drivers: Introduce new OTP subsystem

Introduce a new OTP subsystem to be able to interact with One Time
Programmable(OTP) memory. For now, add basic read()/program() APIs.
Program() API is default disabled due to its sensitivity.

File drivers/otp.h is inspired by drivers/eeprom.h as the basic
features are similar.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>

doc/hardware/peripherals/index.rst

@@ -45,6 +45,7 @@ Peripherals
    mspi.rst
    mbox.rst
    opamp.rst
+   otp/index.rst
    pcie.rst
    peci.rst
    ps2.rst

doc/hardware/peripherals/otp/api.rst

@@ -0,0 +1,23 @@
+.. _otp_api:
+
+OTP API
+#######
+
+Overview
+********
+
+The OTP API provides means to provision and read
+:abbr:`OTP(One Time Programmable)` memory devices
+
+API implementation Reference
+****************************
+.. doxygengroup:: otp_interface
+
+Configuration Options
+*********************
+
+OTP related configuration options:
+
+* :kconfig:option:`CONFIG_OTP`
+* :kconfig:option:`CONFIG_OTP_PROGRAM`
+* :kconfig:option:`CONFIG_OTP_INIT_PRIORITY`

doc/hardware/peripherals/otp/index.rst

@@ -0,0 +1,17 @@
+.. _otp:
+
+One Time Programmable (OTP) memory devices
+##########################################
+
+Overview
+********
+
+OTP memory devices handle memory that is expected to be permanent. This memory
+is usually provisioned during manufacturing, but there are some use-cases in
+which one needs to program the OTP memory at a later lifecycle state (e.g:
+monotonic counters, cryptographic keys, etc...).
+
+.. toctree::
+   :maxdepth: 2
+
+   api.rst

drivers/CMakeLists.txt

@@ -71,6 +71,7 @@ add_subdirectory_ifdef(CONFIG_MODEM modem)
 add_subdirectory_ifdef(CONFIG_MSPI mspi)
 add_subdirectory_ifdef(CONFIG_NET_DRIVERS net)
 add_subdirectory_ifdef(CONFIG_OPAMP opamp)
+add_subdirectory_ifdef(CONFIG_OTP otp)
 add_subdirectory_ifdef(CONFIG_PECI peci)
 add_subdirectory_ifdef(CONFIG_PINCTRL pinctrl)
 add_subdirectory_ifdef(CONFIG_PM_CPU_OPS pm_cpu_ops)

drivers/Kconfig

@@ -67,6 +67,7 @@ source "drivers/modem/Kconfig"
 source "drivers/mspi/Kconfig"
 source "drivers/net/Kconfig"
 source "drivers/opamp/Kconfig"
+source "drivers/otp/Kconfig"
 source "drivers/pcie/Kconfig"
 source "drivers/peci/Kconfig"
 source "drivers/pinctrl/Kconfig"

drivers/otp/CMakeLists.txt

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()

drivers/otp/Kconfig

@@ -0,0 +1,35 @@
+# OTP driver configuration options
+
+# Copyright (c) 2025 STMicroelectronics
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig OTP
+	bool "One Time Programmable (OTP) drivers [EXPERIMENTAL]"
+	select EXPERIMENTAL
+	help
+	  Enable support for hardware OTP. The OTP technology can be anything
+	  from fuses to flash memory option bytes as long as it stays one time
+	  programmable.
+
+if OTP
+
+module = OTP
+module-str = otp
+
+source "subsys/logging/Kconfig.template.log_config"
+
+config OTP_INIT_PRIORITY
+	int "OTP init priority"
+	default KERNEL_INIT_PRIORITY_DEVICE
+	help
+	  OTP device drivers initialization priority. This initialization
+	  priority is used unless the driver implementation has its own
+	  initialization priority.
+
+config OTP_PROGRAM
+	bool "Support OTP programming through Zephyr API"
+	help
+	  Allowing the programming of OTPs may cause irreversible damage
+	  to a platform. Use it very carefully and at your own risk.
+
+endif # OTP

include/zephyr/drivers/otp.h

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2025 STMicroelectronics
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @ingroup otp_interface
+ * @brief Main header file for OTP driver API.
+ */
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_OTP_H_
+#define ZEPHYR_INCLUDE_DRIVERS_OTP_H_
+
+/**
+ * @brief Interfaces for One Time Programmable (OTP) Memory.
+ * @defgroup otp_interface One Time Programmable Memory
+ * @since 4.4
+ * @version 0.1.0
+ * @ingroup io_interfaces
+ * @{
+ */
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <zephyr/device.h>
+#include <zephyr/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @cond INTERNAL_HIDDEN
+ *
+ * For internal driver use only, skip these in public documentation.
+ */
+
+/**
+ * @brief Callback API upon reading from the OTP memory.
+ * See @a otp_read() for argument description
+ */
+typedef int (*otp_api_read)(const struct device *dev, off_t offset, void *data, size_t len);
+
+/**
+ * @brief Callback API upon writing to the OTP memory.
+ * See @a otp_program() for argument description
+ */
+typedef int (*otp_api_program)(const struct device *dev, off_t offset, const void *data,
+			       size_t len);
+
+__subsystem struct otp_driver_api {
+	otp_api_read read;
+#if defined(CONFIG_OTP_PROGRAM) || defined(__DOXYGEN__)
+	otp_api_program program;
+#endif
+};
+
+/** @endcond */
+
+/**
+ *  @brief Read data from OTP memory
+ *
+ *  @param dev OTP device
+ *  @param offset Address offset to read from.
+ *  @param data Buffer to store read data.
+ *  @param len Number of bytes to read.
+ *
+ *  @return 0 on success, negative errno code on failure.
+ */
+__syscall int otp_read(const struct device *dev, off_t offset, void *data, size_t len);
+
+static inline int z_impl_otp_read(const struct device *dev, off_t offset, void *data, size_t len)
+{
+	return DEVICE_API_GET(otp, dev)->read(dev, offset, data, len);
+}
+
+#if defined(CONFIG_OTP_PROGRAM) || defined(__DOXYGEN__)
+/**
+ *  @brief Program data to the given OTP memory
+ *
+ *  @param dev OTP device
+ *  @param offset Address offset to program data to.
+ *  @param data Buffer with data to program.
+ *  @param len Number of bytes to program.
+ *
+ *  @return 0 on success, negative errno code on failure.
+ */
+__syscall int otp_program(const struct device *dev, off_t offset, const void *data, size_t len);
+
+static inline int z_impl_otp_program(const struct device *dev, off_t offset, const void *data,
+				      size_t len)
+{
+	const struct otp_driver_api *api = DEVICE_API_GET(otp, dev);
+
+	if (api->program == NULL) {
+		return -ENOSYS;
+	}
+
+	return api->program(dev, offset, data, len);
+}
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+/**
+ * @}
+ */
+
+#include <zephyr/syscalls/otp.h>
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_OTP_H_ */