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 v5: - Rebased to next-20250107, but seems Srinivas's for-fixes patches not included, so I picked the for-fixes patches and rebase the patchset. - make gates pointer and using ARRAY_SIZE - Use of_parse_phandle_by_args - Read fuse when needed, not cache them in the very beginning - Use %pOF for node name - Check controller node name in imx_ele_ocotp_grant_access - Use dev_info when detach node - Use priv as function parameter to replace pdev. - Link to v4: https://lore.kernel.org/r/20241223-imx-ocotp-v4-0-f504c1420640@xxxxxxx Changes in v4: - Add missing of_node_put(provider) - Typo fix in commit log - Link to v3: https://lore.kernel.org/r/20241219-imx-ocotp-v3-0-b22371098071@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 | 172 ++++++++++++++++++++- include/dt-bindings/nvmem/fsl,imx93-ocotp.h | 24 +++ include/dt-bindings/nvmem/fsl,imx95-ocotp.h | 43 ++++++ 4 files changed, 243 insertions(+), 1 deletion(-) --- base-commit: f3ff6cbe6236ef99719615666f66454d70defc5f change-id: 20241212-imx-ocotp-cbef304140f5 Best regards, -- Peng Fan <peng.fan@xxxxxxx>
