ARM: 5994/1: ARM: Add outer_cache_fns.sync function pointer (2/4)

This patch introduces the outer_cache_fns.sync function pointer together
with the OUTER_CACHE_SYNC config option that can be used to drain the
write buffer of the outer cache.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/outercache.h

@@ -25,6 +25,9 @@ struct outer_cache_fns {
 	void (*inv_range)(unsigned long, unsigned long);
 	void (*clean_range)(unsigned long, unsigned long);
 	void (*flush_range)(unsigned long, unsigned long);
+#ifdef CONFIG_OUTER_CACHE_SYNC
+	void (*sync)(void);
+#endif
 };
 
 #ifdef CONFIG_OUTER_CACHE
@@ -58,4 +61,15 @@ static inline void outer_flush_range(unsigned long start, unsigned long end)
 
 #endif
 
+#ifdef CONFIG_OUTER_CACHE_SYNC
+static inline void outer_sync(void)
+{
+	if (outer_cache.sync)
+		outer_cache.sync();
+}
+#else
+static inline void outer_sync(void)
+{ }
+#endif
+
 #endif	/* __ASM_OUTERCACHE_H */

arch/arm/mm/Kconfig

@@ -736,6 +736,12 @@ config NEEDS_SYSCALL_FOR_CMPXCHG
 config OUTER_CACHE
 	bool
 
+config OUTER_CACHE_SYNC
+	bool
+	help
+	  The outer cache has a outer_cache_fns.sync function pointer
+	  that can be used to drain the write buffer of the outer cache.
+
 config CACHE_FEROCEON_L2
 	bool "Enable the Feroceon L2 cache controller"
 	depends on ARCH_KIRKWOOD || ARCH_MV78XX0