Re: [PATCH v2 1/2] nvmem: add driver for JZ4780 efuse

From: Rob Herring
Date: Wed Jan 03 2018 - 15:02:20 EST


On Thu, Dec 28, 2017 at 10:29:52PM +0100, Mathieu Malaterre wrote:
> From: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
>
> This patch brings support for the JZ4780 efuse. Currently it only expose
> a read only access to the entire 8K bits efuse memory.
>
> Tested-by: Mathieu Malaterre <malat@xxxxxxxxxx>
> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
> Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
> ---
> .../ABI/testing/sysfs-driver-jz4780-efuse | 16 ++
> .../bindings/nvmem/ingenic,jz4780-efuse.txt | 17 ++

Please split bindings to separate patch.

> MAINTAINERS | 5 +
> arch/mips/boot/dts/ingenic/jz4780.dtsi | 40 ++-

dts files should also be separate.

> drivers/nvmem/Kconfig | 10 +
> drivers/nvmem/Makefile | 2 +
> drivers/nvmem/jz4780-efuse.c | 305 +++++++++++++++++++++
> 7 files changed, 383 insertions(+), 12 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-driver-jz4780-efuse
> create mode 100644 Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
> create mode 100644 drivers/nvmem/jz4780-efuse.c
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-jz4780-efuse b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
> new file mode 100644
> index 000000000000..bb6f5d6ceea0
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
> @@ -0,0 +1,16 @@
> +What: /sys/devices/*/<our-device>/nvmem
> +Date: December 2017
> +Contact: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
> +Description: read-only access to the efuse on the Ingenic JZ4780 SoC
> + The SoC has a one time programmable 8K efuse that is
> + split into segments. The driver supports read only.
> + The segments are
> + 0x000 64 bit Random Number
> + 0x008 128 bit Ingenic Chip ID
> + 0x018 128 bit Customer ID
> + 0x028 3520 bit Reserved
> + 0x1E0 8 bit Protect Segment
> + 0x1E1 2296 bit HDMI Key
> + 0x300 2048 bit Security boot key

Why do these need to be exposed to userspace?

sysfs is 1 value per file and this is lots of different things.

We already have ways to feed random data (entropy) to the system. And we
have a way to expose SoC ID info to userspace (socdev).

> +Users: any user space application which wants to read the Chip
> + and Customer ID
> diff --git a/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt b/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
> new file mode 100644
> index 000000000000..cd6d67ec22fc
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
> @@ -0,0 +1,17 @@
> +Ingenic JZ EFUSE driver bindings
> +
> +Required properties:
> +- "compatible" Must be set to "ingenic,jz4780-efuse"
> +- "reg" Register location and length
> +- "clocks" Handle for the ahb clock for the efuse.
> +- "clock-names" Must be "bus_clk"
> +
> +Example:
> +
> +efuse: efuse@134100d0 {
> + compatible = "ingenic,jz4780-efuse";
> + reg = <0x134100D0 0xFF>;
> +
> + clocks = <&cgu JZ4780_CLK_AHB2>;
> + clock-names = "bus_clk";
> +};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a6e86e20761e..7a050c20c533 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6902,6 +6902,11 @@ M: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@xxxxxxxxxx>
> S: Maintained
> F: drivers/dma/dma-jz4780.c
>
> +INGENIC JZ4780 EFUSE Driver
> +M: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
> +S: Maintained
> +F: drivers/nvmem/jz4780-efuse.c

Binding file?

> +
> INGENIC JZ4780 NAND DRIVER
> M: Harvey Hunt <harveyhuntnexus@xxxxxxxxx>
> L: linux-mtd@xxxxxxxxxxxxxxxxxxx
> diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> index 9b5794667aee..3fb9d916a2ea 100644
> --- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
> +++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> @@ -224,21 +224,37 @@
> reg = <0x10002000 0x100>;
> };
>
> - nemc: nemc@13410000 {
> - compatible = "ingenic,jz4780-nemc";
> - reg = <0x13410000 0x10000>;
> - #address-cells = <2>;
> +
> + ahb2: ahb2 {
> + compatible = "simple-bus";

This is an unrelated change and should be its own patch.

> + #address-cells = <1>;
> #size-cells = <1>;
> - ranges = <1 0 0x1b000000 0x1000000
> - 2 0 0x1a000000 0x1000000
> - 3 0 0x19000000 0x1000000
> - 4 0 0x18000000 0x1000000
> - 5 0 0x17000000 0x1000000
> - 6 0 0x16000000 0x1000000>;
> + ranges = <>;
> +
> + nemc: nemc@13410000 {
> + compatible = "ingenic,jz4780-nemc";
> + reg = <0x13410000 0x10000>;
> + #address-cells = <2>;
> + #size-cells = <1>;
> + ranges = <1 0 0x1b000000 0x1000000
> + 2 0 0x1a000000 0x1000000
> + 3 0 0x19000000 0x1000000
> + 4 0 0x18000000 0x1000000
> + 5 0 0x17000000 0x1000000
> + 6 0 0x16000000 0x1000000>;
> +
> + clocks = <&cgu JZ4780_CLK_NEMC>;
> +
> + status = "disabled";
> + };
>
> - clocks = <&cgu JZ4780_CLK_NEMC>;
> + efuse: efuse@134100d0 {
> + compatible = "ingenic,jz4780-efuse";
> + reg = <0x134100d0 0xff>;

You are creating an overlapping region here with nemc above. Don't do
that.

>
> - status = "disabled";
> + clocks = <&cgu JZ4780_CLK_AHB2>;
> + clock-names = "bus_clk";
> + };
> };
>
> bch: bch@134d0000 {