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commit 2c7cf5ab0387aba1c54faaf32cffd178f9a9e738 Author: Liam Howatt <[email protected]> AuthorDate: Wed Sep 16 14:09:23 2026 -0400 Documentation/stm32h5: OTP is supported. Describe the OTP API in stm32h5 platform documentation. Signed-off-by: Liam Howatt <[email protected]> --- Documentation/platforms/arm/stm32h5/index.rst | 29 +++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/Documentation/platforms/arm/stm32h5/index.rst b/Documentation/platforms/arm/stm32h5/index.rst index 1be538f2013..ac6f0b71ab0 100644 --- a/Documentation/platforms/arm/stm32h5/index.rst +++ b/Documentation/platforms/arm/stm32h5/index.rst @@ -83,6 +83,7 @@ TAMP No UCPD No VREFBUF No WWDG Yes +OTP Yes ========== ======= ===== @@ -106,6 +107,34 @@ Options: - STM32H5_USBDRD_DESCSIZE - Maximum size of a descriptor. Default: 128 +OTP +--- + +STM32H5 parts have a 2 KiB one-time programmable (OTP) area. It's organized +into 32 blocks of 32 16-bit words. Each word can be successfully programmed once. +Each block may be permanently locked at any point. Written words may be read. + +Writing the same word more than once is unsupported. Doing so may cause corruption. +Reading an unwritten word raises an exception. +To simplify the programming model, the OTP API +locks blocks after any part is written. The user may check which blocks are locked. +Blocks are tagged as "written" using this lock status +without the need for out-of-band metadata. Some of the words within a locked +block may be left unwritten, so the exception may still be raised if an unwritten word +within a locked block is read. + +.. code:: c + + int stm32_otp_write(const uint16_t *data, uint16_t len, uint32_t offset); + int stm32_otp_read(uint16_t *data, uint16_t len, uint32_t offset); + uint32_t stm32_otp_getlockstatus(void); + +The API allows cross-block reads/writes that don't necessarily start/end at block boundaries. +Any block affected by ``stm32_otp_write`` will be locked. The user should be aware +of the block size and count when partitioning the OTP area for their needs. +``len`` is the number of bytes - not words. It has no alignment requirement. ``offset`` is +the offset in bytes. It must be a multiple of 4. + References ================= [RM0481] Reference Manual: STM32H523/33xx, STM32H562/63xx, and STM32H573xx Arm® -based 32-bit MCUs
