powerpc/pseries: wire up rng during setup_arch()

The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call. Fortunately,
each platform already has a setup_arch function pointer, which means
it's easy to wire this up. This commit also removes some noisy log
messages that don't add much.

Fixes: a489043f ("powerpc/pseries: Implement arch_get_random_long() based on H_RANDOM")
Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220611151015.548325-4-Jason@zx2c4.com

arch/powerpc/platforms/pseries/pseries.h

@@ -122,4 +122,6 @@ void pseries_lpar_read_hblkrm_characteristics(void);
 static inline void pseries_lpar_read_hblkrm_characteristics(void) { }
 #endif
 
+void pseries_rng_init(void);
+
 #endif /* _PSERIES_PSERIES_H */

arch/powerpc/platforms/pseries/rng.c

@@ -10,6 +10,7 @@
 #include <asm/archrandom.h>
 #include <asm/machdep.h>
 #include <asm/plpar_wrappers.h>
+#include "pseries.h"
 
 
 static int pseries_get_random_long(unsigned long *v)
@@ -24,19 +25,13 @@ static int pseries_get_random_long(unsigned long *v)
 	return 0;
 }
 
-static __init int rng_init(void)
+void __init pseries_rng_init(void)
 {
 	struct device_node *dn;
 
 	dn = of_find_compatible_node(NULL, NULL, "ibm,random");
 	if (!dn)
-		return -ENODEV;
-
-	pr_info("Registering arch random hook.\n");
-
+		return;
 	ppc_md.get_random_seed = pseries_get_random_long;
-
 	of_node_put(dn);
-	return 0;
 }
-machine_subsys_initcall(pseries, rng_init);

arch/powerpc/platforms/pseries/setup.c

@@ -839,6 +839,7 @@ static void __init pSeries_setup_arch(void)
 	}
 
 	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
+	pseries_rng_init();
 }
 
 static void pseries_panic(char *str)