The VC4 firmware exposes a mailbox interface that allows the ARM core to access only the customer part (8 cells * 32 bits) of the OTP memory. This version brings read-only support, but could also be extended to write support. Beside the kernelspace support this is also a limited userspace alternative to the vendor specific "vcgencmd otp_dump". I think this driver could be helpful for vendors, which integrate the Raspberry Pi Compute Module in their products need to store unique data like a serial or additional MAC address in the OTP. Note for testers: This series needs "firmware: raspberrypi: Fix firmware calls with large buffers" from James Hughes to work properly. Changes since RFC: - implement improvements suggested by Rob Herring and Eric Anholt - extend Kconfig description - define nvmem type and read only - make MODULE_LICENSE match license text - add patches to enable driver in bcm2835 and multi_v7 defconfig - rebased on current srini/nvmem.git/for-next Stefan Wahren (5): dt-bindings: nvmem: add binding for Raspberry Pi OTP nvmem: add driver for Raspberry Pi OTP ARM: dts: bcm2835-rpi: Enable OTP access for Raspberry Pi ARM: bcm2835_defconfig: Enable Raspberry Pi OTP driver ARM: multi_v7_defconfig: Enable Raspberry Pi OTP driver .../nvmem/raspberrypi,bcm2835-customer-otp.txt | 22 ++++ arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 + arch/arm/configs/bcm2835_defconfig | 2 + arch/arm/configs/multi_v7_defconfig | 1 + drivers/nvmem/Kconfig | 10 ++ drivers/nvmem/Makefile | 2 + drivers/nvmem/raspberrypi-otp.c | 113 +++++++++++++++++++++ 7 files changed, 154 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvmem/raspberrypi,bcm2835-customer-otp.txt create mode 100644 drivers/nvmem/raspberrypi-otp.c -- 2.7.4
