[PATCH v5] hwrng: add Zhaoxin rng driver base on rep_xstore instruction

LeoLiu-oc
2023-12-27T03:59:03Z

From: LeoLiuoc <LeoLiu-oc@zhaoxin.com>

Add support for Zhaoxin hardware random number generator.
This driver base on rep_xstore instruction and uses the same
X86_FEATURE_XSTORE as via-rng driver. Therefore, modify the x86_cpu_id
array in the via-rng driver, so that the corresponding driver can be
correctly loader on respective platforms.

v1 -> v2:
1. Fix assembler code errors
2. Remove redundant CPU model check codes

v2 -> v3:
1. Optimize code details based on the kernel style

v3 -> v4:
1. Fix a typographical error

v4 -> v5:
1. Modified the definition and declaration of the x86_cpu_id table

Signed-off-by: LeoLiuoc <LeoLiu-oc@zhaoxin.com>
---
drivers/char/hw_random/Kconfig | 12 ++++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/via-rng.c | 10 +--
drivers/char/hw_random/zhaoxin-rng.c | 93 ++++++++++++++++++++++++++++
4 files changed, 111 insertions(+), 5 deletions(-)
create mode 100644 drivers/char/hw_random/zhaoxin-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 442c40efb200..3c1c4fa1203c 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -152,6 +152,18 @@ config HW_RANDOM_VIA

If unsure, say Y.

+config HW_RANDOM_ZHAOXIN
+ tristate "Zhaoxin HW Random Number Generator support"
+ depends on X86
+ help
+ This driver provides kernel-side support for the Random Number
+ Generator hardware found on Zhaoxin based motherboards.
+
+ To compile this driver as a module, choose M here: the
+ module will be called zhaoxin-rng.
+
+ If unsure, say Y.
+
config HW_RANDOM_IXP4XX
tristate "Intel IXP4xx NPU HW Pseudo-Random Number Generator support"
depends on ARCH_IXP4XX || COMPILE_TEST
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 32549a1186dc..ef5b3ae0794d 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_HW_RANDOM_GEODE) += geode-rng.o
obj-$(CONFIG_HW_RANDOM_N2RNG) += n2-rng.o
n2-rng-y := n2-drv.o n2-asm.o
obj-$(CONFIG_HW_RANDOM_VIA) += via-rng.o
+obj-$(CONFIG_HW_RANDOM_ZHAOXIN) += zhaoxin-rng.o
obj-$(CONFIG_HW_RANDOM_EXYNOS) += exynos-trng.o
obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index a9a0a3b09c8b..4288e1114fc9 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -35,7 +35,7 @@
#include <asm/cpufeature.h>
#include <asm/fpu/api.h>

-
+static struct x86_cpu_id via_rng_cpu_id[];

enum {
@@ -135,7 +135,7 @@ static int via_rng_init(struct hwrng *rng)
* is always enabled if CPUID rng_en is set. There is no
* RNG configuration like it used to be the case in this
* register */
- if (((c->x86 == 6) && (c->x86_model >= 0x0f)) || (c->x86 > 6)){
+ if ((c->x86 == 6) && (c->x86_model >= 0x0f)) {
if (!boot_cpu_has(X86_FEATURE_XSTORE_EN)) {
pr_err(PFX "can't enable hardware RNG "
"if XSTORE is not enabled\n");
@@ -196,7 +196,7 @@ static int __init via_rng_mod_init(void)
{
int err;

- if (!boot_cpu_has(X86_FEATURE_XSTORE))
+ if (!x86_match_cpu(via_rng_cpu_id))
return -ENODEV;

pr_info("VIA RNG detected\n");
@@ -217,8 +217,8 @@ static void __exit via_rng_mod_exit(void)
}
module_exit(via_rng_mod_exit);

-static struct x86_cpu_id __maybe_unused via_rng_cpu_id[] = {
- X86_MATCH_FEATURE(X86_FEATURE_XSTORE, NULL),
+static struct x86_cpu_id via_rng_cpu_id[] = {
+ X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_XSTORE, NULL),
{}
};
MODULE_DEVICE_TABLE(x86cpu, via_rng_cpu_id);
diff --git a/drivers/char/hw_random/zhaoxin-rng.c b/drivers/char/hw_random/zhaoxin-rng.c
new file mode 100644
index 000000000000..5b4586c6dc8a
--- /dev/null
+++ b/drivers/char/hw_random/zhaoxin-rng.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RNG driver for Zhaoxin RNGs
+ *
+ * Copyright 2023 (c) Zhaoxin Semiconductor Co., Ltd
+ */
+
+#include <asm/cpu_device_id.h>
+#include <asm/fpu/api.h>
+#include <crypto/padlock.h>
+#include <linux/cpufeature.h>
+#include <linux/delay.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+enum {
+ ZHAOXIN_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */
+ ZHAOXIN_RNG_CHUNK_4 = 0x01, /* 32 rand bits, 32 stored bits */
+ ZHAOXIN_RNG_CHUNK_2 = 0x02, /* 16 rand bits, 32 stored bits */
+ ZHAOXIN_RNG_CHUNK_1 = 0x03, /* 8 rand bits, 32 stored bits */
+ ZHAOXIN_RNG_MAX_SIZE = (128 * 1024),
+};
+
+static int zhaoxin_rng_init(struct hwrng *rng)
+{
+ if (!boot_cpu_has(X86_FEATURE_XSTORE_EN)) {
+ pr_err(PFX "can't enable hardware RNG if XSTORE is not enabled\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static inline int rep_xstore(size_t size, size_t factor, void *result)
+{
+ asm(".byte 0xf3, 0x0f, 0xa7, 0xc0"
+ : "=m"(*(size_t *)result), "+c"(size), "+d"(factor), "+D"(result));
+
+ return 0;
+}
+
+static int zhaoxin_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ if (max > ZHAOXIN_RNG_MAX_SIZE)
+ max = ZHAOXIN_RNG_MAX_SIZE;
+
+ rep_xstore(max, ZHAOXIN_RNG_CHUNK_1, data);
+
+ return max;
+}
+
+static struct hwrng zhaoxin_rng = {
+ .name = "zhaoxin",
+ .init = zhaoxin_rng_init,
+ .read = zhaoxin_rng_read,
+};
+
+static struct x86_cpu_id zhaoxin_rng_cpu_ids[] = {
+ X86_MATCH_VENDOR_FAM_FEATURE(ZHAOXIN, 6, X86_FEATURE_XSTORE, NULL),
+ X86_MATCH_VENDOR_FAM_FEATURE(ZHAOXIN, 7, X86_FEATURE_XSTORE, NULL),
+ X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 7, X86_FEATURE_XSTORE, NULL),
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, zhaoxin_rng_cpu_ids);
+
+static int __init zhaoxin_rng_mod_init(void)
+{
+ int err;
+
+ if (!x86_match_cpu(zhaoxin_rng_cpu_ids))
+ return -ENODEV;
+
+ pr_info("Zhaoxin RNG detected\n");
+
+ err = hwrng_register(&zhaoxin_rng);
+ if (err)
+ pr_err(PFX "RNG registering failed (%d)\n", err);
+
+ return err;
+}
+module_init(zhaoxin_rng_mod_init);
+
+static void __exit zhaoxin_rng_mod_exit(void)
+{
+ hwrng_unregister(&zhaoxin_rng);
+}
+module_exit(zhaoxin_rng_mod_exit);
+
+MODULE_DESCRIPTION("H/W RNG driver for Zhaoxin CPUs");
+MODULE_AUTHOR("YunShen@zhaoxin.com");
+MODULE_LICENSE("GPL");
--
2.34.1