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LPDDR and DDR bindings are SDRAM types and are likely to share the same properties (at least for density, io-width and reg). To avoid bindings duplication, factorise the properties. The compatible description has been updated because the MR (Mode registers) used to get manufacturer ID and revision ID are not present in case of DDR. Those information should be in a SPD (Serial Presence Detect) EEPROM in case of DIMM module or are known in case of soldered memory chips as they are in the datasheet of the memory chips. Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Signed-off-by: Clément Le Goffic <legoffic.clement@gmail.com> Link: https://patch.msgid.link/20251118-b4-ddr-bindings-v9-1-a033ac5144da@gmail.com Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
95 lines
3.1 KiB
YAML
95 lines
3.1 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,sdram-props.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Common properties for SDRAM types
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description:
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Different SDRAM types generally use the same properties and only differ in the
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range of legal values for each. This file defines the common parts that can be
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reused for each type. Nodes using this schema should generally be nested under
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a SDRAM channel node.
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maintainers:
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- Krzysztof Kozlowski <krzk@kernel.org>
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properties:
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compatible:
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description: |
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Compatible strings can be either explicit vendor names and part numbers
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(e.g. elpida,ECB240ABACN), or generated strings of the form
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lpddrX-YY,ZZZZ or ddrX-YYYY,AAAA...-ZZ where X, Y, and Z are lowercase
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hexadecimal with leading zeroes, and A is lowercase ASCII.
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For LPDDR and DDR SDRAM, X is the SDRAM version (2, 3, 4, etc.).
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For LPDDR SDRAM:
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- YY is the manufacturer ID (from MR5), 1 byte
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- ZZZZ is the revision ID (from MR6 and MR7), 2 bytes
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For DDR4 SDRAM with SPD, according to JEDEC SPD4.1.2.L-6:
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- YYYY is the manufacturer ID, 2 bytes, from bytes 320 and 321
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- AAAA... is the part number, 20 bytes (20 chars) from bytes 329 to 348
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without trailing spaces
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- ZZ is the revision ID, 1 byte, from byte 349
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The former form is useful when the SDRAM vendor and part number are
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known, for example, when memory is soldered on the board. The latter
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form is useful when SDRAM nodes are created at runtime by boot firmware
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that doesn't have access to static part number information.
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reg:
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description:
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The rank number of this memory rank when used as a subnode to an memory
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channel.
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minimum: 0
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maximum: 3
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revision-id:
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$ref: /schemas/types.yaml#/definitions/uint32-array
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description: |
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SDRAM revision ID:
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- LPDDR SDRAM, decoded from Mode Registers 6 and 7, always 2 bytes.
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- DDR4 SDRAM, decoded from the SPD from byte 349 according to
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JEDEC SPD4.1.2.L-6, always 1 byte.
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One byte per uint32 cell (e.g., <MR6 MR7>).
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maxItems: 2
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items:
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minimum: 0
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maximum: 255
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density:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: |
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Density of the SDRAM chip in megabits:
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- LPDDR SDRAM, decoded from Mode Register 8.
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- DDR4 SDRAM, decoded from the SPD from bits 3-0 of byte 4 according to
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JEDEC SPD4.1.2.L-6.
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enum:
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- 64
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- 128
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- 256
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- 512
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- 1024
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- 2048
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- 3072
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- 4096
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- 6144
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- 8192
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- 12288
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- 16384
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- 24576
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- 32768
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io-width:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: |
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I/O bus width in bits of the SDRAM chip:
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- LPDDR SDRAM, decoded from Mode Register 8.
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- DDR4 SDRAM, decoded from the SPD from bits 2-0 of byte 12 according to
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JEDEC SPD4.1.2.L-6.
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enum:
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- 8
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- 16
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- 32
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additionalProperties: true
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