ARM: trusted_foundations: Provide information about whether firmware is registered

Add a helper that provides information about whether Trusted Foundations
firmware operations have been registered.
Tested-by: Robert Yang <decatf@gmail.com>
Tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/firmware/trusted_foundations.c

@@ -167,3 +167,8 @@ void of_register_trusted_foundations(void)
 		panic("Trusted Foundation: missing version-minor property\n");
 	register_trusted_foundations(&pdata);
 }
+
+bool trusted_foundations_registered(void)
+{
+	return firmware_ops == &trusted_foundations_ops;
+}

arch/arm/include/asm/trusted_foundations.h

@@ -31,6 +31,7 @@
 #include <linux/of.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
+#include <linux/types.h>
 
 #include <asm/hardware/cache-l2x0.h>
 #include <asm/outercache.h>
@@ -50,6 +51,7 @@ struct trusted_foundations_platform_data {
 
 void register_trusted_foundations(struct trusted_foundations_platform_data *pd);
 void of_register_trusted_foundations(void);
+bool trusted_foundations_registered(void);
 
 #else /* CONFIG_TRUSTED_FOUNDATIONS */
 static inline void tf_dummy_write_sec(unsigned long val, unsigned int reg)
@@ -84,6 +86,11 @@ static inline void of_register_trusted_foundations(void)
 	if (of_find_compatible_node(NULL, NULL, "tlm,trusted-foundations"))
 		register_trusted_foundations(NULL);
 }
+
+static inline bool trusted_foundations_registered(void)
+{
+	return false;
+}
 #endif /* CONFIG_TRUSTED_FOUNDATIONS */
 
 #endif