[PATCH v3 0/3] MediaTek Security random number generator support

[PATCH v3 0/3] MediaTek Security random number generator support

[Neal Liu]

These patch series introduce a generic rng driver for Trustzone
based kernel driver which would like to communicate with ATF
SIP services.

Patch #1 initials SMC fid table for Mediatek SIP interfaces and
adds HWRNG related SMC call.

Patch #2..3 adds mtk-sec-rng kernel driver for Trustzone based SoCs.
For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
entropy sources is not accessible from normal world (linux) and
rather accessible from secure world (ATF/TEE) only. This driver aims
to provide a generic interface to ATF rng service.


changes since v1:
- rename mt67xx-rng to mtk-sec-rng since all MediaTek ARMv8 SoCs
can reuse this driver.
- refine coding style and unnecessary check.

changes since v2:
- remove unused comments.
- remove redundant variable.

Neal Liu (3):
  soc: mediatek: add SMC fid table for SIP interface
  dt-bindings: rng: update bindings for MediaTek ARMv8 SoCs
  hwrng: add mtk-sec-rng driver

 .../devicetree/bindings/rng/mtk-rng.txt       | 15 ++-
 drivers/char/hw_random/Kconfig                | 16 +++
 drivers/char/hw_random/Makefile               |  1 +
 drivers/char/hw_random/mtk-sec-rng.c          | 97 +++++++++++++++++++
 include/linux/soc/mediatek/mtk_sip_svc.h      | 33 +++++++
 5 files changed, 159 insertions(+), 3 deletions(-)
 create mode 100644 drivers/char/hw_random/mtk-sec-rng.c
 create mode 100644 include/linux/soc/mediatek/mtk_sip_svc.h

-- 
2.18.0

[PATCH v3 1/3] soc: mediatek: add SMC fid table for SIP interface

[Neal Liu]

1. Add a header file to provide SIP interface to ATF
2. Add hwrng SMC fid

Signed-off-by: Neal Liu <neal.liu@mediatek.com>
---
 include/linux/soc/mediatek/mtk_sip_svc.h |   33 ++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 include/linux/soc/mediatek/mtk_sip_svc.h

diff --git a/include/linux/soc/mediatek/mtk_sip_svc.h b/include/linux/soc/mediatek/mtk_sip_svc.h
new file mode 100644
index 0000000..e70c325
--- /dev/null
+++ b/include/linux/soc/mediatek/mtk_sip_svc.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019 MediaTek Inc.
+ */
+
+#ifndef _MTK_SECURE_API_H_
+#define _MTK_SECURE_API_H_
+
+#include <linux/kernel.h>
+
+/* Error Code */
+#define SIP_SVC_E_SUCCESS		0
+#define SIP_SVC_E_NOT_SUPPORTED		-1
+#define SIP_SVC_E_INVALID_PARAMS	-2
+#define SIP_SVC_E_INVALID_RANGE		-3
+#define SIP_SVC_E_PERMISSION_DENY	-4
+
+#ifdef CONFIG_ARM64
+#define MTK_SIP_SMC_AARCH_BIT		BIT(30)
+#else
+#define MTK_SIP_SMC_AARCH_BIT		0
+#endif
+
+/*******************************************************************************
+ * Defines for Mediatek runtime services func ids
+ ******************************************************************************/
+
+/* Security related SMC call */
+/* HWRNG */
+#define MTK_SIP_KERNEL_GET_RND \
+	(0x82000206 | MTK_SIP_SMC_AARCH_BIT)
+
+#endif /* _MTK_SECURE_API_H_ */
-- 
1.7.9.5

[PATCH v3 2/3] dt-bindings: rng: update bindings for MediaTek ARMv8 SoCs

[Neal Liu]

Document the binding used by the MediaTek ARMv8 SoCs random
number generator with TrustZone enabled.

Signed-off-by: Neal Liu <neal.liu@mediatek.com>
---
 Documentation/devicetree/bindings/rng/mtk-rng.txt |   15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.txt b/Documentation/devicetree/bindings/rng/mtk-rng.txt
index 2bc89f1..fb3dd59 100644
--- a/Documentation/devicetree/bindings/rng/mtk-rng.txt
+++ b/Documentation/devicetree/bindings/rng/mtk-rng.txt
@@ -3,9 +3,13 @@ found in MediaTek SoC family
 
 Required properties:
 - compatible	    : Should be
-			"mediatek,mt7622-rng", 	"mediatek,mt7623-rng" : for MT7622
-			"mediatek,mt7629-rng",  "mediatek,mt7623-rng" : for MT7629
-			"mediatek,mt7623-rng" : for MT7623
+			"mediatek,mt7622-rng", "mediatek,mt7623-rng" for MT7622
+			"mediatek,mt7629-rng", "mediatek,mt7623-rng" for MT7629
+			"mediatek,mt7623-rng" for MT7623
+			"mediatek,mtk-sec-rng" for MediaTek ARMv8 SoCs with
+			security RNG
+
+Optional properties:
 - clocks	    : list of clock specifiers, corresponding to
 		      entries in clock-names property;
 - clock-names	    : Should contain "rng" entries;
@@ -19,3 +23,8 @@ rng: rng@1020f000 {
 	clocks = <&infracfg CLK_INFRA_TRNG>;
 	clock-names = "rng";
 };
+
+/* secure RNG */
+hwrng: hwrng {
+	compatible = "mediatek,mtk-sec-rng";
+};
-- 
1.7.9.5

[PATCH v3 3/3] hwrng: add mtk-sec-rng driver

[Neal Liu]

For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
entropy sources is not accessible from normal world (linux) and
rather accessible from secure world (ATF/TEE) only. This driver aims
to provide a generic interface to ATF rng service.

Signed-off-by: Neal Liu <neal.liu@mediatek.com>
---
 drivers/char/hw_random/Kconfig       |   16 ++++++
 drivers/char/hw_random/Makefile      |    1 +
 drivers/char/hw_random/mtk-sec-rng.c |   97 ++++++++++++++++++++++++++++++++++
 3 files changed, 114 insertions(+)
 create mode 100644 drivers/char/hw_random/mtk-sec-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 25a7d8f..6c82a3b 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -398,6 +398,22 @@ config HW_RANDOM_MTK
 
 	  If unsure, say Y.
 
+config HW_RANDOM_MTK_SEC
+	tristate "MediaTek Security Random Number Generator support"
+	depends on HW_RANDOM
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	default HW_RANDOM
+	help
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on MediaTek SoCs. The difference with
+	  mtk-rng is the Random Number Generator hardware is secure
+	  access only.
+
+	  To compile this driver as a module, choose M here. the
+	  module will be called mtk-sec-rng.
+
+	  If unsure, say Y.
+
 config HW_RANDOM_S390
 	tristate "S390 True Random Number Generator support"
 	depends on S390
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 7c9ef4a..0ae4993 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
 obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o
 obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o
 obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o
+obj-$(CONFIG_HW_RANDOM_MTK_SEC) += mtk-sec-rng.o
 obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
 obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
 obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o
diff --git a/drivers/char/hw_random/mtk-sec-rng.c b/drivers/char/hw_random/mtk-sec-rng.c
new file mode 100644
index 0000000..ecd2e29
--- /dev/null
+++ b/drivers/char/hw_random/mtk-sec-rng.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 MediaTek Inc.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/hw_random.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/soc/mediatek/mtk_sip_svc.h>
+
+#define MT67XX_RNG_MAGIC	0x74726e67
+#define SMC_RET_NUM		4
+#define MTK_SEC_RND_SIZE	(sizeof(u32) * SMC_RET_NUM)
+
+struct mtk_sec_rng_priv {
+	struct hwrng rng;
+};
+
+static void mtk_sec_get_rnd(uint32_t *val)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(MTK_SIP_KERNEL_GET_RND,
+		      MT67XX_RNG_MAGIC, 0, 0, 0, 0, 0, 0, &res);
+
+	val[0] = res.a0;
+	val[1] = res.a1;
+	val[2] = res.a2;
+	val[3] = res.a3;
+}
+
+static int mtk_sec_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	u32 val[4] = {0};
+	int retval = 0;
+	int i;
+
+	while (max >= MTK_SEC_RND_SIZE) {
+		mtk_sec_get_rnd(val);
+
+		for (i = 0; i < SMC_RET_NUM; i++) {
+			*(u32 *)buf = val[i];
+			buf += sizeof(u32);
+		}
+
+		retval += MTK_SEC_RND_SIZE;
+		max -= MTK_SEC_RND_SIZE;
+	}
+
+	return retval;
+}
+
+static int mtk_sec_rng_probe(struct platform_device *pdev)
+{
+	struct mtk_sec_rng_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->rng.name = pdev->name;
+	priv->rng.read = mtk_sec_rng_read;
+	priv->rng.priv = (unsigned long)&pdev->dev;
+	priv->rng.quality = 900;
+
+	ret = devm_hwrng_register(&pdev->dev, &priv->rng);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register rng device: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id mtk_sec_rng_match[] = {
+	{ .compatible = "mediatek,mtk-sec-rng", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mtk_sec_rng_match);
+
+static struct platform_driver mtk_sec_rng_driver = {
+	.probe = mtk_sec_rng_probe,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.owner = THIS_MODULE,
+		.of_match_table = mtk_sec_rng_match,
+	},
+};
+
+module_platform_driver(mtk_sec_rng_driver);
+
+MODULE_DESCRIPTION("MediaTek Security Random Number Generator Driver");
+MODULE_AUTHOR("Neal Liu <neal.liu@mediatek.com>");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5

Re: [PATCH v3 2/3] dt-bindings: rng: update bindings for MediaTek ARMv8 SoCs

[Rob Herring]

On Mon, Jun 10, 2019 at 06:36:23PM +0800, Neal Liu wrote:
> Document the binding used by the MediaTek ARMv8 SoCs random
> number generator with TrustZone enabled.
> 
> Signed-off-by: Neal Liu <neal.liu@mediatek.com>
> ---
>  Documentation/devicetree/bindings/rng/mtk-rng.txt |   15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.txt b/Documentation/devicetree/bindings/rng/mtk-rng.txt
> index 2bc89f1..fb3dd59 100644
> --- a/Documentation/devicetree/bindings/rng/mtk-rng.txt
> +++ b/Documentation/devicetree/bindings/rng/mtk-rng.txt
> @@ -3,9 +3,13 @@ found in MediaTek SoC family
>  
>  Required properties:
>  - compatible	    : Should be
> -			"mediatek,mt7622-rng", 	"mediatek,mt7623-rng" : for MT7622
> -			"mediatek,mt7629-rng",  "mediatek,mt7623-rng" : for MT7629
> -			"mediatek,mt7623-rng" : for MT7623
> +			"mediatek,mt7622-rng", "mediatek,mt7623-rng" for MT7622
> +			"mediatek,mt7629-rng", "mediatek,mt7623-rng" for MT7629
> +			"mediatek,mt7623-rng" for MT7623
> +			"mediatek,mtk-sec-rng" for MediaTek ARMv8 SoCs with
> +			security RNG

Is there any commonality with the prior h/w? If not, make this a 
separate binding doc.

> +
> +Optional properties:
>  - clocks	    : list of clock specifiers, corresponding to
>  		      entries in clock-names property;
>  - clock-names	    : Should contain "rng" entries;
> @@ -19,3 +23,8 @@ rng: rng@1020f000 {
>  	clocks = <&infracfg CLK_INFRA_TRNG>;
>  	clock-names = "rng";
>  };
> +
> +/* secure RNG */
> +hwrng: hwrng {
> +	compatible = "mediatek,mtk-sec-rng";

How does one access this? Seems like this should be part of a node for 
firmware? What about other functions?

> +};
> -- 
> 1.7.9.5
> 

Re: [PATCH v3 2/3] dt-bindings: rng: update bindings for MediaTek ARMv8 SoCs

[Neal Liu]

On Tue, 2019-06-11 at 16:53 -0600, Rob Herring wrote:
> On Mon, Jun 10, 2019 at 06:36:23PM +0800, Neal Liu wrote:
> > Document the binding used by the MediaTek ARMv8 SoCs random
> > number generator with TrustZone enabled.
> > 
> > Signed-off-by: Neal Liu <neal.liu@mediatek.com>
> > ---
> >  Documentation/devicetree/bindings/rng/mtk-rng.txt |   15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.txt b/Documentation/devicetree/bindings/rng/mtk-rng.txt
> > index 2bc89f1..fb3dd59 100644
> > --- a/Documentation/devicetree/bindings/rng/mtk-rng.txt
> > +++ b/Documentation/devicetree/bindings/rng/mtk-rng.txt
> > @@ -3,9 +3,13 @@ found in MediaTek SoC family
> >  
> >  Required properties:
> >  - compatible	    : Should be
> > -			"mediatek,mt7622-rng", 	"mediatek,mt7623-rng" : for MT7622
> > -			"mediatek,mt7629-rng",  "mediatek,mt7623-rng" : for MT7629
> > -			"mediatek,mt7623-rng" : for MT7623
> > +			"mediatek,mt7622-rng", "mediatek,mt7623-rng" for MT7622
> > +			"mediatek,mt7629-rng", "mediatek,mt7623-rng" for MT7629
> > +			"mediatek,mt7623-rng" for MT7623
> > +			"mediatek,mtk-sec-rng" for MediaTek ARMv8 SoCs with
> > +			security RNG
> 
> Is there any commonality with the prior h/w? If not, make this a 
> separate binding doc.

There are less common with the prior h/w... I had been thinking about
make new binding doc. Since your suggestion, I'll make one.

> 
> > +
> > +Optional properties:
> >  - clocks	    : list of clock specifiers, corresponding to
> >  		      entries in clock-names property;
> >  - clock-names	    : Should contain "rng" entries;
> > @@ -19,3 +23,8 @@ rng: rng@1020f000 {
> >  	clocks = <&infracfg CLK_INFRA_TRNG>;
> >  	clock-names = "rng";
> >  };
> > +
> > +/* secure RNG */
> > +hwrng: hwrng {
> > +	compatible = "mediatek,mtk-sec-rng";
> 
> How does one access this? Seems like this should be part of a node for 
> firmware? What about other functions?

Yes, We move all hw register & clock control access to the ATF by smc.

> 
> > +};
> > -- 
> > 1.7.9.5
> >