summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/platforms/microwatt/rng.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/powerpc/platforms/microwatt/rng.c')
-rw-r--r--arch/powerpc/platforms/microwatt/rng.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
new file mode 100644
index 000000000..8ece87d00
--- /dev/null
+++ b/arch/powerpc/platforms/microwatt/rng.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Derived from arch/powerpc/platforms/powernv/rng.c, which is:
+ * Copyright 2013, Michael Ellerman, IBM Corporation.
+ */
+
+#define pr_fmt(fmt) "microwatt-rng: " fmt
+
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <asm/archrandom.h>
+#include <asm/cputable.h>
+#include <asm/machdep.h>
+#include "microwatt.h"
+
+#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
+
+static int microwatt_get_random_darn(unsigned long *v)
+{
+ unsigned long val;
+
+ /* Using DARN with L=1 - 64-bit conditioned random number */
+ asm volatile(PPC_DARN(%0, 1) : "=r"(val));
+
+ if (val == DARN_ERR)
+ return 0;
+
+ *v = val;
+
+ return 1;
+}
+
+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;
+ }
+ }
+}