Previously there was discussion on using "feature-controller" or adding a specific node to group the fuse information for U-Boot to parse and update node. But rejected by DT maintainer(Rob). Since the STM32 engineers added access controller concept and landed the support in Linux Kernel, reuse the concept for i.MX. i.MX OCOTP eFuse has some bits to indicate a specific periphral or function is avaiable for current chip, for example i.MX93 has variants that not have NPU. So introduce '#access-controller-cells' for OCOTP, and add "#access-controllers = <&ocotp [gate_index]>" for periphrals that needs accessing control checking. In OCOTP driver, the nodes under "/" will be iterated, and checked if property "#access-controllers" exsits. If not allow access, detach the node. In the end, cpu nodes should still be handled by bootloader. And I may also update i.MX8M to use same method to support variants if this patchset is good. Signed-off-by: Peng Fan <peng.fan@xxxxxxx> --- Changes in v3: - Add A-b for patch 1 - Use scoped API when iterate nodes and address build warning in patch 2 - I am also thinking that to drop patch 2 to let bootloader to iterate the nodes that have access-controllers property and update the nodes before booting the kernel. Then just need patch 1 for the binding updates. Anyway, comments are welcomed. - Link to v2: https://lore.kernel.org/r/20241217-imx-ocotp-v2-0-3faa6cbff41b@xxxxxxx Changes in v2: - Add R-b for patch 1 - Use '/' root node instead of '/soc' or '/soc@0' for patch 2 - Link to v1: https://lore.kernel.org/r/20241212-imx-ocotp-v1-0-198bb0af86a0@xxxxxxx --- Peng Fan (2): dt-bindings: nvmem: imx-ocotp: Introduce #access-controller-cells nvmem: imx-ocotp-ele: Support accessing controller for i.MX9 .../devicetree/bindings/nvmem/imx-ocotp.yaml | 5 + drivers/nvmem/imx-ocotp-ele.c | 183 ++++++++++++++++++++- include/dt-bindings/nvmem/fsl,imx93-ocotp.h | 24 +++ include/dt-bindings/nvmem/fsl,imx95-ocotp.h | 43 +++++ 4 files changed, 254 insertions(+), 1 deletion(-) --- base-commit: 6d13015b67d58ddba56631c56e0a6f376ade0867 change-id: 20241212-imx-ocotp-cbef304140f5 Best regards, -- Peng Fan <peng.fan@xxxxxxx>
