xref: /linux/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-channel.yaml (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0) 
1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr-channel.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: LPDDR channel with chip/rank topology description
8
9description:
10  An LPDDR channel is a completely independent set of LPDDR pins (DQ, CA, CS,
11  CK, etc.) that connect one or more LPDDR chips to a host system. The main
12  purpose of this node is to overall LPDDR topology of the system, including the
13  amount of individual LPDDR chips and the ranks per chip.
14
15maintainers:
16  - Julius Werner <jwerner@chromium.org>
17
18properties:
19  compatible:
20    enum:
21      - jedec,lpddr2-channel
22      - jedec,lpddr3-channel
23      - jedec,lpddr4-channel
24      - jedec,lpddr5-channel
25
26  io-width:
27    description:
28      The number of DQ pins in the channel. If this number is different
29      from (a multiple of) the io-width of the LPDDR chip, that means that
30      multiple instances of that type of chip are wired in parallel on this
31      channel (with the channel's DQ pins split up between the different
32      chips, and the CA, CS, etc. pins of the different chips all shorted
33      together).  This means that the total physical memory controlled by a
34      channel is equal to the sum of the densities of each rank on the
35      connected LPDDR chip, times the io-width of the channel divided by
36      the io-width of the LPDDR chip.
37    enum:
38      - 8
39      - 16
40      - 32
41      - 64
42      - 128
43
44  "#address-cells":
45    const: 1
46
47  "#size-cells":
48    const: 0
49
50patternProperties:
51  "^rank@[0-9]+$":
52    type: object
53    description:
54      Each physical LPDDR chip may have one or more ranks. Ranks are
55      internal but fully independent sub-units of the chip. Each LPDDR bus
56      transaction on the channel targets exactly one rank, based on the
57      state of the CS pins. Different ranks may have different densities and
58      timing requirements.
59    required:
60      - reg
61
62allOf:
63  - if:
64      properties:
65        compatible:
66          contains:
67            const: jedec,lpddr2-channel
68    then:
69      patternProperties:
70        "^rank@[0-9]+$":
71          $ref: /schemas/memory-controllers/ddr/jedec,lpddr2.yaml#
72  - if:
73      properties:
74        compatible:
75          contains:
76            const: jedec,lpddr3-channel
77    then:
78      patternProperties:
79        "^rank@[0-9]+$":
80          $ref: /schemas/memory-controllers/ddr/jedec,lpddr3.yaml#
81  - if:
82      properties:
83        compatible:
84          contains:
85            const: jedec,lpddr4-channel
86    then:
87      patternProperties:
88        "^rank@[0-9]+$":
89          $ref: /schemas/memory-controllers/ddr/jedec,lpddr4.yaml#
90  - if:
91      properties:
92        compatible:
93          contains:
94            const: jedec,lpddr5-channel
95    then:
96      patternProperties:
97        "^rank@[0-9]+$":
98          $ref: /schemas/memory-controllers/ddr/jedec,lpddr5.yaml#
99
100required:
101  - compatible
102  - io-width
103  - "#address-cells"
104  - "#size-cells"
105
106additionalProperties: false
107
108examples:
109  - |
110    lpddr-channel0 {
111      #address-cells = <1>;
112      #size-cells = <0>;
113      compatible = "jedec,lpddr3-channel";
114      io-width = <32>;
115
116      rank@0 {
117        compatible = "lpddr3-ff,0100", "jedec,lpddr3";
118        reg = <0>;
119        density = <8192>;
120        io-width = <16>;
121        revision-id = <1 0>;
122      };
123    };
124
125    lpddr-channel1 {
126      #address-cells = <1>;
127      #size-cells = <0>;
128      compatible = "jedec,lpddr4-channel";
129      io-width = <32>;
130
131      rank@0 {
132        compatible = "lpddr4-05,0301", "jedec,lpddr4";
133        reg = <0>;
134        density = <4096>;
135        io-width = <32>;
136        revision-id = <3 1>;
137      };
138
139      rank@1 {
140        compatible = "lpddr4-05,0301", "jedec,lpddr4";
141        reg = <1>;
142        density = <2048>;
143        io-width = <32>;
144        revision-id = <3 1>;
145      };
146    };
147