endif
 		kfree(msg);
 	}
 	return 0;
@@ -261,6 +276,13 @@ int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
 			blackfin_dcache_invalidate_range(
 				(unsigned long)(&msg->call_struct.waitmask),
 				(unsigned long)(&msg->call_struct.waitmask));
+#ifdef __ARCH_SYNC_CORE_DCACHE
+		/*
+		 * Invalidate D cache in case shared data was changed by
+		 * other processors to ensure cache coherence.
+		 */
+		resync_core_dcache();
+#endif
 		kfree(msg);
 	}
 	return 0;