xref: /linux/Documentation/devicetree/bindings/display/simple-framebuffer.yaml (revision 3bdab16c55f57a24245c97d707241dd9b48d1a91) 
1# SPDX-License-Identifier: GPL-2.0
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/display/simple-framebuffer.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Simple Framebuffer Device Tree Bindings
8
9maintainers:
10  - Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
11  - Hans de Goede <hdegoede@redhat.com>
12
13description: |+
14  A simple frame-buffer describes a frame-buffer setup by firmware or
15  the bootloader, with the assumption that the display hardware has
16  already been set up to scan out from the memory pointed to by the
17  reg property.
18
19  Since simplefb nodes represent runtime information they must be
20  sub-nodes of the chosen node (*). Simplefb nodes must be named
21  framebuffer@<address>.
22
23  If the devicetree contains nodes for the display hardware used by a
24  simplefb, then the simplefb node must contain a property called
25  display, which contains a phandle pointing to the primary display
26  hw node, so that the OS knows which simplefb to disable when handing
27  over control to a driver for the real hardware. The bindings for the
28  hw nodes must specify which node is considered the primary node.
29
30  It is advised to add display# aliases to help the OS determine how
31  to number things. If display# aliases are used, then if the simplefb
32  node contains a display property then the /aliases/display# path
33  must point to the display hw node the display property points to,
34  otherwise it must point directly to the simplefb node.
35
36  If a simplefb node represents the preferred console for user
37  interaction, then the chosen node stdout-path property should point
38  to it, or to the primary display hw node, as with display#
39  aliases. If display aliases are used then it should be set to the
40  alias instead.
41
42  It is advised that devicetree files contain pre-filled, disabled
43  framebuffer nodes, so that the firmware only needs to update the
44  mode information and enable them. This way if e.g. later on support
45  for more display clocks get added, the simplefb nodes will already
46  contain this info and the firmware does not need to be updated.
47
48  If pre-filled framebuffer nodes are used, the firmware may need
49  extra information to find the right node. In that case an extra
50  platform specific compatible and platform specific properties should
51  be used and documented.
52
53properties:
54  compatible:
55    items:
56      - enum:
57          - allwinner,simple-framebuffer
58          - amlogic,simple-framebuffer
59      - const: simple-framebuffer
60
61  reg:
62    description: Location and size of the framebuffer memory
63
64  clocks:
65    description: List of clocks used by the framebuffer.
66
67  power-domains:
68    description: List of power domains used by the framebuffer.
69
70  width:
71    $ref: /schemas/types.yaml#/definitions/uint32
72    description: Width of the framebuffer in pixels
73
74  height:
75    $ref: /schemas/types.yaml#/definitions/uint32
76    description: Height of the framebuffer in pixels
77
78  stride:
79    $ref: /schemas/types.yaml#/definitions/uint32
80    description: Number of bytes of a line in the framebuffer
81
82  format:
83    description: >
84      Format of the framebuffer:
85        * `a8b8g8r8` - 32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r
86        * `r5g6b5` - 16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b
87    enum:
88      - a8b8g8r8
89      - r5g6b5
90
91  display:
92    $ref: /schemas/types.yaml#/definitions/phandle
93    description: Primary display hardware node
94
95  allwinner,pipeline:
96    description: Pipeline used by the framebuffer on Allwinner SoCs
97    enum:
98      - de_be0-lcd0
99      - de_be0-lcd0-hdmi
100      - de_be0-lcd0-tve0
101      - de_be1-lcd0
102      - de_be1-lcd1-hdmi
103      - de_fe0-de_be0-lcd0
104      - de_fe0-de_be0-lcd0-hdmi
105      - de_fe0-de_be0-lcd0-tve0
106      - mixer0-lcd0
107      - mixer0-lcd0-hdmi
108      - mixer1-lcd1-hdmi
109      - mixer1-lcd1-tve
110
111  amlogic,pipeline:
112    description: Pipeline used by the framebuffer on Amlogic SoCs
113    enum:
114      - vpu-cvbs
115      - vpu-hdmi
116
117patternProperties:
118  "^[a-zA-Z0-9-]+-supply$":
119    $ref: /schemas/types.yaml#/definitions/phandle
120    description:
121      Regulators used by the framebuffer. These should be named
122      according to the names in the device design.
123
124required:
125  # The binding requires also reg, width, height, stride and format,
126  # but usually they will be filled by the bootloader.
127  - compatible
128
129additionalProperties: false
130
131examples:
132  - |
133    aliases {
134      display0 = &lcdc0;
135    };
136
137    chosen {
138      #address-cells = <1>;
139      #size-cells = <1>;
140      stdout-path = "display0";
141      framebuffer0: framebuffer@1d385000 {
142        compatible = "simple-framebuffer";
143        reg = <0x1d385000 3840000>;
144        width = <1600>;
145        height = <1200>;
146        stride = <3200>;
147        format = "r5g6b5";
148        clocks = <&ahb_gates 36>, <&ahb_gates 43>, <&ahb_gates 44>;
149        lcd-supply = <&reg_dc1sw>;
150        display = <&lcdc0>;
151      };
152    };
153
154    soc@1c00000 {
155      lcdc0: lcdc@1c0c000 {
156        compatible = "allwinner,sun4i-a10-lcdc";
157      };
158    };
159
160...
161