On Wed, 3 Oct 2018 21:38:58 +0200
Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx> wrote:
> Add documentation for gpio-addr-flash. This binding allow creating
> flash devices that are paged using GPIOs.
>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
> ---
> .../bindings/mtd/gpio-addr-flash.txt | 54 +++++++++++++++++++
> 1 file changed, 54 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
>
> diff --git a/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> new file mode 100644
> index 000000000000..5006a26e1753
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> @@ -0,0 +1,54 @@
> +Memory Mapped flash with some address lines addressed using GPIOs
> +
> +Handle the case where a flash device is mostly addressed using physical
> +line and supplemented by GPIOs. This way you can hook up say a 8MiB flash
> +to a 2MiB memory range and use the GPIOs to select a particular range.
> +
> + - compatible : "cfi-gpio-addr-flash"
> + - reg : Address range of the mtd chip that is memory mapped, this is,
> + on the previous example 2MiB.
> + - bank-width : Width (in bytes) of the bank. Equal to the
> + device width times the number of interleaved chips.
> + - gpios: List of GPIO specifiers that will be used to address the MSBs address
> + lines. The order goes from LSB to MSB.
> + - probe-type : (optional) "cfi_probe", "jedec_probe". How the mtd chip
> + is going to be probed. If omitted, assumed to be equal to "cfi_probe".
Looks like other bindings are encoding the probe type in the
compatible [1][2], and we should probably follow what's been done by
others.
> + - #address-cells, #size-cells : Must be present if the device has
> + sub-nodes representing partitions (see below). In this case
> + both #address-cells and #size-cells must be equal to 1.
> +
> +The device tree may optionally contain sub-nodes describing partitions of the
> +address space. Check partition.txt for more details.
> +
> +Example:
> +
> + flash@300000 {
> + #address-cells = <1>;
> + #size-cells = <1>;
You should not have the #address-cells and #size-cells props defined at
this level, it's done in the partitions node already.
> + compatible = "cfi-gpio-addr-flash";
> + bank-width = <2>;
> + reg = < 0x00300000 0x00200000 >;
> + gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
> + partitions {
> + compatible = "fixed-partitions";
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + partition@0 {
> + reg = < 0x0 0x200000 >;
> + label = "Golden Bitstream";
> + };
> + partition@200000 {
> + reg = < 0x200000 0x200000 >;
> + label = "User Bitstream";
> + };
> + partition@400000 {
> + reg = < 0x400000 0x200000 >;
> + label = "V4L Controls";
> + };
> + partition@600000 {
> + reg = < 0x600000 0x200000 >;
> + label = "Production Data";
> + };
> + }
> + } ;
[1]https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/mtd/cortina,gemini-flash.txt
[2]https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/mtd/arm-versatile.txt
