The i.MX8MM exists in a Lite variant with no VPUs as well as Solo and Dual variants with one or two cores respectively instead of the default four. For i.MX6, we had a manual fixup taking care of deleting the excess CPUs, but for e.g. the i.MX8MP, we have fuses for the M7, VPUs, CAN, CAN-FD, ISPs, NPU, ... etc. Describing all that in the DT is overly verbose as we need to take care not to rely on specific device node names that should be disabled. There has been an upstream attempt to get a binding for U-Boot to act on: https://lore.kernel.org/all/20220324042024.26813-1-peng.fan@xxxxxxxxxxx/ This was refused by the DT maintainer, because any solution to this problem should also be flexible enough to cover the case of partitioning devices between the secure and normal world. There's a patch series upstream to describe a domain-controller binding that allows a hypervisor to partition devices into domains. With the naming generalized, this fits nicely the use case of gating devices behind specific features: https://lore.kernel.org/all/3ca7cd75-4b62-2380-adb0-646bbeb647a2@xxxxxxxxxxxxxx/ This series does that. See the first two commit messages for details. We use a barebox, prefix as the naming isn't set in stone, but the intention is to drop the prefix and potentially rename once an upstream binding is approved. Ahmad Fatoum (10): driver: add feature controller framework driver: consult feature controller prior to device probe driver: featctrl: fixup kernel device tree dt-bindings: add i.MX8M feature controller bindings soc: imx: add i.MX8M feature controller driver nvmem: import Linux nvmem_cell_read_variable_le_u32 nvmem: ocotp: add i.MX8M[MN] feature controller support ARM: dts: i.MX8MN: describe feature controller RFC: soc: imx: imx8m-featctrl: add i.MX8M[MN] stand-alone driver RFC: ARM: dts: i.MX8MM: describe standlone feature controller arch/arm/dts/imx8mm.dtsi | 61 ++++++++++ arch/arm/dts/imx8mn.dtsi | 32 ++++++ drivers/base/Kconfig | 3 + drivers/base/Makefile | 1 + drivers/base/driver.c | 9 ++ drivers/base/featctrl.c | 160 +++++++++++++++++++++++++++ drivers/nvmem/core.c | 33 ++++++ drivers/nvmem/ocotp.c | 62 +++++++++-- drivers/of/Kconfig | 12 ++ drivers/soc/imx/Kconfig | 6 + drivers/soc/imx/Makefile | 1 + drivers/soc/imx/imx8m-featctrl.c | 101 +++++++++++++++++ include/dt-bindings/features/imx8m.h | 14 +++ include/featctrl.h | 29 +++++ include/linux/nvmem-consumer.h | 9 ++ include/soc/imx8m/featctrl.h | 25 +++++ 16 files changed, 550 insertions(+), 8 deletions(-) create mode 100644 drivers/base/featctrl.c create mode 100644 drivers/soc/imx/imx8m-featctrl.c create mode 100644 include/dt-bindings/features/imx8m.h create mode 100644 include/featctrl.h create mode 100644 include/soc/imx8m/featctrl.h -- 2.30.2
