xref: /linux/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,sdram-props.yaml (revision c17ee635fd3a482b2ad2bf5e269755c2eae5f25e)

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,sdram-props.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Common properties for SDRAM types

description:
  Different SDRAM types generally use the same properties and only differ in the
  range of legal values for each. This file defines the common parts that can be
  reused for each type. Nodes using this schema should generally be nested under
  a SDRAM channel node.

maintainers:
  - Krzysztof Kozlowski <krzk@kernel.org>

properties:
  compatible:
    description: |
      Compatible strings can be either explicit vendor names and part numbers
      (e.g. elpida,ECB240ABACN), or generated strings of the form
      lpddrX-YY,ZZZZ or ddrX-YYYY,AAAA...-ZZ where X, Y, and Z are lowercase
      hexadecimal with leading zeroes, and A is lowercase ASCII.
      For LPDDR and DDR SDRAM, X is the SDRAM version (2, 3, 4, etc.).
      For LPDDR SDRAM:
        - YY is the manufacturer ID (from MR5), 1 byte
        - ZZZZ is the revision ID (from MR6 and MR7), 2 bytes
      For DDR4 SDRAM with SPD, according to JEDEC SPD4.1.2.L-6:
        - YYYY is the manufacturer ID, 2 bytes, from bytes 320 and 321
        - AAAA... is the part number, 20 bytes (20 chars) from bytes 329 to 348
          without trailing spaces
        - ZZ is the revision ID, 1 byte, from byte 349
      The former form is useful when the SDRAM vendor and part number are
      known, for example, when memory is soldered on the board. The latter
      form is useful when SDRAM nodes are created at runtime by boot firmware
      that doesn't have access to static part number information.

  reg:
    description:
      The rank number of this memory rank when used as a subnode to an memory
      channel.
    minimum: 0
    maximum: 3

  revision-id:
    $ref: /schemas/types.yaml#/definitions/uint32-array
    description: |
      SDRAM revision ID:
        - LPDDR SDRAM, decoded from Mode Registers 6 and 7, always 2 bytes.
        - DDR4 SDRAM, decoded from the SPD from byte 349 according to
          JEDEC SPD4.1.2.L-6, always 1 byte.
      One byte per uint32 cell (e.g., <MR6 MR7>).
    maxItems: 2
    items:
      minimum: 0
      maximum: 255

  density:
    $ref: /schemas/types.yaml#/definitions/uint32
    description: |
      Density of the SDRAM chip in megabits:
        - LPDDR SDRAM, decoded from Mode Register 8.
        - DDR4 SDRAM, decoded from the SPD from bits 3-0 of byte 4 according to
          JEDEC SPD4.1.2.L-6.
    enum:
      - 64
      - 128
      - 256
      - 512
      - 1024
      - 2048
      - 3072
      - 4096
      - 6144
      - 8192
      - 12288
      - 16384
      - 24576
      - 32768

  io-width:
    $ref: /schemas/types.yaml#/definitions/uint32
    description: |
      I/O bus width in bits of the SDRAM chip:
        - LPDDR SDRAM, decoded from Mode Register 8.
        - DDR4 SDRAM, decoded from the SPD from bits 2-0 of byte 12 according to
          JEDEC SPD4.1.2.L-6.
    enum:
      - 8
      - 16
      - 32

additionalProperties: true