Soon to be released versions of RPi4's firmware will take of care passing their bootloader's configuration[1] to the OS by copying it into memory and creating a reserved memory node in the board's DT. By modeling this reserved memory node as an nvmem device using 'nvmem-rmem', which this series introduces, user-space applications will be able to query this information through nvmem's sysfs interface. An alternative approach, less nice IMO, would be to create a platform-specific 'soc' driver. Regards, Nicolas [1] https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.md --- Changes since v1: - Avoid the reserved-memory indirection by integrating the nvmem driver into the reserved memory node. Nicolas Saenz Julienne (5): dt-bindings: nvmem: Add bindings for rmem driver nvmem: Add driver to expose reserved memory as nvmem ARM: dts: bcm2711: Add reserved memory template to hold firmware configuration arm64: defconfig: Enable nvmem's rmem driver ARM: multi_v7_defconfig: Enable nvmem's rmem driver .../devicetree/bindings/nvmem/rmem.yaml | 49 ++++++++++ arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 17 ++++ arch/arm/configs/multi_v7_defconfig | 1 + arch/arm64/configs/defconfig | 1 + drivers/nvmem/Kconfig | 8 ++ drivers/nvmem/Makefile | 2 + drivers/nvmem/rmem.c | 97 +++++++++++++++++++ drivers/of/platform.c | 1 + 8 files changed, 176 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvmem/rmem.yaml create mode 100644 drivers/nvmem/rmem.c -- 2.29.2
