xref: /openbmc/linux/Documentation/devicetree/bindings/nvmem/nvmem.yaml (revision c900529f3d9161bfde5cca0754f83b4d3c3e0220)

# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/nvmem/nvmem.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: NVMEM (Non Volatile Memory)

maintainers:
  - Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

description: |
  This binding is intended to represent the location of hardware
  configuration data stored in NVMEMs like eeprom, efuses and so on.

  On a significant proportion of boards, the manufacturer has stored
  some data on NVMEM, for the OS to be able to retrieve these
  information and act upon it. Obviously, the OS has to know about
  where to retrieve these data from, and where they are stored on the
  storage device.

properties:
  "#address-cells":
    const: 1

  "#size-cells":
    const: 1

  read-only:
    $ref: /schemas/types.yaml#/definitions/flag
    description:
      Mark the provider as read only.

  wp-gpios:
    description:
      GPIO to which the write-protect pin of the chip is connected.
      The write-protect GPIO is asserted, when it's driven high
      (logical '1') to block the write operation. It's deasserted,
      when it's driven low (logical '0') to allow writing.
    maxItems: 1

  nvmem-layout:
    $ref: /schemas/nvmem/layouts/nvmem-layout.yaml
    description:
      Alternative to the statically defined nvmem cells, this
      container may reference more advanced (dynamic) layout
      parsers.

patternProperties:
  "@[0-9a-f]+(,[0-7])?$":
    type: object
    allOf:
      - $ref: layouts/fixed-cell.yaml
      - properties:
          compatible: false
    deprecated: true

additionalProperties: true

examples:
  - |
      #include <dt-bindings/gpio/gpio.h>

      qfprom: eeprom@700000 {
          compatible = "qcom,msm8974-qfprom", "qcom,qfprom";
          #address-cells = <1>;
          #size-cells = <1>;
          reg = <0x00700000 0x100000>;

          wp-gpios = <&gpio1 3 GPIO_ACTIVE_HIGH>;

          /* ... */

          nvmem-layout {
              compatible = "fixed-layout";
              #address-cells = <1>;
              #size-cells = <1>;

              /* Data cells */
              tsens_calibration: calib@404 {
                  reg = <0x404 0x10>;
              };

              tsens_calibration_bckp: calib_bckp@504 {
                  reg = <0x504 0x11>;
                  bits = <6 128>;
              };

              pvs_version: pvs-version@6 {
                  reg = <0x6 0x2>;
                  bits = <7 2>;
              };

              speed_bin: speed-bin@c{
                  reg = <0xc 0x1>;
                  bits = <2 3>;
              };
          };
      };

...