[PATCH 0/3] nvmem: Add Raspberry Pi OTP nvmem driver

[PATCH 0/3] nvmem: Add Raspberry Pi OTP nvmem driver

[Gregor Herburger]

Hi,

This series adds support for the Raspberry Pis OTP registers. The
Raspberry Pi has one or more OTP regions. These registers are accessible
through the firmware. Add a driver for it and add the corresponding
devicetree scheme.

I also added the devicetree nodes for the Raspberry Pi as I tested the
series on it.

---
Gregor Herburger (3):
      dt-bindings: nvmem: Add a binding for the RPi Firmware OTP register
      nvmem: Add the Raspberry Pi OTP driver
      arm64: dts: broadcom: bcm2712: Add the otp nodes to firmware

 .../arm/bcm/raspberrypi,bcm2835-firmware.yaml      |  18 +++
 .../boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi    |   8 ++
 drivers/nvmem/Kconfig                              |  12 ++
 drivers/nvmem/Makefile                             |   1 +
 drivers/nvmem/raspberrypi-otp.c                    | 159 +++++++++++++++++++++
 include/soc/bcm2835/raspberrypi-firmware.h         |   2 +
 6 files changed, 200 insertions(+)
---
base-commit: f3e6330d7fe42b204af05a2dbc68b379e0ad179e
change-id: 20260408-rpi-otp-driver-75fce1dcff7d

Best regards,
--  
Gregor Herburger <gregor.herburger@linutronix.de>

[PATCH 1/3] dt-bindings: nvmem: Add a binding for the RPi Firmware OTP register

[Gregor Herburger]

The firmware running on the Raspberry Pi VideoCore can be used to access
OTP registers. There are two OTP regions (private and customer). Add a
binding for these.

Signed-off-by: Gregor Herburger <gregor.herburger@linutronix.de>
---
 .../bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
index 983ea80eaec9..975c8927d75b 100644
--- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
+++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
@@ -137,6 +137,20 @@ required:
   - compatible
   - mboxes
 
+patternProperties:
+  "^otp-(customer|private)$":
+    type: object
+    additionalProperties: false
+
+    properties:
+      compatible:
+        enum:
+          - raspberrypi,firmware-otp-customer
+          - raspberrypi,firmware-otp-private
+
+    required:
+      - compatible
+
 additionalProperties: false
 
 examples:
@@ -156,6 +170,10 @@ examples:
             #gpio-cells = <2>;
         };
 
+        otp: otp-private {
+            compatible = "raspberrypi,firmware-otp-private";
+        };
+
         reset: reset {
             compatible = "raspberrypi,firmware-reset";
             #reset-cells = <1>;

-- 
2.47.3

[PATCH 2/3] nvmem: Add the Raspberry Pi OTP driver

[Gregor Herburger]

Raspberry Pis have OTP registers which can be accessed through the
videocore firmware. Add a nvmem driver to support these OTP registers.

Signed-off-by: Gregor Herburger <gregor.herburger@linutronix.de>
---
 drivers/nvmem/Kconfig                      |  12 +++
 drivers/nvmem/Makefile                     |   1 +
 drivers/nvmem/raspberrypi-otp.c            | 159 +++++++++++++++++++++++++++++
 include/soc/bcm2835/raspberrypi-firmware.h |   2 +
 4 files changed, 174 insertions(+)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 74ddbd0f79b0..892d05fe67be 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -483,4 +483,16 @@ config NVMEM_QORIQ_EFUSE
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem_qoriq_efuse.
 
+config NVMEM_RASPBERRYPI_OTP
+	tristate "Raspberry Pi OTP support"
+	# Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only
+	# happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE.
+	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+	help
+	  This driver provides access to the Raspberry Pi OTP memory via the
+	  nvmem subsystem. The driver supports the customer otp as well as the
+	  device specific private key OTP.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called raspberrypi-otp.
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 7252b8ec88d4..8ca2095e068f 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -95,3 +95,4 @@ obj-$(CONFIG_NVMEM_ZYNQMP)		+= nvmem_zynqmp_nvmem.o
 nvmem_zynqmp_nvmem-y			:= zynqmp_nvmem.o
 obj-$(CONFIG_NVMEM_QORIQ_EFUSE)		+= nvmem-qoriq-efuse.o
 nvmem-qoriq-efuse-y			:= qoriq-efuse.o
+obj-$(CONFIG_NVMEM_RASPBERRYPI_OTP)	+= raspberrypi-otp.o
diff --git a/drivers/nvmem/raspberrypi-otp.c b/drivers/nvmem/raspberrypi-otp.c
new file mode 100644
index 000000000000..13ee3784b137
--- /dev/null
+++ b/drivers/nvmem/raspberrypi-otp.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+struct rpi_otp_priv {
+	struct rpi_firmware *fw;
+	struct device *dev;
+	u32 read_tag;
+	u32 write_tag;
+};
+
+struct rpi_otp_driver_data {
+	const char *name;
+	u32 read_tag;
+	u32 write_tag;
+};
+
+struct rpi_otp_header {
+	u32 start;
+	u32 count;
+	u32 data[];
+};
+
+static int rpi_otp_read(void *context, unsigned int offset, void *buf, size_t bytes)
+{
+	struct rpi_otp_priv *priv = context;
+	struct rpi_otp_header *fwbuf;
+	int ret;
+
+	fwbuf = kmalloc(sizeof(struct rpi_otp_header) + bytes, GFP_KERNEL);
+	if (!fwbuf)
+		return -ENOMEM;
+
+	fwbuf->start = offset / 4;
+	fwbuf->count = bytes / 4;
+
+	ret = rpi_firmware_property(priv->fw, priv->read_tag, fwbuf,
+				    sizeof(struct rpi_otp_header) + bytes);
+	if (ret)
+		goto out;
+
+	memcpy(buf, fwbuf->data, bytes);
+
+out:
+	kfree(fwbuf);
+	return ret;
+}
+
+static int rpi_otp_write(void *context, unsigned int offset, void *val, size_t bytes)
+{
+	struct rpi_otp_priv *priv = context;
+	struct rpi_otp_header *fwbuf;
+	int ret;
+
+	fwbuf = kmalloc(sizeof(struct rpi_otp_header) + bytes, GFP_KERNEL);
+	if (!fwbuf)
+		return -ENOMEM;
+
+	fwbuf->start = offset / 4;
+	fwbuf->count = bytes / 4;
+	memcpy(fwbuf->data, val, bytes);
+
+	ret = rpi_firmware_property(priv->fw, priv->write_tag, fwbuf,
+				    sizeof(struct rpi_otp_header) + bytes);
+
+	kfree(fwbuf);
+	return ret;
+}
+
+static const struct rpi_otp_driver_data rpi_otp_customer = {
+	.name = "rpi-otp-customer",
+	.read_tag = RPI_FIRMWARE_GET_CUSTOMER_OTP,
+	.write_tag = RPI_FIRMWARE_SET_CUSTOMER_OTP,
+};
+
+static const struct rpi_otp_driver_data rpi_otp_private = {
+	.name = "rpi-otp-private",
+	.read_tag = RPI_FIRMWARE_GET_PRIVATE_OTP,
+	.write_tag = RPI_FIRMWARE_SET_PRIVATE_OTP,
+};
+
+static int rpi_otp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nvmem_device *nvmem;
+	struct rpi_otp_priv *priv;
+	struct device_node *np;
+	const struct rpi_otp_driver_data *data;
+	struct nvmem_config config = {
+		.read_only = false,
+		.word_size = 4,
+		.stride = 4,
+		.reg_read = rpi_otp_read,
+		.reg_write = rpi_otp_write,
+		.size = 32,
+	};
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	data = device_get_match_data(dev);
+	if (!data)
+		return -ENODEV;
+
+	np = of_get_parent(dev->of_node);
+	if (!np) {
+		dev_err(dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	priv->fw = devm_rpi_firmware_get(&pdev->dev, np);
+	of_node_put(np);
+	if (!priv->fw)
+		return -EPROBE_DEFER;
+
+	priv->dev = dev;
+	priv->read_tag = data->read_tag;
+	priv->write_tag = data->write_tag;
+	config.dev = dev;
+	config.priv = priv;
+	config.name = data->name;
+
+	nvmem = devm_nvmem_register(dev, &config);
+	if (IS_ERR(nvmem))
+		return dev_err_probe(dev, PTR_ERR(nvmem), "error registering nvmem config\n");
+
+	return 0;
+}
+
+static const struct of_device_id rpi_otp_of_match[] = {
+	{
+		.compatible = "raspberrypi,firmware-otp-customer",
+		.data = &rpi_otp_customer
+	},
+	{
+		.compatible = "raspberrypi,firmware-otp-private",
+		.data = &rpi_otp_private,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rpi_otp_of_match);
+
+static struct platform_driver raspberry_otp_driver = {
+	.probe	= rpi_otp_probe,
+	.driver = {
+		.name	= "rpi-otp",
+		.of_match_table = rpi_otp_of_match,
+	},
+};
+module_platform_driver(raspberry_otp_driver);
+
+MODULE_AUTHOR("Gregor Herburger <gregor.herburger@linutronix.de>");
+MODULE_DESCRIPTION("Raspberry OTP driver");
+MODULE_LICENSE("GPL");
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index e1f87fbfe554..6e94ccf34f47 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -92,6 +92,8 @@ enum rpi_firmware_property_tag {
 	RPI_FIRMWARE_SET_POE_HAT_VAL =                        0x00030050,
 	RPI_FIRMWARE_NOTIFY_XHCI_RESET =                      0x00030058,
 	RPI_FIRMWARE_NOTIFY_DISPLAY_DONE =                    0x00030066,
+	RPI_FIRMWARE_GET_PRIVATE_OTP =                        0x00030081,
+	RPI_FIRMWARE_SET_PRIVATE_OTP =                        0x00038081,
 
 	/* Dispmanx TAGS */
 	RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE =                   0x00040001,

-- 
2.47.3

[PATCH 3/3] arm64: dts: broadcom: bcm2712: Add the otp nodes to firmware

[Gregor Herburger]

The Raspberry Pi 5 has two OTP registers (private and customer), add these
to the devicetree.

Signed-off-by: Gregor Herburger <gregor.herburger@linutronix.de>
---
 arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi b/arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi
index b7a6bc34ae1a..676081198213 100644
--- a/arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi
+++ b/arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b-base.dtsi
@@ -60,6 +60,14 @@ reset: reset {
 				#reset-cells = <1>;
 			};
 
+			otp_customer: otp-customer {
+				compatible = "raspberrypi,firmware-otp-customer";
+			};
+
+			otp_private: otp-private {
+				compatible = "raspberrypi,firmware-otp-private";
+			};
+
 			power: power {
 				compatible = "raspberrypi,bcm2835-power";
 				firmware = <&firmware>;

-- 
2.47.3

Re: [PATCH 2/3] nvmem: Add the Raspberry Pi OTP driver

[Stefan Wahren]

Hi Gregor,

[drop Emma's old address]

Am 08.04.26 um 10:00 schrieb Gregor Herburger:
> Raspberry Pis have OTP registers which can be accessed through the
> videocore firmware. Add a nvmem driver to support these OTP registers.
>
> Signed-off-by: Gregor Herburger <gregor.herburger@linutronix.de>
> ---
>   drivers/nvmem/Kconfig                      |  12 +++
>   drivers/nvmem/Makefile                     |   1 +
>   drivers/nvmem/raspberrypi-otp.c            | 159 +++++++++++++++++++++++++++++
>   include/soc/bcm2835/raspberrypi-firmware.h |   2 +
>   4 files changed, 174 insertions(+)
>
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 74ddbd0f79b0..892d05fe67be 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -483,4 +483,16 @@ config NVMEM_QORIQ_EFUSE
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nvmem_qoriq_efuse.
>   
> +config NVMEM_RASPBERRYPI_OTP
> +	tristate "Raspberry Pi OTP support"
> +	# Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only
> +	# happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE.
I don't think these comments are necessary, because this applies to 
other firmware drivers, too.
> +	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
> +	help
> +	  This driver provides access to the Raspberry Pi OTP memory via the
> +	  nvmem subsystem. The driver supports the customer otp as well as the
> +	  device specific private key OTP.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called raspberrypi-otp.
>   endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 7252b8ec88d4..8ca2095e068f 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -95,3 +95,4 @@ obj-$(CONFIG_NVMEM_ZYNQMP)		+= nvmem_zynqmp_nvmem.o
>   nvmem_zynqmp_nvmem-y			:= zynqmp_nvmem.o
>   obj-$(CONFIG_NVMEM_QORIQ_EFUSE)		+= nvmem-qoriq-efuse.o
>   nvmem-qoriq-efuse-y			:= qoriq-efuse.o
> +obj-$(CONFIG_NVMEM_RASPBERRYPI_OTP)	+= raspberrypi-otp.o
> diff --git a/drivers/nvmem/raspberrypi-otp.c b/drivers/nvmem/raspberrypi-otp.c
> new file mode 100644
> index 000000000000..13ee3784b137
> --- /dev/null
> +++ b/drivers/nvmem/raspberrypi-otp.c
> @@ -0,0 +1,159 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/module.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <soc/bcm2835/raspberrypi-firmware.h>
> +
> +struct rpi_otp_priv {
> +	struct rpi_firmware *fw;
> +	struct device *dev;
> +	u32 read_tag;
> +	u32 write_tag;
> +};
> +
> +struct rpi_otp_driver_data {
> +	const char *name;
> +	u32 read_tag;
> +	u32 write_tag;
> +};
> +
> +struct rpi_otp_header {
> +	u32 start;
> +	u32 count;
> +	u32 data[];
> +};
> +
> +static int rpi_otp_read(void *context, unsigned int offset, void *buf, size_t bytes)
> +{
> +	struct rpi_otp_priv *priv = context;
> +	struct rpi_otp_header *fwbuf;
> +	int ret;
> +
> +	fwbuf = kmalloc(sizeof(struct rpi_otp_header) + bytes, GFP_KERNEL);
> +	if (!fwbuf)
> +		return -ENOMEM;
> +
> +	fwbuf->start = offset / 4;
> +	fwbuf->count = bytes / 4;
> +
> +	ret = rpi_firmware_property(priv->fw, priv->read_tag, fwbuf,
> +				    sizeof(struct rpi_otp_header) + bytes);
> +	if (ret)
> +		goto out;
> +
> +	memcpy(buf, fwbuf->data, bytes);
> +
> +out:
> +	kfree(fwbuf);
> +	return ret;
> +}
> +
> +static int rpi_otp_write(void *context, unsigned int offset, void *val, size_t bytes)
> +{
> +	struct rpi_otp_priv *priv = context;
> +	struct rpi_otp_header *fwbuf;
> +	int ret;
> +
> +	fwbuf = kmalloc(sizeof(struct rpi_otp_header) + bytes, GFP_KERNEL);
> +	if (!fwbuf)
> +		return -ENOMEM;
> +
> +	fwbuf->start = offset / 4;
> +	fwbuf->count = bytes / 4;
> +	memcpy(fwbuf->data, val, bytes);
> +
> +	ret = rpi_firmware_property(priv->fw, priv->write_tag, fwbuf,
> +				    sizeof(struct rpi_otp_header) + bytes);
> +
> +	kfree(fwbuf);
> +	return ret;
> +}
> +
> +static const struct rpi_otp_driver_data rpi_otp_customer = {
> +	.name = "rpi-otp-customer",
> +	.read_tag = RPI_FIRMWARE_GET_CUSTOMER_OTP,
> +	.write_tag = RPI_FIRMWARE_SET_CUSTOMER_OTP,
> +};
> +
> +static const struct rpi_otp_driver_data rpi_otp_private = {
> +	.name = "rpi-otp-private",
> +	.read_tag = RPI_FIRMWARE_GET_PRIVATE_OTP,
> +	.write_tag = RPI_FIRMWARE_SET_PRIVATE_OTP,
> +};
> +
> +static int rpi_otp_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct nvmem_device *nvmem;
> +	struct rpi_otp_priv *priv;
> +	struct device_node *np;
> +	const struct rpi_otp_driver_data *data;
> +	struct nvmem_config config = {
> +		.read_only = false,
> +		.word_size = 4,
> +		.stride = 4,
> +		.reg_read = rpi_otp_read,
> +		.reg_write = rpi_otp_write,
> +		.size = 32,
> +	};
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	data = device_get_match_data(dev);
> +	if (!data)
> +		return -ENODEV;
> +
> +	np = of_get_parent(dev->of_node);
> +	if (!np) {
> +		dev_err(dev, "Missing firmware node\n");
> +		return -ENOENT;
> +	}
> +
> +	priv->fw = devm_rpi_firmware_get(&pdev->dev, np);
> +	of_node_put(np);
> +	if (!priv->fw)
> +		return -EPROBE_DEFER;
> +
> +	priv->dev = dev;
> +	priv->read_tag = data->read_tag;
> +	priv->write_tag = data->write_tag;
> +	config.dev = dev;
> +	config.priv = priv;
> +	config.name = data->name;
> +
> +	nvmem = devm_nvmem_register(dev, &config);
> +	if (IS_ERR(nvmem))
> +		return dev_err_probe(dev, PTR_ERR(nvmem), "error registering nvmem config\n");
> +
> +	return 0;
> +}
Is there any reason, why we cannot register this driver in 
rpi_firmware_probe() like hwmon and clk driver?

I like to avoid the complete dt-binding from patch 1.
> +
> +static const struct of_device_id rpi_otp_of_match[] = {
> +	{
> +		.compatible = "raspberrypi,firmware-otp-customer",
> +		.data = &rpi_otp_customer
> +	},
> +	{
> +		.compatible = "raspberrypi,firmware-otp-private",
> +		.data = &rpi_otp_private,
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, rpi_otp_of_match);
> +
> +static struct platform_driver raspberry_otp_driver = {
> +	.probe	= rpi_otp_probe,
> +	.driver = {
> +		.name	= "rpi-otp",
> +		.of_match_table = rpi_otp_of_match,
> +	},
> +};
> +module_platform_driver(raspberry_otp_driver);
> +
> +MODULE_AUTHOR("Gregor Herburger <gregor.herburger@linutronix.de>");
> +MODULE_DESCRIPTION("Raspberry OTP driver");
Raspberry Pi OTP driver ?

Regards
> +MODULE_LICENSE("GPL");
> diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
> index e1f87fbfe554..6e94ccf34f47 100644
> --- a/include/soc/bcm2835/raspberrypi-firmware.h
> +++ b/include/soc/bcm2835/raspberrypi-firmware.h
> @@ -92,6 +92,8 @@ enum rpi_firmware_property_tag {
>   	RPI_FIRMWARE_SET_POE_HAT_VAL =                        0x00030050,
>   	RPI_FIRMWARE_NOTIFY_XHCI_RESET =                      0x00030058,
>   	RPI_FIRMWARE_NOTIFY_DISPLAY_DONE =                    0x00030066,
> +	RPI_FIRMWARE_GET_PRIVATE_OTP =                        0x00030081,
> +	RPI_FIRMWARE_SET_PRIVATE_OTP =                        0x00038081,
>   
>   	/* Dispmanx TAGS */
>   	RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE =                   0x00040001,
>

Re: [PATCH 2/3] nvmem: Add the Raspberry Pi OTP driver

[Gregor Herburger]

Hi Stefan,

thanks for the review.

> > +config NVMEM_RASPBERRYPI_OTP
> > +	tristate "Raspberry Pi OTP support"
> > +	# Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only
> > +	# happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE.
> I don't think these comments are necessary, because this applies to other
> firmware drivers, too.

I have seen this in all the other drivers that depend on RASPBERRYPI_FIRMWARE
so I added it here as well. I can remove it.
> > +	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
> > +	help
> > +	  This driver provides access to the Raspberry Pi OTP memory via the
> > +	  nvmem subsystem. The driver supports the customer otp as well as the
> > +	  device specific private key OTP.
> > +
> > +	  This driver can also be built as a module. If so, the module
> > +	  will be called raspberrypi-otp.
> >   endif
> > diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> > index 7252b8ec88d4..8ca2095e068f 100644

> Is there any reason, why we cannot register this driver in
> rpi_firmware_probe() like hwmon and clk driver?
> 
> I like to avoid the complete dt-binding from patch 1.

The private OTP registers are not available on all Raspberries. Afaik
only on 4 and 5. So I think these registers must be described through
the device tree. Therefore the bindings are needed.

> > +module_platform_driver(raspberry_otp_driver);
> > +
> > +MODULE_AUTHOR("Gregor Herburger <gregor.herburger@linutronix.de>");
> > +MODULE_DESCRIPTION("Raspberry OTP driver");
> Raspberry Pi OTP driver ?

Yes. I will update in the next version.

Re: [PATCH 2/3] nvmem: Add the Raspberry Pi OTP driver

[Stefan Wahren]

Am 08.04.26 um 21:47 schrieb Gregor Herburger:
> Hi Stefan,
>
> thanks for the review.
>> Is there any reason, why we cannot register this driver in
>> rpi_firmware_probe() like hwmon and clk driver?
>>
>> I like to avoid the complete dt-binding from patch 1.
> The private OTP registers are not available on all Raspberries. Afaik
> only on 4 and 5. So I think these registers must be described through
> the device tree. Therefore the bindings are needed.
This binding doesn't represent some kind of hardware, it's just some 
firmware interface. A proper DT binding would describe the MMIO address 
range for OTP access.
If you need some distinction between the Raspberry Pi generations there 
are firmware tags to do this.

Regards