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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,sdram-channel.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: SDRAM channel with chip/rank topology description
description:
A memory channel of SDRAM memory like DDR SDRAM or LPDDR SDRAM is a completely
independent set of pins (DQ, CA, CS, CK, etc.) that connect one or more memory
chips to a host system. The main purpose of this node is to overall memory
topology of the system, including the amount of individual memory chips and
the ranks per chip.
maintainers:
- Julius Werner <jwerner@chromium.org>
properties:
$nodename:
pattern: "sdram-channel-[0-9]+$"
compatible:
enum:
- jedec,ddr4-channel
- jedec,lpddr2-channel
- jedec,lpddr3-channel
- jedec,lpddr4-channel
- jedec,lpddr5-channel
io-width:
description:
The number of DQ pins in the channel. If this number is different
from (a multiple of) the io-width of the SDRAM chip, that means that
multiple instances of that type of chip are wired in parallel on this
channel (with the channel's DQ pins split up between the different
chips, and the CA, CS, etc. pins of the different chips all shorted
together). This means that the total physical memory controlled by a
channel is equal to the sum of the densities of each rank on the
connected SDRAM chip, times the io-width of the channel divided by
the io-width of the SDRAM chip.
enum:
- 8
- 16
- 32
- 64
- 128
"#address-cells":
const: 1
"#size-cells":
const: 0
patternProperties:
"^rank@[0-9]+$":
type: object
description:
Each physical SDRAM chip may have one or more ranks. Ranks are
internal but fully independent sub-units of the chip. Each SDRAM bus
transaction on the channel targets exactly one rank, based on the
state of the CS pins. Different ranks may have different densities and
timing requirements.
required:
- reg
allOf:
- if:
properties:
compatible:
contains:
const: jedec,ddr4-channel
then:
patternProperties:
"^rank@[0-9]+$":
$ref: /schemas/memory-controllers/ddr/jedec,ddr4.yaml#
- if:
properties:
compatible:
contains:
const: jedec,lpddr2-channel
then:
patternProperties:
"^rank@[0-9]+$":
$ref: /schemas/memory-controllers/ddr/jedec,lpddr2.yaml#
- if:
properties:
compatible:
contains:
const: jedec,lpddr3-channel
then:
patternProperties:
"^rank@[0-9]+$":
$ref: /schemas/memory-controllers/ddr/jedec,lpddr3.yaml#
- if:
properties:
compatible:
contains:
const: jedec,lpddr4-channel
then:
patternProperties:
"^rank@[0-9]+$":
$ref: /schemas/memory-controllers/ddr/jedec,lpddr4.yaml#
- if:
properties:
compatible:
contains:
const: jedec,lpddr5-channel
then:
patternProperties:
"^rank@[0-9]+$":
$ref: /schemas/memory-controllers/ddr/jedec,lpddr5.yaml#
required:
- compatible
- io-width
- "#address-cells"
- "#size-cells"
additionalProperties: false
examples:
- |
sdram-channel-0 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "jedec,lpddr3-channel";
io-width = <32>;
rank@0 {
compatible = "lpddr3-ff,0100", "jedec,lpddr3";
reg = <0>;
density = <8192>;
io-width = <16>;
revision-id = <1 0>;
};
};
sdram-channel-1 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "jedec,lpddr4-channel";
io-width = <32>;
rank@0 {
compatible = "lpddr4-05,0301", "jedec,lpddr4";
reg = <0>;
density = <4096>;
io-width = <32>;
revision-id = <3 1>;
};
rank@1 {
compatible = "lpddr4-05,0301", "jedec,lpddr4";
reg = <1>;
density = <2048>;
io-width = <32>;
revision-id = <3 1>;
};
};
|
