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From da155e990fe763d3a03bdac76054e1d5530b8c16 Mon Sep 17 00:00:00 2001
From: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
Date: Wed, 10 Mar 2021 20:15:10 -0800
Subject: [PATCH] Improve randomness of mac address generation
This commit improves randomness of mac address generation using
AST2600's hardware random number generator.
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
---
lib/rand.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/lib/rand.c b/lib/rand.c
index af4cf3a0e8cf..0a12b0b82276 100644
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -8,16 +8,32 @@
*/
#include <common.h>
+#include <asm/io.h>
static unsigned int y = 1U;
unsigned int rand_r(unsigned int *seedp)
{
+#ifdef CONFIG_ASPEED_AST2600
+#define SCU_524 0x1e6e2524
+ int i;
+
+ /*
+ * Use hardware random number generator. It generates a new number on
+ * each 1us or on each 32 read command cycle so this code makes
+ * intentional dummy 32 reads.
+ */
+ for (i = 0; i < 32; i++)
+ *seedp ^= readl(SCU_524);
+
+ return readl(SCU_524);
+#else
*seedp ^= (*seedp << 13);
*seedp ^= (*seedp >> 17);
*seedp ^= (*seedp << 5);
return *seedp;
+#endif
}
unsigned int rand(void)
--
2.17.1
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