[PATCH 0/3] hwrng: add support for Silex Insight BA431

[PATCH 0/3] hwrng: add support for Silex Insight BA431

[Olivier Sobrie]

Hello all,

This set of patches aims at introducing a linux hwrng driver for the
Silex Insight BA431 IP which is available for various FPGA.
This hardware is for instance present in Silex Insight Viper OEM boards.

The two first patches are documenting the device tree bindings.
The last one contains the BA431 hwrng driver.

Olivier Sobrie (3):
  dt-bindings: vendor-prefixes: Add Silex Insight vendor prefix
  dt-bindings: rng: document Silex Insight BA431 hwrng
  hwrng: ba431-rng: add support for BA431 hwrng

 .../bindings/rng/silex-insight,ba431-rng.yaml |  33 +++
 .../devicetree/bindings/vendor-prefixes.yaml  |   2 +
 drivers/char/hw_random/Kconfig                |  10 +
 drivers/char/hw_random/Makefile               |   1 +
 drivers/char/hw_random/ba431-rng.c            | 241 ++++++++++++++++++
 5 files changed, 287 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml
 create mode 100644 drivers/char/hw_random/ba431-rng.c

-- 
2.26.2

[PATCH 1/3] dt-bindings: vendor-prefixes: Add Silex Insight vendor prefix

[Olivier Sobrie]

Silex Insight is a microelectronic company whose headquarter is located
in Belgium.
Web site of the company: https://www.silexinsight.com/

Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
---
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index d3891386d6710..45e555774be42 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -918,6 +918,8 @@ patternProperties:
     description: Silead Inc.
   "^silergy,.*":
     description: Silergy Corp.
+  "^silex-insight,.*":
+    description: Silex Insight
   "^siliconmitus,.*":
     description: Silicon Mitus, Inc.
   "^simtek,.*":
-- 
2.26.2

[PATCH 2/3] dt-bindings: rng: document Silex Insight BA431 hwrng

[Olivier Sobrie]

This patch documents the device tree bindings of the BA431 hardware
random number generator.

This IP is for instance present in the Viper OEM boards sold by Silex
Insight.

Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
---
 .../bindings/rng/silex-insight,ba431-rng.yaml | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml

diff --git a/Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml b/Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml
new file mode 100644
index 0000000000000..48ab82abf50ec
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/silex-insight,ba431-rng.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Silex Insight BA431 RNG bindings
+
+description: |
+  The BA431 hardware random number generator is an IP that is FIPS-140-2/3
+  certified.
+
+maintainers:
+  - Olivier Sobrie <olivier.sobrie@silexinsight.com>
+
+properties:
+  compatible:
+    const: silex-insight,ba431-rng
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng@42800000 {
+      compatible = "silex-insight,ba431-rng";
+      reg = <0x42800000 0x1000>;
+    };
+
+...
-- 
2.26.2

[PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng

[Olivier Sobrie]

Silex insight BA431 is an IP designed to generate random numbers that
can be integrated in various FPGA.
This driver adds support for it through the hwrng interface.

This driver is used in Silex Insight Viper OEM boards.

Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
Signed-off-by: Waleed Ziad <waleed94ziad@gmail.com>
---
 drivers/char/hw_random/Kconfig     |  10 ++
 drivers/char/hw_random/Makefile    |   1 +
 drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++
 3 files changed, 251 insertions(+)
 create mode 100644 drivers/char/hw_random/ba431-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 9bc46da8d77a8..ef8928fc9999d 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -74,6 +74,16 @@ config HW_RANDOM_ATMEL
 
 	  If unsure, say Y.
 
+config HW_RANDOM_BA431
+	tristate "Silex Insight BA431 Random Number Generator support"
+	default HW_RANDOM
+	help
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware based on Silex Insight BA431 IP.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ba431-rng
+
 config HW_RANDOM_BCM2835
 	tristate "Broadcom BCM2835/BCM63xx Random Number Generator support"
 	depends on ARCH_BCM2835 || ARCH_BCM_NSP || ARCH_BCM_5301X || \
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index a7801b49ce6c0..02ccadafcca99 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_HW_RANDOM_TIMERIOMEM) += timeriomem-rng.o
 obj-$(CONFIG_HW_RANDOM_INTEL) += intel-rng.o
 obj-$(CONFIG_HW_RANDOM_AMD) += amd-rng.o
 obj-$(CONFIG_HW_RANDOM_ATMEL) += atmel-rng.o
+obj-$(CONFIG_HW_RANDOM_BA431) += ba431-rng.o
 obj-$(CONFIG_HW_RANDOM_GEODE) += geode-rng.o
 obj-$(CONFIG_HW_RANDOM_N2RNG) += n2-rng.o
 n2-rng-y := n2-drv.o n2-asm.o
diff --git a/drivers/char/hw_random/ba431-rng.c b/drivers/char/hw_random/ba431-rng.c
new file mode 100644
index 0000000000000..d3bec75d405e4
--- /dev/null
+++ b/drivers/char/hw_random/ba431-rng.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Silex Insight sa.
+
+#include <linux/delay.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+
+#define BA431_RESET_DELAY			1 /* usec */
+#define BA431_RESET_READ_STATUS_RETRIES		100
+#define BA431_RESET_READ_STATUS_INTERVAL	10 /* usec */
+#define BA431_READ_RETRY_INTERVAL		1 /* usec */
+
+#define BA431_REG_CTRL				0x00
+#define BA431_REG_FIFO_LEVEL			0x04
+#define BA431_REG_STATUS			0x30
+#define BA431_REG_FIFODATA			0x80
+
+#define BA431_CTRL_ENABLE			BIT(0)
+#define BA431_CTRL_SOFTRESET			BIT(8)
+
+#define BA431_STATUS_STATE_MASK			(BIT(1) | BIT(2) | BIT(3))
+#define BA431_STATUS_STATE_OFFSET		1
+
+enum ba431_state {
+	BA431_STATE_RESET,
+	BA431_STATE_STARTUP,
+	BA431_STATE_FIFOFULLON,
+	BA431_STATE_FIFOFULLOFF,
+	BA431_STATE_RUNNING,
+	BA431_STATE_ERROR
+};
+
+struct ba431_trng {
+	struct device *dev;
+	void __iomem *base;
+	struct hwrng rng;
+	atomic_t reset_pending;
+	struct work_struct reset_work;
+};
+
+static inline u32 ba431_trng_read_reg(struct ba431_trng *ba431, u32 reg)
+{
+	return ioread32(ba431->base + reg);
+}
+
+static inline void ba431_trng_write_reg(struct ba431_trng *ba431, u32 reg,
+					u32 val)
+{
+	iowrite32(val, ba431->base + reg);
+}
+
+static inline enum ba431_state ba431_trng_get_state(struct ba431_trng *ba431)
+{
+	u32 status = ba431_trng_read_reg(ba431, BA431_REG_STATUS);
+
+	return (status & BA431_STATUS_STATE_MASK) >> BA431_STATUS_STATE_OFFSET;
+}
+
+static int ba431_trng_is_in_error(struct ba431_trng *ba431)
+{
+	enum ba431_state state = ba431_trng_get_state(ba431);
+
+	if ((state < BA431_STATE_STARTUP) ||
+	    (state >= BA431_STATE_ERROR))
+		return 1;
+
+	return 0;
+}
+
+static int ba431_trng_reset(struct ba431_trng *ba431)
+{
+	unsigned int i;
+	enum ba431_state state;
+
+	/* Disable interrupts, random generation and enable the softreset */
+	ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_SOFTRESET);
+	udelay(BA431_RESET_DELAY);
+	ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_ENABLE);
+
+	/* Wait until the state changed */
+	for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) {
+		state = ba431_trng_get_state(ba431);
+		if (state >= BA431_STATE_STARTUP)
+			break;
+
+		udelay(BA431_RESET_READ_STATUS_INTERVAL);
+	}
+
+	if ((state < BA431_STATE_STARTUP) || (state >= BA431_STATE_ERROR)) {
+		dev_err(ba431->dev, "reset failed (state: %d)\n",
+			state);
+		return -1;
+	}
+
+	dev_info(ba431->dev, "reset done\n");
+
+	return 0;
+}
+
+static void ba431_trng_reset_work(struct work_struct *work)
+{
+	struct ba431_trng *ba431 = container_of(work, struct ba431_trng,
+						reset_work);
+	ba431_trng_reset(ba431);
+	atomic_set(&ba431->reset_pending, 0);
+}
+
+static void ba431_trng_schedule_reset(struct ba431_trng *ba431)
+{
+	if (atomic_cmpxchg(&ba431->reset_pending, 0, 1))
+		return;
+
+	schedule_work(&ba431->reset_work);
+}
+
+static int ba431_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+	u32 *data = buf;
+	unsigned int level, i;
+	int n = 0;
+
+	while (max > 0) {
+		level = ba431_trng_read_reg(ba431, BA431_REG_FIFO_LEVEL);
+		if (!level) {
+			if (ba431_trng_is_in_error(ba431)) {
+				ba431_trng_schedule_reset(ba431);
+				break;
+			}
+
+			if (!wait)
+				break;
+
+			udelay(BA431_READ_RETRY_INTERVAL);
+			continue;
+		}
+
+		i = level;
+		do {
+			data[n++] = ba431_trng_read_reg(ba431,
+							BA431_REG_FIFODATA);
+			max -= sizeof(*data);
+		} while (--i && (max > 0));
+
+		if (ba431_trng_is_in_error(ba431)) {
+			n -= (level - i);
+			ba431_trng_schedule_reset(ba431);
+			break;
+		}
+	}
+
+	n *= sizeof(data);
+	return (n || !wait) ? n : -EIO;
+}
+
+static void ba431_trng_cleanup(struct hwrng *rng)
+{
+	struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+
+	ba431_trng_write_reg(ba431, BA431_REG_CTRL, 0);
+	cancel_work_sync(&ba431->reset_work);
+}
+
+static int ba431_trng_init(struct hwrng *rng)
+{
+	struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+
+	return ba431_trng_reset(ba431);
+}
+
+static int ba431_trng_probe(struct platform_device *pdev)
+{
+	struct ba431_trng *ba431;
+	struct resource *res;
+	int ret;
+
+	ba431 = devm_kzalloc(&pdev->dev, sizeof(*ba431), GFP_KERNEL);
+	if (!ba431)
+		return -ENOMEM;
+
+	ba431->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ba431->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ba431->base))
+		return PTR_ERR(ba431->base);
+
+	atomic_set(&ba431->reset_pending, 0);
+	INIT_WORK(&ba431->reset_work, ba431_trng_reset_work);
+	ba431->rng.name = pdev->name;
+	ba431->rng.init = ba431_trng_init;
+	ba431->rng.cleanup = ba431_trng_cleanup;
+	ba431->rng.read = ba431_trng_read;
+
+	platform_set_drvdata(pdev, ba431);
+
+	ret = hwrng_register(&ba431->rng);
+	if (ret) {
+		dev_err(&pdev->dev, "BA431 registration failed (%d)\n", ret);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "BA431 TRNG registered\n");
+
+	return 0;
+}
+
+static int ba431_trng_remove(struct platform_device *pdev)
+{
+	struct ba431_trng *ba431 = platform_get_drvdata(pdev);
+
+	hwrng_unregister(&ba431->rng);
+
+	return 0;
+}
+
+static const struct of_device_id ba431_trng_dt_ids[] = {
+	{ .compatible = "silex-insight,ba431-rng", .data = NULL },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ba431_trng_dt_ids);
+
+static struct platform_driver ba431_trng_driver = {
+	.driver = {
+		.name = "ba431-rng",
+		.of_match_table = ba431_trng_dt_ids,
+	},
+	.probe = ba431_trng_probe,
+	.remove = ba431_trng_remove,
+};
+
+module_platform_driver(ba431_trng_driver);
+
+MODULE_AUTHOR("Olivier Sobrie <olivier@sobrie.be>");
+MODULE_DESCRIPTION("TRNG driver for Silex Insight BA431");
+MODULE_LICENSE("GPL");
-- 
2.26.2

Re: [PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng

[Arnd Bergmann]

On Mon, May 25, 2020 at 10:07 PM Olivier Sobrie
<olivier.sobrie@silexinsight.com> wrote:
>
> Silex insight BA431 is an IP designed to generate random numbers that
> can be integrated in various FPGA.
> This driver adds support for it through the hwrng interface.
>
> This driver is used in Silex Insight Viper OEM boards.
>
> Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> Signed-off-by: Waleed Ziad <waleed94ziad@gmail.com>

The driver looks good to me.

Acked-by: Arnd Bergmann  <arnd@arndb.de>

>  drivers/char/hw_random/Kconfig     |  10 ++
>  drivers/char/hw_random/Makefile    |   1 +
>  drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++

I wonder if we should move drivers/char/hw_random to its own top-level drivers
subsystem outside of drivers/char. It seems to be growing steadily and is larger
than a lot of other subsystems with currently 34 drivers in there.

Not your problem though.

> +       /* Wait until the state changed */
> +       for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) {
> +               state = ba431_trng_get_state(ba431);
> +               if (state >= BA431_STATE_STARTUP)
> +                       break;
> +
> +               udelay(BA431_RESET_READ_STATUS_INTERVAL);
> +       }

Looking for something to improve, I noticed that this loop can take over
a millisecond to time out, and it always runs in non-atomic context.
It may be better to use usleep_range() than udelay().

      Arnd

Re: [PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng

[Olivier Sobrie]

On Mon, May 25, 2020 at 10:28:46PM +0200, Arnd Bergmann wrote:
> On Mon, May 25, 2020 at 10:07 PM Olivier Sobrie
> <olivier.sobrie@silexinsight.com> wrote:
> >
> > Silex insight BA431 is an IP designed to generate random numbers that
> > can be integrated in various FPGA.
> > This driver adds support for it through the hwrng interface.
> >
> > This driver is used in Silex Insight Viper OEM boards.
> >
> > Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> > Signed-off-by: Waleed Ziad <waleed94ziad@gmail.com>
> 
> The driver looks good to me.
> 
> Acked-by: Arnd Bergmann  <arnd@arndb.de>
> 
> >  drivers/char/hw_random/Kconfig     |  10 ++
> >  drivers/char/hw_random/Makefile    |   1 +
> >  drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++
> 
> I wonder if we should move drivers/char/hw_random to its own top-level drivers
> subsystem outside of drivers/char. It seems to be growing steadily and is larger
> than a lot of other subsystems with currently 34 drivers in there.
> 
> Not your problem though.
> 
> > +       /* Wait until the state changed */
> > +       for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) {
> > +               state = ba431_trng_get_state(ba431);
> > +               if (state >= BA431_STATE_STARTUP)
> > +                       break;
> > +
> > +               udelay(BA431_RESET_READ_STATUS_INTERVAL);
> > +       }
> 
> Looking for something to improve, I noticed that this loop can take over
> a millisecond to time out, and it always runs in non-atomic context.
> It may be better to use usleep_range() than udelay().

Ok I'll change that and send a v2 later this week.

Thank you,

Olivier

Re: [PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng

[Rob Herring]

On Mon, May 25, 2020 at 10:28:46PM +0200, Arnd Bergmann wrote:
> On Mon, May 25, 2020 at 10:07 PM Olivier Sobrie
> <olivier.sobrie@silexinsight.com> wrote:
> >
> > Silex insight BA431 is an IP designed to generate random numbers that
> > can be integrated in various FPGA.
> > This driver adds support for it through the hwrng interface.
> >
> > This driver is used in Silex Insight Viper OEM boards.
> >
> > Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> > Signed-off-by: Waleed Ziad <waleed94ziad@gmail.com>
> 
> The driver looks good to me.
> 
> Acked-by: Arnd Bergmann  <arnd@arndb.de>
> 
> >  drivers/char/hw_random/Kconfig     |  10 ++
> >  drivers/char/hw_random/Makefile    |   1 +
> >  drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++
> 
> I wonder if we should move drivers/char/hw_random to its own top-level drivers
> subsystem outside of drivers/char. It seems to be growing steadily and is larger
> than a lot of other subsystems with currently 34 drivers in there.
> 
> Not your problem though.
> 
> > +       /* Wait until the state changed */
> > +       for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) {
> > +               state = ba431_trng_get_state(ba431);
> > +               if (state >= BA431_STATE_STARTUP)
> > +                       break;
> > +
> > +               udelay(BA431_RESET_READ_STATUS_INTERVAL);
> > +       }
> 
> Looking for something to improve, I noticed that this loop can take over
> a millisecond to time out, and it always runs in non-atomic context.
> It may be better to use usleep_range() than udelay().

Or better yet, use the register polling helpers.

Rob

Re: [PATCH 1/3] dt-bindings: vendor-prefixes: Add Silex Insight vendor prefix

[Rob Herring]

On Mon, 25 May 2020 21:56:04 +0200, Olivier Sobrie wrote:
> Silex Insight is a microelectronic company whose headquarter is located
> in Belgium.
> Web site of the company: https://www.silexinsight.com/
> 
> Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> ---
>  Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 

Applied, thanks!

Re: [PATCH 2/3] dt-bindings: rng: document Silex Insight BA431 hwrng

[Rob Herring]

On Mon, 25 May 2020 21:56:05 +0200, Olivier Sobrie wrote:
> This patch documents the device tree bindings of the BA431 hardware
> random number generator.
> 
> This IP is for instance present in the Viper OEM boards sold by Silex
> Insight.
> 
> Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> ---
>  .../bindings/rng/silex-insight,ba431-rng.yaml | 36 +++++++++++++++++++
>  1 file changed, 36 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/silex-insight,ba431-rng.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng

[Olivier Sobrie]

On Fri, May 29, 2020 at 11:12:31AM -0600, Rob Herring wrote:
> On Mon, May 25, 2020 at 10:28:46PM +0200, Arnd Bergmann wrote:
> > On Mon, May 25, 2020 at 10:07 PM Olivier Sobrie
> > <olivier.sobrie@silexinsight.com> wrote:
> > >
> > > Silex insight BA431 is an IP designed to generate random numbers that
> > > can be integrated in various FPGA.
> > > This driver adds support for it through the hwrng interface.
> > >
> > > This driver is used in Silex Insight Viper OEM boards.
> > >
> > > Signed-off-by: Olivier Sobrie <olivier.sobrie@silexinsight.com>
> > > Signed-off-by: Waleed Ziad <waleed94ziad@gmail.com>
> > 
> > The driver looks good to me.
> > 
> > Acked-by: Arnd Bergmann  <arnd@arndb.de>
> > 
> > >  drivers/char/hw_random/Kconfig     |  10 ++
> > >  drivers/char/hw_random/Makefile    |   1 +
> > >  drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++
> > 
> > I wonder if we should move drivers/char/hw_random to its own top-level drivers
> > subsystem outside of drivers/char. It seems to be growing steadily and is larger
> > than a lot of other subsystems with currently 34 drivers in there.
> > 
> > Not your problem though.
> > 
> > > +       /* Wait until the state changed */
> > > +       for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) {
> > > +               state = ba431_trng_get_state(ba431);
> > > +               if (state >= BA431_STATE_STARTUP)
> > > +                       break;
> > > +
> > > +               udelay(BA431_RESET_READ_STATUS_INTERVAL);
> > > +       }
> > 
> > Looking for something to improve, I noticed that this loop can take over
> > a millisecond to time out, and it always runs in non-atomic context.
> > It may be better to use usleep_range() than udelay().
> 
> Or better yet, use the register polling helpers.

Indeed, thanks for the suggestion.
I'll replace this loop by the readx_poll_timeout() macro.

Olivier