powerpc/microwatt: 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: c25769f ("powerpc/microwatt: Add support for hardware random number generator")
Cc: stable@vger.kernel.org # v5.14+
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/20220611151015.548325-2-Jason@zx2c4.com

Author: zx2c4

arch/powerpc/platforms/microwatt/microwatt.h

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MICROWATT_H
+#define _MICROWATT_H
+
+void microwatt_rng_init(void);
+
+#endif /* _MICROWATT_H */

arch/powerpc/platforms/microwatt/rng.c

@@ -11,6 +11,7 @@
 #include <asm/archrandom.h>
 #include <asm/cputable.h>
 #include <asm/machdep.h>
+#include "microwatt.h"
 
 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
 
@@ -29,20 +30,15 @@ static int microwatt_get_random_darn(unsigned long *v)
 	return 1;
 }
 
-static __init int rng_init(void)
+void __init microwatt_rng_init(void)
 {
 	unsigned long val;
 	int i;
 
 	for (i = 0; i < 10; i++) {
 		if (microwatt_get_random_darn(&val)) {
 			ppc_md.get_random_seed = microwatt_get_random_darn;
-			return 0;
+			return;
 		}
 	}
-
-	pr_warn("Unable to use DARN for get_random_seed()\n");
-
-	return -EIO;
 }
-machine_subsys_initcall(, rng_init);

arch/powerpc/platforms/microwatt/setup.c

@@ -16,6 +16,8 @@
 #include <asm/xics.h>
 #include <asm/udbg.h>
 
+#include "microwatt.h"
+
 static void __init microwatt_init_IRQ(void)
 {
 	xics_init();
@@ -32,10 +34,16 @@ static int __init microwatt_populate(void)
 }
 machine_arch_initcall(microwatt, microwatt_populate);
 
+static void __init microwatt_setup_arch(void)
+{
+	microwatt_rng_init();
+}
+
 define_machine(microwatt) {
 	.name			= "microwatt",
 	.probe			= microwatt_probe,
 	.init_IRQ		= microwatt_init_IRQ,
+	.setup_arch		= microwatt_setup_arch,
 	.progress		= udbg_progress,
 	.calibrate_decr		= generic_calibrate_decr,
 };