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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr-channel.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LPDDR channel with chip/rank topology description
+
+description:
+ An LPDDR channel is a completely independent set of LPDDR pins (DQ, CA, CS,
+ CK, etc.) that connect one or more LPDDR chips to a host system. The main
+ purpose of this node is to overall LPDDR topology of the system, including the
+ amount of individual LPDDR chips and the ranks per chip.
+
+maintainers:
+ - Julius Werner <jwerner@chromium.org>
+
+properties:
+ compatible:
+ enum:
+ - 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 LPDDR 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 LPDDR chip, times the io-width of the channel divided by
+ the io-width of the LPDDR chip.
+ enum:
+ - 8
+ - 16
+ - 32
+ - 64
+ - 128
+
+ "#address-cells":
+ const: 1
+
+ "#size-cells":
+ const: 0
+
+patternProperties:
+ "^rank@[0-9]+$":
+ type: object
+ description:
+ Each physical LPDDR chip may have one or more ranks. Ranks are
+ internal but fully independent sub-units of the chip. Each LPDDR bus
+ transaction on the channel targets exactly one rank, based on the
+ state of the CS pins. Different ranks may have different densities and
+ timing requirements.
+ required:
+ - reg
+
+allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: jedec,lpddr2-channel
+ then:
+ patternProperties:
+ "^rank@[0-9]+$":
+ $ref: /schemas/memory-controllers/ddr/jedec,lpddr2.yaml#
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: jedec,lpddr3-channel
+ then:
+ patternProperties:
+ "^rank@[0-9]+$":
+ $ref: /schemas/memory-controllers/ddr/jedec,lpddr3.yaml#
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: jedec,lpddr4-channel
+ then:
+ patternProperties:
+ "^rank@[0-9]+$":
+ $ref: /schemas/memory-controllers/ddr/jedec,lpddr4.yaml#
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: jedec,lpddr5-channel
+ then:
+ patternProperties:
+ "^rank@[0-9]+$":
+ $ref: /schemas/memory-controllers/ddr/jedec,lpddr5.yaml#
+
+required:
+ - compatible
+ - io-width
+ - "#address-cells"
+ - "#size-cells"
+
+additionalProperties: false
+
+examples:
+ - |
+ lpddr-channel0 {
+ #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>;
+ };
+ };
+
+ lpddr-channel1 {
+ #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>;
+ };
+ };