Hi all,
R-Car Gen3/Gen4 SoCs contain fuses indicating hardware support or
hardware parameters. Unfortunately the various SoCs require different
mechanisms to read the state of the fuses:
- On R-Car Gen3, the fuse monitor registers are in the middle of the
Pin Function Controller (PFC) register block,
- On R-Car V3U and S4-8, the E-FUSE non-volatile memory is accessible
through a separate register block in the PFC,
- On R-Car V4H and V4M, the E-FUSE non-volatile memory is accessible
through the second register block of OTP_MEM.
As the first variant is quite different from the other two, and there is
currently no use case requiring support for it, this patch series adds
support for the last 2 variants only.
Note that the first two revisions of this series implemented only basic
nvmem support, and a custom in-kernel API, mimicked after the
fuse-tregra driver. Then, Arnd told me on IRC that the R-Car E-FUSE
driver should use the nvmem framework fully.
The fuses' states can be read using the nvmem subsystem:
- In kernelspace, through the nvmem_cell_*() API.
A first known use case is reading tuning parameters for the
Universal Flash Storage controller on R-Car S4-8 ES1.2.
- In userspace, through sysfs. E.g. on R-Car S4-8 ES1.2:
/ # hd /sys/bus/nvmem/devices/rcar-fuse/nvmem
00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000000e0 00 00 00 00 fe 00 00 00 00 00 00 00 00 00 00 00 |....�...........|
000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000140 00 00 00 00 23 51 23 51 52 98 52 98 00 00 00 00 |....#Q#QR�R�....|
00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000200
Changes compared to v2[1]:
- Dropped accepted dt-bindings,
- Drop "pinctrl: renesas: Add R-Car Gen3 fuse support",
- New patch "dt-bindings: fuse: Move renesas,rcar-{efuse,otp} to
nvmem",
- Drop superfluous semicolon,
- Drop the custom rcar_fuse_read() kernel API, in favor of the
standard nvmem_cell_*() API,
- Drop support for explicitly-instantiated platform devices with
accompanying platform data, which would be needed to support fuses
tightly integrated with the Pin Function Controller on R-Car Gen3
SoCs. It can be added when a use case shows up.
- Move from drivers/soc/renesas/ to drivers/nvmem/,
- Register the full register block that contains the E-FUSE data
registers with the nvmem subsystem, but use keepouts to ignore all
registers before the first or after the last documented data
register. Undocumented registers in between are still accessible.
- Replace offset/nregs in rcar_fuse_data by start/end,
- Use __ioread32_copy() helper,
- Initialize most fields of struct nvmem_config in its declaration,
- Rename nvmem device from "fuse" to "rcar-fuse",
- Use NVMEM_DEVID_NONE,
- Add an entry to the MAINTAINERS file,
- Fix reg size,
- New patch "arm64: dts: renesas: r8a779f4: Add UFS tuning parameters
in E-FUSE".
Changes compared to v1[2]:
- Drop RFC state and broaden audience,
- Fix typo in one-line summary,
- Add Reviewed-by.
This has been tested on R-Car V3U, S4-8 ES1.0 and ES1.2, V4H, and V4M.
Thanks for your comments!
[1] https://lore.kernel.org/cover.1716974502.git.geert+renesas@xxxxxxxxx
[2] https://lore.kernel.org/cover.1714642390.git.geert+renesas@xxxxxxxxx
Geert Uytterhoeven (7):
dt-bindings: fuse: Move renesas,rcar-{efuse,otp} to nvmem
nvmem: Add R-Car E-FUSE driver
arm64: dts: renesas: r8a779a0: Add E-FUSE node
arm64: dts: renesas: r8a779f0: Add E-FUSE node
arm64: dts: renesas: r8a779f4: Add UFS tuning parameters in E-FUSE
arm64: dts: renesas: r8a779g0: Add OTP_MEM node
arm64: dts: renesas: r8a779h0: Add OTP_MEM node
.../{fuse => nvmem}/renesas,rcar-efuse.yaml | 35 +++--
.../{fuse => nvmem}/renesas,rcar-otp.yaml | 17 ++-
MAINTAINERS | 2 +
arch/arm64/boot/dts/renesas/r8a779a0.dtsi | 8 +
arch/arm64/boot/dts/renesas/r8a779f0.dtsi | 8 +
arch/arm64/boot/dts/renesas/r8a779f4.dtsi | 12 ++
arch/arm64/boot/dts/renesas/r8a779g0.dtsi | 5 +
arch/arm64/boot/dts/renesas/r8a779h0.dtsi | 5 +
drivers/nvmem/Kconfig | 11 ++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/rcar-efuse.c | 142 ++++++++++++++++++
11 files changed, 230 insertions(+), 17 deletions(-)
rename Documentation/devicetree/bindings/{fuse => nvmem}/renesas,rcar-efuse.yaml (54%)
rename Documentation/devicetree/bindings/{fuse => nvmem}/renesas,rcar-otp.yaml (60%)
create mode 100644 drivers/nvmem/rcar-efuse.c
--
2.34.1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
