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nvmem: imx-ocotp: read uniq CPU ID and export as system serial number

PATCH In review Marcus Folkesson 3 participants 4 messages Oct 4, 2017 – Oct 7, 2017

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Device tree bindings Arm i.MX and Layerscape NVMEM framework
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Marcus Folkesson

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#0 lore raw

PATCH 1/1 nvmem: imx-ocotp: read uniq CPU ID and export as system serial number

The uniq ID is usually exported as ATAG_SERIAL but in case of devicetrees, this information is not passed.

The uniq ID is stored in OCOTP memory (bank 0, Word 1,2) on imx CPUs. Read the ID and set as system serial number.

This function is activated by setting read-system-serial dt property for the imx-ocotp node.

Signed-off-by Marcus Folkesson <[email protected]>

---

Comment:
I'm not sure if this functionality really should be in a device driver. Maybe it should be in arch/arm/mach-imx/. However, it's not completely wrong so I give it a shot.

 .../devicetree/bindings/nvmem/imx-ocotp.txt        |  1 +
 drivers/nvmem/imx-ocotp.c                          | 38 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)
Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +1 -0
index 70d791b03ea1..bf0cc9e5e50f 100644
@@ -16,6 +16,7 @@ Required properties:
 
 Optional properties:
 - read-only: disable write access
+- read-system-serial: read uniq ID and export as system serial number. Available in /proc/cpuinfo
 
 Example:
drivers/nvmem/imx-ocotp.c +38 -0
index 193ca8fd350a..574cab017611 100644
@@ -28,10 +28,16 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
+#include <asm/system_info.h>
 
 #define IMX_OCOTP_OFFSET_B0W0		0x400 /* Offset from base address of the
 					       * OTP Bank0 Word0
 					       */
+
+/* Uniq ID used for Serial number */
+#define IMX_OCOTP_OFFSET_UID_LOW	(IMX_OCOTP_OFFSET_B0W0 + 0x10)
+#define IMX_OCOTP_OFFSET_UID_HIGH	(IMX_OCOTP_OFFSET_B0W0 + 0x20)
+
 #define IMX_OCOTP_OFFSET_PER_WORD	0x10  /* Offset between the start addr
 					       * of two consecutive OTP words.
 					       */

@@ -298,6 +304,34 @@ static int imx_ocotp_write(void *context, unsigned int offset, void *val,
 	return bytes;
 }
 
+static int imx_ocotp_setserial(struct ocotp_priv *priv)
+{
+	int ret;
+
+	mutex_lock(&ocotp_mutex);
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret < 0) {
+		mutex_unlock(&ocotp_mutex);
+		dev_err(priv->dev, "failed to prepare/enable ocotp clk\n");
+		return ret;
+	}
+
+	ret = imx_ocotp_wait_for_busy(priv->base, 0);
+	if (ret < 0) {
+		dev_err(priv->dev, "timeout during read setup\n");
+		goto out;
+	}
+
+	system_serial_low = readl(priv->base + IMX_OCOTP_OFFSET_UID_LOW);
+	system_serial_high = readl(priv->base + IMX_OCOTP_OFFSET_UID_HIGH);
+
+out:
+	clk_disable_unprepare(priv->clk);
+	mutex_unlock(&ocotp_mutex);
+	return ret;
+}
+
 static struct nvmem_config imx_ocotp_nvmem_config = {
 	.name = "imx-ocotp",
 	.read_only = false,

@@ -352,6 +386,10 @@ static int imx_ocotp_probe(struct platform_device *pdev)
 	if (IS_ERR(nvmem))
 		return PTR_ERR(nvmem);
 
+	if (of_property_read_bool(pdev->dev.of_node, "read-system-serial")) {
+		if (!imx_ocotp_setserial(priv))
+			dev_warn(&pdev->dev, "Could not read CPU uniq serial number");
+	}
 	platform_set_drvdata(pdev, nvmem);
 
 	return 0;
Signature · 6 lines
2.13.1

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#1 lore raw
Quoted 26 lines · Marcus Folkesson

The uniq ID is usually exported as ATAG_SERIAL but in case of devicetrees, this information is not passed.

The uniq ID is stored in OCOTP memory (bank 0, Word 1,2) on imx CPUs. Read the ID and set as system serial number.

This function is activated by setting read-system-serial dt property for the imx-ocotp node.

Signed-off-by Marcus Folkesson <[email protected]>

---

Comment:
I'm not sure if this functionality really should be in a device driver. Maybe it should be in arch/arm/mach-imx/. However, it's not completely wrong so I give it a shot.

 .../devicetree/bindings/nvmem/imx-ocotp.txt        |  1 +
 drivers/nvmem/imx-ocotp.c                          | 38 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)
Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +0 -0
index 70d791b03ea1..bf0cc9e5e50f 100644

Documentation/devicetree/bindings/nvmem/imx-ocotp.txt Required properties: · line 19

Quoted 4 lines
Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +1 -0
@@ -16,6 +16,7 @@ Required properties:
 
 Optional properties:
 - read-only: disable write access
+- read-system-serial: read uniq ID and export as system serial number. Available in /proc/cpuinfo

As described, this is a pure SW option (

/proc/cpuinfo is a not a HW detail, and whether or not to export this information there is a policy. So as described, this shouldn't be in the DT.

Are you just trying to describe whether hte information is available in the OCOTP memory?

e.g. maybe this should be something like:

- has-unique-id: OCOTP bank0, Words 1 & 2 contain a unique ID identifying the system.

Thanks,
Mark.
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author
#2 lore raw

Hi Mark,

Quoted 34 lines · Mark Rutland
Quoted 26 lines · Marcus Folkesson

The uniq ID is usually exported as ATAG_SERIAL but in case of devicetrees, this information is not passed.

The uniq ID is stored in OCOTP memory (bank 0, Word 1,2) on imx CPUs. Read the ID and set as system serial number.

This function is activated by setting read-system-serial dt property for the imx-ocotp node.

Signed-off-by Marcus Folkesson <[email protected]>

---

Comment:
I'm not sure if this functionality really should be in a device driver. Maybe it should be in arch/arm/mach-imx/. However, it's not completely wrong so I give it a shot.

 .../devicetree/bindings/nvmem/imx-ocotp.txt        |  1 +
 drivers/nvmem/imx-ocotp.c                          | 38 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)
Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +0 -0
index 70d791b03ea1..bf0cc9e5e50f 100644

Documentation/devicetree/bindings/nvmem/imx-ocotp.txt Required properties: · line 19

Quoted 4 lines
Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +1 -0
@@ -16,6 +16,7 @@ Required properties:
 
 Optional properties:
 - read-only: disable write access
+- read-system-serial: read uniq ID and export as system serial number. Available in /proc/cpuinfo

As described, this is a pure SW option (

Quoted 3 lines

/proc/cpuinfo is a not a HW detail, and whether or not to export this information there is a policy. So as described, this shouldn't be in the DT.

Ok, I agree with that.

Quoted 3 lines

Are you just trying to describe whether hte information is available in the OCOTP memory?

No, the information is available for all concerned iMX CPUs what I can tell. My intention was to flag if the driver should make use of it, but the DT seems to be the wrong way to go.

Quoted 8 lines

e.g. maybe this should be something like:

- has-unique-id: OCOTP bank0, Words 1 & 2 contain a unique ID identifying the system.

Thanks,
Mark.

I will come up with an v2 where this is not configurable.

Thanks,
Marcus Folkesson

build bot
#3 lore raw
In reply to Marcus Folkesson
url: https://github.com/0day-ci/linux/commits/Marcus-Folkesson/nvmem-imx-ocotp-read-uniq-CPU-ID-and-export-as-system-serial-number/20171007-122234 config: i386-allmodconfig (attached as .config)…

Hi Marcus,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.14-rc3 next-20170929]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Marcus-Folkesson/nvmem-imx-ocotp-read-uniq-CPU-ID-and-export-as-system-serial-number/20171007-122234
config: i386-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386

All errors (new ones prefixed by >>):

>> drivers/nvmem/imx-ocotp.c:31:29: fatal error: asm/system_info.h: No such file or directory
    #include <asm/system_info.h>
                                ^

compilation terminated.

vim +31 drivers/nvmem/imx-ocotp.c

  > 31	#include <asm/system_info.h>
    32

---
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