Description ----------- Implement a bootcount (1) related driver that uses NVMEM as a backend. The patchset will also update the `snvs_lpgpr` driver to support 2 bytes NVMEM cells. 1. https://www.denx.de/wiki/view/DULG/UBootBootCountLimit Testing ------- Hardware: i.MX6sx evaluation board Kernel: linux-imx-5.4.24 1. Configure the bootcount hardware in DT to use a NVMEM cell provided by `snvs_lpgpr` driver as backend. e.g. This will configure a 4 bytes long NVMEM cell ``` bootcount_regs: bootcount-snvs-regs@0 { reg = <0x0 0x04>; }; ``` 2. Record the current NVMEM cell content: ``` ~ # hexdump -C /sys/devices/soc0/soc/2000000.aips-bus/20cc000.snvs/20cc000.snvs:snvs-lpgpr/20cc000.snvs:snvs-lpgpr0/nvmem 00000000 00 00 01 b0 |....| 00000004 ``` 3. Write the bootcount and check that is successful: PASS ``` ~ # echo 1 > /sys/bus/platform/drivers/bootcount-nvmem/bootcount/value bootcount: Write regval: 0xb0010001 ~ # hexdump -C /sys/devices/soc0/soc/2000000.aips-bus/20cc000.snvs/20cc000.snvs:snvs-lpgpr/20cc000.snvs:snvs-lpgpr0/nvmem 00000000 01 00 01 b0 |....| 00000004 ``` Note: similar tests were done also for 2 bytes NVMEM cell size. Kernel: linux-next, tag: next-20210322 1. Enable bootcount and snvs_lpgpr drivers 2. Verify that they compile succesfully: PASS ``` kernel-master> make -j2 drivers/nvmem/ DESCEND objtool CALL scripts/atomic/check-atomics.sh CC arch/x86/kernel/asm-offsets.s CALL scripts/checksyscalls.sh CC drivers/nvmem/core.o CC drivers/nvmem/bootcount-nvmem.o CC drivers/nvmem/snvs_lpgpr.o AR drivers/nvmem/built-in. ``` Testing the bootcount YAML document: 1. Check the document by running the command: `make DT_CHECKER_FLAGS=-m dt_binding_check` 2. Verify that is successful: PASS 3. Verify that no warnings are generated by bootcount related yaml file: PASS ``` ... CHECK Documentation/devicetree/bindings/nvmem/brcm,nvram.example.dt.yaml DTC Documentation/devicetree/bindings/nvmem/bootcount-nvmem.example.dt.yaml CHECK Documentation/devicetree/bindings/nvmem/bootcount-nvmem.example.dt.yaml DTC Documentation/devicetree/bindings/opp/allwinner,sun50i-h6-operating-points.example.dt.yaml ... ``` Changes since v1 ---------------- - Fix the dt-bindings YAML document. Changes since v2 ---------------- - Fix the dt-bindings YAML document warnings. Changes since v3 ---------------- - Remove the dependencies from the bindings documentation - Fix the `bootcount-magic` description from bindings documentation Nandor Han (4): dt-bindings: nvmem: Add bootcount-nvmem nvmem: bootcount: add bootcount driver nvmem: snvs_lpgpr: use cell stride for regmap size calculation nvmem: snvs_lpgpr: support two bytes NVMEM cell size .../bindings/nvmem/bootcount-nvmem.yaml | 71 +++++++ drivers/nvmem/Kconfig | 10 + drivers/nvmem/Makefile | 1 + drivers/nvmem/bootcount-nvmem.c | 195 ++++++++++++++++++ drivers/nvmem/snvs_lpgpr.c | 67 +++++- 5 files changed, 338 insertions(+), 6 deletions(-) create mode 100644 Documentation/devicetree/bindings/nvmem/bootcount-nvmem.yaml create mode 100644 drivers/nvmem/bootcount-nvmem.c -- 2.26.3
