[PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[David Mosberger-Tang]

Signed-off-by: David Mosberger <davidm@egauge.net>
---
 .../devicetree/bindings/nvmem/atmel-secumod.txt    |  46 ++++++++
 drivers/nvmem/atmel-secumod.c                      | 125 +++++++++++++++++++++
 2 files changed, 171 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
 create mode 100644 drivers/nvmem/atmel-secumod.c

diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
new file mode 100644
index 0000000..85db709
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
@@ -0,0 +1,46 @@
+= Atmel Secumod device tree bindings =
+
+This binding is intended to represent Atmel's Secumod which is found
+in SAMA5D2 and perhaps others.
+
+Required properties:
+- compatible: should be "atmel,sama5d2-secumod"
+- reg: Should contain registers location and length of the RAM, followed
+       by register location and length of the Secumod controller.
+
+= Data cells =
+Are child nodes of secumod, bindings of which as described in
+bindings/nvmem/nvmem.txt
+
+Example:
+
+    secumod@fc040000 {
+            compatible = "atmel,sama5d2-secumod";
+            reg = <0xf8044000 0x1420
+                   0xfc040000 0x4000>;
+            status = "okay";
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+
+            secram_auto_erasable@0000 {
+                    reg = <0x0000 0x1000>;
+            };
+            secram@1000 {
+                    reg = <0x1000 0x400>;
+            };
+            ram@1400 {
+                    reg = <0x1400 0x20>;
+            };
+    };
+
+= Data consumers =
+Are device nodes which consume nvmem data cells.
+
+For example:
+
+	ram {
+		...
+		nvmem-cells = <&ram>;
+		nvmem-cell-names = "RAM";
+	};
diff --git a/drivers/nvmem/atmel-secumod.c b/drivers/nvmem/atmel-secumod.c
new file mode 100644
index 0000000..fda83c9
--- /dev/null
+++ b/drivers/nvmem/atmel-secumod.c
@@ -0,0 +1,125 @@
+/*
+ * Driver for SAMA5D2 secure module (SECUMOD).
+ *
+ * Copyright (C) 2016 eGauge Systems LLC
+ *
+ * David Mosberger <davidm@egauge.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+static struct regmap_config secumod_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4
+};
+
+static struct nvmem_config econfig = {
+	.name = "secumod",
+	.owner = THIS_MODULE,
+};
+
+/*
+ * Security-module register definitions:
+ */
+#define SECUMOD_RAMRDY	0x0014
+
+/*
+ * Since the secure module may need to automatically erase some of the
+ * RAM, it may take a while for it to be ready.  As far as I know,
+ * it's not documented how long this might take in the worst-case.
+ */
+static void
+secumod_wait_ready (void *regs)
+{
+	unsigned long start, stop;
+
+	start = jiffies;
+	while (!(readl(regs + SECUMOD_RAMRDY) & 1))
+		msleep_interruptible(1);
+	stop = jiffies;
+	if (stop != start)
+		pr_info("nvmem-atmel-secumod: it took %u msec for SECUMOD "
+			"to become ready...\n", jiffies_to_msecs(stop - start));
+	else
+		pr_info("nvmem-atmel-secumod: ready\n");
+}
+
+static int secumod_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static int secumod_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	struct regmap *regmap;
+	void __iomem *base;
+
+	/*
+	 * Map controller address temporarily so we can ensure that
+	 * the hardware is ready:
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	secumod_wait_ready(base);
+	devm_iounmap(dev, base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	secumod_regmap_config.max_register = resource_size(res) - 1;
+
+	regmap = devm_regmap_init_mmio(dev, base, &secumod_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "%s: regmap init failed\n", __func__);
+		return PTR_ERR(regmap);
+	}
+	econfig.dev = dev;
+	nvmem = nvmem_register(&econfig);
+	if (IS_ERR(nvmem))
+		return PTR_ERR(nvmem);
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static const struct of_device_id secumod_of_match[] = {
+	{ .compatible = "atmel,sama5d2-secumod",},
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, secumod_of_match);
+
+static struct platform_driver secumod_driver = {
+	.probe = secumod_probe,
+	.remove = secumod_remove,
+	.driver = {
+		.name = "atmel,sama5d2-secumod",
+		.of_match_table = secumod_of_match,
+	},
+};
+module_platform_driver(secumod_driver);
+MODULE_AUTHOR("David Mosberger <davidm@egauge.net>");
+MODULE_DESCRIPTION("Atmel Secumod driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

Re: [PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[Rob Herring]

On Mon, May 16, 2016 at 02:17:10PM -0600, David Mosberger-Tang wrote:
> Signed-off-by: David Mosberger <davidm-haPfTeumbwasTnJN9+BGXg@public.gmane.org>
> ---
>  .../devicetree/bindings/nvmem/atmel-secumod.txt    |  46 ++++++++
>  drivers/nvmem/atmel-secumod.c                      | 125 +++++++++++++++++++++
>  2 files changed, 171 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
>  create mode 100644 drivers/nvmem/atmel-secumod.c
> 
> diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> new file mode 100644
> index 0000000..85db709
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> @@ -0,0 +1,46 @@
> += Atmel Secumod device tree bindings =
> +
> +This binding is intended to represent Atmel's Secumod which is found
> +in SAMA5D2 and perhaps others.
> +
> +Required properties:
> +- compatible: should be "atmel,sama5d2-secumod"
> +- reg: Should contain registers location and length of the RAM, followed

registers or RAM location?

"Should contain RAM location and length, ..."

> +       by register location and length of the Secumod controller.
> +
> += Data cells =
> +Are child nodes of secumod, bindings of which as described in
> +bindings/nvmem/nvmem.txt
> +
> +Example:
> +
> +    secumod@fc040000 {
> +            compatible = "atmel,sama5d2-secumod";
> +            reg = <0xf8044000 0x1420
> +                   0xfc040000 0x4000>;

You are missing ranges property.

> +            status = "okay";
> +
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +
> +            secram_auto_erasable@0000 {

Use '-' rather than '_' and drop leading 0s.

> +                    reg = <0x0000 0x1000>;
> +            };
> +            secram@1000 {
> +                    reg = <0x1000 0x400>;
> +            };
> +            ram@1400 {
> +                    reg = <0x1400 0x20>;
> +            };
> +    };
> +
> += Data consumers =
> +Are device nodes which consume nvmem data cells.
> +
> +For example:
> +
> +	ram {
> +		...
> +		nvmem-cells = <&ram>;
> +		nvmem-cell-names = "RAM";
> +	};
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Re: [PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[David Mosberger]

Thanks for the feedback. Rob!  I'll make the changes and resend the
patch (which has now also been updated to work with linux-next).

[PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[David Mosberger-Tang]

Signed-off-by: David Mosberger <davidm-haPfTeumbwasTnJN9+BGXg@public.gmane.org>
---
 .../devicetree/bindings/nvmem/atmel-secumod.txt    |  47 +++++++
 drivers/nvmem/Kconfig                              |   7 +
 drivers/nvmem/Makefile                             |   2 +
 drivers/nvmem/atmel-secumod.c                      | 143 +++++++++++++++++++++
 4 files changed, 199 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
 create mode 100644 drivers/nvmem/atmel-secumod.c

diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
new file mode 100644
index 0000000..d65cad5
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
@@ -0,0 +1,47 @@
+= Atmel Secumod device tree bindings =
+
+This binding is intended to represent Atmel's Secumod which is found
+in SAMA5D2 and perhaps others.
+
+Required properties:
+- compatible: should be "atmel,sama5d2-secumod"
+- reg: Should contain RAM location and length, followed
+       by register location and length of the Secumod controller.
+
+= Data cells =
+Are child nodes of secumod, bindings of which as described in
+bindings/nvmem/nvmem.txt
+
+Example:
+
+    secumod@fc040000 {
+            compatible = "atmel,sama5d2-secumod";
+            reg = <0xf8044000 0x1420>, <0xfc040000 0x4000>;
+            reg-names = "SECURAM", "SECUMOD";
+            status = "okay";
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges;
+
+            secram-auto-erasable@0 {
+                    reg = <0x0000 0x1000>;
+            };
+            secram@1000 {
+                    reg = <0x1000 0x400>;
+            };
+            ram@1400 {
+                    reg = <0x1400 0x20>;
+            };
+    };
+
+= Data consumers =
+Are device nodes which consume nvmem data cells.
+
+For example:
+
+	ram {
+		...
+		nvmem-cells = <&ram>;
+		nvmem-cell-names = "RAM";
+	};
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 3041d48..88b21e3 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -101,4 +101,11 @@ config NVMEM_VF610_OCOTP
 	  This driver can also be build as a module. If so, the module will
 	  be called nvmem-vf610-ocotp.
 
+config NVMEM_ATMEL_SECUMOD
+       tristate "Atmel Secure Module driver"
+       depends on ARCH_AT91
+       help
+         Select this to get support for the secure module (SECUMOD) built
+	 into the SAMA5D2 chips.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 45ab1ae..9cbd950 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_NVMEM_SUNXI_SID)	+= nvmem_sunxi_sid.o
 nvmem_sunxi_sid-y		:= sunxi_sid.o
 obj-$(CONFIG_NVMEM_VF610_OCOTP)	+= nvmem-vf610-ocotp.o
 nvmem-vf610-ocotp-y		:= vf610-ocotp.o
+obj-$(CONFIG_NVMEM_ATMEL_SECUMOD)	+= nvmem-atmel-secumod.o
+nvmem-atmel-secumod-y		:= atmel-secumod.o
diff --git a/drivers/nvmem/atmel-secumod.c b/drivers/nvmem/atmel-secumod.c
new file mode 100644
index 0000000..fc5a96b
--- /dev/null
+++ b/drivers/nvmem/atmel-secumod.c
@@ -0,0 +1,143 @@
+/*
+ * Driver for SAMA5D2 secure module (SECUMOD).
+ *
+ * Copyright (C) 2016 eGauge Systems LLC
+ *
+ * David Mosberger <davidm-haPfTeumbwasTnJN9+BGXg@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static int
+secumod_reg_read(void *context, unsigned int reg, void *_val, size_t bytes)
+{
+	void __iomem *base = context;
+	u32 *val = _val;
+	int i = 0, words = bytes / 4;
+
+	while (words--)
+		*val++ = readl(base + reg + (i++ * 4));
+
+	return 0;
+}
+
+static int
+secumod_reg_write(void *context, unsigned int reg, void *_val, size_t bytes)
+{
+	void __iomem *base = context;
+	u32 *val = _val;
+	int i = 0, words = bytes / 4;
+
+	while (words--)
+		writel(*val++, base + reg + (i++ * 4));
+
+	return 0;
+}
+
+static struct nvmem_config econfig = {
+	.name = "secumod",
+	.owner = THIS_MODULE,
+	.stride = 4,
+	.word_size = 1,
+	.reg_read = secumod_reg_read,
+	.reg_write = secumod_reg_write,
+};
+
+/*
+ * Security-module register definitions:
+ */
+#define SECUMOD_RAMRDY	0x0014
+
+/*
+ * Since the secure module may need to automatically erase some of the
+ * RAM, it may take a while for it to be ready.  As far as I know,
+ * it's not documented how long this might take in the worst-case.
+ */
+static void
+secumod_wait_ready (void *regs)
+{
+	unsigned long start, stop;
+
+	start = jiffies;
+	while (!(readl(regs + SECUMOD_RAMRDY) & 1))
+		msleep_interruptible(1);
+	stop = jiffies;
+	if (stop != start)
+		pr_info("nvmem-atmel-secumod: it took %u msec for SECUMOD "
+			"to become ready...\n", jiffies_to_msecs(stop - start));
+	else
+		pr_info("nvmem-atmel-secumod: ready\n");
+}
+
+static int secumod_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static int secumod_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	void __iomem *base;
+
+	/*
+	 * Map controller address temporarily so we can ensure that
+	 * the hardware is ready:
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	secumod_wait_ready(base);
+	devm_iounmap(dev, base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	econfig.size = resource_size(res);
+	econfig.dev = dev;
+	econfig.priv = base;
+
+	nvmem = nvmem_register(&econfig);
+	if (IS_ERR(nvmem))
+		return PTR_ERR(nvmem);
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static const struct of_device_id secumod_of_match[] = {
+	{ .compatible = "atmel,sama5d2-secumod",},
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, secumod_of_match);
+
+static struct platform_driver secumod_driver = {
+	.probe = secumod_probe,
+	.remove = secumod_remove,
+	.driver = {
+		.name = "atmel,sama5d2-secumod",
+		.of_match_table = secumod_of_match,
+	},
+};
+module_platform_driver(secumod_driver);
+MODULE_AUTHOR("David Mosberger <davidm-haPfTeumbwasTnJN9+BGXg@public.gmane.org>");
+MODULE_DESCRIPTION("Atmel Secumod driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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Re: [PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[Rob Herring]

On Wed, May 18, 2016 at 03:06:04PM -0600, David Mosberger-Tang wrote:
> Signed-off-by: David Mosberger <davidm@egauge.net>
> ---
>  .../devicetree/bindings/nvmem/atmel-secumod.txt    |  47 +++++++
>  drivers/nvmem/Kconfig                              |   7 +
>  drivers/nvmem/Makefile                             |   2 +
>  drivers/nvmem/atmel-secumod.c                      | 143 +++++++++++++++++++++
>  4 files changed, 199 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
>  create mode 100644 drivers/nvmem/atmel-secumod.c
> 
> diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> new file mode 100644
> index 0000000..d65cad5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> @@ -0,0 +1,47 @@
> += Atmel Secumod device tree bindings =
> +
> +This binding is intended to represent Atmel's Secumod which is found
> +in SAMA5D2 and perhaps others.
> +
> +Required properties:
> +- compatible: should be "atmel,sama5d2-secumod"
> +- reg: Should contain RAM location and length, followed
> +       by register location and length of the Secumod controller.
> +
> += Data cells =
> +Are child nodes of secumod, bindings of which as described in
> +bindings/nvmem/nvmem.txt
> +
> +Example:
> +
> +    secumod@fc040000 {

This unit-address should match the first reg address.

> +            compatible = "atmel,sama5d2-secumod";
> +            reg = <0xf8044000 0x1420>, <0xfc040000 0x4000>;
> +            reg-names = "SECURAM", "SECUMOD";
> +            status = "okay";
> +
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            ranges;

Sorry, to be clear, you need values here too.

> +
> +            secram-auto-erasable@0 {
> +                    reg = <0x0000 0x1000>;

The 0 here is address 0xf8044000, right? So ranges is what is used to 
translate from child address of 0 to the parent address.

> +            };
> +            secram@1000 {
> +                    reg = <0x1000 0x400>;
> +            };
> +            ram@1400 {
> +                    reg = <0x1400 0x20>;
> +            };
> +    };
> +
> += Data consumers =
> +Are device nodes which consume nvmem data cells.
> +
> +For example:
> +
> +	ram {
> +		...
> +		nvmem-cells = <&ram>;
> +		nvmem-cell-names = "RAM";
> +	};

Re: [PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

[Srinivas Kandagatla]

Thanks for the patch,
Few minors comments below.

On 18/05/16 22:06, David Mosberger-Tang wrote:
> Signed-off-by: David Mosberger <davidm@egauge.net>
> ---
>   .../devicetree/bindings/nvmem/atmel-secumod.txt    |  47 +++++++
>   drivers/nvmem/Kconfig                              |   7 +
>   drivers/nvmem/Makefile                             |   2 +
>   drivers/nvmem/atmel-secumod.c                      | 143 +++++++++++++++++++++
>   4 files changed, 199 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
>   create mode 100644 drivers/nvmem/atmel-secumod.c
>
> diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> new file mode 100644
> index 0000000..d65cad5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
> @@ -0,0 +1,47 @@
> += Atmel Secumod device tree bindings =
> +

Can you split the dt-bindings into separate patch.

> +This binding is intended to represent Atmel's Secumod which is found
> +in SAMA5D2 and perhaps others.
> +
> +Required properties:
> +- compatible: should be "atmel,sama5d2-secumod"
> +- reg: Should contain RAM location and length, followed
> +       by register location and length of the Secumod controller.
> +
> += Data cells =
> +Are child nodes of secumod, bindings of which as described in
> +bindings/nvmem/nvmem.txt
> +
> +Example:
> +
> +    secumod@fc040000 {
> +            compatible = "atmel,sama5d2-secumod";
> +            reg = <0xf8044000 0x1420>, <0xfc040000 0x4000>;
> +            reg-names = "SECURAM", "SECUMOD";
> +            status = "okay";
> +
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            ranges;
> +
> +            secram-auto-erasable@0 {
> +                    reg = <0x0000 0x1000>;
> +            };
> +            secram@1000 {
> +                    reg = <0x1000 0x400>;
> +            };
> +            ram@1400 {
> +                    reg = <0x1400 0x20>;
> +            };
> +    };
> +
> += Data consumers =
> +Are device nodes which consume nvmem data cells.
> +
> +For example:
> +
> +	ram {
> +		...
> +		nvmem-cells = <&ram>;
> +		nvmem-cell-names = "RAM";
> +	};
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 3041d48..88b21e3 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -101,4 +101,11 @@ config NVMEM_VF610_OCOTP
>   	  This driver can also be build as a module. If so, the module will
>   	  be called nvmem-vf610-ocotp.
>
> +config NVMEM_ATMEL_SECUMOD
> +       tristate "Atmel Secure Module driver"
> +       depends on ARCH_AT91

COMPILE_TEST ?
Also please add
depends on HAS_IOMEM

> +       help
> +         Select this to get support for the secure module (SECUMOD) built
> +	 into the SAMA5D2 chips.
> +
>   endif
...

> index 0000000..fc5a96b
> --- /dev/null
> +++ b/drivers/nvmem/atmel-secumod.c

...
> +
> +/*
> + * Security-module register definitions:
> + */
> +#define SECUMOD_RAMRDY	0x0014
> +
> +/*
> + * Since the secure module may need to automatically erase some of the
> + * RAM, it may take a while for it to be ready.  As far as I know,
> + * it's not documented how long this might take in the worst-case.
> + */
> +static void
> +secumod_wait_ready (void *regs)
> +{
> +	unsigned long start, stop;
> +
> +	start = jiffies;
> +	while (!(readl(regs + SECUMOD_RAMRDY) & 1))
> +		msleep_interruptible(1);

Worst case would be the system loop here forever, Can we add worst case 
timeout for this, and get out of this loop.

> +	stop = jiffies;
> +	if (stop != start)
> +		pr_info("nvmem-atmel-secumod: it took %u msec for SECUMOD "
> +			"to become ready...\n", jiffies_to_msecs(stop - start));
> +	else
> +		pr_info("nvmem-atmel-secumod: ready\n");
I dont see any use of this prints, We should probably remove these and 
add just a one dev_dbg.

> +}
> +
...
thanks,
srini