From: Paul Mackerras <paulus@ozlabs.org>
To: linuxppc-dev@ozlabs.org
Subject: [PATCH v2 6/9] powerpc/microwatt: Add support for hardware random number generator
Date: Fri, 18 Jun 2021 13:47:08 +1000 [thread overview]
Message-ID: <YMwXPHlV/ZleiQUY@thinks.paulus.ozlabs.org> (raw)
In-Reply-To: <YMwWPcsaWzMlDPqQ@thinks.paulus.ozlabs.org>
Microwatt's hardware RNG is accessed using the DARN instruction.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
arch/powerpc/platforms/microwatt/Kconfig | 1 +
arch/powerpc/platforms/microwatt/Makefile | 2 +-
arch/powerpc/platforms/microwatt/rng.c | 48 +++++++++++++++++++++++
3 files changed, 50 insertions(+), 1 deletion(-)
create mode 100644 arch/powerpc/platforms/microwatt/rng.c
diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
index 50ed0cedb5f1..8f6a81978461 100644
--- a/arch/powerpc/platforms/microwatt/Kconfig
+++ b/arch/powerpc/platforms/microwatt/Kconfig
@@ -7,6 +7,7 @@ config PPC_MICROWATT
select PPC_ICP_NATIVE
select PPC_NATIVE
select PPC_UDBG_16550
+ select ARCH_RANDOM
help
This option enables support for FPGA-based Microwatt implementations.
diff --git a/arch/powerpc/platforms/microwatt/Makefile b/arch/powerpc/platforms/microwatt/Makefile
index e6885b3b2ee7..116d6d3ad3f0 100644
--- a/arch/powerpc/platforms/microwatt/Makefile
+++ b/arch/powerpc/platforms/microwatt/Makefile
@@ -1 +1 @@
-obj-y += setup.o
+obj-y += setup.o rng.o
diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
new file mode 100644
index 000000000000..3d8ee6eb7dad
--- /dev/null
+++ b/arch/powerpc/platforms/microwatt/rng.c
@@ -0,0 +1,48 @@
+// 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>
+
+#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
+
+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;
+}
+
+static __init int 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;
+ }
+ }
+
+ pr_warn("Unable to use DARN for get_random_seed()\n");
+
+ return -EIO;
+}
+machine_subsys_initcall(, rng_init);
--
2.31.1
next prev parent reply other threads:[~2021-06-18 3:56 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 3:42 [PATCH v2 0/9] powerpc: Add support for Microwatt soft-core Paul Mackerras
2021-06-18 3:43 ` [PATCH v2 1/9] powerpc: Add Microwatt platform Paul Mackerras
2021-06-19 3:03 ` Nicholas Piggin
2021-06-18 3:44 ` [PATCH v2 2/9] powerpc: Add Microwatt device tree Paul Mackerras
2021-06-19 14:26 ` Segher Boessenkool
2021-06-20 12:08 ` Paul Mackerras
2021-06-21 13:54 ` Segher Boessenkool
2021-06-18 3:45 ` [PATCH v2 3/9] powerpc/microwatt: Populate platform bus from device-tree Paul Mackerras
2021-06-18 3:45 ` [PATCH v2 4/9] powerpc/xics: Add a native ICS backend for microwatt Paul Mackerras
2021-06-18 3:46 ` [PATCH v2 5/9] powerpc/microwatt: Use standard 16550 UART for console Paul Mackerras
2021-06-18 7:40 ` Nicholas Piggin
2021-06-18 12:12 ` Paul Mackerras
2021-06-19 2:58 ` Nicholas Piggin
2021-08-12 13:14 ` Christophe Leroy
2021-08-12 16:09 ` Segher Boessenkool
2021-06-18 3:47 ` Paul Mackerras [this message]
2021-06-19 3:08 ` [PATCH v2 6/9] powerpc/microwatt: Add support for hardware random number generator Nicholas Piggin
2021-06-19 14:36 ` Segher Boessenkool
2021-06-20 8:19 ` Nicholas Piggin
2021-06-18 3:48 ` [PATCH v2 7/9] powerpc/microwatt: Add microwatt_defconfig Paul Mackerras
2021-06-18 3:49 ` [PATCH v2 8/9] powerpc/boot: Fixup device-tree on little endian Paul Mackerras
2021-06-19 3:14 ` Nicholas Piggin
2021-06-18 3:49 ` [PATCH v2 9/9] powerpc/boot: Add a boot wrapper for Microwatt Paul Mackerras
2021-06-19 3:16 ` Nicholas Piggin
2021-06-19 14:45 ` [PATCH v2 0/9] powerpc: Add support for Microwatt soft-core Segher Boessenkool
2021-06-24 14:03 ` Michael Ellerman
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