Documentation/devicetree/bindings/nvmem/nvmem.yaml

# 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) Device Tree Bindings

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:
  $nodename:
    pattern: "^(eeprom|efuse|nvram)(@.*|-[0-9a-f])*$"

  "#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

patternProperties:
  "^.*@[0-9a-f]+$":
    type: object

    properties:
      reg:
        maxItems: 1
        description:
          Offset and size in bytes within the storage device.

      bits:
        maxItems: 1
        items:
          items:
            - minimum: 0
              maximum: 7
              description:
                Offset in bit within the address range specified by reg.
            - minimum: 1
              description:
                Size in bit within the address range specified by reg.

    required:
      - reg

    additionalProperties: false

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

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

          wp-gpios = <&gpio1 3 GPIO_ACTIVE_HIGH>;

          /* ... */

          /* 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>;
          };
      };

...